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diff --git a/gcc-4.2.1-5666.3/gcc/doc/extend.texi b/gcc-4.2.1-5666.3/gcc/doc/extend.texi deleted file mode 100644 index 123b15dab..000000000 --- a/gcc-4.2.1-5666.3/gcc/doc/extend.texi +++ /dev/null @@ -1,11636 +0,0 @@ -@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1996, 1998, 1999, 2000, -@c 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. - -@c This is part of the GCC manual. -@c For copying conditions, see the file gcc.texi. - -@node C Extensions -@chapter Extensions to the C Language Family -@cindex extensions, C language -@cindex C language extensions - -@opindex pedantic -GNU C provides several language features not found in ISO standard C@. -(The @option{-pedantic} option directs GCC to print a warning message if -any of these features is used.) To test for the availability of these -features in conditional compilation, check for a predefined macro -@code{__GNUC__}, which is always defined under GCC@. - -These extensions are available in C and Objective-C@. Most of them are -also available in C++. @xref{C++ Extensions,,Extensions to the -C++ Language}, for extensions that apply @emph{only} to C++. - -Some features that are in ISO C99 but not C89 or C++ are also, as -extensions, accepted by GCC in C89 mode and in C++. - -@menu -* Statement Exprs:: Putting statements and declarations inside expressions. -* Local Labels:: Labels local to a block. -* Labels as Values:: Getting pointers to labels, and computed gotos. -* Nested Functions:: As in Algol and Pascal, lexical scoping of functions. -* Constructing Calls:: Dispatching a call to another function. -* Typeof:: @code{typeof}: referring to the type of an expression. -* Conditionals:: Omitting the middle operand of a @samp{?:} expression. -* Long Long:: Double-word integers---@code{long long int}. -* Complex:: Data types for complex numbers. -* Decimal Float:: Decimal Floating Types. -* Hex Floats:: Hexadecimal floating-point constants. -* Zero Length:: Zero-length arrays. -* Variable Length:: Arrays whose length is computed at run time. -* Empty Structures:: Structures with no members. -* Variadic Macros:: Macros with a variable number of arguments. -* Escaped Newlines:: Slightly looser rules for escaped newlines. -* Subscripting:: Any array can be subscripted, even if not an lvalue. -* Pointer Arith:: Arithmetic on @code{void}-pointers and function pointers. -* Initializers:: Non-constant initializers. -* Compound Literals:: Compound literals give structures, unions - or arrays as values. -* Designated Inits:: Labeling elements of initializers. -* Cast to Union:: Casting to union type from any member of the union. -* Case Ranges:: `case 1 ... 9' and such. -* Mixed Declarations:: Mixing declarations and code. -* Function Attributes:: Declaring that functions have no side effects, - or that they can never return. -* Attribute Syntax:: Formal syntax for attributes. -* Function Prototypes:: Prototype declarations and old-style definitions. -* C++ Comments:: C++ comments are recognized. -* Dollar Signs:: Dollar sign is allowed in identifiers. -* Character Escapes:: @samp{\e} stands for the character @key{ESC}. -@c APPLE LOCAL begin pascal strings -* Pascal Strings:: Constructing string literals with a Pascal-style - length byte. -@c APPLE LOCAL end pascal strings -* Variable Attributes:: Specifying attributes of variables. -* Type Attributes:: Specifying attributes of types. -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -* Label Attributes:: Specifying attributes of labels and statements. -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -* Alignment:: Inquiring about the alignment of a type or variable. -* Inline:: Defining inline functions (as fast as macros). -* Extended Asm:: Assembler instructions with C expressions as operands. - (With them you can define ``built-in'' functions.) -* Constraints:: Constraints for asm operands -* Asm Labels:: Specifying the assembler name to use for a C symbol. -* Explicit Reg Vars:: Defining variables residing in specified registers. -@c APPLE LOCAL CW asm blocks -* Asm Blocks and Functions:: Block and functions of assembly code. -* Alternate Keywords:: @code{__const__}, @code{__asm__}, etc., for header files. -* Incomplete Enums:: @code{enum foo;}, with details to follow. -* Function Names:: Printable strings which are the name of the current - function. -* Return Address:: Getting the return or frame address of a function. -* Vector Extensions:: Using vector instructions through built-in functions. -* Offsetof:: Special syntax for implementing @code{offsetof}. -* Atomic Builtins:: Built-in functions for atomic memory access. -* Object Size Checking:: Built-in functions for limited buffer overflow - checking. -* Other Builtins:: Other built-in functions. -* Target Builtins:: Built-in functions specific to particular targets. -* Target Format Checks:: Format checks specific to particular targets. -* Pragmas:: Pragmas accepted by GCC. -* Unnamed Fields:: Unnamed struct/union fields within structs/unions. -* Thread-Local:: Per-thread variables. -@c APPLE LOCAL blocks 7205047 5811887 -* Blocks:: Anonymous functions (closures). -@end menu - -@node Statement Exprs -@section Statements and Declarations in Expressions -@cindex statements inside expressions -@cindex declarations inside expressions -@cindex expressions containing statements -@cindex macros, statements in expressions - -@c the above section title wrapped and causes an underfull hbox.. i -@c changed it from "within" to "in". --mew 4feb93 -A compound statement enclosed in parentheses may appear as an expression -in GNU C@. This allows you to use loops, switches, and local variables -within an expression. - -Recall that a compound statement is a sequence of statements surrounded -by braces; in this construct, parentheses go around the braces. For -example: - -@smallexample -(@{ int y = foo (); int z; - if (y > 0) z = y; - else z = - y; - z; @}) -@end smallexample - -@noindent -is a valid (though slightly more complex than necessary) expression -for the absolute value of @code{foo ()}. - -The last thing in the compound statement should be an expression -followed by a semicolon; the value of this subexpression serves as the -value of the entire construct. (If you use some other kind of statement -last within the braces, the construct has type @code{void}, and thus -effectively no value.) - -This feature is especially useful in making macro definitions ``safe'' (so -that they evaluate each operand exactly once). For example, the -``maximum'' function is commonly defined as a macro in standard C as -follows: - -@smallexample -#define max(a,b) ((a) > (b) ? (a) : (b)) -@end smallexample - -@noindent -@cindex side effects, macro argument -But this definition computes either @var{a} or @var{b} twice, with bad -results if the operand has side effects. In GNU C, if you know the -type of the operands (here taken as @code{int}), you can define -the macro safely as follows: - -@smallexample -#define maxint(a,b) \ - (@{int _a = (a), _b = (b); _a > _b ? _a : _b; @}) -@end smallexample - -Embedded statements are not allowed in constant expressions, such as -the value of an enumeration constant, the width of a bit-field, or -the initial value of a static variable. - -If you don't know the type of the operand, you can still do this, but you -must use @code{typeof} (@pxref{Typeof}). - -In G++, the result value of a statement expression undergoes array and -function pointer decay, and is returned by value to the enclosing -expression. For instance, if @code{A} is a class, then - -@smallexample - A a; - - (@{a;@}).Foo () -@end smallexample - -@noindent -will construct a temporary @code{A} object to hold the result of the -statement expression, and that will be used to invoke @code{Foo}. -Therefore the @code{this} pointer observed by @code{Foo} will not be the -address of @code{a}. - -Any temporaries created within a statement within a statement expression -will be destroyed at the statement's end. This makes statement -expressions inside macros slightly different from function calls. In -the latter case temporaries introduced during argument evaluation will -be destroyed at the end of the statement that includes the function -call. In the statement expression case they will be destroyed during -the statement expression. For instance, - -@smallexample -#define macro(a) (@{__typeof__(a) b = (a); b + 3; @}) -template<typename T> T function(T a) @{ T b = a; return b + 3; @} - -void foo () -@{ - macro (X ()); - function (X ()); -@} -@end smallexample - -@noindent -will have different places where temporaries are destroyed. For the -@code{macro} case, the temporary @code{X} will be destroyed just after -the initialization of @code{b}. In the @code{function} case that -temporary will be destroyed when the function returns. - -These considerations mean that it is probably a bad idea to use -statement-expressions of this form in header files that are designed to -work with C++. (Note that some versions of the GNU C Library contained -header files using statement-expression that lead to precisely this -bug.) - -Jumping into a statement expression with @code{goto} or using a -@code{switch} statement outside the statement expression with a -@code{case} or @code{default} label inside the statement expression is -not permitted. Jumping into a statement expression with a computed -@code{goto} (@pxref{Labels as Values}) yields undefined behavior. -Jumping out of a statement expression is permitted, but if the -statement expression is part of a larger expression then it is -unspecified which other subexpressions of that expression have been -evaluated except where the language definition requires certain -subexpressions to be evaluated before or after the statement -expression. In any case, as with a function call the evaluation of a -statement expression is not interleaved with the evaluation of other -parts of the containing expression. For example, - -@smallexample - foo (), ((@{ bar1 (); goto a; 0; @}) + bar2 ()), baz(); -@end smallexample - -@noindent -will call @code{foo} and @code{bar1} and will not call @code{baz} but -may or may not call @code{bar2}. If @code{bar2} is called, it will be -called after @code{foo} and before @code{bar1} - -@node Local Labels -@section Locally Declared Labels -@cindex local labels -@cindex macros, local labels - -GCC allows you to declare @dfn{local labels} in any nested block -scope. A local label is just like an ordinary label, but you can -only reference it (with a @code{goto} statement, or by taking its -address) within the block in which it was declared. - -A local label declaration looks like this: - -@smallexample -__label__ @var{label}; -@end smallexample - -@noindent -or - -@smallexample -__label__ @var{label1}, @var{label2}, /* @r{@dots{}} */; -@end smallexample - -Local label declarations must come at the beginning of the block, -before any ordinary declarations or statements. - -The label declaration defines the label @emph{name}, but does not define -the label itself. You must do this in the usual way, with -@code{@var{label}:}, within the statements of the statement expression. - -The local label feature is useful for complex macros. If a macro -contains nested loops, a @code{goto} can be useful for breaking out of -them. However, an ordinary label whose scope is the whole function -cannot be used: if the macro can be expanded several times in one -function, the label will be multiply defined in that function. A -local label avoids this problem. For example: - -@smallexample -#define SEARCH(value, array, target) \ -do @{ \ - __label__ found; \ - typeof (target) _SEARCH_target = (target); \ - typeof (*(array)) *_SEARCH_array = (array); \ - int i, j; \ - int value; \ - for (i = 0; i < max; i++) \ - for (j = 0; j < max; j++) \ - if (_SEARCH_array[i][j] == _SEARCH_target) \ - @{ (value) = i; goto found; @} \ - (value) = -1; \ - found:; \ -@} while (0) -@end smallexample - -This could also be written using a statement-expression: - -@smallexample -#define SEARCH(array, target) \ -(@{ \ - __label__ found; \ - typeof (target) _SEARCH_target = (target); \ - typeof (*(array)) *_SEARCH_array = (array); \ - int i, j; \ - int value; \ - for (i = 0; i < max; i++) \ - for (j = 0; j < max; j++) \ - if (_SEARCH_array[i][j] == _SEARCH_target) \ - @{ value = i; goto found; @} \ - value = -1; \ - found: \ - value; \ -@}) -@end smallexample - -Local label declarations also make the labels they declare visible to -nested functions, if there are any. @xref{Nested Functions}, for details. - -@node Labels as Values -@section Labels as Values -@cindex labels as values -@cindex computed gotos -@cindex goto with computed label -@cindex address of a label - -You can get the address of a label defined in the current function -(or a containing function) with the unary operator @samp{&&}. The -value has type @code{void *}. This value is a constant and can be used -wherever a constant of that type is valid. For example: - -@smallexample -void *ptr; -/* @r{@dots{}} */ -ptr = &&foo; -@end smallexample - -To use these values, you need to be able to jump to one. This is done -with the computed goto statement@footnote{The analogous feature in -Fortran is called an assigned goto, but that name seems inappropriate in -C, where one can do more than simply store label addresses in label -variables.}, @code{goto *@var{exp};}. For example, - -@smallexample -goto *ptr; -@end smallexample - -@noindent -Any expression of type @code{void *} is allowed. - -One way of using these constants is in initializing a static array that -will serve as a jump table: - -@smallexample -static void *array[] = @{ &&foo, &&bar, &&hack @}; -@end smallexample - -Then you can select a label with indexing, like this: - -@smallexample -goto *array[i]; -@end smallexample - -@noindent -Note that this does not check whether the subscript is in bounds---array -indexing in C never does that. - -Such an array of label values serves a purpose much like that of the -@code{switch} statement. The @code{switch} statement is cleaner, so -use that rather than an array unless the problem does not fit a -@code{switch} statement very well. - -Another use of label values is in an interpreter for threaded code. -The labels within the interpreter function can be stored in the -threaded code for super-fast dispatching. - -You may not use this mechanism to jump to code in a different function. -If you do that, totally unpredictable things will happen. The best way to -avoid this is to store the label address only in automatic variables and -never pass it as an argument. - -An alternate way to write the above example is - -@smallexample -static const int array[] = @{ &&foo - &&foo, &&bar - &&foo, - &&hack - &&foo @}; -goto *(&&foo + array[i]); -@end smallexample - -@noindent -This is more friendly to code living in shared libraries, as it reduces -the number of dynamic relocations that are needed, and by consequence, -allows the data to be read-only. - -@node Nested Functions -@section Nested Functions -@cindex nested functions -@cindex downward funargs -@cindex thunks - -A @dfn{nested function} is a function defined inside another function. -@c APPLE LOCAL begin nested functions 4357979 -Nested functions are not supported for GNU C++ and are disable by -default on Darwin. The @option{-fnested-functions} and -@option{-fno-nested-functions} options can be used to enable and -disable nested function suppport. The nested function's name is local -to the block where it is defined. For example, here we define a -nested function named @code{square}, and call it twice: -@c APPLE LOCAL end nested functions 4357979 - -@smallexample -@group -foo (double a, double b) -@{ - double square (double z) @{ return z * z; @} - - return square (a) + square (b); -@} -@end group -@end smallexample - -The nested function can access all the variables of the containing -function that are visible at the point of its definition. This is -called @dfn{lexical scoping}. For example, here we show a nested -function which uses an inherited variable named @code{offset}: - -@smallexample -@group -bar (int *array, int offset, int size) -@{ - int access (int *array, int index) - @{ return array[index + offset]; @} - int i; - /* @r{@dots{}} */ - for (i = 0; i < size; i++) - /* @r{@dots{}} */ access (array, i) /* @r{@dots{}} */ -@} -@end group -@end smallexample - -Nested function definitions are permitted within functions in the places -where variable definitions are allowed; that is, in any block, mixed -with the other declarations and statements in the block. - -It is possible to call the nested function from outside the scope of its -name by storing its address or passing the address to another function: - -@smallexample -hack (int *array, int size) -@{ - void store (int index, int value) - @{ array[index] = value; @} - - intermediate (store, size); -@} -@end smallexample - -Here, the function @code{intermediate} receives the address of -@code{store} as an argument. If @code{intermediate} calls @code{store}, -the arguments given to @code{store} are used to store into @code{array}. -But this technique works only so long as the containing function -(@code{hack}, in this example) does not exit. - -If you try to call the nested function through its address after the -containing function has exited, all hell will break loose. If you try -to call it after a containing scope level has exited, and if it refers -to some of the variables that are no longer in scope, you may be lucky, -but it's not wise to take the risk. If, however, the nested function -does not refer to anything that has gone out of scope, you should be -safe. - -GCC implements taking the address of a nested function using a technique -called @dfn{trampolines}. A paper describing them is available as - -@noindent -@uref{http://people.debian.org/~aaronl/Usenix88-lexic.pdf}. - -A nested function can jump to a label inherited from a containing -function, provided the label was explicitly declared in the containing -function (@pxref{Local Labels}). Such a jump returns instantly to the -containing function, exiting the nested function which did the -@code{goto} and any intermediate functions as well. Here is an example: - -@smallexample -@group -bar (int *array, int offset, int size) -@{ - __label__ failure; - int access (int *array, int index) - @{ - if (index > size) - goto failure; - return array[index + offset]; - @} - int i; - /* @r{@dots{}} */ - for (i = 0; i < size; i++) - /* @r{@dots{}} */ access (array, i) /* @r{@dots{}} */ - /* @r{@dots{}} */ - return 0; - - /* @r{Control comes here from @code{access} - if it detects an error.} */ - failure: - return -1; -@} -@end group -@end smallexample - -A nested function always has no linkage. Declaring one with -@code{extern} or @code{static} is erroneous. If you need to declare the nested function -before its definition, use @code{auto} (which is otherwise meaningless -for function declarations). - -@smallexample -bar (int *array, int offset, int size) -@{ - __label__ failure; - auto int access (int *, int); - /* @r{@dots{}} */ - int access (int *array, int index) - @{ - if (index > size) - goto failure; - return array[index + offset]; - @} - /* @r{@dots{}} */ -@} -@end smallexample - -@node Constructing Calls -@section Constructing Function Calls -@cindex constructing calls -@cindex forwarding calls - -Using the built-in functions described below, you can record -the arguments a function received, and call another function -with the same arguments, without knowing the number or types -of the arguments. - -You can also record the return value of that function call, -and later return that value, without knowing what data type -the function tried to return (as long as your caller expects -that data type). - -However, these built-in functions may interact badly with some -sophisticated features or other extensions of the language. It -is, therefore, not recommended to use them outside very simple -functions acting as mere forwarders for their arguments. - -@deftypefn {Built-in Function} {void *} __builtin_apply_args () -This built-in function returns a pointer to data -describing how to perform a call with the same arguments as were passed -to the current function. - -The function saves the arg pointer register, structure value address, -and all registers that might be used to pass arguments to a function -into a block of memory allocated on the stack. Then it returns the -address of that block. -@end deftypefn - -@deftypefn {Built-in Function} {void *} __builtin_apply (void (*@var{function})(), void *@var{arguments}, size_t @var{size}) -This built-in function invokes @var{function} -with a copy of the parameters described by @var{arguments} -and @var{size}. - -The value of @var{arguments} should be the value returned by -@code{__builtin_apply_args}. The argument @var{size} specifies the size -of the stack argument data, in bytes. - -This function returns a pointer to data describing -how to return whatever value was returned by @var{function}. The data -is saved in a block of memory allocated on the stack. - -It is not always simple to compute the proper value for @var{size}. The -value is used by @code{__builtin_apply} to compute the amount of data -that should be pushed on the stack and copied from the incoming argument -area. -@end deftypefn - -@deftypefn {Built-in Function} {void} __builtin_return (void *@var{result}) -This built-in function returns the value described by @var{result} from -the containing function. You should specify, for @var{result}, a value -returned by @code{__builtin_apply}. -@end deftypefn - -@node Typeof -@section Referring to a Type with @code{typeof} -@findex typeof -@findex sizeof -@cindex macros, types of arguments - -Another way to refer to the type of an expression is with @code{typeof}. -The syntax of using of this keyword looks like @code{sizeof}, but the -construct acts semantically like a type name defined with @code{typedef}. - -There are two ways of writing the argument to @code{typeof}: with an -expression or with a type. Here is an example with an expression: - -@smallexample -typeof (x[0](1)) -@end smallexample - -@noindent -This assumes that @code{x} is an array of pointers to functions; -the type described is that of the values of the functions. - -Here is an example with a typename as the argument: - -@smallexample -typeof (int *) -@end smallexample - -@noindent -Here the type described is that of pointers to @code{int}. - -If you are writing a header file that must work when included in ISO C -programs, write @code{__typeof__} instead of @code{typeof}. -@xref{Alternate Keywords}. - -A @code{typeof}-construct can be used anywhere a typedef name could be -used. For example, you can use it in a declaration, in a cast, or inside -of @code{sizeof} or @code{typeof}. - -@code{typeof} is often useful in conjunction with the -statements-within-expressions feature. Here is how the two together can -be used to define a safe ``maximum'' macro that operates on any -arithmetic type and evaluates each of its arguments exactly once: - -@smallexample -#define max(a,b) \ - (@{ typeof (a) _a = (a); \ - typeof (b) _b = (b); \ - _a > _b ? _a : _b; @}) -@end smallexample - -@cindex underscores in variables in macros -@cindex @samp{_} in variables in macros -@cindex local variables in macros -@cindex variables, local, in macros -@cindex macros, local variables in - -The reason for using names that start with underscores for the local -variables is to avoid conflicts with variable names that occur within the -expressions that are substituted for @code{a} and @code{b}. Eventually we -hope to design a new form of declaration syntax that allows you to declare -variables whose scopes start only after their initializers; this will be a -more reliable way to prevent such conflicts. - -@noindent -Some more examples of the use of @code{typeof}: - -@itemize @bullet -@item -This declares @code{y} with the type of what @code{x} points to. - -@smallexample -typeof (*x) y; -@end smallexample - -@item -This declares @code{y} as an array of such values. - -@smallexample -typeof (*x) y[4]; -@end smallexample - -@item -This declares @code{y} as an array of pointers to characters: - -@smallexample -typeof (typeof (char *)[4]) y; -@end smallexample - -@noindent -It is equivalent to the following traditional C declaration: - -@smallexample -char *y[4]; -@end smallexample - -To see the meaning of the declaration using @code{typeof}, and why it -might be a useful way to write, rewrite it with these macros: - -@smallexample -#define pointer(T) typeof(T *) -#define array(T, N) typeof(T [N]) -@end smallexample - -@noindent -Now the declaration can be rewritten this way: - -@smallexample -array (pointer (char), 4) y; -@end smallexample - -@noindent -Thus, @code{array (pointer (char), 4)} is the type of arrays of 4 -pointers to @code{char}. -@end itemize - -@emph{Compatibility Note:} In addition to @code{typeof}, GCC 2 supported -a more limited extension which permitted one to write - -@smallexample -typedef @var{T} = @var{expr}; -@end smallexample - -@noindent -with the effect of declaring @var{T} to have the type of the expression -@var{expr}. This extension does not work with GCC 3 (versions between -3.0 and 3.2 will crash; 3.2.1 and later give an error). Code which -relies on it should be rewritten to use @code{typeof}: - -@smallexample -typedef typeof(@var{expr}) @var{T}; -@end smallexample - -@noindent -This will work with all versions of GCC@. - -@node Conditionals -@section Conditionals with Omitted Operands -@cindex conditional expressions, extensions -@cindex omitted middle-operands -@cindex middle-operands, omitted -@cindex extensions, @code{?:} -@cindex @code{?:} extensions - -The middle operand in a conditional expression may be omitted. Then -if the first operand is nonzero, its value is the value of the conditional -expression. - -Therefore, the expression - -@smallexample -x ? : y -@end smallexample - -@noindent -has the value of @code{x} if that is nonzero; otherwise, the value of -@code{y}. - -This example is perfectly equivalent to - -@smallexample -x ? x : y -@end smallexample - -@cindex side effect in ?: -@cindex ?: side effect -@noindent -In this simple case, the ability to omit the middle operand is not -especially useful. When it becomes useful is when the first operand does, -or may (if it is a macro argument), contain a side effect. Then repeating -the operand in the middle would perform the side effect twice. Omitting -the middle operand uses the value already computed without the undesirable -effects of recomputing it. - -@node Long Long -@section Double-Word Integers -@cindex @code{long long} data types -@cindex double-word arithmetic -@cindex multiprecision arithmetic -@cindex @code{LL} integer suffix -@cindex @code{ULL} integer suffix - -ISO C99 supports data types for integers that are at least 64 bits wide, -and as an extension GCC supports them in C89 mode and in C++. -Simply write @code{long long int} for a signed integer, or -@code{unsigned long long int} for an unsigned integer. To make an -integer constant of type @code{long long int}, add the suffix @samp{LL} -to the integer. To make an integer constant of type @code{unsigned long -long int}, add the suffix @samp{ULL} to the integer. - -You can use these types in arithmetic like any other integer types. -Addition, subtraction, and bitwise boolean operations on these types -are open-coded on all types of machines. Multiplication is open-coded -if the machine supports fullword-to-doubleword a widening multiply -instruction. Division and shifts are open-coded only on machines that -provide special support. The operations that are not open-coded use -special library routines that come with GCC@. - -There may be pitfalls when you use @code{long long} types for function -arguments, unless you declare function prototypes. If a function -expects type @code{int} for its argument, and you pass a value of type -@code{long long int}, confusion will result because the caller and the -subroutine will disagree about the number of bytes for the argument. -Likewise, if the function expects @code{long long int} and you pass -@code{int}. The best way to avoid such problems is to use prototypes. - -@node Complex -@section Complex Numbers -@cindex complex numbers -@cindex @code{_Complex} keyword -@cindex @code{__complex__} keyword - -ISO C99 supports complex floating data types, and as an extension GCC -supports them in C89 mode and in C++, and supports complex integer data -types which are not part of ISO C99. You can declare complex types -using the keyword @code{_Complex}. As an extension, the older GNU -keyword @code{__complex__} is also supported. - -For example, @samp{_Complex double x;} declares @code{x} as a -variable whose real part and imaginary part are both of type -@code{double}. @samp{_Complex short int y;} declares @code{y} to -have real and imaginary parts of type @code{short int}; this is not -likely to be useful, but it shows that the set of complex types is -complete. - -To write a constant with a complex data type, use the suffix @samp{i} or -@samp{j} (either one; they are equivalent). For example, @code{2.5fi} -has type @code{_Complex float} and @code{3i} has type -@code{_Complex int}. Such a constant always has a pure imaginary -value, but you can form any complex value you like by adding one to a -real constant. This is a GNU extension; if you have an ISO C99 -conforming C library (such as GNU libc), and want to construct complex -constants of floating type, you should include @code{<complex.h>} and -use the macros @code{I} or @code{_Complex_I} instead. - -@cindex @code{__real__} keyword -@cindex @code{__imag__} keyword -To extract the real part of a complex-valued expression @var{exp}, write -@code{__real__ @var{exp}}. Likewise, use @code{__imag__} to -extract the imaginary part. This is a GNU extension; for values of -floating type, you should use the ISO C99 functions @code{crealf}, -@code{creal}, @code{creall}, @code{cimagf}, @code{cimag} and -@code{cimagl}, declared in @code{<complex.h>} and also provided as -built-in functions by GCC@. - -@cindex complex conjugation -The operator @samp{~} performs complex conjugation when used on a value -with a complex type. This is a GNU extension; for values of -floating type, you should use the ISO C99 functions @code{conjf}, -@code{conj} and @code{conjl}, declared in @code{<complex.h>} and also -provided as built-in functions by GCC@. - -GCC can allocate complex automatic variables in a noncontiguous -fashion; it's even possible for the real part to be in a register while -the imaginary part is on the stack (or vice-versa). Only the DWARF2 -debug info format can represent this, so use of DWARF2 is recommended. -If you are using the stabs debug info format, GCC describes a noncontiguous -complex variable as if it were two separate variables of noncomplex type. -If the variable's actual name is @code{foo}, the two fictitious -variables are named @code{foo$real} and @code{foo$imag}. You can -examine and set these two fictitious variables with your debugger. - -@node Decimal Float -@section Decimal Floating Types -@cindex decimal floating types -@cindex @code{_Decimal32} data type -@cindex @code{_Decimal64} data type -@cindex @code{_Decimal128} data type -@cindex @code{df} integer suffix -@cindex @code{dd} integer suffix -@cindex @code{dl} integer suffix -@cindex @code{DF} integer suffix -@cindex @code{DD} integer suffix -@cindex @code{DL} integer suffix - -As an extension, the GNU C compiler supports decimal floating types as -defined in the N1176 draft of ISO/IEC WDTR24732. Support for decimal -floating types in GCC will evolve as the draft technical report changes. -Calling conventions for any target might also change. Not all targets -support decimal floating types. - -The decimal floating types are @code{_Decimal32}, @code{_Decimal64}, and -@code{_Decimal128}. They use a radix of ten, unlike the floating types -@code{float}, @code{double}, and @code{long double} whose radix is not -specified by the C standard but is usually two. - -Support for decimal floating types includes the arithmetic operators -add, subtract, multiply, divide; unary arithmetic operators; -relational operators; equality operators; and conversions to and from -integer and other floating types. Use a suffix @samp{df} or -@samp{DF} in a literal constant of type @code{_Decimal32}, @samp{dd} -or @samp{DD} for @code{_Decimal64}, and @samp{dl} or @samp{DL} for -@code{_Decimal128}. - -GCC support of decimal float as specified by the draft technical report -is incomplete: - -@itemize @bullet -@item -Translation time data type (TTDT) is not supported. - -@item -Characteristics of decimal floating types are defined in header file -@file{decfloat.h} rather than @file{float.h}. - -@item -When the value of a decimal floating type cannot be represented in the -integer type to which it is being converted, the result is undefined -rather than the result value specified by the draft technical report. -@end itemize - -Types @code{_Decimal32}, @code{_Decimal64}, and @code{_Decimal128} -are supported by the DWARF2 debug information format. - -@node Hex Floats -@section Hex Floats -@cindex hex floats - -ISO C99 supports floating-point numbers written not only in the usual -decimal notation, such as @code{1.55e1}, but also numbers such as -@code{0x1.fp3} written in hexadecimal format. As a GNU extension, GCC -supports this in C89 mode (except in some cases when strictly -conforming) and in C++. In that format the -@samp{0x} hex introducer and the @samp{p} or @samp{P} exponent field are -mandatory. The exponent is a decimal number that indicates the power of -2 by which the significant part will be multiplied. Thus @samp{0x1.f} is -@tex -$1 {15\over16}$, -@end tex -@ifnottex -1 15/16, -@end ifnottex -@samp{p3} multiplies it by 8, and the value of @code{0x1.fp3} -is the same as @code{1.55e1}. - -Unlike for floating-point numbers in the decimal notation the exponent -is always required in the hexadecimal notation. Otherwise the compiler -would not be able to resolve the ambiguity of, e.g., @code{0x1.f}. This -could mean @code{1.0f} or @code{1.9375} since @samp{f} is also the -extension for floating-point constants of type @code{float}. - -@node Zero Length -@section Arrays of Length Zero -@cindex arrays of length zero -@cindex zero-length arrays -@cindex length-zero arrays -@cindex flexible array members - -Zero-length arrays are allowed in GNU C@. They are very useful as the -last element of a structure which is really a header for a variable-length -object: - -@smallexample -struct line @{ - int length; - char contents[0]; -@}; - -struct line *thisline = (struct line *) - malloc (sizeof (struct line) + this_length); -thisline->length = this_length; -@end smallexample - -In ISO C90, you would have to give @code{contents} a length of 1, which -means either you waste space or complicate the argument to @code{malloc}. - -In ISO C99, you would use a @dfn{flexible array member}, which is -slightly different in syntax and semantics: - -@itemize @bullet -@item -Flexible array members are written as @code{contents[]} without -the @code{0}. - -@item -Flexible array members have incomplete type, and so the @code{sizeof} -operator may not be applied. As a quirk of the original implementation -of zero-length arrays, @code{sizeof} evaluates to zero. - -@item -Flexible array members may only appear as the last member of a -@code{struct} that is otherwise non-empty. - -@item -A structure containing a flexible array member, or a union containing -such a structure (possibly recursively), may not be a member of a -structure or an element of an array. (However, these uses are -permitted by GCC as extensions.) -@end itemize - -GCC versions before 3.0 allowed zero-length arrays to be statically -initialized, as if they were flexible arrays. In addition to those -cases that were useful, it also allowed initializations in situations -that would corrupt later data. Non-empty initialization of zero-length -arrays is now treated like any case where there are more initializer -elements than the array holds, in that a suitable warning about "excess -elements in array" is given, and the excess elements (all of them, in -this case) are ignored. - -Instead GCC allows static initialization of flexible array members. -This is equivalent to defining a new structure containing the original -structure followed by an array of sufficient size to contain the data. -I.e.@: in the following, @code{f1} is constructed as if it were declared -like @code{f2}. - -@smallexample -struct f1 @{ - int x; int y[]; -@} f1 = @{ 1, @{ 2, 3, 4 @} @}; - -struct f2 @{ - struct f1 f1; int data[3]; -@} f2 = @{ @{ 1 @}, @{ 2, 3, 4 @} @}; -@end smallexample - -@noindent -The convenience of this extension is that @code{f1} has the desired -type, eliminating the need to consistently refer to @code{f2.f1}. - -This has symmetry with normal static arrays, in that an array of -unknown size is also written with @code{[]}. - -Of course, this extension only makes sense if the extra data comes at -the end of a top-level object, as otherwise we would be overwriting -data at subsequent offsets. To avoid undue complication and confusion -with initialization of deeply nested arrays, we simply disallow any -non-empty initialization except when the structure is the top-level -object. For example: - -@smallexample -struct foo @{ int x; int y[]; @}; -struct bar @{ struct foo z; @}; - -struct foo a = @{ 1, @{ 2, 3, 4 @} @}; // @r{Valid.} -struct bar b = @{ @{ 1, @{ 2, 3, 4 @} @} @}; // @r{Invalid.} -struct bar c = @{ @{ 1, @{ @} @} @}; // @r{Valid.} -struct foo d[1] = @{ @{ 1 @{ 2, 3, 4 @} @} @}; // @r{Invalid.} -@end smallexample - -@node Empty Structures -@section Structures With No Members -@cindex empty structures -@cindex zero-size structures - -GCC permits a C structure to have no members: - -@smallexample -struct empty @{ -@}; -@end smallexample - -The structure will have size zero. In C++, empty structures are part -of the language. G++ treats empty structures as if they had a single -member of type @code{char}. - -@node Variable Length -@section Arrays of Variable Length -@cindex variable-length arrays -@cindex arrays of variable length -@cindex VLAs - -Variable-length automatic arrays are allowed in ISO C99, and as an -extension GCC accepts them in C89 mode and in C++. (However, GCC's -implementation of variable-length arrays does not yet conform in detail -to the ISO C99 standard.) These arrays are -declared like any other automatic arrays, but with a length that is not -a constant expression. The storage is allocated at the point of -declaration and deallocated when the brace-level is exited. For -example: - -@smallexample -FILE * -concat_fopen (char *s1, char *s2, char *mode) -@{ - char str[strlen (s1) + strlen (s2) + 1]; - strcpy (str, s1); - strcat (str, s2); - return fopen (str, mode); -@} -@end smallexample - -@cindex scope of a variable length array -@cindex variable-length array scope -@cindex deallocating variable length arrays -Jumping or breaking out of the scope of the array name deallocates the -storage. Jumping into the scope is not allowed; you get an error -message for it. - -@cindex @code{alloca} vs variable-length arrays -You can use the function @code{alloca} to get an effect much like -variable-length arrays. The function @code{alloca} is available in -many other C implementations (but not in all). On the other hand, -variable-length arrays are more elegant. - -There are other differences between these two methods. Space allocated -with @code{alloca} exists until the containing @emph{function} returns. -The space for a variable-length array is deallocated as soon as the array -name's scope ends. (If you use both variable-length arrays and -@code{alloca} in the same function, deallocation of a variable-length array -will also deallocate anything more recently allocated with @code{alloca}.) - -You can also use variable-length arrays as arguments to functions: - -@smallexample -struct entry -tester (int len, char data[len][len]) -@{ - /* @r{@dots{}} */ -@} -@end smallexample - -The length of an array is computed once when the storage is allocated -and is remembered for the scope of the array in case you access it with -@code{sizeof}. - -If you want to pass the array first and the length afterward, you can -use a forward declaration in the parameter list---another GNU extension. - -@smallexample -struct entry -tester (int len; char data[len][len], int len) -@{ - /* @r{@dots{}} */ -@} -@end smallexample - -@cindex parameter forward declaration -The @samp{int len} before the semicolon is a @dfn{parameter forward -declaration}, and it serves the purpose of making the name @code{len} -known when the declaration of @code{data} is parsed. - -You can write any number of such parameter forward declarations in the -parameter list. They can be separated by commas or semicolons, but the -last one must end with a semicolon, which is followed by the ``real'' -parameter declarations. Each forward declaration must match a ``real'' -declaration in parameter name and data type. ISO C99 does not support -parameter forward declarations. - -@node Variadic Macros -@section Macros with a Variable Number of Arguments. -@cindex variable number of arguments -@cindex macro with variable arguments -@cindex rest argument (in macro) -@cindex variadic macros - -In the ISO C standard of 1999, a macro can be declared to accept a -variable number of arguments much as a function can. The syntax for -defining the macro is similar to that of a function. Here is an -example: - -@smallexample -#define debug(format, ...) fprintf (stderr, format, __VA_ARGS__) -@end smallexample - -Here @samp{@dots{}} is a @dfn{variable argument}. In the invocation of -such a macro, it represents the zero or more tokens until the closing -parenthesis that ends the invocation, including any commas. This set of -tokens replaces the identifier @code{__VA_ARGS__} in the macro body -wherever it appears. See the CPP manual for more information. - -GCC has long supported variadic macros, and used a different syntax that -allowed you to give a name to the variable arguments just like any other -argument. Here is an example: - -@smallexample -#define debug(format, args...) fprintf (stderr, format, args) -@end smallexample - -This is in all ways equivalent to the ISO C example above, but arguably -more readable and descriptive. - -GNU CPP has two further variadic macro extensions, and permits them to -be used with either of the above forms of macro definition. - -In standard C, you are not allowed to leave the variable argument out -entirely; but you are allowed to pass an empty argument. For example, -this invocation is invalid in ISO C, because there is no comma after -the string: - -@smallexample -debug ("A message") -@end smallexample - -GNU CPP permits you to completely omit the variable arguments in this -way. In the above examples, the compiler would complain, though since -the expansion of the macro still has the extra comma after the format -string. - -To help solve this problem, CPP behaves specially for variable arguments -used with the token paste operator, @samp{##}. If instead you write - -@smallexample -#define debug(format, ...) fprintf (stderr, format, ## __VA_ARGS__) -@end smallexample - -and if the variable arguments are omitted or empty, the @samp{##} -operator causes the preprocessor to remove the comma before it. If you -do provide some variable arguments in your macro invocation, GNU CPP -does not complain about the paste operation and instead places the -variable arguments after the comma. Just like any other pasted macro -argument, these arguments are not macro expanded. - -@node Escaped Newlines -@section Slightly Looser Rules for Escaped Newlines -@cindex escaped newlines -@cindex newlines (escaped) - -Recently, the preprocessor has relaxed its treatment of escaped -newlines. Previously, the newline had to immediately follow a -backslash. The current implementation allows whitespace in the form -of spaces, horizontal and vertical tabs, and form feeds between the -backslash and the subsequent newline. The preprocessor issues a -warning, but treats it as a valid escaped newline and combines the two -lines to form a single logical line. This works within comments and -tokens, as well as between tokens. Comments are @emph{not} treated as -whitespace for the purposes of this relaxation, since they have not -yet been replaced with spaces. - -@node Subscripting -@section Non-Lvalue Arrays May Have Subscripts -@cindex subscripting -@cindex arrays, non-lvalue - -@cindex subscripting and function values -In ISO C99, arrays that are not lvalues still decay to pointers, and -may be subscripted, although they may not be modified or used after -the next sequence point and the unary @samp{&} operator may not be -applied to them. As an extension, GCC allows such arrays to be -subscripted in C89 mode, though otherwise they do not decay to -pointers outside C99 mode. For example, -this is valid in GNU C though not valid in C89: - -@smallexample -@group -struct foo @{int a[4];@}; - -struct foo f(); - -bar (int index) -@{ - return f().a[index]; -@} -@end group -@end smallexample - -@node Pointer Arith -@section Arithmetic on @code{void}- and Function-Pointers -@cindex void pointers, arithmetic -@cindex void, size of pointer to -@cindex function pointers, arithmetic -@cindex function, size of pointer to - -In GNU C, addition and subtraction operations are supported on pointers to -@code{void} and on pointers to functions. This is done by treating the -size of a @code{void} or of a function as 1. - -A consequence of this is that @code{sizeof} is also allowed on @code{void} -and on function types, and returns 1. - -@opindex Wpointer-arith -The option @option{-Wpointer-arith} requests a warning if these extensions -are used. - -@node Initializers -@section Non-Constant Initializers -@cindex initializers, non-constant -@cindex non-constant initializers - -As in standard C++ and ISO C99, the elements of an aggregate initializer for an -automatic variable are not required to be constant expressions in GNU C@. -Here is an example of an initializer with run-time varying elements: - -@smallexample -foo (float f, float g) -@{ - float beat_freqs[2] = @{ f-g, f+g @}; - /* @r{@dots{}} */ -@} -@end smallexample - -@node Compound Literals -@section Compound Literals -@cindex constructor expressions -@cindex initializations in expressions -@cindex structures, constructor expression -@cindex expressions, constructor -@cindex compound literals -@c The GNU C name for what C99 calls compound literals was "constructor expressions". - -ISO C99 supports compound literals. A compound literal looks like -a cast containing an initializer. Its value is an object of the -type specified in the cast, containing the elements specified in -the initializer; it is an lvalue. As an extension, GCC supports -compound literals in C89 mode and in C++. - -Usually, the specified type is a structure. Assume that -@code{struct foo} and @code{structure} are declared as shown: - -@smallexample -struct foo @{int a; char b[2];@} structure; -@end smallexample - -@noindent -Here is an example of constructing a @code{struct foo} with a compound literal: - -@smallexample -structure = ((struct foo) @{x + y, 'a', 0@}); -@end smallexample - -@noindent -This is equivalent to writing the following: - -@smallexample -@{ - struct foo temp = @{x + y, 'a', 0@}; - structure = temp; -@} -@end smallexample - -You can also construct an array. If all the elements of the compound literal -are (made up of) simple constant expressions, suitable for use in -initializers of objects of static storage duration, then the compound -literal can be coerced to a pointer to its first element and used in -such an initializer, as shown here: - -@smallexample -char **foo = (char *[]) @{ "x", "y", "z" @}; -@end smallexample - -Compound literals for scalar types and union types are is -also allowed, but then the compound literal is equivalent -to a cast. - -As a GNU extension, GCC allows initialization of objects with static storage -duration by compound literals (which is not possible in ISO C99, because -the initializer is not a constant). -It is handled as if the object was initialized only with the bracket -enclosed list if the types of the compound literal and the object match. -The initializer list of the compound literal must be constant. -If the object being initialized has array type of unknown size, the size is -determined by compound literal size. - -@smallexample -static struct foo x = (struct foo) @{1, 'a', 'b'@}; -static int y[] = (int []) @{1, 2, 3@}; -static int z[] = (int [3]) @{1@}; -@end smallexample - -@noindent -The above lines are equivalent to the following: -@smallexample -static struct foo x = @{1, 'a', 'b'@}; -static int y[] = @{1, 2, 3@}; -static int z[] = @{1, 0, 0@}; -@end smallexample - -@node Designated Inits -@section Designated Initializers -@cindex initializers with labeled elements -@cindex labeled elements in initializers -@cindex case labels in initializers -@cindex designated initializers - -Standard C89 requires the elements of an initializer to appear in a fixed -order, the same as the order of the elements in the array or structure -being initialized. - -In ISO C99 you can give the elements in any order, specifying the array -indices or structure field names they apply to, and GNU C allows this as -an extension in C89 mode as well. This extension is not -implemented in GNU C++. - -To specify an array index, write -@samp{[@var{index}] =} before the element value. For example, - -@smallexample -int a[6] = @{ [4] = 29, [2] = 15 @}; -@end smallexample - -@noindent -is equivalent to - -@smallexample -int a[6] = @{ 0, 0, 15, 0, 29, 0 @}; -@end smallexample - -@noindent -The index values must be constant expressions, even if the array being -initialized is automatic. - -An alternative syntax for this which has been obsolete since GCC 2.5 but -GCC still accepts is to write @samp{[@var{index}]} before the element -value, with no @samp{=}. - -To initialize a range of elements to the same value, write -@samp{[@var{first} ... @var{last}] = @var{value}}. This is a GNU -extension. For example, - -@smallexample -int widths[] = @{ [0 ... 9] = 1, [10 ... 99] = 2, [100] = 3 @}; -@end smallexample - -@noindent -If the value in it has side-effects, the side-effects will happen only once, -not for each initialized field by the range initializer. - -@noindent -Note that the length of the array is the highest value specified -plus one. - -In a structure initializer, specify the name of a field to initialize -with @samp{.@var{fieldname} =} before the element value. For example, -given the following structure, - -@smallexample -struct point @{ int x, y; @}; -@end smallexample - -@noindent -the following initialization - -@smallexample -struct point p = @{ .y = yvalue, .x = xvalue @}; -@end smallexample - -@noindent -is equivalent to - -@smallexample -struct point p = @{ xvalue, yvalue @}; -@end smallexample - -Another syntax which has the same meaning, obsolete since GCC 2.5, is -@samp{@var{fieldname}:}, as shown here: - -@smallexample -struct point p = @{ y: yvalue, x: xvalue @}; -@end smallexample - -@cindex designators -The @samp{[@var{index}]} or @samp{.@var{fieldname}} is known as a -@dfn{designator}. You can also use a designator (or the obsolete colon -syntax) when initializing a union, to specify which element of the union -should be used. For example, - -@smallexample -union foo @{ int i; double d; @}; - -union foo f = @{ .d = 4 @}; -@end smallexample - -@noindent -will convert 4 to a @code{double} to store it in the union using -the second element. By contrast, casting 4 to type @code{union foo} -would store it into the union as the integer @code{i}, since it is -an integer. (@xref{Cast to Union}.) - -You can combine this technique of naming elements with ordinary C -initialization of successive elements. Each initializer element that -does not have a designator applies to the next consecutive element of the -array or structure. For example, - -@smallexample -int a[6] = @{ [1] = v1, v2, [4] = v4 @}; -@end smallexample - -@noindent -is equivalent to - -@smallexample -int a[6] = @{ 0, v1, v2, 0, v4, 0 @}; -@end smallexample - -Labeling the elements of an array initializer is especially useful -when the indices are characters or belong to an @code{enum} type. -For example: - -@smallexample -int whitespace[256] - = @{ [' '] = 1, ['\t'] = 1, ['\h'] = 1, - ['\f'] = 1, ['\n'] = 1, ['\r'] = 1 @}; -@end smallexample - -@cindex designator lists -You can also write a series of @samp{.@var{fieldname}} and -@samp{[@var{index}]} designators before an @samp{=} to specify a -nested subobject to initialize; the list is taken relative to the -subobject corresponding to the closest surrounding brace pair. For -example, with the @samp{struct point} declaration above: - -@smallexample -struct point ptarray[10] = @{ [2].y = yv2, [2].x = xv2, [0].x = xv0 @}; -@end smallexample - -@noindent -If the same field is initialized multiple times, it will have value from -the last initialization. If any such overridden initialization has -side-effect, it is unspecified whether the side-effect happens or not. -Currently, GCC will discard them and issue a warning. - -@node Case Ranges -@section Case Ranges -@cindex case ranges -@cindex ranges in case statements - -You can specify a range of consecutive values in a single @code{case} label, -like this: - -@smallexample -case @var{low} ... @var{high}: -@end smallexample - -@noindent -This has the same effect as the proper number of individual @code{case} -labels, one for each integer value from @var{low} to @var{high}, inclusive. - -This feature is especially useful for ranges of ASCII character codes: - -@smallexample -case 'A' ... 'Z': -@end smallexample - -@strong{Be careful:} Write spaces around the @code{...}, for otherwise -it may be parsed wrong when you use it with integer values. For example, -write this: - -@smallexample -case 1 ... 5: -@end smallexample - -@noindent -rather than this: - -@smallexample -case 1...5: -@end smallexample - -@node Cast to Union -@section Cast to a Union Type -@cindex cast to a union -@cindex union, casting to a - -A cast to union type is similar to other casts, except that the type -specified is a union type. You can specify the type either with -@code{union @var{tag}} or with a typedef name. A cast to union is actually -a constructor though, not a cast, and hence does not yield an lvalue like -normal casts. (@xref{Compound Literals}.) - -The types that may be cast to the union type are those of the members -of the union. Thus, given the following union and variables: - -@smallexample -union foo @{ int i; double d; @}; -int x; -double y; -@end smallexample - -@noindent -both @code{x} and @code{y} can be cast to type @code{union foo}. - -Using the cast as the right-hand side of an assignment to a variable of -union type is equivalent to storing in a member of the union: - -@smallexample -union foo u; -/* @r{@dots{}} */ -u = (union foo) x @equiv{} u.i = x -u = (union foo) y @equiv{} u.d = y -@end smallexample - -You can also use the union cast as a function argument: - -@smallexample -void hack (union foo); -/* @r{@dots{}} */ -hack ((union foo) x); -@end smallexample - -@node Mixed Declarations -@section Mixed Declarations and Code -@cindex mixed declarations and code -@cindex declarations, mixed with code -@cindex code, mixed with declarations - -ISO C99 and ISO C++ allow declarations and code to be freely mixed -within compound statements. As an extension, GCC also allows this in -C89 mode. For example, you could do: - -@smallexample -int i; -/* @r{@dots{}} */ -i++; -int j = i + 2; -@end smallexample - -Each identifier is visible from where it is declared until the end of -the enclosing block. - -@node Function Attributes -@section Declaring Attributes of Functions -@cindex function attributes -@cindex declaring attributes of functions -@cindex functions that never return -@cindex functions that return more than once -@cindex functions that have no side effects -@cindex functions in arbitrary sections -@cindex functions that behave like malloc -@cindex @code{volatile} applied to function -@cindex @code{const} applied to function -@cindex functions with @code{printf}, @code{scanf}, @code{strftime} or @code{strfmon} style arguments -@cindex functions with non-null pointer arguments -@cindex functions that are passed arguments in registers on the 386 -@cindex functions that pop the argument stack on the 386 -@cindex functions that do not pop the argument stack on the 386 - -In GNU C, you declare certain things about functions called in your program -which help the compiler optimize function calls and check your code more -carefully. - -The keyword @code{__attribute__} allows you to specify special -attributes when making a declaration. This keyword is followed by an -attribute specification inside double parentheses. The following -attributes are currently defined for functions on all targets: -@c APPLE LOCAL mainline aligned functions 5933878 -@code{aligned}, -@code{noreturn}, @code{returns_twice}, @code{noinline}, @code{always_inline}, -@c APPLE LOCAL nodebug -@code{nodebug}, -@c APPLE LOCAL regparmandstackparm -@code{regparmandstackparm}, -@code{flatten}, @code{pure}, @code{const}, @code{nothrow}, @code{sentinel}, -@code{format}, @code{format_arg}, @code{no_instrument_function}, -@code{section}, @code{constructor}, @code{destructor}, @code{used}, -@code{unused}, @code{deprecated}, @code{weak}, @code{malloc}, -@code{alias}, @code{warn_unused_result}, @code{nonnull}, -@code{gnu_inline} and @code{externally_visible}. Several other -attributes are defined for functions on particular target systems. Other -attributes, including @code{section} are supported for variables declarations -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -(@pxref{Variable Attributes}), for types (@pxref{Type Attributes}), -and labels (@pxref{Label Attributes}). - -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -You may also specify attributes with @samp{__} preceding and following -each keyword. This allows you to use them in header files without -being concerned about a possible macro of the same name. For example, -you may use @code{__noreturn__} instead of @code{noreturn}. - -@xref{Attribute Syntax}, for details of the exact syntax for using -attributes. - -@table @code -@c Keep this table alphabetized by attribute name. Treat _ as space. - -@item alias ("@var{target}") -@cindex @code{alias} attribute -The @code{alias} attribute causes the declaration to be emitted as an -alias for another symbol, which must be specified. For instance, - -@smallexample -void __f () @{ /* @r{Do something.} */; @} -void f () __attribute__ ((weak, alias ("__f"))); -@end smallexample - -defines @samp{f} to be a weak alias for @samp{__f}. In C++, the -mangled name for the target must be used. It is an error if @samp{__f} -is not defined in the same translation unit. - -Not all target machines support this attribute. - -@c APPLE LOCAL begin mainline aligned functions 5933878 -@item aligned (@var{alignment}) -@cindex @code{aligned} attribute -This attribute specifies a minimum alignment for the function, -measured in bytes. - -You cannot use this attribute to decrease the alignment of a function, -only to increase it. However, when you explicitly specify a function -alignment this will override the effect of the -@option{-falign-functions} (@pxref{Optimize Options}) option for this -function. - -Note that the effectiveness of @code{aligned} attributes may be -limited by inherent limitations in your linker. On many systems, the -linker is only able to arrange for functions to be aligned up to a -certain maximum alignment. (For some linkers, the maximum supported -alignment may be very very small.) See your linker documentation for -further information. - -The @code{aligned} attribute can also be used for variables and fields -(@pxref{Variable Attributes}.) -@c APPLE LOCAL end mainline aligned functions 5933878 - -@item always_inline -@cindex @code{always_inline} function attribute -Generally, functions are not inlined unless optimization is specified. -For functions declared inline, this attribute inlines the function even -if no optimization level was specified. - -@item gnu_inline -@cindex @code{gnu_inline} function attribute -This attribute should be used with a function which is also declared -with the @code{inline} keyword. It directs GCC to treat the function -as if it were defined in gnu89 mode even when compiling in C99 or -gnu99 mode. - -If the function is declared @code{extern}, then this definition of the -function is used only for inlining. In no case is the function -compiled as a standalone function, not even if you take its address -explicitly. Such an address becomes an external reference, as if you -had only declared the function, and had not defined it. This has -almost the effect of a macro. The way to use this is to put a -function definition in a header file with this attribute, and put -another copy of the function, without @code{extern}, in a library -file. The definition in the header file will cause most calls to the -function to be inlined. If any uses of the function remain, they will -refer to the single copy in the library. Note that the two -definitions of the functions need not be precisely the same, although -if they do not have the same effect your program may behave oddly. - -If the function is neither @code{extern} nor @code{static}, then the -function is compiled as a standalone function, as well as being -inlined where possible. - -This is how GCC traditionally handled functions declared -@code{inline}. Since ISO C99 specifies a different semantics for -@code{inline}, this function attribute is provided as a transition -measure and as a useful feature in its own right. This attribute is -available in GCC 4.1.3 and later. It is available if either of the -preprocessor macros @code{__GNUC_GNU_INLINE__} or -@code{__GNUC_STDC_INLINE__} are defined. @xref{Inline,,An Inline -Function is As Fast As a Macro}. - -Note that since the first version of GCC to support C99 inline semantics -/* APPLE LOCAL extern inline */ -is 4.3 (4.2 for Apple's gcc), earlier versions of GCC which accept this attribute effectively -assume that it is always present, whether or not it is given explicitly. -/* APPLE LOCAL extern inline */ -In versions prior to 4.3 (4.2 for Apple's gcc), the only effect of explicitly including it is -to disable warnings about using inline functions in C99 mode. - -@c APPLE LOCAL begin nodebug -@item nodebug -@cindex @code{nodebug} function attribute -This attribute prevents debug information to be generated for the function. -This is to avoid stepping into the function which is of no interest to the -user how it is implemented. An example is the x86 vector intrinsics. -This is temporary and will be removed in some future version of the compiler. -@c APPLE LOCAL end nodebug - -@cindex @code{flatten} function attribute -@item flatten -Generally, inlining into a function is limited. For a function marked with -this attribute, every call inside this function will be inlined, if possible. -Whether the function itself is considered for inlining depends on its size and -the current inlining parameters. The @code{flatten} attribute only works -reliably in unit-at-a-time mode. - -@item cdecl -@cindex functions that do pop the argument stack on the 386 -@opindex mrtd -On the Intel 386, the @code{cdecl} attribute causes the compiler to -assume that the calling function will pop off the stack space used to -pass arguments. This is -useful to override the effects of the @option{-mrtd} switch. - -@item const -@cindex @code{const} function attribute -Many functions do not examine any values except their arguments, and -have no effects except the return value. Basically this is just slightly -more strict class than the @code{pure} attribute below, since function is not -allowed to read global memory. - -@cindex pointer arguments -Note that a function that has pointer arguments and examines the data -pointed to must @emph{not} be declared @code{const}. Likewise, a -function that calls a non-@code{const} function usually must not be -@code{const}. It does not make sense for a @code{const} function to -return @code{void}. - -The attribute @code{const} is not implemented in GCC versions earlier -than 2.5. An alternative way to declare that a function has no side -effects, which works in the current version and in some older versions, -is as follows: - -@smallexample -typedef int intfn (); - -extern const intfn square; -@end smallexample - -This approach does not work in GNU C++ from 2.6.0 on, since the language -specifies that the @samp{const} must be attached to the return value. - -@item constructor -@itemx destructor -@cindex @code{constructor} function attribute -@cindex @code{destructor} function attribute -The @code{constructor} attribute causes the function to be called -automatically before execution enters @code{main ()}. Similarly, the -@code{destructor} attribute causes the function to be called -automatically after @code{main ()} has completed or @code{exit ()} has -been called. Functions with these attributes are useful for -initializing data that will be used implicitly during the execution of -the program. - -These attributes are not currently implemented for Objective-C@. - -@item deprecated -@cindex @code{deprecated} attribute. -The @code{deprecated} attribute results in a warning if the function -is used anywhere in the source file. This is useful when identifying -functions that are expected to be removed in a future version of a -program. The warning also includes the location of the declaration -of the deprecated function, to enable users to easily find further -information about why the function is deprecated, or what they should -do instead. Note that the warnings only occurs for uses: - -@smallexample -int old_fn () __attribute__ ((deprecated)); -int old_fn (); -int (*fn_ptr)() = old_fn; -@end smallexample - -results in a warning on line 3 but not line 2. - -The @code{deprecated} attribute can also be used for variables and -types (@pxref{Variable Attributes}, @pxref{Type Attributes}.) - -@item dllexport -@cindex @code{__declspec(dllexport)} -On Microsoft Windows targets and Symbian OS targets the -@code{dllexport} attribute causes the compiler to provide a global -pointer to a pointer in a DLL, so that it can be referenced with the -@code{dllimport} attribute. On Microsoft Windows targets, the pointer -name is formed by combining @code{_imp__} and the function or variable -name. - -You can use @code{__declspec(dllexport)} as a synonym for -@code{__attribute__ ((dllexport))} for compatibility with other -compilers. - -On systems that support the @code{visibility} attribute, this -attribute also implies ``default'' visibility, unless a -@code{visibility} attribute is explicitly specified. You should avoid -the use of @code{dllexport} with ``hidden'' or ``internal'' -visibility; in the future GCC may issue an error for those cases. - -Currently, the @code{dllexport} attribute is ignored for inlined -functions, unless the @option{-fkeep-inline-functions} flag has been -used. The attribute is also ignored for undefined symbols. - -When applied to C++ classes, the attribute marks defined non-inlined -member functions and static data members as exports. Static consts -initialized in-class are not marked unless they are also defined -out-of-class. - -For Microsoft Windows targets there are alternative methods for -including the symbol in the DLL's export table such as using a -@file{.def} file with an @code{EXPORTS} section or, with GNU ld, using -the @option{--export-all} linker flag. - -@item dllimport -@cindex @code{__declspec(dllimport)} -On Microsoft Windows and Symbian OS targets, the @code{dllimport} -attribute causes the compiler to reference a function or variable via -a global pointer to a pointer that is set up by the DLL exporting the -symbol. The attribute implies @code{extern} storage. On Microsoft -Windows targets, the pointer name is formed by combining @code{_imp__} -and the function or variable name. - -You can use @code{__declspec(dllimport)} as a synonym for -@code{__attribute__ ((dllimport))} for compatibility with other -compilers. - -Currently, the attribute is ignored for inlined functions. If the -attribute is applied to a symbol @emph{definition}, an error is reported. -If a symbol previously declared @code{dllimport} is later defined, the -attribute is ignored in subsequent references, and a warning is emitted. -The attribute is also overridden by a subsequent declaration as -@code{dllexport}. - -When applied to C++ classes, the attribute marks non-inlined -member functions and static data members as imports. However, the -attribute is ignored for virtual methods to allow creation of vtables -using thunks. - -On the SH Symbian OS target the @code{dllimport} attribute also has -another affect---it can cause the vtable and run-time type information -for a class to be exported. This happens when the class has a -dllimport'ed constructor or a non-inline, non-pure virtual function -and, for either of those two conditions, the class also has a inline -constructor or destructor and has a key function that is defined in -the current translation unit. - -For Microsoft Windows based targets the use of the @code{dllimport} -attribute on functions is not necessary, but provides a small -performance benefit by eliminating a thunk in the DLL@. The use of the -@code{dllimport} attribute on imported variables was required on older -versions of the GNU linker, but can now be avoided by passing the -@option{--enable-auto-import} switch to the GNU linker. As with -functions, using the attribute for a variable eliminates a thunk in -the DLL@. - -One drawback to using this attribute is that a pointer to a function -or variable marked as @code{dllimport} cannot be used as a constant -address. On Microsoft Windows targets, the attribute can be disabled -for functions by setting the @option{-mnop-fun-dllimport} flag. - -@item eightbit_data -@cindex eight bit data on the H8/300, H8/300H, and H8S -Use this attribute on the H8/300, H8/300H, and H8S to indicate that the specified -variable should be placed into the eight bit data section. -The compiler will generate more efficient code for certain operations -on data in the eight bit data area. Note the eight bit data area is limited to -256 bytes of data. - -You must use GAS and GLD from GNU binutils version 2.7 or later for -this attribute to work correctly. - -@item exception_handler -@cindex exception handler functions on the Blackfin processor -Use this attribute on the Blackfin to indicate that the specified function -is an exception handler. The compiler will generate function entry and -exit sequences suitable for use in an exception handler when this -attribute is present. - -@item far -@cindex functions which handle memory bank switching -On 68HC11 and 68HC12 the @code{far} attribute causes the compiler to -use a calling convention that takes care of switching memory banks when -entering and leaving a function. This calling convention is also the -default when using the @option{-mlong-calls} option. - -On 68HC12 the compiler will use the @code{call} and @code{rtc} instructions -to call and return from a function. - -On 68HC11 the compiler will generate a sequence of instructions -to invoke a board-specific routine to switch the memory bank and call the -real function. The board-specific routine simulates a @code{call}. -At the end of a function, it will jump to a board-specific routine -instead of using @code{rts}. The board-specific return routine simulates -the @code{rtc}. - -@item fastcall -@cindex functions that pop the argument stack on the 386 -On the Intel 386, the @code{fastcall} attribute causes the compiler to -pass the first argument (if of integral type) in the register ECX and -the second argument (if of integral type) in the register EDX@. Subsequent -and other typed arguments are passed on the stack. The called function will -pop the arguments off the stack. If the number of arguments is variable all -arguments are pushed on the stack. - -@item format (@var{archetype}, @var{string-index}, @var{first-to-check}) -@cindex @code{format} function attribute -@opindex Wformat -The @code{format} attribute specifies that a function takes @code{printf}, -@code{scanf}, @code{strftime} or @code{strfmon} style arguments which -should be type-checked against a format string. For example, the -declaration: - -@smallexample -extern int -my_printf (void *my_object, const char *my_format, ...) - __attribute__ ((format (printf, 2, 3))); -@end smallexample - -@noindent -causes the compiler to check the arguments in calls to @code{my_printf} -for consistency with the @code{printf} style format string argument -@code{my_format}. - -The parameter @var{archetype} determines how the format string is -interpreted, and should be @code{printf}, @code{scanf}, @code{strftime} -or @code{strfmon}. (You can also use @code{__printf__}, -@code{__scanf__}, @code{__strftime__} or @code{__strfmon__}.) The -parameter @var{string-index} specifies which argument is the format -string argument (starting from 1), while @var{first-to-check} is the -number of the first argument to check against the format string. For -functions where the arguments are not available to be checked (such as -@code{vprintf}), specify the third parameter as zero. In this case the -compiler only checks the format string for consistency. For -@code{strftime} formats, the third parameter is required to be zero. -Since non-static C++ methods have an implicit @code{this} argument, the -arguments of such methods should be counted from two, not one, when -giving values for @var{string-index} and @var{first-to-check}. - -In the example above, the format string (@code{my_format}) is the second -argument of the function @code{my_print}, and the arguments to check -start with the third argument, so the correct parameters for the format -attribute are 2 and 3. - -@opindex ffreestanding -@opindex fno-builtin -The @code{format} attribute allows you to identify your own functions -which take format strings as arguments, so that GCC can check the -calls to these functions for errors. The compiler always (unless -@option{-ffreestanding} or @option{-fno-builtin} is used) checks formats -for the standard library functions @code{printf}, @code{fprintf}, -@code{sprintf}, @code{scanf}, @code{fscanf}, @code{sscanf}, @code{strftime}, -@code{vprintf}, @code{vfprintf} and @code{vsprintf} whenever such -warnings are requested (using @option{-Wformat}), so there is no need to -modify the header file @file{stdio.h}. In C99 mode, the functions -@code{snprintf}, @code{vsnprintf}, @code{vscanf}, @code{vfscanf} and -@code{vsscanf} are also checked. Except in strictly conforming C -standard modes, the X/Open function @code{strfmon} is also checked as -are @code{printf_unlocked} and @code{fprintf_unlocked}. -@xref{C Dialect Options,,Options Controlling C Dialect}. - -The target may provide additional types of format checks. -@xref{Target Format Checks,,Format Checks Specific to Particular -Target Machines}. - -@item format_arg (@var{string-index}) -@cindex @code{format_arg} function attribute -@opindex Wformat-nonliteral -The @code{format_arg} attribute specifies that a function takes a format -string for a @code{printf}, @code{scanf}, @code{strftime} or -@code{strfmon} style function and modifies it (for example, to translate -it into another language), so the result can be passed to a -@code{printf}, @code{scanf}, @code{strftime} or @code{strfmon} style -function (with the remaining arguments to the format function the same -as they would have been for the unmodified string). For example, the -declaration: - -@smallexample -extern char * -my_dgettext (char *my_domain, const char *my_format) - __attribute__ ((format_arg (2))); -@end smallexample - -@noindent -causes the compiler to check the arguments in calls to a @code{printf}, -@code{scanf}, @code{strftime} or @code{strfmon} type function, whose -format string argument is a call to the @code{my_dgettext} function, for -consistency with the format string argument @code{my_format}. If the -@code{format_arg} attribute had not been specified, all the compiler -could tell in such calls to format functions would be that the format -string argument is not constant; this would generate a warning when -@option{-Wformat-nonliteral} is used, but the calls could not be checked -without the attribute. - -The parameter @var{string-index} specifies which argument is the format -string argument (starting from one). Since non-static C++ methods have -an implicit @code{this} argument, the arguments of such methods should -be counted from two. - -The @code{format-arg} attribute allows you to identify your own -functions which modify format strings, so that GCC can check the -calls to @code{printf}, @code{scanf}, @code{strftime} or @code{strfmon} -type function whose operands are a call to one of your own function. -The compiler always treats @code{gettext}, @code{dgettext}, and -@code{dcgettext} in this manner except when strict ISO C support is -requested by @option{-ansi} or an appropriate @option{-std} option, or -@option{-ffreestanding} or @option{-fno-builtin} -is used. @xref{C Dialect Options,,Options -Controlling C Dialect}. - -@item function_vector -@cindex calling functions through the function vector on the H8/300 processors -Use this attribute on the H8/300, H8/300H, and H8S to indicate that the specified -function should be called through the function vector. Calling a -function through the function vector will reduce code size, however; -the function vector has a limited size (maximum 128 entries on the H8/300 -and 64 entries on the H8/300H and H8S) and shares space with the interrupt vector. - -You must use GAS and GLD from GNU binutils version 2.7 or later for -this attribute to work correctly. - -@item interrupt -@cindex interrupt handler functions -Use this attribute on the ARM, AVR, C4x, CRX, M32C, M32R/D, MS1, and Xstormy16 -ports to indicate that the specified function is an interrupt handler. -The compiler will generate function entry and exit sequences suitable -for use in an interrupt handler when this attribute is present. - -Note, interrupt handlers for the Blackfin, m68k, H8/300, H8/300H, H8S, and -SH processors can be specified via the @code{interrupt_handler} attribute. - -Note, on the AVR, interrupts will be enabled inside the function. - -Note, for the ARM, you can specify the kind of interrupt to be handled by -adding an optional parameter to the interrupt attribute like this: - -@smallexample -void f () __attribute__ ((interrupt ("IRQ"))); -@end smallexample - -Permissible values for this parameter are: IRQ, FIQ, SWI, ABORT and UNDEF@. - -@item interrupt_handler -@cindex interrupt handler functions on the Blackfin, m68k, H8/300 and SH processors -Use this attribute on the Blackfin, m68k, H8/300, H8/300H, H8S, and SH to -indicate that the specified function is an interrupt handler. The compiler -will generate function entry and exit sequences suitable for use in an -interrupt handler when this attribute is present. - -@item kspisusp -@cindex User stack pointer in interrupts on the Blackfin -When used together with @code{interrupt_handler}, @code{exception_handler} -or @code{nmi_handler}, code will be generated to load the stack pointer -from the USP register in the function prologue. - -@c APPLE LOCAL prune man page -@ignore -@item long_call/short_call -@cindex indirect calls on ARM -This attribute specifies how a particular function is called on -ARM@. Both attributes override the @option{-mlong-calls} (@pxref{ARM Options}) -command line switch and @code{#pragma long_calls} settings. The -@code{long_call} attribute indicates that the function might be far -away from the call site and require a different (more expensive) -calling sequence. The @code{short_call} attribute always places -the offset to the function from the call site into the @samp{BL} -instruction directly. -@c APPLE LOCAL prune man page -@end ignore - -@item longcall/shortcall -@cindex functions called via pointer on the RS/6000 and PowerPC -On the Blackfin, RS/6000 and PowerPC, the @code{longcall} attribute -indicates that the function might be far away from the call site and -require a different (more expensive) calling sequence. The -@code{shortcall} attribute indicates that the function is always close -enough for the shorter calling sequence to be used. These attributes -override both the @option{-mlongcall} switch and, on the RS/6000 and -PowerPC, the @code{#pragma longcall} setting. - -@xref{RS/6000 and PowerPC Options}, for more information on whether long -calls are necessary. - -@c APPLE LOCAL prune man page -@ignore -@item long_call -@cindex indirect calls on MIPS -This attribute specifies how a particular function is called on MIPS@. -The attribute overrides the @option{-mlong-calls} (@pxref{MIPS Options}) -command line switch. This attribute causes the compiler to always call -the function by first loading its address into a register, and then using -the contents of that register. -@c APPLE LOCAL prune man page -@end ignore - -@item malloc -@cindex @code{malloc} attribute -The @code{malloc} attribute is used to tell the compiler that a function -may be treated as if any non-@code{NULL} pointer it returns cannot -alias any other pointer valid when the function returns. -This will often improve optimization. -Standard functions with this property include @code{malloc} and -@code{calloc}. @code{realloc}-like functions have this property as -long as the old pointer is never referred to (including comparing it -to the new pointer) after the function returns a non-@code{NULL} -value. - -@item model (@var{model-name}) -@cindex function addressability on the M32R/D -@cindex variable addressability on the IA-64 - -On the M32R/D, use this attribute to set the addressability of an -object, and of the code generated for a function. The identifier -@var{model-name} is one of @code{small}, @code{medium}, or -@code{large}, representing each of the code models. - -Small model objects live in the lower 16MB of memory (so that their -addresses can be loaded with the @code{ld24} instruction), and are -callable with the @code{bl} instruction. - -Medium model objects may live anywhere in the 32-bit address space (the -compiler will generate @code{seth/add3} instructions to load their addresses), -and are callable with the @code{bl} instruction. - -Large model objects may live anywhere in the 32-bit address space (the -compiler will generate @code{seth/add3} instructions to load their addresses), -and may not be reachable with the @code{bl} instruction (the compiler will -generate the much slower @code{seth/add3/jl} instruction sequence). - -On IA-64, use this attribute to set the addressability of an object. -At present, the only supported identifier for @var{model-name} is -@code{small}, indicating addressability via ``small'' (22-bit) -addresses (so that their addresses can be loaded with the @code{addl} -instruction). Caveat: such addressing is by definition not position -independent and hence this attribute must not be used for objects -defined by shared libraries. - -@item naked -@cindex function without a prologue/epilogue code -Use this attribute on the ARM, AVR, C4x and IP2K ports to indicate that the -specified function does not need prologue/epilogue sequences generated by -the compiler. It is up to the programmer to provide these sequences. - -@item near -@cindex functions which do not handle memory bank switching on 68HC11/68HC12 -On 68HC11 and 68HC12 the @code{near} attribute causes the compiler to -use the normal calling convention based on @code{jsr} and @code{rts}. -This attribute can be used to cancel the effect of the @option{-mlong-calls} -option. - -@item nesting -@cindex Allow nesting in an interrupt handler on the Blackfin processor. -Use this attribute together with @code{interrupt_handler}, -@code{exception_handler} or @code{nmi_handler} to indicate that the function -entry code should enable nested interrupts or exceptions. - -@item nmi_handler -@cindex NMI handler functions on the Blackfin processor -Use this attribute on the Blackfin to indicate that the specified function -is an NMI handler. The compiler will generate function entry and -exit sequences suitable for use in an NMI handler when this -attribute is present. - -@item no_instrument_function -@cindex @code{no_instrument_function} function attribute -@opindex finstrument-functions -If @option{-finstrument-functions} is given, profiling function calls will -be generated at entry and exit of most user-compiled functions. -Functions with this attribute will not be so instrumented. - -@item noinline -@cindex @code{noinline} function attribute -This function attribute prevents a function from being considered for -inlining. - -@item nonnull (@var{arg-index}, @dots{}) -@cindex @code{nonnull} function attribute -The @code{nonnull} attribute specifies that some function parameters should -be non-null pointers. For instance, the declaration: - -@smallexample -extern void * -my_memcpy (void *dest, const void *src, size_t len) - __attribute__((nonnull (1, 2))); -@end smallexample - -@noindent -causes the compiler to check that, in calls to @code{my_memcpy}, -arguments @var{dest} and @var{src} are non-null. If the compiler -determines that a null pointer is passed in an argument slot marked -as non-null, and the @option{-Wnonnull} option is enabled, a warning -is issued. The compiler may also choose to make optimizations based -on the knowledge that certain function arguments will not be null. - -If no argument index list is given to the @code{nonnull} attribute, -all pointer arguments are marked as non-null. To illustrate, the -following declaration is equivalent to the previous example: - -@smallexample -extern void * -my_memcpy (void *dest, const void *src, size_t len) - __attribute__((nonnull)); -@end smallexample - -@item noreturn -@cindex @code{noreturn} function attribute -A few standard library functions, such as @code{abort} and @code{exit}, -cannot return. GCC knows this automatically. Some programs define -their own functions that never return. You can declare them -@code{noreturn} to tell the compiler this fact. For example, - -@smallexample -@group -void fatal () __attribute__ ((noreturn)); - -void -fatal (/* @r{@dots{}} */) -@{ - /* @r{@dots{}} */ /* @r{Print error message.} */ /* @r{@dots{}} */ - exit (1); -@} -@end group -@end smallexample - -The @code{noreturn} keyword tells the compiler to assume that -@code{fatal} cannot return. It can then optimize without regard to what -would happen if @code{fatal} ever did return. This makes slightly -better code. More importantly, it helps avoid spurious warnings of -uninitialized variables. - -The @code{noreturn} keyword does not affect the exceptional path when that -applies: a @code{noreturn}-marked function may still return to the caller -by throwing an exception or calling @code{longjmp}. - -Do not assume that registers saved by the calling function are -restored before calling the @code{noreturn} function. - -It does not make sense for a @code{noreturn} function to have a return -type other than @code{void}. - -The attribute @code{noreturn} is not implemented in GCC versions -earlier than 2.5. An alternative way to declare that a function does -not return, which works in the current version and in some older -versions, is as follows: - -@smallexample -typedef void voidfn (); - -volatile voidfn fatal; -@end smallexample - -This approach does not work in GNU C++. - -@item nothrow -@cindex @code{nothrow} function attribute -The @code{nothrow} attribute is used to inform the compiler that a -function cannot throw an exception. For example, most functions in -the standard C library can be guaranteed not to throw an exception -with the notable exceptions of @code{qsort} and @code{bsearch} that -take function pointer arguments. The @code{nothrow} attribute is not -implemented in GCC versions earlier than 3.3. - -@item pure -@cindex @code{pure} function attribute -Many functions have no effects except the return value and their -return value depends only on the parameters and/or global variables. -Such a function can be subject -to common subexpression elimination and loop optimization just as an -arithmetic operator would be. These functions should be declared -with the attribute @code{pure}. For example, - -@smallexample -int square (int) __attribute__ ((pure)); -@end smallexample - -@noindent -says that the hypothetical function @code{square} is safe to call -fewer times than the program says. - -Some of common examples of pure functions are @code{strlen} or @code{memcmp}. -Interesting non-pure functions are functions with infinite loops or those -depending on volatile memory or other system resource, that may change between -two consecutive calls (such as @code{feof} in a multithreading environment). - -The attribute @code{pure} is not implemented in GCC versions earlier -than 2.96. - -@item regparm (@var{number}) -@cindex @code{regparm} attribute -@cindex functions that are passed arguments in registers on the 386 -On the Intel 386, the @code{regparm} attribute causes the compiler to -pass arguments number one to @var{number} if they are of integral type -in registers EAX, EDX, and ECX instead of on the stack. Functions that -take a variable number of arguments will continue to be passed all of their -arguments on the stack. - -Beware that on some ELF systems this attribute is unsuitable for -global functions in shared libraries with lazy binding (which is the -default). Lazy binding will send the first call via resolving code in -the loader, which might assume EAX, EDX and ECX can be clobbered, as -per the standard calling conventions. Solaris 8 is affected by this. -GNU systems with GLIBC 2.1 or higher, and FreeBSD, are believed to be -safe since the loaders there save all registers. (Lazy binding can be -disabled with the linker or the loader if desired, to avoid the -problem.) - -@item sseregparm -@cindex @code{sseregparm} attribute -On the Intel 386 with SSE support, the @code{sseregparm} attribute -causes the compiler to pass up to 3 floating point arguments in -SSE registers instead of on the stack. Functions that take a -variable number of arguments will continue to pass all of their -floating point arguments on the stack. - -@item force_align_arg_pointer -@cindex @code{force_align_arg_pointer} attribute -On the Intel x86, the @code{force_align_arg_pointer} attribute may be -applied to individual function definitions, generating an alternate -prologue and epilogue that realigns the runtime stack. This supports -mixing legacy codes that run with a 4-byte aligned stack with modern -codes that keep a 16-byte stack for SSE compatibility. The alternate -prologue and epilogue are slower and bigger than the regular ones, and -the alternate prologue requires a scratch register; this lowers the -number of registers available if used in conjunction with the -@code{regparm} attribute. The @code{force_align_arg_pointer} -attribute is incompatible with nested functions; this is considered a -hard error. - -@item returns_twice -@cindex @code{returns_twice} attribute -The @code{returns_twice} attribute tells the compiler that a function may -return more than one time. The compiler will ensure that all registers -are dead before calling such a function and will emit a warning about -the variables that may be clobbered after the second return from the -function. Examples of such functions are @code{setjmp} and @code{vfork}. -The @code{longjmp}-like counterpart of such function, if any, might need -to be marked with the @code{noreturn} attribute. - -@item saveall -@cindex save all registers on the Blackfin, H8/300, H8/300H, and H8S -Use this attribute on the Blackfin, H8/300, H8/300H, and H8S to indicate that -all registers except the stack pointer should be saved in the prologue -regardless of whether they are used or not. - -@item section ("@var{section-name}") -@cindex @code{section} function attribute -Normally, the compiler places the code it generates in the @code{text} section. -Sometimes, however, you need additional sections, or you need certain -particular functions to appear in special sections. The @code{section} -attribute specifies that a function lives in a particular section. -For example, the declaration: - -@smallexample -extern void foobar (void) __attribute__ ((section ("bar"))); -@end smallexample - -@noindent -puts the function @code{foobar} in the @code{bar} section. - -Some file formats do not support arbitrary sections so the @code{section} -attribute is not available on all platforms. -If you need to map the entire contents of a module to a particular -section, consider using the facilities of the linker instead. - -@item sentinel -@cindex @code{sentinel} function attribute -This function attribute ensures that a parameter in a function call is -an explicit @code{NULL}. The attribute is only valid on variadic -functions. By default, the sentinel is located at position zero, the -last parameter of the function call. If an optional integer position -argument P is supplied to the attribute, the sentinel must be located at -position P counting backwards from the end of the argument list. - -@smallexample -__attribute__ ((sentinel)) -is equivalent to -__attribute__ ((sentinel(0))) -@end smallexample - -The attribute is automatically set with a position of 0 for the built-in -functions @code{execl} and @code{execlp}. The built-in function -@code{execle} has the attribute set with a position of 1. - -A valid @code{NULL} in this context is defined as zero with any pointer -type. If your system defines the @code{NULL} macro with an integer type -then you need to add an explicit cast. GCC replaces @code{stddef.h} -with a copy that redefines NULL appropriately. - -The warnings for missing or incorrect sentinels are enabled with -@option{-Wformat}. - -@item short_call -See long_call/short_call. - -@item shortcall -See longcall/shortcall. - -@item signal -@cindex signal handler functions on the AVR processors -Use this attribute on the AVR to indicate that the specified -function is a signal handler. The compiler will generate function -entry and exit sequences suitable for use in a signal handler when this -attribute is present. Interrupts will be disabled inside the function. - -@c APPLE LOCAL begin regparmandstackparm -@item regparmandstackparm - -This is an X86_32-specific attribute. - -Two entry points will be created for this function. One will have the -traditional calling convention, and the other will have a mangled name -and a register-based calling convention. - -The register-based calling convention will pass up to four float or -double values in XMM registers, and up to two integral values in -integer registers. Long double values are still passed on the stack, -and functions returning long double will still use the x87 stacktop. - -Other modules linked with this function may use either entry point. -If a calling module has seen an extern declaration with the -@code{regparmandstackparm} attribute, it will call the register-based -entry point; otherwise, it will use the traditional entry point in the -usual way. - -When taking the address of a @code{regparmandstackparm} function, the -address of the traditional entry point will be used. Calls through -function pointers always use the traditional calling convention. - -The mangled name is currently created by appending ``$3SSE'' to the -original function name (before any C++ name-mangling), but users -should not rely upon this. - -The current implementation associates the original function body with -the register-based entry point. The traditional entry point will load -some registers from the stack and call the register-based entry point. -This means the traditional entry point will be slightly less efficient -than a function without the @code{regparmandstackparm} attribute, and the -generated code will be slightly larger. Depending upon sizes and -optimization levels, the inliner may inline the register-based body -into the traditional entry point; nothing is done to preclude this. -If the function was declared @code{static}, optimization may discard -the original entry point entirely. - -@smallexample -extern double __attribute__ ((regparmandstackparm)) my_cos (double d); -@end smallexample -@c APPLE LOCAL end regparmandstackparm - -@item sp_switch -Use this attribute on the SH to indicate an @code{interrupt_handler} -function should switch to an alternate stack. It expects a string -argument that names a global variable holding the address of the -alternate stack. - -@smallexample -void *alt_stack; -void f () __attribute__ ((interrupt_handler, - sp_switch ("alt_stack"))); -@end smallexample - -@item stdcall -@cindex functions that pop the argument stack on the 386 -On the Intel 386, the @code{stdcall} attribute causes the compiler to -assume that the called function will pop off the stack space used to -pass arguments, unless it takes a variable number of arguments. - -@item tiny_data -@cindex tiny data section on the H8/300H and H8S -Use this attribute on the H8/300H and H8S to indicate that the specified -variable should be placed into the tiny data section. -The compiler will generate more efficient code for loads and stores -on data in the tiny data section. Note the tiny data area is limited to -slightly under 32kbytes of data. - -@item trap_exit -Use this attribute on the SH for an @code{interrupt_handler} to return using -@code{trapa} instead of @code{rte}. This attribute expects an integer -argument specifying the trap number to be used. - -@item unused -@cindex @code{unused} attribute. -This attribute, attached to a function, means that the function is meant -to be possibly unused. GCC will not produce a warning for this -function. - -@item used -@cindex @code{used} attribute. -This attribute, attached to a function, means that code must be emitted -for the function even if it appears that the function is not referenced. -This is useful, for example, when the function is referenced only in -inline assembly. - -@item visibility ("@var{visibility_type}") -@cindex @code{visibility} attribute -This attribute affects the linkage of the declaration to which it is attached. -There are four supported @var{visibility_type} values: default, -hidden, protected or internal visibility. - -@smallexample -void __attribute__ ((visibility ("protected"))) -f () @{ /* @r{Do something.} */; @} -int i __attribute__ ((visibility ("hidden"))); -@end smallexample - -The possible values of @var{visibility_type} correspond to the -visibility settings in the ELF gABI. - -@table @dfn -@c keep this list of visibilities in alphabetical order. - -@item default -Default visibility is the normal case for the object file format. -This value is available for the visibility attribute to override other -options that may change the assumed visibility of entities. - -On ELF, default visibility means that the declaration is visible to other -modules and, in shared libraries, means that the declared entity may be -overridden. - -On Darwin, default visibility means that the declaration is visible to -other modules. - -Default visibility corresponds to ``external linkage'' in the language. - -@item hidden -Hidden visibility indicates that the entity declared will have a new -form of linkage, which we'll call ``hidden linkage''. Two -declarations of an object with hidden linkage refer to the same object -if they are in the same shared object. - -@item internal -Internal visibility is like hidden visibility, but with additional -processor specific semantics. Unless otherwise specified by the -psABI, GCC defines internal visibility to mean that a function is -@emph{never} called from another module. Compare this with hidden -functions which, while they cannot be referenced directly by other -modules, can be referenced indirectly via function pointers. By -indicating that a function cannot be called from outside the module, -GCC may for instance omit the load of a PIC register since it is known -that the calling function loaded the correct value. - -@item protected -Protected visibility is like default visibility except that it -indicates that references within the defining module will bind to the -definition in that module. That is, the declared entity cannot be -overridden by another module. - -@end table - -All visibilities are supported on many, but not all, ELF targets -(supported when the assembler supports the @samp{.visibility} -pseudo-op). Default visibility is supported everywhere. Hidden -visibility is supported on Darwin targets. - -The visibility attribute should be applied only to declarations which -would otherwise have external linkage. The attribute should be applied -consistently, so that the same entity should not be declared with -different settings of the attribute. - -In C++, the visibility attribute applies to types as well as functions -and objects, because in C++ types have linkage. A class must not have -greater visibility than its non-static data member types and bases, -and class members default to the visibility of their class. Also, a -declaration without explicit visibility is limited to the visibility -of its type. - -In C++, you can mark member functions and static member variables of a -class with the visibility attribute. This is useful if if you know a -particular method or static member variable should only be used from -one shared object; then you can mark it hidden while the rest of the -class has default visibility. Care must be taken to avoid breaking -the One Definition Rule; for example, it is usually not useful to mark -an inline method as hidden without marking the whole class as hidden. - -A C++ namespace declaration can also have the visibility attribute. -This attribute applies only to the particular namespace body, not to -other definitions of the same namespace; it is equivalent to using -@samp{#pragma GCC visibility} before and after the namespace -definition (@pxref{Visibility Pragmas}). - -In C++, if a template argument has limited visibility, this -restriction is implicitly propagated to the template instantiation. -Otherwise, template instantiations and specializations default to the -visibility of their template. - -If both the template and enclosing class have explicit visibility, the -visibility from the template is used. - -@item warn_unused_result -@cindex @code{warn_unused_result} attribute -The @code{warn_unused_result} attribute causes a warning to be emitted -if a caller of the function with this attribute does not use its -return value. This is useful for functions where not checking -the result is either a security problem or always a bug, such as -@code{realloc}. - -@smallexample -int fn () __attribute__ ((warn_unused_result)); -int foo () -@{ - if (fn () < 0) return -1; - fn (); - return 0; -@} -@end smallexample - -results in warning on line 5. - -@item weak -@cindex @code{weak} attribute -The @code{weak} attribute causes the declaration to be emitted as a weak -symbol rather than a global. This is primarily useful in defining -library functions which can be overridden in user code, though it can -also be used with non-function declarations. Weak symbols are supported -for ELF targets, and also for a.out targets when using the GNU assembler -and linker. - -@item weakref -@itemx weakref ("@var{target}") -@cindex @code{weakref} attribute -The @code{weakref} attribute marks a declaration as a weak reference. -Without arguments, it should be accompanied by an @code{alias} attribute -naming the target symbol. Optionally, the @var{target} may be given as -an argument to @code{weakref} itself. In either case, @code{weakref} -implicitly marks the declaration as @code{weak}. Without a -@var{target}, given as an argument to @code{weakref} or to @code{alias}, -@code{weakref} is equivalent to @code{weak}. - -@smallexample -static int x() __attribute__ ((weakref ("y"))); -/* is equivalent to... */ -static int x() __attribute__ ((weak, weakref, alias ("y"))); -/* and to... */ -static int x() __attribute__ ((weakref)); -static int x() __attribute__ ((alias ("y"))); -@end smallexample - -A weak reference is an alias that does not by itself require a -definition to be given for the target symbol. If the target symbol is -only referenced through weak references, then the becomes a @code{weak} -undefined symbol. If it is directly referenced, however, then such -strong references prevail, and a definition will be required for the -symbol, not necessarily in the same translation unit. - -The effect is equivalent to moving all references to the alias to a -separate translation unit, renaming the alias to the aliased symbol, -declaring it as weak, compiling the two separate translation units and -performing a reloadable link on them. - -At present, a declaration to which @code{weakref} is attached can -only be @code{static}. - -@item externally_visible -@cindex @code{externally_visible} attribute. -This attribute, attached to a global variable or function nullify -effect of @option{-fwhole-program} command line option, so the object -remain visible outside the current compilation unit - -@end table - -You can specify multiple attributes in a declaration by separating them -by commas within the double parentheses or by immediately following an -attribute declaration with another attribute declaration. - -@cindex @code{#pragma}, reason for not using -@cindex pragma, reason for not using -Some people object to the @code{__attribute__} feature, suggesting that -ISO C's @code{#pragma} should be used instead. At the time -@code{__attribute__} was designed, there were two reasons for not doing -this. - -@enumerate -@item -It is impossible to generate @code{#pragma} commands from a macro. - -@item -There is no telling what the same @code{#pragma} might mean in another -compiler. -@end enumerate - -These two reasons applied to almost any application that might have been -proposed for @code{#pragma}. It was basically a mistake to use -@code{#pragma} for @emph{anything}. - -The ISO C99 standard includes @code{_Pragma}, which now allows pragmas -to be generated from macros. In addition, a @code{#pragma GCC} -namespace is now in use for GCC-specific pragmas. However, it has been -found convenient to use @code{__attribute__} to achieve a natural -attachment of attributes to their corresponding declarations, whereas -@code{#pragma GCC} is of use for constructs that do not naturally form -part of the grammar. @xref{Other Directives,,Miscellaneous -Preprocessing Directives, cpp, The GNU C Preprocessor}. - -@node Attribute Syntax -@section Attribute Syntax -@cindex attribute syntax - -This section describes the syntax with which @code{__attribute__} may be -used, and the constructs to which attribute specifiers bind, for the C -language. Some details may vary for C++ and Objective-C@. Because of -infelicities in the grammar for attributes, some forms described here -may not be successfully parsed in all cases. - -There are some problems with the semantics of attributes in C++. For -example, there are no manglings for attributes, although they may affect -code generation, so problems may arise when attributed types are used in -conjunction with templates or overloading. Similarly, @code{typeid} -does not distinguish between types with different attributes. Support -for attributes in C++ may be restricted in future to attributes on -declarations only, but not on nested declarators. - -@xref{Function Attributes}, for details of the semantics of attributes -applying to functions. @xref{Variable Attributes}, for details of the -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -semantics of attributes applying to variables. @xref{Type -Attributes}, for details of the semantics of attributes applying to -structure, union and enumerated types. @xref{Label Attributes}, for -details of the semantics of attributes applying to labels and -statements. - -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -An @dfn{attribute specifier} is of the form -@code{__attribute__ ((@var{attribute-list}))}. An @dfn{attribute list} -is a possibly empty comma-separated sequence of @dfn{attributes}, where -each attribute is one of the following: - -@itemize @bullet -@item -Empty. Empty attributes are ignored. - -@item -A word (which may be an identifier such as @code{unused}, or a reserved -word such as @code{const}). - -@item -A word, followed by, in parentheses, parameters for the attribute. -These parameters take one of the following forms: - -@itemize @bullet -@item -An identifier. For example, @code{mode} attributes use this form. - -@item -An identifier followed by a comma and a non-empty comma-separated list -of expressions. For example, @code{format} attributes use this form. - -@item -A possibly empty comma-separated list of expressions. For example, -@code{format_arg} attributes use this form with the list being a single -integer constant expression, and @code{alias} attributes use this form -with the list being a single string constant. -@end itemize -@end itemize - -An @dfn{attribute specifier list} is a sequence of one or more attribute -specifiers, not separated by any other tokens. - -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -In GNU C, an attribute specifier list may appear after the colon -following a label, other than a @code{case} or @code{default} label. -GNU C++ does not permit such placement of attribute lists, as it is -permissible for a declaration, which could begin with an attribute -list, to be labelled in C++. Declarations cannot be labelled in C90 -or C99, so the ambiguity does not arise there. - -In GNU C an attribute specifier list may also appear after the keyword -@code{while} in a while loop, after @code{do} and after @code{for}. - -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -An attribute specifier list may appear as part of a @code{struct}, -@code{union} or @code{enum} specifier. It may go either immediately -after the @code{struct}, @code{union} or @code{enum} keyword, or after -the closing brace. The former syntax is preferred. -Where attribute specifiers follow the closing brace, they are considered -to relate to the structure, union or enumerated type defined, not to any -enclosing declaration the type specifier appears in, and the type -defined is not complete until after the attribute specifiers. -@c Otherwise, there would be the following problems: a shift/reduce -@c conflict between attributes binding the struct/union/enum and -@c binding to the list of specifiers/qualifiers; and "aligned" -@c attributes could use sizeof for the structure, but the size could be -@c changed later by "packed" attributes. - -Otherwise, an attribute specifier appears as part of a declaration, -counting declarations of unnamed parameters and type names, and relates -to that declaration (which may be nested in another declaration, for -example in the case of a parameter declaration), or to a particular declarator -within a declaration. Where an -attribute specifier is applied to a parameter declared as a function or -an array, it should apply to the function or array rather than the -pointer to which the parameter is implicitly converted, but this is not -yet correctly implemented. - -Any list of specifiers and qualifiers at the start of a declaration may -contain attribute specifiers, whether or not such a list may in that -context contain storage class specifiers. (Some attributes, however, -are essentially in the nature of storage class specifiers, and only make -sense where storage class specifiers may be used; for example, -@code{section}.) There is one necessary limitation to this syntax: the -first old-style parameter declaration in a function definition cannot -begin with an attribute specifier, because such an attribute applies to -the function instead by syntax described below (which, however, is not -yet implemented in this case). In some other cases, attribute -specifiers are permitted by this grammar but not yet supported by the -compiler. All attribute specifiers in this place relate to the -declaration as a whole. In the obsolescent usage where a type of -@code{int} is implied by the absence of type specifiers, such a list of -specifiers and qualifiers may be an attribute specifier list with no -other specifiers or qualifiers. - -At present, the first parameter in a function prototype must have some -type specifier which is not an attribute specifier; this resolves an -ambiguity in the interpretation of @code{void f(int -(__attribute__((foo)) x))}, but is subject to change. At present, if -the parentheses of a function declarator contain only attributes then -those attributes are ignored, rather than yielding an error or warning -or implying a single parameter of type int, but this is subject to -change. - -An attribute specifier list may appear immediately before a declarator -(other than the first) in a comma-separated list of declarators in a -declaration of more than one identifier using a single list of -specifiers and qualifiers. Such attribute specifiers apply -only to the identifier before whose declarator they appear. For -example, in - -@smallexample -__attribute__((noreturn)) void d0 (void), - __attribute__((format(printf, 1, 2))) d1 (const char *, ...), - d2 (void) -@end smallexample - -@noindent -the @code{noreturn} attribute applies to all the functions -declared; the @code{format} attribute only applies to @code{d1}. - -An attribute specifier list may appear immediately before the comma, -@code{=} or semicolon terminating the declaration of an identifier other -than a function definition. At present, such attribute specifiers apply -to the declared object or function, but in future they may attach to the -outermost adjacent declarator. In simple cases there is no difference, -but, for example, in - -@smallexample -void (****f)(void) __attribute__((noreturn)); -@end smallexample - -@noindent -at present the @code{noreturn} attribute applies to @code{f}, which -causes a warning since @code{f} is not a function, but in future it may -apply to the function @code{****f}. The precise semantics of what -attributes in such cases will apply to are not yet specified. Where an -assembler name for an object or function is specified (@pxref{Asm -Labels}), at present the attribute must follow the @code{asm} -specification; in future, attributes before the @code{asm} specification -may apply to the adjacent declarator, and those after it to the declared -object or function. - -An attribute specifier list may, in future, be permitted to appear after -the declarator in a function definition (before any old-style parameter -declarations or the function body). - -Attribute specifiers may be mixed with type qualifiers appearing inside -the @code{[]} of a parameter array declarator, in the C99 construct by -which such qualifiers are applied to the pointer to which the array is -implicitly converted. Such attribute specifiers apply to the pointer, -not to the array, but at present this is not implemented and they are -ignored. - -An attribute specifier list may appear at the start of a nested -declarator. At present, there are some limitations in this usage: the -attributes correctly apply to the declarator, but for most individual -attributes the semantics this implies are not implemented. -When attribute specifiers follow the @code{*} of a pointer -declarator, they may be mixed with any type qualifiers present. -The following describes the formal semantics of this syntax. It will make the -most sense if you are familiar with the formal specification of -declarators in the ISO C standard. - -Consider (as in C99 subclause 6.7.5 paragraph 4) a declaration @code{T -D1}, where @code{T} contains declaration specifiers that specify a type -@var{Type} (such as @code{int}) and @code{D1} is a declarator that -contains an identifier @var{ident}. The type specified for @var{ident} -for derived declarators whose type does not include an attribute -specifier is as in the ISO C standard. - -If @code{D1} has the form @code{( @var{attribute-specifier-list} D )}, -and the declaration @code{T D} specifies the type -``@var{derived-declarator-type-list} @var{Type}'' for @var{ident}, then -@code{T D1} specifies the type ``@var{derived-declarator-type-list} -@var{attribute-specifier-list} @var{Type}'' for @var{ident}. - -If @code{D1} has the form @code{* -@var{type-qualifier-and-attribute-specifier-list} D}, and the -declaration @code{T D} specifies the type -``@var{derived-declarator-type-list} @var{Type}'' for @var{ident}, then -@code{T D1} specifies the type ``@var{derived-declarator-type-list} -@var{type-qualifier-and-attribute-specifier-list} @var{Type}'' for -@var{ident}. - -For example, - -@smallexample -void (__attribute__((noreturn)) ****f) (void); -@end smallexample - -@noindent -specifies the type ``pointer to pointer to pointer to pointer to -non-returning function returning @code{void}''. As another example, - -@smallexample -char *__attribute__((aligned(8))) *f; -@end smallexample - -@noindent -specifies the type ``pointer to 8-byte-aligned pointer to @code{char}''. -Note again that this does not work with most attributes; for example, -the usage of @samp{aligned} and @samp{noreturn} attributes given above -is not yet supported. - -For compatibility with existing code written for compiler versions that -did not implement attributes on nested declarators, some laxity is -allowed in the placing of attributes. If an attribute that only applies -to types is applied to a declaration, it will be treated as applying to -the type of that declaration. If an attribute that only applies to -declarations is applied to the type of a declaration, it will be treated -as applying to that declaration; and, for compatibility with code -placing the attributes immediately before the identifier declared, such -an attribute applied to a function return type will be treated as -applying to the function type, and such an attribute applied to an array -element type will be treated as applying to the array type. If an -attribute that only applies to function types is applied to a -pointer-to-function type, it will be treated as applying to the pointer -target type; if such an attribute is applied to a function return type -that is not a pointer-to-function type, it will be treated as applying -to the function type. - -@node Function Prototypes -@section Prototypes and Old-Style Function Definitions -@cindex function prototype declarations -@cindex old-style function definitions -@cindex promotion of formal parameters - -GNU C extends ISO C to allow a function prototype to override a later -old-style non-prototype definition. Consider the following example: - -@smallexample -/* @r{Use prototypes unless the compiler is old-fashioned.} */ -#ifdef __STDC__ -#define P(x) x -#else -#define P(x) () -#endif - -/* @r{Prototype function declaration.} */ -int isroot P((uid_t)); - -/* @r{Old-style function definition.} */ -int -isroot (x) /* @r{??? lossage here ???} */ - uid_t x; -@{ - return x == 0; -@} -@end smallexample - -Suppose the type @code{uid_t} happens to be @code{short}. ISO C does -not allow this example, because subword arguments in old-style -non-prototype definitions are promoted. Therefore in this example the -function definition's argument is really an @code{int}, which does not -match the prototype argument type of @code{short}. - -This restriction of ISO C makes it hard to write code that is portable -to traditional C compilers, because the programmer does not know -whether the @code{uid_t} type is @code{short}, @code{int}, or -@code{long}. Therefore, in cases like these GNU C allows a prototype -to override a later old-style definition. More precisely, in GNU C, a -function prototype argument type overrides the argument type specified -by a later old-style definition if the former type is the same as the -latter type before promotion. Thus in GNU C the above example is -equivalent to the following: - -@smallexample -int isroot (uid_t); - -int -isroot (uid_t x) -@{ - return x == 0; -@} -@end smallexample - -@noindent -GNU C++ does not support old-style function definitions, so this -extension is irrelevant. - -@node C++ Comments -@section C++ Style Comments -@cindex // -@cindex C++ comments -@cindex comments, C++ style - -In GNU C, you may use C++ style comments, which start with @samp{//} and -continue until the end of the line. Many other C implementations allow -such comments, and they are included in the 1999 C standard. However, -C++ style comments are not recognized if you specify an @option{-std} -option specifying a version of ISO C before C99, or @option{-ansi} -(equivalent to @option{-std=c89}). - -@node Dollar Signs -@section Dollar Signs in Identifier Names -@cindex $ -@cindex dollar signs in identifier names -@cindex identifier names, dollar signs in - -In GNU C, you may normally use dollar signs in identifier names. -This is because many traditional C implementations allow such identifiers. -However, dollar signs in identifiers are not supported on a few target -machines, typically because the target assembler does not allow them. - -@node Character Escapes -@section The Character @key{ESC} in Constants - -You can use the sequence @samp{\e} in a string or character constant to -stand for the ASCII character @key{ESC}. - -@c APPLE LOCAL begin pascal strings -@node Pascal Strings -@section Constructing String Literals with a Pascal-style Length Byte -@cindex Pascal length byte -@cindex Pascal strings - -Specifying the @w{@option{-fpascal-strings}} option will cause the -compiler to recognize and construct Pascal-style string literals. This -functionality is disabled by default; furthermore, its use in new code -is discouraged. - -Pascal string literals take the form @samp{"\pstring"}. The special -escape sequence @samp{\p} denotes the Pascal length byte for the string, -and will be replaced at compile time with the number of characters that -follow. The @samp{\p} may only appear at the beginning of a string -literal, and may @emph{not} appear in wide string literals or as an -integral constant. - -As is the case with C string literals, Pascal string literals are -terminated with a NUL character; this character is @emph{not} counted -when computing the value of the length byte. The maximum @samp{unsigned -char} value that can be stored in the length byte is also the maximum -permissible length for the Pascal literal itself. On most target -platforms, this value is 255 (excluding both the length byte and the -terminating NUL). - -Pascal-style literals are treated by the compiler as being of type -@samp{const unsigned char []} in C++ and @samp{unsigned char []} (or -@samp{const unsigned char []}, if the @w{@option{-Wwrite-strings}} -option is given) in C. Pascal string literals may be used as static -initializers for @samp{char} arrays (whose elements need not be -@samp{unsigned} or @samp{const}). They may also be converted to -@samp{const unsigned char *} and, in the C language to @samp{const char -*} of any signedness (In C, if the @w{@option{-Wwrite-strings}} is not -given, then @samp{const} may be omitted as well). For example: - -@example -const unsigned char a[] = "\pHello"; -char b[] = "\pGoodbye"; -const unsigned char *c = "\pHello"; -const signed char *d = "\pHello"; /* error in C++ */ -char *e = "\pHi"; /* error in C++; warning in C with -Wwrite-strings */ -unsigned char *f = "\pHello"; /* error in C++ */ -@end example - -@noindent -In all other respects, Pascal-style string literals behave the same as -ordinary string literals. For example, if a program attempts to modify -the conents of a Pascal-style string literal at run-time, the behaviour -is undefined, unless the @w{@option{-fwritable-strings}} option is used. - -Pascal-style literals are useful for calling external routines that -expect Pascal strings as arguments, as is true with some Apple MacOS -Toolbox calls. -@c APPLE LOCAL end pascal strings - -@node Alignment -@section Inquiring on Alignment of Types or Variables -@cindex alignment -@cindex type alignment -@cindex variable alignment - -The keyword @code{__alignof__} allows you to inquire about how an object -is aligned, or the minimum alignment usually required by a type. Its -syntax is just like @code{sizeof}. - -For example, if the target machine requires a @code{double} value to be -aligned on an 8-byte boundary, then @code{__alignof__ (double)} is 8. -This is true on many RISC machines. On more traditional machine -designs, @code{__alignof__ (double)} is 4 or even 2. - -Some machines never actually require alignment; they allow reference to any -data type even at an odd address. For these machines, @code{__alignof__} -reports the @emph{recommended} alignment of a type. - -If the operand of @code{__alignof__} is an lvalue rather than a type, -its value is the required alignment for its type, taking into account -any minimum alignment specified with GCC's @code{__attribute__} -extension (@pxref{Variable Attributes}). For example, after this -declaration: - -@smallexample -struct foo @{ int x; char y; @} foo1; -@end smallexample - -@noindent -the value of @code{__alignof__ (foo1.y)} is 1, even though its actual -alignment is probably 2 or 4, the same as @code{__alignof__ (int)}. - -It is an error to ask for the alignment of an incomplete type. - -@node Variable Attributes -@section Specifying Attributes of Variables -@cindex attribute of variables -@cindex variable attributes - -The keyword @code{__attribute__} allows you to specify special -attributes of variables or structure fields. This keyword is followed -by an attribute specification inside double parentheses. Some -attributes are currently defined generically for variables. -Other attributes are defined for variables on particular target -systems. Other attributes are available for functions -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -(@pxref{Function Attributes}), types (@pxref{Type Attributes}) and -labels (@pxref{Label Attributes}). Other front ends might define -more attributes (@pxref{C++ Extensions,,Extensions to the C++ Language}). - -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -You may also specify attributes with @samp{__} preceding and following -each keyword. This allows you to use them in header files without -being concerned about a possible macro of the same name. For example, -you may use @code{__aligned__} instead of @code{aligned}. - -@xref{Attribute Syntax}, for details of the exact syntax for using -attributes. - -@table @code -@cindex @code{aligned} attribute -@item aligned (@var{alignment}) -This attribute specifies a minimum alignment for the variable or -structure field, measured in bytes. For example, the declaration: - -@smallexample -int x __attribute__ ((aligned (16))) = 0; -@end smallexample - -@noindent -causes the compiler to allocate the global variable @code{x} on a -16-byte boundary. On a 68040, this could be used in conjunction with -an @code{asm} expression to access the @code{move16} instruction which -requires 16-byte aligned operands. - -You can also specify the alignment of structure fields. For example, to -create a double-word aligned @code{int} pair, you could write: - -@smallexample -struct foo @{ int x[2] __attribute__ ((aligned (8))); @}; -@end smallexample - -@noindent -This is an alternative to creating a union with a @code{double} member -that forces the union to be double-word aligned. - -As in the preceding examples, you can explicitly specify the alignment -(in bytes) that you wish the compiler to use for a given variable or -structure field. Alternatively, you can leave out the alignment factor -and just ask the compiler to align a variable or field to the maximum -useful alignment for the target machine you are compiling for. For -example, you could write: - -@smallexample -short array[3] __attribute__ ((aligned)); -@end smallexample - -Whenever you leave out the alignment factor in an @code{aligned} attribute -specification, the compiler automatically sets the alignment for the declared -variable or field to the largest alignment which is ever used for any data -type on the target machine you are compiling for. Doing this can often make -copy operations more efficient, because the compiler can use whatever -instructions copy the biggest chunks of memory when performing copies to -or from the variables or fields that you have aligned this way. - -The @code{aligned} attribute can only increase the alignment; but you -can decrease it by specifying @code{packed} as well. See below. - -Note that the effectiveness of @code{aligned} attributes may be limited -by inherent limitations in your linker. On many systems, the linker is -only able to arrange for variables to be aligned up to a certain maximum -alignment. (For some linkers, the maximum supported alignment may -be very very small.) If your linker is only able to align variables -up to a maximum of 8 byte alignment, then specifying @code{aligned(16)} -in an @code{__attribute__} will still only provide you with 8 byte -alignment. See your linker documentation for further information. - -@c APPLE LOCAL begin aligned functions 5933878 -The @code{aligned} attribute can also be used for functions -(@pxref{Function Attributes}.) -@c APPLE LOCAL end aligned functions 5933878 - -@item cleanup (@var{cleanup_function}) -@cindex @code{cleanup} attribute -The @code{cleanup} attribute runs a function when the variable goes -out of scope. This attribute can only be applied to auto function -scope variables; it may not be applied to parameters or variables -with static storage duration. The function must take one parameter, -a pointer to a type compatible with the variable. The return value -of the function (if any) is ignored. - -If @option{-fexceptions} is enabled, then @var{cleanup_function} -will be run during the stack unwinding that happens during the -processing of the exception. Note that the @code{cleanup} attribute -does not allow the exception to be caught, only to perform an action. -It is undefined what happens if @var{cleanup_function} does not -return normally. - -@item common -@itemx nocommon -@cindex @code{common} attribute -@cindex @code{nocommon} attribute -@opindex fcommon -@opindex fno-common -The @code{common} attribute requests GCC to place a variable in -``common'' storage. The @code{nocommon} attribute requests the -opposite---to allocate space for it directly. - -These attributes override the default chosen by the -@option{-fno-common} and @option{-fcommon} flags respectively. - -@item deprecated -@cindex @code{deprecated} attribute -The @code{deprecated} attribute results in a warning if the variable -is used anywhere in the source file. This is useful when identifying -variables that are expected to be removed in a future version of a -program. The warning also includes the location of the declaration -of the deprecated variable, to enable users to easily find further -information about why the variable is deprecated, or what they should -do instead. Note that the warning only occurs for uses: - -@smallexample -extern int old_var __attribute__ ((deprecated)); -extern int old_var; -int new_fn () @{ return old_var; @} -@end smallexample - -results in a warning on line 3 but not line 2. - -The @code{deprecated} attribute can also be used for functions and -types (@pxref{Function Attributes}, @pxref{Type Attributes}.) - -@item mode (@var{mode}) -@cindex @code{mode} attribute -This attribute specifies the data type for the declaration---whichever -type corresponds to the mode @var{mode}. This in effect lets you -request an integer or floating point type according to its width. - -You may also specify a mode of @samp{byte} or @samp{__byte__} to -indicate the mode corresponding to a one-byte integer, @samp{word} or -@samp{__word__} for the mode of a one-word integer, and @samp{pointer} -or @samp{__pointer__} for the mode used to represent pointers. - -@item packed -@cindex @code{packed} attribute -The @code{packed} attribute specifies that a variable or structure field -should have the smallest possible alignment---one byte for a variable, -and one bit for a field, unless you specify a larger value with the -@code{aligned} attribute. - -Here is a structure in which the field @code{x} is packed, so that it -immediately follows @code{a}: - -@smallexample -struct foo -@{ - char a; - int x[2] __attribute__ ((packed)); -@}; -@end smallexample - -@item section ("@var{section-name}") -@cindex @code{section} variable attribute -Normally, the compiler places the objects it generates in sections like -@code{data} and @code{bss}. Sometimes, however, you need additional sections, -or you need certain particular variables to appear in special sections, -for example to map to special hardware. The @code{section} -attribute specifies that a variable (or function) lives in a particular -section. For example, this small program uses several specific section names: - -@smallexample -struct duart a __attribute__ ((section ("DUART_A"))) = @{ 0 @}; -struct duart b __attribute__ ((section ("DUART_B"))) = @{ 0 @}; -char stack[10000] __attribute__ ((section ("STACK"))) = @{ 0 @}; -int init_data __attribute__ ((section ("INITDATA"))) = 0; - -main() -@{ - /* @r{Initialize stack pointer} */ - init_sp (stack + sizeof (stack)); - - /* @r{Initialize initialized data} */ - memcpy (&init_data, &data, &edata - &data); - - /* @r{Turn on the serial ports} */ - init_duart (&a); - init_duart (&b); -@} -@end smallexample - -@noindent -Use the @code{section} attribute with an @emph{initialized} definition -of a @emph{global} variable, as shown in the example. GCC issues -a warning and otherwise ignores the @code{section} attribute in -uninitialized variable declarations. - -You may only use the @code{section} attribute with a fully initialized -global definition because of the way linkers work. The linker requires -each object be defined once, with the exception that uninitialized -variables tentatively go in the @code{common} (or @code{bss}) section -and can be multiply ``defined''. You can force a variable to be -initialized with the @option{-fno-common} flag or the @code{nocommon} -attribute. - -Some file formats do not support arbitrary sections so the @code{section} -attribute is not available on all platforms. -If you need to map the entire contents of a module to a particular -section, consider using the facilities of the linker instead. - -@item shared -@cindex @code{shared} variable attribute -On Microsoft Windows, in addition to putting variable definitions in a named -section, the section can also be shared among all running copies of an -executable or DLL@. For example, this small program defines shared data -by putting it in a named section @code{shared} and marking the section -shareable: - -@smallexample -int foo __attribute__((section ("shared"), shared)) = 0; - -int -main() -@{ - /* @r{Read and write foo. All running - copies see the same value.} */ - return 0; -@} -@end smallexample - -@noindent -You may only use the @code{shared} attribute along with @code{section} -attribute with a fully initialized global definition because of the way -linkers work. See @code{section} attribute for more information. - -The @code{shared} attribute is only available on Microsoft Windows@. - -@item tls_model ("@var{tls_model}") -@cindex @code{tls_model} attribute -The @code{tls_model} attribute sets thread-local storage model -(@pxref{Thread-Local}) of a particular @code{__thread} variable, -overriding @option{-ftls-model=} command line switch on a per-variable -basis. -The @var{tls_model} argument should be one of @code{global-dynamic}, -@code{local-dynamic}, @code{initial-exec} or @code{local-exec}. - -Not all targets support this attribute. - -@item unused -This attribute, attached to a variable, means that the variable is meant -to be possibly unused. GCC will not produce a warning for this -variable. - -@item used -This attribute, attached to a variable, means that the variable must be -emitted even if it appears that the variable is not referenced. - -@item vector_size (@var{bytes}) -This attribute specifies the vector size for the variable, measured in -bytes. For example, the declaration: - -@smallexample -int foo __attribute__ ((vector_size (16))); -@end smallexample - -@noindent -causes the compiler to set the mode for @code{foo}, to be 16 bytes, -divided into @code{int} sized units. Assuming a 32-bit int (a vector of -4 units of 4 bytes), the corresponding mode of @code{foo} will be V4SI@. - -This attribute is only applicable to integral and float scalars, -although arrays, pointers, and function return values are allowed in -conjunction with this construct. - -Aggregates with this attribute are invalid, even if they are of the same -size as a corresponding scalar. For example, the declaration: - -@smallexample -struct S @{ int a; @}; -struct S __attribute__ ((vector_size (16))) foo; -@end smallexample - -@noindent -is invalid even if the size of the structure is the same as the size of -the @code{int}. - -@item selectany -The @code{selectany} attribute causes an initialized global variable to -have link-once semantics. When multiple definitions of the variable are -encountered by the linker, the first is selected and the remainder are -discarded. Following usage by the Microsoft compiler, the linker is told -@emph{not} to warn about size or content differences of the multiple -definitions. - -Although the primary usage of this attribute is for POD types, the -attribute can also be applied to global C++ objects that are initialized -by a constructor. In this case, the static initialization and destruction -code for the object is emitted in each translation defining the object, -but the calls to the constructor and destructor are protected by a -link-once guard variable. - -The @code{selectany} attribute is only available on Microsoft Windows -targets. You can use @code{__declspec (selectany)} as a synonym for -@code{__attribute__ ((selectany))} for compatibility with other -compilers. - -@item weak -The @code{weak} attribute is described in @xref{Function Attributes}. - -@item dllimport -The @code{dllimport} attribute is described in @xref{Function Attributes}. - -@item dllexport -The @code{dllexport} attribute is described in @xref{Function Attributes}. - -@end table - -@subsection M32R/D Variable Attributes - -One attribute is currently defined for the M32R/D@. - -@table @code -@item model (@var{model-name}) -@cindex variable addressability on the M32R/D -Use this attribute on the M32R/D to set the addressability of an object. -The identifier @var{model-name} is one of @code{small}, @code{medium}, -or @code{large}, representing each of the code models. - -Small model objects live in the lower 16MB of memory (so that their -addresses can be loaded with the @code{ld24} instruction). - -Medium and large model objects may live anywhere in the 32-bit address space -(the compiler will generate @code{seth/add3} instructions to load their -addresses). -@end table - -@c APPLE LOCAL begin 5946347 ms_struct support -@anchor{PowerPC Variable Attributes} -@subsection PowerPC Variable Attributes - -One is defined for PowerPC configurations: @code{altivec}. - -For documentation of the @code{altivec} attribute please see the -documentation in the @xref{PowerPC Type Attributes}, section. -@c APPLE LOCAL end 5946347 ms_struct support - -@subsection Xstormy16 Variable Attributes - -One attribute is currently defined for xstormy16 configurations: -@code{below100} - -@table @code -@item below100 -@cindex @code{below100} attribute - -If a variable has the @code{below100} attribute (@code{BELOW100} is -allowed also), GCC will place the variable in the first 0x100 bytes of -memory and use special opcodes to access it. Such variables will be -placed in either the @code{.bss_below100} section or the -@code{.data_below100} section. - -@end table - -@node Type Attributes -@section Specifying Attributes of Types -@cindex attribute of types -@cindex type attributes - -The keyword @code{__attribute__} allows you to specify special -attributes of @code{struct} and @code{union} types when you define -such types. This keyword is followed by an attribute specification -inside double parentheses. Seven attributes are currently defined for -types: @code{aligned}, @code{packed}, @code{transparent_union}, -@code{unused}, @code{deprecated}, @code{visibility}, and -@code{may_alias}. Other attributes are defined for functions -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -(@pxref{Function Attributes}), variables (@pxref{Variable -Attributes}), and labels (@pxref{Label Attributes}). - -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -You may also specify any one of these attributes with @samp{__} -preceding and following its keyword. This allows you to use these -attributes in header files without being concerned about a possible -macro of the same name. For example, you may use @code{__aligned__} -instead of @code{aligned}. - -You may specify type attributes either in a @code{typedef} declaration -or in an enum, struct or union type declaration or definition. - -For an enum, struct or union type, you may specify attributes either -between the enum, struct or union tag and the name of the type, or -just past the closing curly brace of the @emph{definition}. The -former syntax is preferred. - -@xref{Attribute Syntax}, for details of the exact syntax for using -attributes. - -@table @code -@cindex @code{aligned} attribute -@item aligned (@var{alignment}) -This attribute specifies a minimum alignment (in bytes) for variables -of the specified type. For example, the declarations: - -@smallexample -struct S @{ short f[3]; @} __attribute__ ((aligned (8))); -typedef int more_aligned_int __attribute__ ((aligned (8))); -@end smallexample - -@noindent -force the compiler to insure (as far as it can) that each variable whose -type is @code{struct S} or @code{more_aligned_int} will be allocated and -aligned @emph{at least} on a 8-byte boundary. On a SPARC, having all -variables of type @code{struct S} aligned to 8-byte boundaries allows -the compiler to use the @code{ldd} and @code{std} (doubleword load and -store) instructions when copying one variable of type @code{struct S} to -another, thus improving run-time efficiency. - -Note that the alignment of any given @code{struct} or @code{union} type -is required by the ISO C standard to be at least a perfect multiple of -the lowest common multiple of the alignments of all of the members of -the @code{struct} or @code{union} in question. This means that you @emph{can} -effectively adjust the alignment of a @code{struct} or @code{union} -type by attaching an @code{aligned} attribute to any one of the members -of such a type, but the notation illustrated in the example above is a -more obvious, intuitive, and readable way to request the compiler to -adjust the alignment of an entire @code{struct} or @code{union} type. - -As in the preceding example, you can explicitly specify the alignment -(in bytes) that you wish the compiler to use for a given @code{struct} -or @code{union} type. Alternatively, you can leave out the alignment factor -and just ask the compiler to align a type to the maximum -useful alignment for the target machine you are compiling for. For -example, you could write: - -@smallexample -struct S @{ short f[3]; @} __attribute__ ((aligned)); -@end smallexample - -Whenever you leave out the alignment factor in an @code{aligned} -attribute specification, the compiler automatically sets the alignment -for the type to the largest alignment which is ever used for any data -type on the target machine you are compiling for. Doing this can often -make copy operations more efficient, because the compiler can use -whatever instructions copy the biggest chunks of memory when performing -copies to or from the variables which have types that you have aligned -this way. - -In the example above, if the size of each @code{short} is 2 bytes, then -the size of the entire @code{struct S} type is 6 bytes. The smallest -power of two which is greater than or equal to that is 8, so the -compiler sets the alignment for the entire @code{struct S} type to 8 -bytes. - -Note that although you can ask the compiler to select a time-efficient -alignment for a given type and then declare only individual stand-alone -objects of that type, the compiler's ability to select a time-efficient -alignment is primarily useful only when you plan to create arrays of -variables having the relevant (efficiently aligned) type. If you -declare or use arrays of variables of an efficiently-aligned type, then -it is likely that your program will also be doing pointer arithmetic (or -subscripting, which amounts to the same thing) on pointers to the -relevant type, and the code that the compiler generates for these -pointer arithmetic operations will often be more efficient for -efficiently-aligned types than for other types. - -The @code{aligned} attribute can only increase the alignment; but you -can decrease it by specifying @code{packed} as well. See below. - -Note that the effectiveness of @code{aligned} attributes may be limited -by inherent limitations in your linker. On many systems, the linker is -only able to arrange for variables to be aligned up to a certain maximum -alignment. (For some linkers, the maximum supported alignment may -be very very small.) If your linker is only able to align variables -up to a maximum of 8 byte alignment, then specifying @code{aligned(16)} -in an @code{__attribute__} will still only provide you with 8 byte -alignment. See your linker documentation for further information. - -@item packed -This attribute, attached to @code{struct} or @code{union} type -definition, specifies that each member (other than zero-width bitfields) -of the structure or union is placed to minimize the memory required. When -attached to an @code{enum} definition, it indicates that the smallest -integral type should be used. - -@opindex fshort-enums -Specifying this attribute for @code{struct} and @code{union} types is -equivalent to specifying the @code{packed} attribute on each of the -structure or union members. Specifying the @option{-fshort-enums} -flag on the line is equivalent to specifying the @code{packed} -attribute on all @code{enum} definitions. - -In the following example @code{struct my_packed_struct}'s members are -packed closely together, but the internal layout of its @code{s} member -is not packed---to do that, @code{struct my_unpacked_struct} would need to -be packed too. - -@smallexample -struct my_unpacked_struct - @{ - char c; - int i; - @}; - -struct __attribute__ ((__packed__)) my_packed_struct - @{ - char c; - int i; - struct my_unpacked_struct s; - @}; -@end smallexample - -You may only specify this attribute on the definition of a @code{enum}, -@code{struct} or @code{union}, not on a @code{typedef} which does not -also define the enumerated type, structure or union. - -@item transparent_union -This attribute, attached to a @code{union} type definition, indicates -that any function parameter having that union type causes calls to that -function to be treated in a special way. - -First, the argument corresponding to a transparent union type can be of -any type in the union; no cast is required. Also, if the union contains -a pointer type, the corresponding argument can be a null pointer -constant or a void pointer expression; and if the union contains a void -pointer type, the corresponding argument can be any pointer expression. -If the union member type is a pointer, qualifiers like @code{const} on -the referenced type must be respected, just as with normal pointer -conversions. - -Second, the argument is passed to the function using the calling -conventions of the first member of the transparent union, not the calling -conventions of the union itself. All members of the union must have the -same machine representation; this is necessary for this argument passing -to work properly. - -Transparent unions are designed for library functions that have multiple -interfaces for compatibility reasons. For example, suppose the -@code{wait} function must accept either a value of type @code{int *} to -comply with Posix, or a value of type @code{union wait *} to comply with -the 4.1BSD interface. If @code{wait}'s parameter were @code{void *}, -@code{wait} would accept both kinds of arguments, but it would also -accept any other pointer type and this would make argument type checking -less useful. Instead, @code{<sys/wait.h>} might define the interface -as follows: - -@smallexample -typedef union - @{ - int *__ip; - union wait *__up; - @} wait_status_ptr_t __attribute__ ((__transparent_union__)); - -pid_t wait (wait_status_ptr_t); -@end smallexample - -This interface allows either @code{int *} or @code{union wait *} -arguments to be passed, using the @code{int *} calling convention. -The program can call @code{wait} with arguments of either type: - -@smallexample -int w1 () @{ int w; return wait (&w); @} -int w2 () @{ union wait w; return wait (&w); @} -@end smallexample - -With this interface, @code{wait}'s implementation might look like this: - -@smallexample -pid_t wait (wait_status_ptr_t p) -@{ - return waitpid (-1, p.__ip, 0); -@} -@end smallexample - -@item unused -When attached to a type (including a @code{union} or a @code{struct}), -this attribute means that variables of that type are meant to appear -possibly unused. GCC will not produce a warning for any variables of -that type, even if the variable appears to do nothing. This is often -the case with lock or thread classes, which are usually defined and then -not referenced, but contain constructors and destructors that have -nontrivial bookkeeping functions. - -@item deprecated -The @code{deprecated} attribute results in a warning if the type -is used anywhere in the source file. This is useful when identifying -types that are expected to be removed in a future version of a program. -If possible, the warning also includes the location of the declaration -of the deprecated type, to enable users to easily find further -information about why the type is deprecated, or what they should do -instead. Note that the warnings only occur for uses and then only -if the type is being applied to an identifier that itself is not being -declared as deprecated. - -@smallexample -typedef int T1 __attribute__ ((deprecated)); -T1 x; -typedef T1 T2; -T2 y; -typedef T1 T3 __attribute__ ((deprecated)); -T3 z __attribute__ ((deprecated)); -@end smallexample - -results in a warning on line 2 and 3 but not lines 4, 5, or 6. No -warning is issued for line 4 because T2 is not explicitly -deprecated. Line 5 has no warning because T3 is explicitly -deprecated. Similarly for line 6. - -The @code{deprecated} attribute can also be used for functions and -variables (@pxref{Function Attributes}, @pxref{Variable Attributes}.) - -@item may_alias -Accesses to objects with types with this attribute are not subjected to -type-based alias analysis, but are instead assumed to be able to alias -any other type of objects, just like the @code{char} type. See -@option{-fstrict-aliasing} for more information on aliasing issues. - -Example of use: - -@smallexample -typedef short __attribute__((__may_alias__)) short_a; - -int -main (void) -@{ - int a = 0x12345678; - short_a *b = (short_a *) &a; - - b[1] = 0; - - if (a == 0x12345678) - abort(); - - exit(0); -@} -@end smallexample - -If you replaced @code{short_a} with @code{short} in the variable -declaration, the above program would abort when compiled with -@option{-fstrict-aliasing}, which is on by default at @option{-O2} or -above in recent GCC versions. - -@item visibility -In C++, attribute visibility (@pxref{Function Attributes}) can also be -applied to class, struct, union and enum types. Unlike other type -attributes, the attribute must appear between the initial keyword and -the name of the type; it cannot appear after the body of the type. - -Note that the type visibility is applied to vague linkage entities -associated with the class (vtable, typeinfo node, etc.). In -particular, if a class is thrown as an exception in one shared object -and caught in another, the class must have default visibility. -Otherwise the two shared objects will be unable to use the same -typeinfo node and exception handling will break. - -@c APPLE LOCAL begin weak types 5954418 -@item weak -In C++, attribute weak can be applied to a class to ensure that all -non-hidden instances of the type are treated as the same type across -shared library boundaries on platforms (such as darwin and arm aapcs) -that can emit vtables and the type info meta data as non-comdat -symbols. This is useful when the class has a key method and the -translation unit that contains the key method is used in more than one -shared library or in a shared library and the application. Doing this -results in more expensive startup times. This attribute is inherited -by subclasses, so it is only necessary to mark a base type. The -typical use would be to mark any types used for throwing across shared -library boundaries or those used in dynamic_cast operations across a -shared library boundary. -@c APPLE LOCAL end weak types 5954418 - -@c APPLE LOCAL begin 5946347 ms_struct support -@end table - -To specify multiple attributes, separate them by commas within the -double parentheses: for example, @samp{__attribute__ ((aligned (16), -packed))}. - -@anchor{i386 Type Attributes} -@subsection i386 Type Attributes - -Two attributes are currently defined for i386 configurations: -@code{ms_struct} and @code{gcc_struct} - -@table @code -@item ms_struct -@itemx gcc_struct -@cindex @code{ms_struct} attribute -@cindex @code{gcc_struct} attribute - -If @code{packed} is used on a structure, or if bit-fields are used -it may be that the Microsoft ABI packs them differently -than GCC would normally pack them. Particularly when moving packed -data between functions compiled with GCC and the native Microsoft compiler -(either via function call or as data in a file), it may be necessary to access -either format. - -Currently @option{-m[no-]ms-bitfields} is provided for the Microsoft Windows X86 -compilers to match the native Microsoft compiler. - -The Microsoft structure layout algorithm is fairly simple with the exception -of the bitfield packing: - -The padding and alignment of members of structures and whether a bit field -can straddle a storage-unit boundary - -@enumerate -@item Structure members are stored sequentially in the order in which they are -declared: the first member has the lowest memory address and the last member -the highest. - -@item Every data object has an alignment-requirement. The alignment-requirement -for all data except structures, unions, and arrays is either the size of the -object or the current packing size (specified with either the aligned attribute -or the pack pragma), whichever is less. For structures, unions, and arrays, -the alignment-requirement is the largest alignment-requirement of its members. -Every object is allocated an offset so that: - -offset % alignment-requirement == 0 - -@item Adjacent bit fields are packed into the same 1-, 2-, or 4-byte allocation -unit if the integral types are the same size and if the next bit field fits -into the current allocation unit without crossing the boundary imposed by the -common alignment requirements of the bit fields. -@end enumerate - -Handling of zero-length bitfields: - -MSVC interprets zero-length bitfields in the following ways: - -@enumerate -@item If a zero-length bitfield is inserted between two bitfields that would -normally be coalesced, the bitfields will not be coalesced. - -For example: - -@smallexample -struct - @{ - unsigned long bf_1 : 12; - unsigned long : 0; - unsigned long bf_2 : 12; - @} t1; -@end smallexample - -The size of @code{t1} would be 8 bytes with the zero-length bitfield. If the -zero-length bitfield were removed, @code{t1}'s size would be 4 bytes. - -@item If a zero-length bitfield is inserted after a bitfield, @code{foo}, and the -alignment of the zero-length bitfield is greater than the member that follows it, -@code{bar}, @code{bar} will be aligned as the type of the zero-length bitfield. - -For example: - -@smallexample -struct - @{ - char foo : 4; - short : 0; - char bar; - @} t2; - -struct - @{ - char foo : 4; - short : 0; - double bar; - @} t3; -@end smallexample - -For @code{t2}, @code{bar} will be placed at offset 2, rather than offset 1. -Accordingly, the size of @code{t2} will be 4. For @code{t3}, the zero-length -bitfield will not affect the alignment of @code{bar} or, as a result, the size -of the structure. - -Taking this into account, it is important to note the following: - -@enumerate -@item If a zero-length bitfield follows a normal bitfield, the type of the -zero-length bitfield may affect the alignment of the structure as whole. For -example, @code{t2} has a size of 4 bytes, since the zero-length bitfield follows a -normal bitfield, and is of type short. - -@item Even if a zero-length bitfield is not followed by a normal bitfield, it may -still affect the alignment of the structure: - -@smallexample -struct - @{ - char foo : 6; - long : 0; - @} t4; -@end smallexample - -Here, @code{t4} will take up 4 bytes. -@end enumerate - -@item Zero-length bitfields following non-bitfield members are ignored: - -@smallexample -struct - @{ - char foo; - long : 0; - char bar; - @} t5; -@end smallexample - -Here, @code{t5} will take up 2 bytes. -@end enumerate -@end table - -@anchor{ARM Type Attributes} -@subsection ARM Type Attributes - -Two attributes currently are defined for ARM configurations: -@code{ms_struct} and @code{gcc_struct}. - -For full documentation of the struct attributes please see the -documentation in the @xref{i386 Type Attributes}, section. - -On those ARM targets that support @code{dllimport} (such as Symbian -OS), you can use the @code{notshared} attribute to indicate that the -virtual table and other similar data for a class should not be -exported from a DLL@. For example: - -@smallexample -class __declspec(notshared) C @{ -public: - __declspec(dllimport) C(); - virtual void f(); -@} - -__declspec(dllexport) -C::C() @{@} -@end smallexample - -In this code, @code{C::C} is exported from the current DLL, but the -virtual table for @code{C} is not exported. (You can use -@code{__attribute__} instead of @code{__declspec} if you prefer, but -most Symbian OS code uses @code{__declspec}.) -@c APPLE LOCAL end 5946347 ms_struct support - -@anchor{PowerPC Type Attributes} -@subsection PowerPC Type Attributes - -Three attributes currently are defined for PowerPC configurations: -@code{altivec}, @code{ms_struct} and @code{gcc_struct}. - -For full documentation of the struct attributes please see the -documentation in the @xref{i386 Type Attributes}, section. - -The @code{altivec} attribute allows one to declare AltiVec vector data -types supported by the AltiVec Programming Interface Manual. The -attribute requires an argument to specify one of three vector types: -@code{vector__}, @code{pixel__} (always followed by unsigned short), -and @code{bool__} (always followed by unsigned). - -@smallexample -__attribute__((altivec(vector__))) -__attribute__((altivec(pixel__))) unsigned short -__attribute__((altivec(bool__))) unsigned -@end smallexample - -These attributes mainly are intended to support the @code{__vector}, -@code{__pixel}, and @code{__bool} AltiVec keywords. - -@c APPLE LOCAL begin for-fsf-4_4 3274130 5295549 -@node Label Attributes -@section Specifying Attributes of Labels and Statements -@cindex attribute of labels -@cindex label attributes -@cindex attribute of statements -@cindex statement attributes - -The keyword @code{__attribute__} allows you to specify special -attributes of labels and statements. - -Some attributes are currently defined generically for variables. -Other attributes are defined for variables on particular target -systems. Other attributes are available for functions -(@pxref{Function Attributes}), types (@pxref{Type Attributes}) and -variables (@pxref{Variable Attributes}). - -You may also specify attributes with @samp{__} preceding and following -each keyword. This allows you to use them in header files without -being concerned about a possible macro of the same name. For example, -you may use @code{__aligned__} instead of @code{aligned}. - -@xref{Attribute Syntax}, for details of the exact syntax for using -attributes. - -@table @code -@cindex @code{aligned} attribute -@item aligned (@var{alignment}) -This attribute specifies a minimum alignment for the label, -measured in bytes. For example, the declaration: - -@smallexample - some_label: __attribute__((aligned(16))) -@end smallexample - -@noindent -requests the compiler to align the label, inserting @code{nop}s as necessary, -to a 16-byte boundary. - -The alignment is only a request. The compiler will usually be able to -honour it but sometimes the label will be eliminated by the compiler, -in which case its alignment will be eliminated too. - -When applied to loops, the @code{aligned} attribute causes the loop to -be aligned. - -@item unused -When attached to a label this attribute means that the label might not -be used. GCC will not produce a warning for the label, even if the -label doesn't seem to be referenced. This feature is intended for -code generated by programs which contains labels that may be unused -but which is compiled with @option{-Wall}. It would not normally be -appropriate to use in it human-written code, though it could be useful -in cases where the code that jumps to the label is contained within an -@code{#ifdef} conditional. - -This attribute can only be applied to labels, not statements, because -there is no warning if a statement is removed. -@end table - -@c APPLE LOCAL end for-fsf-4_4 3274130 5295549 -@node Inline -@section An Inline Function is As Fast As a Macro -@cindex inline functions -@cindex integrating function code -@cindex open coding -@cindex macros, inline alternative - -@c APPLE LOCAL begin mainline 4.3 2006-10-31 4134307 -By declaring a function inline, you can direct GCC to make -calls to that function faster. One way GCC can achieve this is to -integrate that function's code into the code for its callers. This -makes execution faster by eliminating the function-call overhead; in -addition, if any of the actual argument values are constant, their -known values may permit simplifications at compile time so that not -all of the inline function's code needs to be included. The effect on -code size is less predictable; object code may be larger or smaller -with function inlining, depending on the particular case. You can -also direct GCC to try to integrate all ``simple enough'' functions -into their callers with the option @option{-finline-functions}. - -GCC implements three different semantics of declaring a function -inline. One is available with @option{-std=gnu89} or -@option{-fgnu89-inline} or when @code{gnu_inline} attribute is present -on all inline declarations, another when @option{-std=c99} or -@option{-std=gnu99} (without @option{-fgnu89-inline}), and the third -is used when compiling C++. - -@c APPLE LOCAL begin Ians 4.2 wording for extern inline -The preprocessor macros -@code{__GNUC_GNU_INLINE__} and @code{__GNUC_STDC_INLINE__} may be used -to determine the handling of @code{inline} during a particular -compilation (@pxref{Common Predefined Macros,,,cpp,The C -Preprocessor}). -@c APPLE LOCAL end Ians 4.2 wording for extern inline - -To declare a function inline, use the @code{inline} keyword in its -declaration, like this: - -@smallexample -static inline int -inc (int *a) -@{ - (*a)++; -@} -@end smallexample - -If you are writing a header file to be included in ISO C89 programs, write -@code{__inline__} instead of @code{inline}. @xref{Alternate Keywords}. - -The three types of inlining behave similarly in two important cases: -when the @code{inline} keyword is used on a @code{static} function, -like the example above, and when a function is first declared without -using the @code{inline} keyword and then is defined with -@code{inline}, like this: - -@smallexample -extern int inc (int *a); -inline int -inc (int *a) -@{ - (*a)++; -@} -@end smallexample - -In both of these common cases, the program behaves the same as if you -had not used the @code{inline} keyword, except for its speed. - -@cindex inline functions, omission of -@opindex fkeep-inline-functions -When a function is both inline and @code{static}, if all calls to the -function are integrated into the caller, and the function's address is -never used, then the function's own assembler code is never referenced. -In this case, GCC does not actually output assembler code for the -function, unless you specify the option @option{-fkeep-inline-functions}. -Some calls cannot be integrated for various reasons (in particular, -calls that precede the function's definition cannot be integrated, and -neither can recursive calls within the definition). If there is a -nonintegrated call, then the function is compiled to assembler code as -usual. The function must also be compiled as usual if the program -refers to its address, because that can't be inlined. - -@opindex Winline -Note that certain usages in a function definition can make it unsuitable -for inline substitution. Among these usages are: use of varargs, use of -alloca, use of variable sized data types (@pxref{Variable Length}), -use of computed goto (@pxref{Labels as Values}), use of nonlocal goto, -and nested functions (@pxref{Nested Functions}). Using @option{-Winline} -will warn when a function marked @code{inline} could not be substituted, -and will give the reason for the failure. - -@cindex automatic @code{inline} for C++ member fns -@cindex @code{inline} automatic for C++ member fns -@cindex member fns, automatically @code{inline} -@cindex C++ member fns, automatically @code{inline} -@opindex fno-default-inline -As required by ISO C++, GCC considers member functions defined within -the body of a class to be marked inline even if they are -not explicitly declared with the @code{inline} keyword. You can -override this with @option{-fno-default-inline}; @pxref{C++ Dialect -Options,,Options Controlling C++ Dialect}. - -GCC does not inline any functions when not optimizing unless you specify -the @samp{always_inline} attribute for the function, like this: - -@smallexample -/* @r{Prototype.} */ -inline void foo (const char) __attribute__((always_inline)); -@end smallexample - -The remainder of this section is specific to GNU C89 inlining. - -@cindex non-static inline function -When an inline function is not @code{static}, then the compiler must assume -that there may be calls from other source files; since a global symbol can -be defined only once in any program, the function must not be defined in -the other source files, so the calls therein cannot be integrated. -Therefore, a non-@code{static} inline function is always compiled on its -own in the usual fashion. - -If you specify both @code{inline} and @code{extern} in the function -definition, then the definition is used only for inlining. In no case -is the function compiled on its own, not even if you refer to its -address explicitly. Such an address becomes an external reference, as -if you had only declared the function, and had not defined it. - -This combination of @code{inline} and @code{extern} has almost the -effect of a macro. The way to use it is to put a function definition in -a header file with these keywords, and put another copy of the -definition (lacking @code{inline} and @code{extern}) in a library file. -The definition in the header file will cause most calls to the function -to be inlined. If any uses of the function remain, they will refer to -the single copy in the library. -@c APPLE LOCAL end mainline 4.3 2006-10-31 4134307 - -GCC does not inline any functions when not optimizing unless you specify -the @samp{always_inline} attribute for the function, like this: - -@smallexample -/* @r{Prototype.} */ -inline void foo (const char) __attribute__((always_inline)); -@end smallexample - -@node Extended Asm -@section Assembler Instructions with C Expression Operands -@cindex extended @code{asm} -@cindex @code{asm} expressions -@cindex assembler instructions -@cindex registers - -In an assembler instruction using @code{asm}, you can specify the -operands of the instruction using C expressions. This means you need not -guess which registers or memory locations will contain the data you want -to use. - -You must specify an assembler instruction template much like what -appears in a machine description, plus an operand constraint string for -each operand. - -For example, here is how to use the 68881's @code{fsinx} instruction: - -@smallexample -asm ("fsinx %1,%0" : "=f" (result) : "f" (angle)); -@end smallexample - -@noindent -Here @code{angle} is the C expression for the input operand while -@code{result} is that of the output operand. Each has @samp{"f"} as its -operand constraint, saying that a floating point register is required. -The @samp{=} in @samp{=f} indicates that the operand is an output; all -output operands' constraints must use @samp{=}. The constraints use the -same language used in the machine description (@pxref{Constraints}). - -Each operand is described by an operand-constraint string followed by -the C expression in parentheses. A colon separates the assembler -template from the first output operand and another separates the last -output operand from the first input, if any. Commas separate the -operands within each group. The total number of operands is currently -limited to 30; this limitation may be lifted in some future version of -GCC@. - -If there are no output operands but there are input operands, you must -place two consecutive colons surrounding the place where the output -operands would go. - -As of GCC version 3.1, it is also possible to specify input and output -operands using symbolic names which can be referenced within the -assembler code. These names are specified inside square brackets -preceding the constraint string, and can be referenced inside the -assembler code using @code{%[@var{name}]} instead of a percentage sign -followed by the operand number. Using named operands the above example -could look like: - -@smallexample -asm ("fsinx %[angle],%[output]" - : [output] "=f" (result) - : [angle] "f" (angle)); -@end smallexample - -@noindent -Note that the symbolic operand names have no relation whatsoever to -other C identifiers. You may use any name you like, even those of -existing C symbols, but you must ensure that no two operands within the same -assembler construct use the same symbolic name. - -Output operand expressions must be lvalues; the compiler can check this. -The input operands need not be lvalues. The compiler cannot check -whether the operands have data types that are reasonable for the -instruction being executed. It does not parse the assembler instruction -template and does not know what it means or even whether it is valid -assembler input. The extended @code{asm} feature is most often used for -machine instructions the compiler itself does not know exist. If -the output expression cannot be directly addressed (for example, it is a -bit-field), your constraint must allow a register. In that case, GCC -will use the register as the output of the @code{asm}, and then store -that register into the output. - -The ordinary output operands must be write-only; GCC will assume that -the values in these operands before the instruction are dead and need -not be generated. Extended asm supports input-output or read-write -operands. Use the constraint character @samp{+} to indicate such an -operand and list it with the output operands. You should only use -read-write operands when the constraints for the operand (or the -operand in which only some of the bits are to be changed) allow a -register. - -You may, as an alternative, logically split its function into two -separate operands, one input operand and one write-only output -operand. The connection between them is expressed by constraints -which say they need to be in the same location when the instruction -executes. You can use the same C expression for both operands, or -different expressions. For example, here we write the (fictitious) -@samp{combine} instruction with @code{bar} as its read-only source -operand and @code{foo} as its read-write destination: - -@smallexample -asm ("combine %2,%0" : "=r" (foo) : "0" (foo), "g" (bar)); -@end smallexample - -@noindent -The constraint @samp{"0"} for operand 1 says that it must occupy the -same location as operand 0. A number in constraint is allowed only in -an input operand and it must refer to an output operand. - -Only a number in the constraint can guarantee that one operand will be in -the same place as another. The mere fact that @code{foo} is the value -of both operands is not enough to guarantee that they will be in the -same place in the generated assembler code. The following would not -work reliably: - -@smallexample -asm ("combine %2,%0" : "=r" (foo) : "r" (foo), "g" (bar)); -@end smallexample - -Various optimizations or reloading could cause operands 0 and 1 to be in -different registers; GCC knows no reason not to do so. For example, the -compiler might find a copy of the value of @code{foo} in one register and -use it for operand 1, but generate the output operand 0 in a different -register (copying it afterward to @code{foo}'s own address). Of course, -since the register for operand 1 is not even mentioned in the assembler -code, the result will not work, but GCC can't tell that. - -As of GCC version 3.1, one may write @code{[@var{name}]} instead of -the operand number for a matching constraint. For example: - -@smallexample -asm ("cmoveq %1,%2,%[result]" - : [result] "=r"(result) - : "r" (test), "r"(new), "[result]"(old)); -@end smallexample - -Sometimes you need to make an @code{asm} operand be a specific register, -but there's no matching constraint letter for that register @emph{by -itself}. To force the operand into that register, use a local variable -for the operand and specify the register in the variable declaration. -@xref{Explicit Reg Vars}. Then for the @code{asm} operand, use any -register constraint letter that matches the register: - -@smallexample -register int *p1 asm ("r0") = @dots{}; -register int *p2 asm ("r1") = @dots{}; -register int *result asm ("r0"); -asm ("sysint" : "=r" (result) : "0" (p1), "r" (p2)); -@end smallexample - -@anchor{Example of asm with clobbered asm reg} -In the above example, beware that a register that is call-clobbered by -the target ABI will be overwritten by any function call in the -assignment, including library calls for arithmetic operators. -Assuming it is a call-clobbered register, this may happen to @code{r0} -above by the assignment to @code{p2}. If you have to use such a -register, use temporary variables for expressions between the register -assignment and use: - -@smallexample -int t1 = @dots{}; -register int *p1 asm ("r0") = @dots{}; -register int *p2 asm ("r1") = t1; -register int *result asm ("r0"); -asm ("sysint" : "=r" (result) : "0" (p1), "r" (p2)); -@end smallexample - -Some instructions clobber specific hard registers. To describe this, -write a third colon after the input operands, followed by the names of -the clobbered hard registers (given as strings). Here is a realistic -example for the VAX: - -@smallexample -asm volatile ("movc3 %0,%1,%2" - : /* @r{no outputs} */ - : "g" (from), "g" (to), "g" (count) - : "r0", "r1", "r2", "r3", "r4", "r5"); -@end smallexample - -You may not write a clobber description in a way that overlaps with an -input or output operand. For example, you may not have an operand -describing a register class with one member if you mention that register -in the clobber list. Variables declared to live in specific registers -(@pxref{Explicit Reg Vars}), and used as asm input or output operands must -have no part mentioned in the clobber description. -There is no way for you to specify that an input -operand is modified without also specifying it as an output -operand. Note that if all the output operands you specify are for this -purpose (and hence unused), you will then also need to specify -@code{volatile} for the @code{asm} construct, as described below, to -prevent GCC from deleting the @code{asm} statement as unused. - -If you refer to a particular hardware register from the assembler code, -you will probably have to list the register after the third colon to -tell the compiler the register's value is modified. In some assemblers, -the register names begin with @samp{%}; to produce one @samp{%} in the -assembler code, you must write @samp{%%} in the input. - -If your assembler instruction can alter the condition code register, add -@samp{cc} to the list of clobbered registers. GCC on some machines -represents the condition codes as a specific hardware register; -@samp{cc} serves to name this register. On other machines, the -condition code is handled differently, and specifying @samp{cc} has no -effect. But it is valid no matter what the machine. - -If your assembler instructions access memory in an unpredictable -fashion, add @samp{memory} to the list of clobbered registers. This -will cause GCC to not keep memory values cached in registers across the -assembler instruction and not optimize stores or loads to that memory. -You will also want to add the @code{volatile} keyword if the memory -affected is not listed in the inputs or outputs of the @code{asm}, as -the @samp{memory} clobber does not count as a side-effect of the -@code{asm}. If you know how large the accessed memory is, you can add -it as input or output but if this is not known, you should add -@samp{memory}. As an example, if you access ten bytes of a string, you -can use a memory input like: - -@smallexample -@{"m"( (@{ struct @{ char x[10]; @} *p = (void *)ptr ; *p; @}) )@}. -@end smallexample - -Note that in the following example the memory input is necessary, -otherwise GCC might optimize the store to @code{x} away: -@smallexample -int foo () -@{ - int x = 42; - int *y = &x; - int result; - asm ("magic stuff accessing an 'int' pointed to by '%1'" - "=&d" (r) : "a" (y), "m" (*y)); - return result; -@} -@end smallexample - -You can put multiple assembler instructions together in a single -@code{asm} template, separated by the characters normally used in assembly -code for the system. A combination that works in most places is a newline -to break the line, plus a tab character to move to the instruction field -(written as @samp{\n\t}). Sometimes semicolons can be used, if the -assembler allows semicolons as a line-breaking character. Note that some -assembler dialects use semicolons to start a comment. -The input operands are guaranteed not to use any of the clobbered -registers, and neither will the output operands' addresses, so you can -read and write the clobbered registers as many times as you like. Here -is an example of multiple instructions in a template; it assumes the -subroutine @code{_foo} accepts arguments in registers 9 and 10: - -@smallexample -asm ("movl %0,r9\n\tmovl %1,r10\n\tcall _foo" - : /* no outputs */ - : "g" (from), "g" (to) - : "r9", "r10"); -@end smallexample - -Unless an output operand has the @samp{&} constraint modifier, GCC -may allocate it in the same register as an unrelated input operand, on -the assumption the inputs are consumed before the outputs are produced. -This assumption may be false if the assembler code actually consists of -more than one instruction. In such a case, use @samp{&} for each output -operand that may not overlap an input. @xref{Modifiers}. - -If you want to test the condition code produced by an assembler -instruction, you must include a branch and a label in the @code{asm} -construct, as follows: - -@smallexample -asm ("clr %0\n\tfrob %1\n\tbeq 0f\n\tmov #1,%0\n0:" - : "g" (result) - : "g" (input)); -@end smallexample - -@noindent -This assumes your assembler supports local labels, as the GNU assembler -and most Unix assemblers do. - -Speaking of labels, jumps from one @code{asm} to another are not -supported. The compiler's optimizers do not know about these jumps, and -therefore they cannot take account of them when deciding how to -optimize. - -@cindex macros containing @code{asm} -Usually the most convenient way to use these @code{asm} instructions is to -encapsulate them in macros that look like functions. For example, - -@smallexample -#define sin(x) \ -(@{ double __value, __arg = (x); \ - asm ("fsinx %1,%0": "=f" (__value): "f" (__arg)); \ - __value; @}) -@end smallexample - -@noindent -Here the variable @code{__arg} is used to make sure that the instruction -operates on a proper @code{double} value, and to accept only those -arguments @code{x} which can convert automatically to a @code{double}. - -Another way to make sure the instruction operates on the correct data -type is to use a cast in the @code{asm}. This is different from using a -variable @code{__arg} in that it converts more different types. For -example, if the desired type were @code{int}, casting the argument to -@code{int} would accept a pointer with no complaint, while assigning the -argument to an @code{int} variable named @code{__arg} would warn about -using a pointer unless the caller explicitly casts it. - -If an @code{asm} has output operands, GCC assumes for optimization -purposes the instruction has no side effects except to change the output -operands. This does not mean instructions with a side effect cannot be -used, but you must be careful, because the compiler may eliminate them -if the output operands aren't used, or move them out of loops, or -replace two with one if they constitute a common subexpression. Also, -if your instruction does have a side effect on a variable that otherwise -appears not to change, the old value of the variable may be reused later -if it happens to be found in a register. - -You can prevent an @code{asm} instruction from being deleted -by writing the keyword @code{volatile} after -the @code{asm}. For example: - -@smallexample -#define get_and_set_priority(new) \ -(@{ int __old; \ - asm volatile ("get_and_set_priority %0, %1" \ - : "=g" (__old) : "g" (new)); \ - __old; @}) -@end smallexample - -@noindent -The @code{volatile} keyword indicates that the instruction has -important side-effects. GCC will not delete a volatile @code{asm} if -it is reachable. (The instruction can still be deleted if GCC can -prove that control-flow will never reach the location of the -instruction.) Note that even a volatile @code{asm} instruction -can be moved relative to other code, including across jump -instructions. For example, on many targets there is a system -register which can be set to control the rounding mode of -floating point operations. You might try -setting it with a volatile @code{asm}, like this PowerPC example: - -@smallexample - asm volatile("mtfsf 255,%0" : : "f" (fpenv)); - sum = x + y; -@end smallexample - -@noindent -This will not work reliably, as the compiler may move the addition back -before the volatile @code{asm}. To make it work you need to add an -artificial dependency to the @code{asm} referencing a variable in the code -you don't want moved, for example: - -@smallexample - asm volatile ("mtfsf 255,%1" : "=X"(sum): "f"(fpenv)); - sum = x + y; -@end smallexample - -Similarly, you can't expect a -sequence of volatile @code{asm} instructions to remain perfectly -consecutive. If you want consecutive output, use a single @code{asm}. -Also, GCC will perform some optimizations across a volatile @code{asm} -instruction; GCC does not ``forget everything'' when it encounters -a volatile @code{asm} instruction the way some other compilers do. - -An @code{asm} instruction without any output operands will be treated -identically to a volatile @code{asm} instruction. - -It is a natural idea to look for a way to give access to the condition -code left by the assembler instruction. However, when we attempted to -implement this, we found no way to make it work reliably. The problem -is that output operands might need reloading, which would result in -additional following ``store'' instructions. On most machines, these -instructions would alter the condition code before there was time to -test it. This problem doesn't arise for ordinary ``test'' and -``compare'' instructions because they don't have any output operands. - -For reasons similar to those described above, it is not possible to give -an assembler instruction access to the condition code left by previous -instructions. - -If you are writing a header file that should be includable in ISO C -programs, write @code{__asm__} instead of @code{asm}. @xref{Alternate -Keywords}. - -@subsection Size of an @code{asm} - -Some targets require that GCC track the size of each instruction used in -order to generate correct code. Because the final length of an -@code{asm} is only known by the assembler, GCC must make an estimate as -to how big it will be. The estimate is formed by counting the number of -statements in the pattern of the @code{asm} and multiplying that by the -length of the longest instruction on that processor. Statements in the -@code{asm} are identified by newline characters and whatever statement -separator characters are supported by the assembler; on most processors -this is the `@code{;}' character. - -Normally, GCC's estimate is perfectly adequate to ensure that correct -code is generated, but it is possible to confuse the compiler if you use -pseudo instructions or assembler macros that expand into multiple real -instructions or if you use assembler directives that expand to more -space in the object file than would be needed for a single instruction. -If this happens then the assembler will produce a diagnostic saying that -a label is unreachable. - -@subsection i386 floating point asm operands - -There are several rules on the usage of stack-like regs in -asm_operands insns. These rules apply only to the operands that are -stack-like regs: - -@enumerate -@item -Given a set of input regs that die in an asm_operands, it is -necessary to know which are implicitly popped by the asm, and -which must be explicitly popped by gcc. - -An input reg that is implicitly popped by the asm must be -explicitly clobbered, unless it is constrained to match an -output operand. - -@item -For any input reg that is implicitly popped by an asm, it is -necessary to know how to adjust the stack to compensate for the pop. -If any non-popped input is closer to the top of the reg-stack than -the implicitly popped reg, it would not be possible to know what the -stack looked like---it's not clear how the rest of the stack ``slides -up''. - -All implicitly popped input regs must be closer to the top of -the reg-stack than any input that is not implicitly popped. - -It is possible that if an input dies in an insn, reload might -use the input reg for an output reload. Consider this example: - -@smallexample -asm ("foo" : "=t" (a) : "f" (b)); -@end smallexample - -This asm says that input B is not popped by the asm, and that -the asm pushes a result onto the reg-stack, i.e., the stack is one -deeper after the asm than it was before. But, it is possible that -reload will think that it can use the same reg for both the input and -the output, if input B dies in this insn. - -If any input operand uses the @code{f} constraint, all output reg -constraints must use the @code{&} earlyclobber. - -The asm above would be written as - -@smallexample -asm ("foo" : "=&t" (a) : "f" (b)); -@end smallexample - -@item -Some operands need to be in particular places on the stack. All -output operands fall in this category---there is no other way to -know which regs the outputs appear in unless the user indicates -this in the constraints. - -Output operands must specifically indicate which reg an output -appears in after an asm. @code{=f} is not allowed: the operand -constraints must select a class with a single reg. - -@item -Output operands may not be ``inserted'' between existing stack regs. -Since no 387 opcode uses a read/write operand, all output operands -are dead before the asm_operands, and are pushed by the asm_operands. -It makes no sense to push anywhere but the top of the reg-stack. - -Output operands must start at the top of the reg-stack: output -operands may not ``skip'' a reg. - -@item -Some asm statements may need extra stack space for internal -calculations. This can be guaranteed by clobbering stack registers -unrelated to the inputs and outputs. - -@end enumerate - -Here are a couple of reasonable asms to want to write. This asm -takes one input, which is internally popped, and produces two outputs. - -@smallexample -asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp)); -@end smallexample - -This asm takes two inputs, which are popped by the @code{fyl2xp1} opcode, -and replaces them with one output. The user must code the @code{st(1)} -clobber for reg-stack.c to know that @code{fyl2xp1} pops both inputs. - -@smallexample -asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)"); -@end smallexample - -@include md.texi - -@node Asm Labels -@section Controlling Names Used in Assembler Code -@cindex assembler names for identifiers -@cindex names used in assembler code -@cindex identifiers, names in assembler code - -You can specify the name to be used in the assembler code for a C -function or variable by writing the @code{asm} (or @code{__asm__}) -keyword after the declarator as follows: - -@smallexample -int foo asm ("myfoo") = 2; -@end smallexample - -@noindent -This specifies that the name to be used for the variable @code{foo} in -the assembler code should be @samp{myfoo} rather than the usual -@samp{_foo}. - -On systems where an underscore is normally prepended to the name of a C -function or variable, this feature allows you to define names for the -linker that do not start with an underscore. - -It does not make sense to use this feature with a non-static local -variable since such variables do not have assembler names. If you are -trying to put the variable in a particular register, see @ref{Explicit -Reg Vars}. GCC presently accepts such code with a warning, but will -probably be changed to issue an error, rather than a warning, in the -future. - -You cannot use @code{asm} in this way in a function @emph{definition}; but -you can get the same effect by writing a declaration for the function -before its definition and putting @code{asm} there, like this: - -@smallexample -extern func () asm ("FUNC"); - -func (x, y) - int x, y; -/* @r{@dots{}} */ -@end smallexample - -It is up to you to make sure that the assembler names you choose do not -conflict with any other assembler symbols. Also, you must not use a -register name; that would produce completely invalid assembler code. GCC -does not as yet have the ability to store static variables in registers. -Perhaps that will be added. - -@node Explicit Reg Vars -@section Variables in Specified Registers -@cindex explicit register variables -@cindex variables in specified registers -@cindex specified registers -@cindex registers, global allocation - -GNU C allows you to put a few global variables into specified hardware -registers. You can also specify the register in which an ordinary -register variable should be allocated. - -@itemize @bullet -@item -Global register variables reserve registers throughout the program. -This may be useful in programs such as programming language -interpreters which have a couple of global variables that are accessed -very often. - -@item -Local register variables in specific registers do not reserve the -registers, except at the point where they are used as input or output -operands in an @code{asm} statement and the @code{asm} statement itself is -not deleted. The compiler's data flow analysis is capable of determining -where the specified registers contain live values, and where they are -available for other uses. Stores into local register variables may be deleted -when they appear to be dead according to dataflow analysis. References -to local register variables may be deleted or moved or simplified. - -These local variables are sometimes convenient for use with the extended -@code{asm} feature (@pxref{Extended Asm}), if you want to write one -output of the assembler instruction directly into a particular register. -(This will work provided the register you specify fits the constraints -specified for that operand in the @code{asm}.) -@end itemize - -@menu -* Global Reg Vars:: -* Local Reg Vars:: -@end menu - -@node Global Reg Vars -@subsection Defining Global Register Variables -@cindex global register variables -@cindex registers, global variables in - -You can define a global register variable in GNU C like this: - -@smallexample -register int *foo asm ("a5"); -@end smallexample - -@noindent -Here @code{a5} is the name of the register which should be used. Choose a -register which is normally saved and restored by function calls on your -machine, so that library routines will not clobber it. - -Naturally the register name is cpu-dependent, so you would need to -conditionalize your program according to cpu type. The register -@code{a5} would be a good choice on a 68000 for a variable of pointer -type. On machines with register windows, be sure to choose a ``global'' -register that is not affected magically by the function call mechanism. - -In addition, operating systems on one type of cpu may differ in how they -name the registers; then you would need additional conditionals. For -example, some 68000 operating systems call this register @code{%a5}. - -Eventually there may be a way of asking the compiler to choose a register -automatically, but first we need to figure out how it should choose and -how to enable you to guide the choice. No solution is evident. - -Defining a global register variable in a certain register reserves that -register entirely for this use, at least within the current compilation. -The register will not be allocated for any other purpose in the functions -in the current compilation. The register will not be saved and restored by -these functions. Stores into this register are never deleted even if they -would appear to be dead, but references may be deleted or moved or -simplified. - -It is not safe to access the global register variables from signal -handlers, or from more than one thread of control, because the system -library routines may temporarily use the register for other things (unless -you recompile them specially for the task at hand). - -@cindex @code{qsort}, and global register variables -It is not safe for one function that uses a global register variable to -call another such function @code{foo} by way of a third function -@code{lose} that was compiled without knowledge of this variable (i.e.@: in a -different source file in which the variable wasn't declared). This is -because @code{lose} might save the register and put some other value there. -For example, you can't expect a global register variable to be available in -the comparison-function that you pass to @code{qsort}, since @code{qsort} -might have put something else in that register. (If you are prepared to -recompile @code{qsort} with the same global register variable, you can -solve this problem.) - -If you want to recompile @code{qsort} or other source files which do not -actually use your global register variable, so that they will not use that -register for any other purpose, then it suffices to specify the compiler -option @option{-ffixed-@var{reg}}. You need not actually add a global -register declaration to their source code. - -A function which can alter the value of a global register variable cannot -safely be called from a function compiled without this variable, because it -could clobber the value the caller expects to find there on return. -Therefore, the function which is the entry point into the part of the -program that uses the global register variable must explicitly save and -restore the value which belongs to its caller. - -@cindex register variable after @code{longjmp} -@cindex global register after @code{longjmp} -@cindex value after @code{longjmp} -@findex longjmp -@findex setjmp -On most machines, @code{longjmp} will restore to each global register -variable the value it had at the time of the @code{setjmp}. On some -machines, however, @code{longjmp} will not change the value of global -register variables. To be portable, the function that called @code{setjmp} -should make other arrangements to save the values of the global register -variables, and to restore them in a @code{longjmp}. This way, the same -thing will happen regardless of what @code{longjmp} does. - -All global register variable declarations must precede all function -definitions. If such a declaration could appear after function -definitions, the declaration would be too late to prevent the register from -being used for other purposes in the preceding functions. - -Global register variables may not have initial values, because an -executable file has no means to supply initial contents for a register. - -On the SPARC, there are reports that g3 @dots{} g7 are suitable -registers, but certain library functions, such as @code{getwd}, as well -as the subroutines for division and remainder, modify g3 and g4. g1 and -g2 are local temporaries. - -On the 68000, a2 @dots{} a5 should be suitable, as should d2 @dots{} d7. -Of course, it will not do to use more than a few of those. - -@node Local Reg Vars -@subsection Specifying Registers for Local Variables -@cindex local variables, specifying registers -@cindex specifying registers for local variables -@cindex registers for local variables - -You can define a local register variable with a specified register -like this: - -@smallexample -register int *foo asm ("a5"); -@end smallexample - -@noindent -Here @code{a5} is the name of the register which should be used. Note -that this is the same syntax used for defining global register -variables, but for a local variable it would appear within a function. - -Naturally the register name is cpu-dependent, but this is not a -problem, since specific registers are most often useful with explicit -assembler instructions (@pxref{Extended Asm}). Both of these things -generally require that you conditionalize your program according to -cpu type. - -In addition, operating systems on one type of cpu may differ in how they -name the registers; then you would need additional conditionals. For -example, some 68000 operating systems call this register @code{%a5}. - -Defining such a register variable does not reserve the register; it -remains available for other uses in places where flow control determines -the variable's value is not live. - -This option does not guarantee that GCC will generate code that has -this variable in the register you specify at all times. You may not -code an explicit reference to this register in the @emph{assembler -instruction template} part of an @code{asm} statement and assume it will -always refer to this variable. However, using the variable as an -@code{asm} @emph{operand} guarantees that the specified register is used -for the operand. - -Stores into local register variables may be deleted when they appear to be dead -according to dataflow analysis. References to local register variables may -be deleted or moved or simplified. - -As for global register variables, it's recommended that you choose a -register which is normally saved and restored by function calls on -your machine, so that library routines will not clobber it. A common -pitfall is to initialize multiple call-clobbered registers with -arbitrary expressions, where a function call or library call for an -arithmetic operator will overwrite a register value from a previous -assignment, for example @code{r0} below: -@smallexample -register int *p1 asm ("r0") = @dots{}; -register int *p2 asm ("r1") = @dots{}; -@end smallexample -In those cases, a solution is to use a temporary variable for -each arbitrary expression. @xref{Example of asm with clobbered asm reg}. - -@c APPLE LOCAL begin CW asm blocks -@node Asm Blocks and Functions -@section Blocks and Functions of Assembly Language - -(This feature is APPLE ONLY.) - -In addition to writing single statements in assembly, you can also -define blocks and entire functions to use a mixed assembly and C -syntax. The syntax follows that used in Metrowerks' CodeWarrior on -PowerPC and Microsoft Visual Studio on x86. This extension must be -explicitly enabled with the @option{-fasm-blocks} option. - -The block syntax consists of @code{asm} followed by braces, with the -assembly instructions on separate lines. (However, @code{';'} may be -used to put several instructions on one line in CW-style, and -@code{asm} in either style.) You write labels with either a preceding -@code{'@@'} or a trailing @code{':'} (or both, if you prefer); labels -are always local to the asm blocks of the function. Comments and -lexical rules are as for standard C/C++. - -@verbatim -int foo (int arg) { - register int bar; - asm { - li bar, 42 - add bar, arg, bar ; nop ; ; nop - } - return bar; -} -@end verbatim - -The function syntax uses @code{asm} as a keyword in the function -definition. In this form, C declarations may appear at the beginning -of the function body, in order to declare variables that you want to -use in the body, but may not be used after the first assembly opcode -or label (even in C99 or C++). - -@verbatim -asm int baz (int arg1) { - register int loc1, loc2; - @123 - li loc1,4 * 89 - nand. r5,arg1,loc1 - ble- cr0, @123 - otherlab: nop - mr r3,r5 -} -@end verbatim - -Note that the compiler just passes the instructions through to the -assembler with only necessary changes, such as a substitution of -globally unique labels. Assembly syntax errors will therefore be -reported by the assembler. - -Also note that the use of literal registers (such as r3) in functions -may not work properly with functions that are being inlined. - -The following PowerPC instructions are assumed to affect memory: @code{l...} -except @code{la}, @code{li} and @code{lis} (all memory loads), -@code{st...} (all memory stores), @code{sc}, @code{td...}, -@code{trap}, @code{tw...}. All other instructions are assumed to not -affect memory. - -The following PowerPC instructions take a memory operand (address operand) as -their second operand, all other instructions are assumed to not: - -@code{la}, @code{lbzu}, @code{ld}, @code{ldu}, @code{lfd}, -@code{lfdu}, @code{lfs}, @code{lfsu}, @code{lha}, @code{lhau}, -@code{lhz}, @code{lhzu}, @code{lmw}, @code{lwa}, @code{lwz}, -@code{lwzu}, @code{stb}, @code{stbu}, @code{std}, @code{stdu}, -@code{stfd}, @code{stfdu}, @code{stfs}, @code{stfsu}, @code{sth}, -@code{sthu}, @code{stmw}, @code{stw}, @code{stwu}. - -Arguments that require substitution beyond vector registers, floating -point registers, general registers are not supported; an example -would be trying to use the compiler to allocate condition code -registers instead of just writting a specific condition code register. - -On x86, the following instructions are not yet implemented by the assembler: - -@code{bound r m}, -@code{cmovpe r rm}, -@code{cmovpo r rm}, -@code{cmovz r rm}, -@code{ins m d}, -@code{lods m}, -@code{movs m m} -@code{scas m}, -@code{stos m}, and -@code{xlat m}. - -Note, the letters after the instructions are the usual x86 contraint -letters for the operands. -@c APPLE LOCAL end CW asm blocks - -@node Alternate Keywords -@section Alternate Keywords -@cindex alternate keywords -@cindex keywords, alternate - -@option{-ansi} and the various @option{-std} options disable certain -keywords. This causes trouble when you want to use GNU C extensions, or -a general-purpose header file that should be usable by all programs, -including ISO C programs. The keywords @code{asm}, @code{typeof} and -@code{inline} are not available in programs compiled with -@option{-ansi} or @option{-std} (although @code{inline} can be used in a -program compiled with @option{-std=c99}). The ISO C99 keyword -@code{restrict} is only available when @option{-std=gnu99} (which will -eventually be the default) or @option{-std=c99} (or the equivalent -@option{-std=iso9899:1999}) is used. - -The way to solve these problems is to put @samp{__} at the beginning and -end of each problematical keyword. For example, use @code{__asm__} -instead of @code{asm}, and @code{__inline__} instead of @code{inline}. - -Other C compilers won't accept these alternative keywords; if you want to -compile with another compiler, you can define the alternate keywords as -macros to replace them with the customary keywords. It looks like this: - -@smallexample -#ifndef __GNUC__ -#define __asm__ asm -#endif -@end smallexample - -@findex __extension__ -@opindex pedantic -@option{-pedantic} and other options cause warnings for many GNU C extensions. -You can -prevent such warnings within one expression by writing -@code{__extension__} before the expression. @code{__extension__} has no -effect aside from this. - -@node Incomplete Enums -@section Incomplete @code{enum} Types - -You can define an @code{enum} tag without specifying its possible values. -This results in an incomplete type, much like what you get if you write -@code{struct foo} without describing the elements. A later declaration -which does specify the possible values completes the type. - -You can't allocate variables or storage using the type while it is -incomplete. However, you can work with pointers to that type. - -This extension may not be very useful, but it makes the handling of -@code{enum} more consistent with the way @code{struct} and @code{union} -are handled. - -This extension is not supported by GNU C++. - -@node Function Names -@section Function Names as Strings -@cindex @code{__func__} identifier -@cindex @code{__FUNCTION__} identifier -@cindex @code{__PRETTY_FUNCTION__} identifier - -GCC provides three magic variables which hold the name of the current -function, as a string. The first of these is @code{__func__}, which -is part of the C99 standard: - -@display -The identifier @code{__func__} is implicitly declared by the translator -as if, immediately following the opening brace of each function -definition, the declaration - -@smallexample -static const char __func__[] = "function-name"; -@end smallexample - -appeared, where function-name is the name of the lexically-enclosing -function. This name is the unadorned name of the function. -@end display - -@code{__FUNCTION__} is another name for @code{__func__}. Older -versions of GCC recognize only this name. However, it is not -standardized. For maximum portability, we recommend you use -@code{__func__}, but provide a fallback definition with the -preprocessor: - -@smallexample -#if __STDC_VERSION__ < 199901L -# if __GNUC__ >= 2 -# define __func__ __FUNCTION__ -# else -# define __func__ "<unknown>" -# endif -#endif -@end smallexample - -In C, @code{__PRETTY_FUNCTION__} is yet another name for -@code{__func__}. However, in C++, @code{__PRETTY_FUNCTION__} contains -the type signature of the function as well as its bare name. For -example, this program: - -@smallexample -extern "C" @{ -extern int printf (char *, ...); -@} - -class a @{ - public: - void sub (int i) - @{ - printf ("__FUNCTION__ = %s\n", __FUNCTION__); - printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__); - @} -@}; - -int -main (void) -@{ - a ax; - ax.sub (0); - return 0; -@} -@end smallexample - -@noindent -gives this output: - -@smallexample -__FUNCTION__ = sub -__PRETTY_FUNCTION__ = void a::sub(int) -@end smallexample - -These identifiers are not preprocessor macros. In GCC 3.3 and -earlier, in C only, @code{__FUNCTION__} and @code{__PRETTY_FUNCTION__} -were treated as string literals; they could be used to initialize -@code{char} arrays, and they could be concatenated with other string -literals. GCC 3.4 and later treat them as variables, like -@code{__func__}. In C++, @code{__FUNCTION__} and -@code{__PRETTY_FUNCTION__} have always been variables. - -@node Return Address -@section Getting the Return or Frame Address of a Function - -These functions may be used to get information about the callers of a -function. - -@deftypefn {Built-in Function} {void *} __builtin_return_address (unsigned int @var{level}) -This function returns the return address of the current function, or of -one of its callers. The @var{level} argument is number of frames to -scan up the call stack. A value of @code{0} yields the return address -of the current function, a value of @code{1} yields the return address -of the caller of the current function, and so forth. When inlining -the expected behavior is that the function will return the address of -the function that will be returned to. To work around this behavior use -the @code{noinline} function attribute. - -The @var{level} argument must be a constant integer. - -On some machines it may be impossible to determine the return address of -any function other than the current one; in such cases, or when the top -of the stack has been reached, this function will return @code{0} or a -random value. In addition, @code{__builtin_frame_address} may be used -to determine if the top of the stack has been reached. - -This function should only be used with a nonzero argument for debugging -purposes. -@end deftypefn - -@deftypefn {Built-in Function} {void *} __builtin_frame_address (unsigned int @var{level}) -This function is similar to @code{__builtin_return_address}, but it -returns the address of the function frame rather than the return address -of the function. Calling @code{__builtin_frame_address} with a value of -@code{0} yields the frame address of the current function, a value of -@code{1} yields the frame address of the caller of the current function, -and so forth. - -The frame is the area on the stack which holds local variables and saved -registers. The frame address is normally the address of the first word -pushed on to the stack by the function. However, the exact definition -depends upon the processor and the calling convention. If the processor -has a dedicated frame pointer register, and the function has a frame, -then @code{__builtin_frame_address} will return the value of the frame -pointer register. - -On some machines it may be impossible to determine the frame address of -any function other than the current one; in such cases, or when the top -of the stack has been reached, this function will return @code{0} if -the first frame pointer is properly initialized by the startup code. - -This function should only be used with a nonzero argument for debugging -purposes. -@end deftypefn - -@node Vector Extensions -@section Using vector instructions through built-in functions - -On some targets, the instruction set contains SIMD vector instructions that -operate on multiple values contained in one large register at the same time. -For example, on the i386 the MMX, 3Dnow! and SSE extensions can be used -this way. - -The first step in using these extensions is to provide the necessary data -types. This should be done using an appropriate @code{typedef}: - -@smallexample -typedef int v4si __attribute__ ((vector_size (16))); -@end smallexample - -The @code{int} type specifies the base type, while the attribute specifies -the vector size for the variable, measured in bytes. For example, the -declaration above causes the compiler to set the mode for the @code{v4si} -type to be 16 bytes wide and divided into @code{int} sized units. For -a 32-bit @code{int} this means a vector of 4 units of 4 bytes, and the -corresponding mode of @code{foo} will be @acronym{V4SI}. - -The @code{vector_size} attribute is only applicable to integral and -float scalars, although arrays, pointers, and function return values -are allowed in conjunction with this construct. - -All the basic integer types can be used as base types, both as signed -and as unsigned: @code{char}, @code{short}, @code{int}, @code{long}, -@code{long long}. In addition, @code{float} and @code{double} can be -used to build floating-point vector types. - -Specifying a combination that is not valid for the current architecture -will cause GCC to synthesize the instructions using a narrower mode. -For example, if you specify a variable of type @code{V4SI} and your -architecture does not allow for this specific SIMD type, GCC will -produce code that uses 4 @code{SIs}. - -The types defined in this manner can be used with a subset of normal C -operations. Currently, GCC will allow using the following operators -on these types: @code{+, -, *, /, unary minus, ^, |, &, ~}@. - -The operations behave like C++ @code{valarrays}. Addition is defined as -the addition of the corresponding elements of the operands. For -example, in the code below, each of the 4 elements in @var{a} will be -added to the corresponding 4 elements in @var{b} and the resulting -vector will be stored in @var{c}. - -@smallexample -typedef int v4si __attribute__ ((vector_size (16))); - -v4si a, b, c; - -c = a + b; -@end smallexample - -Subtraction, multiplication, division, and the logical operations -operate in a similar manner. Likewise, the result of using the unary -minus or complement operators on a vector type is a vector whose -elements are the negative or complemented values of the corresponding -elements in the operand. - -You can declare variables and use them in function calls and returns, as -well as in assignments and some casts. You can specify a vector type as -a return type for a function. Vector types can also be used as function -arguments. It is possible to cast from one vector type to another, -provided they are of the same size (in fact, you can also cast vectors -to and from other datatypes of the same size). - -You cannot operate between vectors of different lengths or different -signedness without a cast. - -A port that supports hardware vector operations, usually provides a set -of built-in functions that can be used to operate on vectors. For -example, a function to add two vectors and multiply the result by a -third could look like this: - -@smallexample -v4si f (v4si a, v4si b, v4si c) -@{ - v4si tmp = __builtin_addv4si (a, b); - return __builtin_mulv4si (tmp, c); -@} - -@end smallexample - -@node Offsetof -@section Offsetof -@findex __builtin_offsetof - -GCC implements for both C and C++ a syntactic extension to implement -the @code{offsetof} macro. - -@smallexample -primary: - "__builtin_offsetof" "(" @code{typename} "," offsetof_member_designator ")" - -offsetof_member_designator: - @code{identifier} - | offsetof_member_designator "." @code{identifier} - | offsetof_member_designator "[" @code{expr} "]" -@end smallexample - -This extension is sufficient such that - -@smallexample -#define offsetof(@var{type}, @var{member}) __builtin_offsetof (@var{type}, @var{member}) -@end smallexample - -is a suitable definition of the @code{offsetof} macro. In C++, @var{type} -may be dependent. In either case, @var{member} may consist of a single -identifier, or a sequence of member accesses and array references. - -@node Atomic Builtins -@section Built-in functions for atomic memory access - -The following builtins are intended to be compatible with those described -in the @cite{Intel Itanium Processor-specific Application Binary Interface}, -section 7.4. As such, they depart from the normal GCC practice of using -the ``__builtin_'' prefix, and further that they are overloaded such that -they work on multiple types. - -The definition given in the Intel documentation allows only for the use of -the types @code{int}, @code{long}, @code{long long} as well as their unsigned -counterparts. GCC will allow any integral scalar or pointer type that is -1, 2, 4 or 8 bytes in length. - -Not all operations are supported by all target processors. If a particular -operation cannot be implemented on the target processor, a warning will be -generated and a call an external function will be generated. The external -function will carry the same name as the builtin, with an additional suffix -@samp{_@var{n}} where @var{n} is the size of the data type. - -@c ??? Should we have a mechanism to suppress this warning? This is almost -@c useful for implementing the operation under the control of an external -@c mutex. - -In most cases, these builtins are considered a @dfn{full barrier}. That is, -no memory operand will be moved across the operation, either forward or -backward. Further, instructions will be issued as necessary to prevent the -processor from speculating loads across the operation and from queuing stores -after the operation. - -All of the routines are are described in the Intel documentation to take -``an optional list of variables protected by the memory barrier''. It's -not clear what is meant by that; it could mean that @emph{only} the -following variables are protected, or it could mean that these variables -should in addition be protected. At present GCC ignores this list and -protects all variables which are globally accessible. If in the future -we make some use of this list, an empty list will continue to mean all -globally accessible variables. - -@table @code -@item @var{type} __sync_fetch_and_add (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_fetch_and_sub (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_fetch_and_or (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_fetch_and_and (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_fetch_and_xor (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_fetch_and_nand (@var{type} *ptr, @var{type} value, ...) -@findex __sync_fetch_and_add -@findex __sync_fetch_and_sub -@findex __sync_fetch_and_or -@findex __sync_fetch_and_and -@findex __sync_fetch_and_xor -@findex __sync_fetch_and_nand -These builtins perform the operation suggested by the name, and -returns the value that had previously been in memory. That is, - -@smallexample -@{ tmp = *ptr; *ptr @var{op}= value; return tmp; @} -@{ tmp = *ptr; *ptr = ~tmp & value; return tmp; @} // nand -@end smallexample - -@item @var{type} __sync_add_and_fetch (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_sub_and_fetch (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_or_and_fetch (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_and_and_fetch (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_xor_and_fetch (@var{type} *ptr, @var{type} value, ...) -@itemx @var{type} __sync_nand_and_fetch (@var{type} *ptr, @var{type} value, ...) -@findex __sync_add_and_fetch -@findex __sync_sub_and_fetch -@findex __sync_or_and_fetch -@findex __sync_and_and_fetch -@findex __sync_xor_and_fetch -@findex __sync_nand_and_fetch -These builtins perform the operation suggested by the name, and -return the new value. That is, - -@smallexample -@{ *ptr @var{op}= value; return *ptr; @} -@{ *ptr = ~*ptr & value; return *ptr; @} // nand -@end smallexample - -@item bool __sync_bool_compare_and_swap (@var{type} *ptr, @var{type} oldval @var{type} newval, ...) -@itemx @var{type} __sync_val_compare_and_swap (@var{type} *ptr, @var{type} oldval @var{type} newval, ...) -@findex __sync_bool_compare_and_swap -@findex __sync_val_compare_and_swap -These builtins perform an atomic compare and swap. That is, if the current -value of @code{*@var{ptr}} is @var{oldval}, then write @var{newval} into -@code{*@var{ptr}}. - -The ``bool'' version returns true if the comparison is successful and -@var{newval} was written. The ``val'' version returns the contents -of @code{*@var{ptr}} before the operation. - -@item __sync_synchronize (...) -@findex __sync_synchronize -This builtin issues a full memory barrier. - -@item @var{type} __sync_lock_test_and_set (@var{type} *ptr, @var{type} value, ...) -@findex __sync_lock_test_and_set -This builtin, as described by Intel, is not a traditional test-and-set -operation, but rather an atomic exchange operation. It writes @var{value} -into @code{*@var{ptr}}, and returns the previous contents of -@code{*@var{ptr}}. - -Many targets have only minimal support for such locks, and do not support -a full exchange operation. In this case, a target may support reduced -functionality here by which the @emph{only} valid value to store is the -immediate constant 1. The exact value actually stored in @code{*@var{ptr}} -is implementation defined. - -This builtin is not a full barrier, but rather an @dfn{acquire barrier}. -This means that references after the builtin cannot move to (or be -speculated to) before the builtin, but previous memory stores may not -be globally visible yet, and previous memory loads may not yet be -satisfied. - -@item void __sync_lock_release (@var{type} *ptr, ...) -@findex __sync_lock_release -This builtin releases the lock acquired by @code{__sync_lock_test_and_set}. -Normally this means writing the constant 0 to @code{*@var{ptr}}. - -This builtin is not a full barrier, but rather a @dfn{release barrier}. -This means that all previous memory stores are globally visible, and all -previous memory loads have been satisfied, but following memory reads -are not prevented from being speculated to before the barrier. -@end table - -@node Object Size Checking -@section Object Size Checking Builtins -@findex __builtin_object_size -@findex __builtin___memcpy_chk -@findex __builtin___mempcpy_chk -@findex __builtin___memmove_chk -@findex __builtin___memset_chk -@findex __builtin___strcpy_chk -@findex __builtin___stpcpy_chk -@findex __builtin___strncpy_chk -@findex __builtin___strcat_chk -@findex __builtin___strncat_chk -@findex __builtin___sprintf_chk -@findex __builtin___snprintf_chk -@findex __builtin___vsprintf_chk -@findex __builtin___vsnprintf_chk -@findex __builtin___printf_chk -@findex __builtin___vprintf_chk -@findex __builtin___fprintf_chk -@findex __builtin___vfprintf_chk - -GCC implements a limited buffer overflow protection mechanism -that can prevent some buffer overflow attacks. - -@deftypefn {Built-in Function} {size_t} __builtin_object_size (void * @var{ptr}, int @var{type}) -is a built-in construct that returns a constant number of bytes from -@var{ptr} to the end of the object @var{ptr} pointer points to -(if known at compile time). @code{__builtin_object_size} never evaluates -its arguments for side-effects. If there are any side-effects in them, it -returns @code{(size_t) -1} for @var{type} 0 or 1 and @code{(size_t) 0} -for @var{type} 2 or 3. If there are multiple objects @var{ptr} can -point to and all of them are known at compile time, the returned number -is the maximum of remaining byte counts in those objects if @var{type} & 2 is -0 and minimum if nonzero. If it is not possible to determine which objects -@var{ptr} points to at compile time, @code{__builtin_object_size} should -return @code{(size_t) -1} for @var{type} 0 or 1 and @code{(size_t) 0} -for @var{type} 2 or 3. - -@var{type} is an integer constant from 0 to 3. If the least significant -bit is clear, objects are whole variables, if it is set, a closest -surrounding subobject is considered the object a pointer points to. -The second bit determines if maximum or minimum of remaining bytes -is computed. - -@smallexample -struct V @{ char buf1[10]; int b; char buf2[10]; @} var; -char *p = &var.buf1[1], *q = &var.b; - -/* Here the object p points to is var. */ -assert (__builtin_object_size (p, 0) == sizeof (var) - 1); -/* The subobject p points to is var.buf1. */ -assert (__builtin_object_size (p, 1) == sizeof (var.buf1) - 1); -/* The object q points to is var. */ -assert (__builtin_object_size (q, 0) - == (char *) (&var + 1) - (char *) &var.b); -/* The subobject q points to is var.b. */ -assert (__builtin_object_size (q, 1) == sizeof (var.b)); -@end smallexample -@end deftypefn - -There are built-in functions added for many common string operation -functions, e.g. for @code{memcpy} @code{__builtin___memcpy_chk} -built-in is provided. This built-in has an additional last argument, -which is the number of bytes remaining in object the @var{dest} -argument points to or @code{(size_t) -1} if the size is not known. - -The built-in functions are optimized into the normal string functions -like @code{memcpy} if the last argument is @code{(size_t) -1} or if -it is known at compile time that the destination object will not -be overflown. If the compiler can determine at compile time the -object will be always overflown, it issues a warning. - -The intended use can be e.g. - -@smallexample -#undef memcpy -#define bos0(dest) __builtin_object_size (dest, 0) -#define memcpy(dest, src, n) \ - __builtin___memcpy_chk (dest, src, n, bos0 (dest)) - -char *volatile p; -char buf[10]; -/* It is unknown what object p points to, so this is optimized - into plain memcpy - no checking is possible. */ -memcpy (p, "abcde", n); -/* Destination is known and length too. It is known at compile - time there will be no overflow. */ -memcpy (&buf[5], "abcde", 5); -/* Destination is known, but the length is not known at compile time. - This will result in __memcpy_chk call that can check for overflow - at runtime. */ -memcpy (&buf[5], "abcde", n); -/* Destination is known and it is known at compile time there will - be overflow. There will be a warning and __memcpy_chk call that - will abort the program at runtime. */ -memcpy (&buf[6], "abcde", 5); -@end smallexample - -Such built-in functions are provided for @code{memcpy}, @code{mempcpy}, -@code{memmove}, @code{memset}, @code{strcpy}, @code{stpcpy}, @code{strncpy}, -@code{strcat} and @code{strncat}. - -There are also checking built-in functions for formatted output functions. -@smallexample -int __builtin___sprintf_chk (char *s, int flag, size_t os, const char *fmt, ...); -int __builtin___snprintf_chk (char *s, size_t maxlen, int flag, size_t os, - const char *fmt, ...); -int __builtin___vsprintf_chk (char *s, int flag, size_t os, const char *fmt, - va_list ap); -int __builtin___vsnprintf_chk (char *s, size_t maxlen, int flag, size_t os, - const char *fmt, va_list ap); -@end smallexample - -The added @var{flag} argument is passed unchanged to @code{__sprintf_chk} -etc. functions and can contain implementation specific flags on what -additional security measures the checking function might take, such as -handling @code{%n} differently. - -The @var{os} argument is the object size @var{s} points to, like in the -other built-in functions. There is a small difference in the behavior -though, if @var{os} is @code{(size_t) -1}, the built-in functions are -optimized into the non-checking functions only if @var{flag} is 0, otherwise -the checking function is called with @var{os} argument set to -@code{(size_t) -1}. - -In addition to this, there are checking built-in functions -@code{__builtin___printf_chk}, @code{__builtin___vprintf_chk}, -@code{__builtin___fprintf_chk} and @code{__builtin___vfprintf_chk}. -These have just one additional argument, @var{flag}, right before -format string @var{fmt}. If the compiler is able to optimize them to -@code{fputc} etc. functions, it will, otherwise the checking function -should be called and the @var{flag} argument passed to it. - -@node Other Builtins -@section Other built-in functions provided by GCC -@cindex built-in functions -@findex __builtin_isgreater -@findex __builtin_isgreaterequal -@findex __builtin_isless -@findex __builtin_islessequal -@findex __builtin_islessgreater -@findex __builtin_isunordered -@findex __builtin_powi -@findex __builtin_powif -@findex __builtin_powil -@findex _Exit -@findex _exit -@findex abort -@findex abs -@findex acos -@findex acosf -@findex acosh -@findex acoshf -@findex acoshl -@findex acosl -@findex alloca -@findex asin -@findex asinf -@findex asinh -@findex asinhf -@findex asinhl -@findex asinl -@findex atan -@findex atan2 -@findex atan2f -@findex atan2l -@findex atanf -@findex atanh -@findex atanhf -@findex atanhl -@findex atanl -@findex bcmp -@findex bzero -@findex cabs -@findex cabsf -@findex cabsl -@findex cacos -@findex cacosf -@findex cacosh -@findex cacoshf -@findex cacoshl -@findex cacosl -@findex calloc -@findex carg -@findex cargf -@findex cargl -@findex casin -@findex casinf -@findex casinh -@findex casinhf -@findex casinhl -@findex casinl -@findex catan -@findex catanf -@findex catanh -@findex catanhf -@findex catanhl -@findex catanl -@findex cbrt -@findex cbrtf -@findex cbrtl -@findex ccos -@findex ccosf -@findex ccosh -@findex ccoshf -@findex ccoshl -@findex ccosl -@findex ceil -@findex ceilf -@findex ceill -@findex cexp -@findex cexpf -@findex cexpl -@findex cimag -@findex cimagf -@findex cimagl -@findex clog -@findex clogf -@findex clogl -@findex conj -@findex conjf -@findex conjl -@findex copysign -@findex copysignf -@findex copysignl -@findex cos -@findex cosf -@findex cosh -@findex coshf -@findex coshl -@findex cosl -@findex cpow -@findex cpowf -@findex cpowl -@findex cproj -@findex cprojf -@findex cprojl -@findex creal -@findex crealf -@findex creall -@findex csin -@findex csinf -@findex csinh -@findex csinhf -@findex csinhl -@findex csinl -@findex csqrt -@findex csqrtf -@findex csqrtl -@findex ctan -@findex ctanf -@findex ctanh -@findex ctanhf -@findex ctanhl -@findex ctanl -@findex dcgettext -@findex dgettext -@findex drem -@findex dremf -@findex dreml -@findex erf -@findex erfc -@findex erfcf -@findex erfcl -@findex erff -@findex erfl -@findex exit -@findex exp -@findex exp10 -@findex exp10f -@findex exp10l -@findex exp2 -@findex exp2f -@findex exp2l -@findex expf -@findex expl -@findex expm1 -@findex expm1f -@findex expm1l -@findex fabs -@findex fabsf -@findex fabsl -@findex fdim -@findex fdimf -@findex fdiml -@findex ffs -@findex floor -@findex floorf -@findex floorl -@findex fma -@findex fmaf -@findex fmal -@findex fmax -@findex fmaxf -@findex fmaxl -@findex fmin -@findex fminf -@findex fminl -@findex fmod -@findex fmodf -@findex fmodl -@findex fprintf -@findex fprintf_unlocked -@findex fputs -@findex fputs_unlocked -@findex frexp -@findex frexpf -@findex frexpl -@findex fscanf -@findex gamma -@findex gammaf -@findex gammal -@findex gettext -@findex hypot -@findex hypotf -@findex hypotl -@findex ilogb -@findex ilogbf -@findex ilogbl -@findex imaxabs -@findex index -@findex isalnum -@findex isalpha -@findex isascii -@findex isblank -@findex iscntrl -@findex isdigit -@findex isgraph -@findex islower -@findex isprint -@findex ispunct -@findex isspace -@findex isupper -@findex iswalnum -@findex iswalpha -@findex iswblank -@findex iswcntrl -@findex iswdigit -@findex iswgraph -@findex iswlower -@findex iswprint -@findex iswpunct -@findex iswspace -@findex iswupper -@findex iswxdigit -@findex isxdigit -@findex j0 -@findex j0f -@findex j0l -@findex j1 -@findex j1f -@findex j1l -@findex jn -@findex jnf -@findex jnl -@findex labs -@findex ldexp -@findex ldexpf -@findex ldexpl -@findex lgamma -@findex lgammaf -@findex lgammal -@findex llabs -@findex llrint -@findex llrintf -@findex llrintl -@findex llround -@findex llroundf -@findex llroundl -@findex log -@findex log10 -@findex log10f -@findex log10l -@findex log1p -@findex log1pf -@findex log1pl -@findex log2 -@findex log2f -@findex log2l -@findex logb -@findex logbf -@findex logbl -@findex logf -@findex logl -@findex lrint -@findex lrintf -@findex lrintl -@findex lround -@findex lroundf -@findex lroundl -@findex malloc -@findex memcmp -@findex memcpy -@findex mempcpy -@findex memset -@findex modf -@findex modff -@findex modfl -@findex nearbyint -@findex nearbyintf -@findex nearbyintl -@findex nextafter -@findex nextafterf -@findex nextafterl -@findex nexttoward -@findex nexttowardf -@findex nexttowardl -@findex pow -@findex pow10 -@findex pow10f -@findex pow10l -@findex powf -@findex powl -@findex printf -@findex printf_unlocked -@findex putchar -@findex puts -@findex remainder -@findex remainderf -@findex remainderl -@findex remquo -@findex remquof -@findex remquol -@findex rindex -@findex rint -@findex rintf -@findex rintl -@findex round -@findex roundf -@findex roundl -@findex scalb -@findex scalbf -@findex scalbl -@findex scalbln -@findex scalblnf -@findex scalblnf -@findex scalbn -@findex scalbnf -@findex scanfnl -@findex signbit -@findex signbitf -@findex signbitl -@findex significand -@findex significandf -@findex significandl -@findex sin -@findex sincos -@findex sincosf -@findex sincosl -@findex sinf -@findex sinh -@findex sinhf -@findex sinhl -@findex sinl -@findex snprintf -@findex sprintf -@findex sqrt -@findex sqrtf -@findex sqrtl -@findex sscanf -@findex stpcpy -@findex stpncpy -@findex strcasecmp -@findex strcat -@findex strchr -@findex strcmp -@findex strcpy -@findex strcspn -@findex strdup -@findex strfmon -@findex strftime -@findex strlen -@findex strncasecmp -@findex strncat -@findex strncmp -@findex strncpy -@findex strndup -@findex strpbrk -@findex strrchr -@findex strspn -@findex strstr -@findex tan -@findex tanf -@findex tanh -@findex tanhf -@findex tanhl -@findex tanl -@findex tgamma -@findex tgammaf -@findex tgammal -@findex toascii -@findex tolower -@findex toupper -@findex towlower -@findex towupper -@findex trunc -@findex truncf -@findex truncl -@findex vfprintf -@findex vfscanf -@findex vprintf -@findex vscanf -@findex vsnprintf -@findex vsprintf -@findex vsscanf -@findex y0 -@findex y0f -@findex y0l -@findex y1 -@findex y1f -@findex y1l -@findex yn -@findex ynf -@findex ynl - -GCC provides a large number of built-in functions other than the ones -mentioned above. Some of these are for internal use in the processing -of exceptions or variable-length argument lists and will not be -documented here because they may change from time to time; we do not -recommend general use of these functions. - -The remaining functions are provided for optimization purposes. - -@opindex fno-builtin -GCC includes built-in versions of many of the functions in the standard -C library. The versions prefixed with @code{__builtin_} will always be -treated as having the same meaning as the C library function even if you -specify the @option{-fno-builtin} option. (@pxref{C Dialect Options}) -Many of these functions are only optimized in certain cases; if they are -not optimized in a particular case, a call to the library function will -be emitted. - -@opindex ansi -@opindex std -Outside strict ISO C mode (@option{-ansi}, @option{-std=c89} or -@option{-std=c99}), the functions -@code{_exit}, @code{alloca}, @code{bcmp}, @code{bzero}, -@code{dcgettext}, @code{dgettext}, @code{dremf}, @code{dreml}, -@code{drem}, @code{exp10f}, @code{exp10l}, @code{exp10}, @code{ffsll}, -@code{ffsl}, @code{ffs}, @code{fprintf_unlocked}, @code{fputs_unlocked}, -@code{gammaf}, @code{gammal}, @code{gamma}, @code{gettext}, -@code{index}, @code{isascii}, @code{j0f}, @code{j0l}, @code{j0}, -@code{j1f}, @code{j1l}, @code{j1}, @code{jnf}, @code{jnl}, @code{jn}, -@code{mempcpy}, @code{pow10f}, @code{pow10l}, @code{pow10}, -@code{printf_unlocked}, @code{rindex}, @code{scalbf}, @code{scalbl}, -@code{scalb}, @code{signbit}, @code{signbitf}, @code{signbitl}, -@code{significandf}, @code{significandl}, @code{significand}, -@code{sincosf}, @code{sincosl}, @code{sincos}, @code{stpcpy}, -@code{stpncpy}, @code{strcasecmp}, @code{strdup}, @code{strfmon}, -@code{strncasecmp}, @code{strndup}, @code{toascii}, @code{y0f}, -@code{y0l}, @code{y0}, @code{y1f}, @code{y1l}, @code{y1}, @code{ynf}, -@code{ynl} and @code{yn} -may be handled as built-in functions. -All these functions have corresponding versions -prefixed with @code{__builtin_}, which may be used even in strict C89 -mode. - -The ISO C99 functions -@code{_Exit}, @code{acoshf}, @code{acoshl}, @code{acosh}, @code{asinhf}, -@code{asinhl}, @code{asinh}, @code{atanhf}, @code{atanhl}, @code{atanh}, -@code{cabsf}, @code{cabsl}, @code{cabs}, @code{cacosf}, @code{cacoshf}, -@code{cacoshl}, @code{cacosh}, @code{cacosl}, @code{cacos}, -@code{cargf}, @code{cargl}, @code{carg}, @code{casinf}, @code{casinhf}, -@code{casinhl}, @code{casinh}, @code{casinl}, @code{casin}, -@code{catanf}, @code{catanhf}, @code{catanhl}, @code{catanh}, -@code{catanl}, @code{catan}, @code{cbrtf}, @code{cbrtl}, @code{cbrt}, -@code{ccosf}, @code{ccoshf}, @code{ccoshl}, @code{ccosh}, @code{ccosl}, -@code{ccos}, @code{cexpf}, @code{cexpl}, @code{cexp}, @code{cimagf}, -@code{cimagl}, @code{cimag}, @code{clogf}, @code{clogl}, @code{clog}, -@code{conjf}, @code{conjl}, @code{conj}, @code{copysignf}, @code{copysignl}, -@code{copysign}, @code{cpowf}, @code{cpowl}, @code{cpow}, @code{cprojf}, -@code{cprojl}, @code{cproj}, @code{crealf}, @code{creall}, @code{creal}, -@code{csinf}, @code{csinhf}, @code{csinhl}, @code{csinh}, @code{csinl}, -@code{csin}, @code{csqrtf}, @code{csqrtl}, @code{csqrt}, @code{ctanf}, -@code{ctanhf}, @code{ctanhl}, @code{ctanh}, @code{ctanl}, @code{ctan}, -@code{erfcf}, @code{erfcl}, @code{erfc}, @code{erff}, @code{erfl}, -@code{erf}, @code{exp2f}, @code{exp2l}, @code{exp2}, @code{expm1f}, -@code{expm1l}, @code{expm1}, @code{fdimf}, @code{fdiml}, @code{fdim}, -@code{fmaf}, @code{fmal}, @code{fmaxf}, @code{fmaxl}, @code{fmax}, -@code{fma}, @code{fminf}, @code{fminl}, @code{fmin}, @code{hypotf}, -@code{hypotl}, @code{hypot}, @code{ilogbf}, @code{ilogbl}, @code{ilogb}, -@code{imaxabs}, @code{isblank}, @code{iswblank}, @code{lgammaf}, -@code{lgammal}, @code{lgamma}, @code{llabs}, @code{llrintf}, @code{llrintl}, -@code{llrint}, @code{llroundf}, @code{llroundl}, @code{llround}, -@code{log1pf}, @code{log1pl}, @code{log1p}, @code{log2f}, @code{log2l}, -@code{log2}, @code{logbf}, @code{logbl}, @code{logb}, @code{lrintf}, -@code{lrintl}, @code{lrint}, @code{lroundf}, @code{lroundl}, -@code{lround}, @code{nearbyintf}, @code{nearbyintl}, @code{nearbyint}, -@code{nextafterf}, @code{nextafterl}, @code{nextafter}, -@code{nexttowardf}, @code{nexttowardl}, @code{nexttoward}, -@code{remainderf}, @code{remainderl}, @code{remainder}, @code{remquof}, -@code{remquol}, @code{remquo}, @code{rintf}, @code{rintl}, @code{rint}, -@code{roundf}, @code{roundl}, @code{round}, @code{scalblnf}, -@code{scalblnl}, @code{scalbln}, @code{scalbnf}, @code{scalbnl}, -@code{scalbn}, @code{snprintf}, @code{tgammaf}, @code{tgammal}, -@code{tgamma}, @code{truncf}, @code{truncl}, @code{trunc}, -@code{vfscanf}, @code{vscanf}, @code{vsnprintf} and @code{vsscanf} -are handled as built-in functions -except in strict ISO C90 mode (@option{-ansi} or @option{-std=c89}). - -There are also built-in versions of the ISO C99 functions -@code{acosf}, @code{acosl}, @code{asinf}, @code{asinl}, @code{atan2f}, -@code{atan2l}, @code{atanf}, @code{atanl}, @code{ceilf}, @code{ceill}, -@code{cosf}, @code{coshf}, @code{coshl}, @code{cosl}, @code{expf}, -@code{expl}, @code{fabsf}, @code{fabsl}, @code{floorf}, @code{floorl}, -@code{fmodf}, @code{fmodl}, @code{frexpf}, @code{frexpl}, @code{ldexpf}, -@code{ldexpl}, @code{log10f}, @code{log10l}, @code{logf}, @code{logl}, -@code{modfl}, @code{modf}, @code{powf}, @code{powl}, @code{sinf}, -@code{sinhf}, @code{sinhl}, @code{sinl}, @code{sqrtf}, @code{sqrtl}, -@code{tanf}, @code{tanhf}, @code{tanhl} and @code{tanl} -that are recognized in any mode since ISO C90 reserves these names for -the purpose to which ISO C99 puts them. All these functions have -corresponding versions prefixed with @code{__builtin_}. - -The ISO C94 functions -@code{iswalnum}, @code{iswalpha}, @code{iswcntrl}, @code{iswdigit}, -@code{iswgraph}, @code{iswlower}, @code{iswprint}, @code{iswpunct}, -@code{iswspace}, @code{iswupper}, @code{iswxdigit}, @code{towlower} and -@code{towupper} -are handled as built-in functions -except in strict ISO C90 mode (@option{-ansi} or @option{-std=c89}). - -The ISO C90 functions -@code{abort}, @code{abs}, @code{acos}, @code{asin}, @code{atan2}, -@code{atan}, @code{calloc}, @code{ceil}, @code{cosh}, @code{cos}, -@code{exit}, @code{exp}, @code{fabs}, @code{floor}, @code{fmod}, -@code{fprintf}, @code{fputs}, @code{frexp}, @code{fscanf}, -@code{isalnum}, @code{isalpha}, @code{iscntrl}, @code{isdigit}, -@code{isgraph}, @code{islower}, @code{isprint}, @code{ispunct}, -@code{isspace}, @code{isupper}, @code{isxdigit}, @code{tolower}, -@code{toupper}, @code{labs}, @code{ldexp}, @code{log10}, @code{log}, -@code{malloc}, @code{memcmp}, @code{memcpy}, @code{memset}, @code{modf}, -@code{pow}, @code{printf}, @code{putchar}, @code{puts}, @code{scanf}, -@code{sinh}, @code{sin}, @code{snprintf}, @code{sprintf}, @code{sqrt}, -@code{sscanf}, @code{strcat}, @code{strchr}, @code{strcmp}, -@code{strcpy}, @code{strcspn}, @code{strlen}, @code{strncat}, -@code{strncmp}, @code{strncpy}, @code{strpbrk}, @code{strrchr}, -@code{strspn}, @code{strstr}, @code{tanh}, @code{tan}, @code{vfprintf}, -@code{vprintf} and @code{vsprintf} -are all recognized as built-in functions unless -@option{-fno-builtin} is specified (or @option{-fno-builtin-@var{function}} -is specified for an individual function). All of these functions have -corresponding versions prefixed with @code{__builtin_}. - -GCC provides built-in versions of the ISO C99 floating point comparison -macros that avoid raising exceptions for unordered operands. They have -the same names as the standard macros ( @code{isgreater}, -@code{isgreaterequal}, @code{isless}, @code{islessequal}, -@code{islessgreater}, and @code{isunordered}) , with @code{__builtin_} -prefixed. We intend for a library implementor to be able to simply -@code{#define} each standard macro to its built-in equivalent. - -@deftypefn {Built-in Function} int __builtin_types_compatible_p (@var{type1}, @var{type2}) - -You can use the built-in function @code{__builtin_types_compatible_p} to -determine whether two types are the same. - -This built-in function returns 1 if the unqualified versions of the -types @var{type1} and @var{type2} (which are types, not expressions) are -compatible, 0 otherwise. The result of this built-in function can be -used in integer constant expressions. - -This built-in function ignores top level qualifiers (e.g., @code{const}, -@code{volatile}). For example, @code{int} is equivalent to @code{const -int}. - -The type @code{int[]} and @code{int[5]} are compatible. On the other -hand, @code{int} and @code{char *} are not compatible, even if the size -of their types, on the particular architecture are the same. Also, the -amount of pointer indirection is taken into account when determining -similarity. Consequently, @code{short *} is not similar to -@code{short **}. Furthermore, two types that are typedefed are -considered compatible if their underlying types are compatible. - -An @code{enum} type is not considered to be compatible with another -@code{enum} type even if both are compatible with the same integer -type; this is what the C standard specifies. -For example, @code{enum @{foo, bar@}} is not similar to -@code{enum @{hot, dog@}}. - -You would typically use this function in code whose execution varies -depending on the arguments' types. For example: - -@smallexample -#define foo(x) \ - (@{ \ - typeof (x) tmp = (x); \ - if (__builtin_types_compatible_p (typeof (x), long double)) \ - tmp = foo_long_double (tmp); \ - else if (__builtin_types_compatible_p (typeof (x), double)) \ - tmp = foo_double (tmp); \ - else if (__builtin_types_compatible_p (typeof (x), float)) \ - tmp = foo_float (tmp); \ - else \ - abort (); \ - tmp; \ - @}) -@end smallexample - -@emph{Note:} This construct is only available for C@. - -@end deftypefn - -@deftypefn {Built-in Function} @var{type} __builtin_choose_expr (@var{const_exp}, @var{exp1}, @var{exp2}) - -You can use the built-in function @code{__builtin_choose_expr} to -evaluate code depending on the value of a constant expression. This -built-in function returns @var{exp1} if @var{const_exp}, which is a -constant expression that must be able to be determined at compile time, -is nonzero. Otherwise it returns 0. - -This built-in function is analogous to the @samp{? :} operator in C, -except that the expression returned has its type unaltered by promotion -rules. Also, the built-in function does not evaluate the expression -that was not chosen. For example, if @var{const_exp} evaluates to true, -@var{exp2} is not evaluated even if it has side-effects. - -This built-in function can return an lvalue if the chosen argument is an -lvalue. - -If @var{exp1} is returned, the return type is the same as @var{exp1}'s -type. Similarly, if @var{exp2} is returned, its return type is the same -as @var{exp2}. - -Example: - -@smallexample -#define foo(x) \ - __builtin_choose_expr ( \ - __builtin_types_compatible_p (typeof (x), double), \ - foo_double (x), \ - __builtin_choose_expr ( \ - __builtin_types_compatible_p (typeof (x), float), \ - foo_float (x), \ - /* @r{The void expression results in a compile-time error} \ - @r{when assigning the result to something.} */ \ - (void)0)) -@end smallexample - -@emph{Note:} This construct is only available for C@. Furthermore, the -unused expression (@var{exp1} or @var{exp2} depending on the value of -@var{const_exp}) may still generate syntax errors. This may change in -future revisions. - -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_constant_p (@var{exp}) -You can use the built-in function @code{__builtin_constant_p} to -determine if a value is known to be constant at compile-time and hence -that GCC can perform constant-folding on expressions involving that -value. The argument of the function is the value to test. The function -returns the integer 1 if the argument is known to be a compile-time -constant and 0 if it is not known to be a compile-time constant. A -return of 0 does not indicate that the value is @emph{not} a constant, -but merely that GCC cannot prove it is a constant with the specified -value of the @option{-O} option. - -You would typically use this function in an embedded application where -memory was a critical resource. If you have some complex calculation, -you may want it to be folded if it involves constants, but need to call -a function if it does not. For example: - -@smallexample -#define Scale_Value(X) \ - (__builtin_constant_p (X) \ - ? ((X) * SCALE + OFFSET) : Scale (X)) -@end smallexample - -You may use this built-in function in either a macro or an inline -function. However, if you use it in an inlined function and pass an -argument of the function as the argument to the built-in, GCC will -never return 1 when you call the inline function with a string constant -or compound literal (@pxref{Compound Literals}) and will not return 1 -when you pass a constant numeric value to the inline function unless you -specify the @option{-O} option. - -You may also use @code{__builtin_constant_p} in initializers for static -data. For instance, you can write - -@smallexample -static const int table[] = @{ - __builtin_constant_p (EXPRESSION) ? (EXPRESSION) : -1, - /* @r{@dots{}} */ -@}; -@end smallexample - -@noindent -This is an acceptable initializer even if @var{EXPRESSION} is not a -constant expression. GCC must be more conservative about evaluating the -built-in in this case, because it has no opportunity to perform -optimization. - -Previous versions of GCC did not accept this built-in in data -initializers. The earliest version where it is completely safe is -3.0.1. -@end deftypefn - -@deftypefn {Built-in Function} long __builtin_expect (long @var{exp}, long @var{c}) -@opindex fprofile-arcs -You may use @code{__builtin_expect} to provide the compiler with -branch prediction information. In general, you should prefer to -use actual profile feedback for this (@option{-fprofile-arcs}), as -programmers are notoriously bad at predicting how their programs -actually perform. However, there are applications in which this -data is hard to collect. - -The return value is the value of @var{exp}, which should be an -integral expression. The value of @var{c} must be a compile-time -constant. The semantics of the built-in are that it is expected -that @var{exp} == @var{c}. For example: - -@smallexample -if (__builtin_expect (x, 0)) - foo (); -@end smallexample - -@noindent -would indicate that we do not expect to call @code{foo}, since -we expect @code{x} to be zero. Since you are limited to integral -expressions for @var{exp}, you should use constructions such as - -@smallexample -if (__builtin_expect (ptr != NULL, 1)) - error (); -@end smallexample - -@noindent -when testing pointer or floating-point values. -@end deftypefn - -@deftypefn {Built-in Function} void __builtin_prefetch (const void *@var{addr}, ...) -This function is used to minimize cache-miss latency by moving data into -a cache before it is accessed. -You can insert calls to @code{__builtin_prefetch} into code for which -you know addresses of data in memory that is likely to be accessed soon. -If the target supports them, data prefetch instructions will be generated. -If the prefetch is done early enough before the access then the data will -be in the cache by the time it is accessed. - -The value of @var{addr} is the address of the memory to prefetch. -There are two optional arguments, @var{rw} and @var{locality}. -The value of @var{rw} is a compile-time constant one or zero; one -means that the prefetch is preparing for a write to the memory address -and zero, the default, means that the prefetch is preparing for a read. -The value @var{locality} must be a compile-time constant integer between -zero and three. A value of zero means that the data has no temporal -locality, so it need not be left in the cache after the access. A value -of three means that the data has a high degree of temporal locality and -should be left in all levels of cache possible. Values of one and two -mean, respectively, a low or moderate degree of temporal locality. The -default is three. - -@smallexample -for (i = 0; i < n; i++) - @{ - a[i] = a[i] + b[i]; - __builtin_prefetch (&a[i+j], 1, 1); - __builtin_prefetch (&b[i+j], 0, 1); - /* @r{@dots{}} */ - @} -@end smallexample - -Data prefetch does not generate faults if @var{addr} is invalid, but -the address expression itself must be valid. For example, a prefetch -of @code{p->next} will not fault if @code{p->next} is not a valid -address, but evaluation will fault if @code{p} is not a valid address. - -If the target does not support data prefetch, the address expression -is evaluated if it includes side effects but no other code is generated -and GCC does not issue a warning. -@end deftypefn - -@deftypefn {Built-in Function} double __builtin_huge_val (void) -Returns a positive infinity, if supported by the floating-point format, -else @code{DBL_MAX}. This function is suitable for implementing the -ISO C macro @code{HUGE_VAL}. -@end deftypefn - -@deftypefn {Built-in Function} float __builtin_huge_valf (void) -Similar to @code{__builtin_huge_val}, except the return type is @code{float}. -@end deftypefn - -@deftypefn {Built-in Function} {long double} __builtin_huge_vall (void) -Similar to @code{__builtin_huge_val}, except the return -type is @code{long double}. -@end deftypefn - -@deftypefn {Built-in Function} double __builtin_inf (void) -Similar to @code{__builtin_huge_val}, except a warning is generated -if the target floating-point format does not support infinities. -@end deftypefn - -@deftypefn {Built-in Function} _Decimal32 __builtin_infd32 (void) -Similar to @code{__builtin_inf}, except the return type is @code{_Decimal32}. -@end deftypefn - -@deftypefn {Built-in Function} _Decimal64 __builtin_infd64 (void) -Similar to @code{__builtin_inf}, except the return type is @code{_Decimal64}. -@end deftypefn - -@deftypefn {Built-in Function} _Decimal128 __builtin_infd128 (void) -Similar to @code{__builtin_inf}, except the return type is @code{_Decimal128}. -@end deftypefn - -@deftypefn {Built-in Function} float __builtin_inff (void) -Similar to @code{__builtin_inf}, except the return type is @code{float}. -This function is suitable for implementing the ISO C99 macro @code{INFINITY}. -@end deftypefn - -@deftypefn {Built-in Function} {long double} __builtin_infl (void) -Similar to @code{__builtin_inf}, except the return -type is @code{long double}. -@end deftypefn - -@deftypefn {Built-in Function} double __builtin_nan (const char *str) -This is an implementation of the ISO C99 function @code{nan}. - -Since ISO C99 defines this function in terms of @code{strtod}, which we -do not implement, a description of the parsing is in order. The string -is parsed as by @code{strtol}; that is, the base is recognized by -leading @samp{0} or @samp{0x} prefixes. The number parsed is placed -in the significand such that the least significant bit of the number -is at the least significant bit of the significand. The number is -truncated to fit the significand field provided. The significand is -forced to be a quiet NaN@. - -This function, if given a string literal all of which would have been -consumed by strtol, is evaluated early enough that it is considered a -compile-time constant. -@end deftypefn - -@deftypefn {Built-in Function} _Decimal32 __builtin_nand32 (const char *str) -Similar to @code{__builtin_nan}, except the return type is @code{_Decimal32}. -@end deftypefn - -@deftypefn {Built-in Function} _Decimal64 __builtin_nand64 (const char *str) -Similar to @code{__builtin_nan}, except the return type is @code{_Decimal64}. -@end deftypefn - -@deftypefn {Built-in Function} _Decimal128 __builtin_nand128 (const char *str) -Similar to @code{__builtin_nan}, except the return type is @code{_Decimal128}. -@end deftypefn - -@deftypefn {Built-in Function} float __builtin_nanf (const char *str) -Similar to @code{__builtin_nan}, except the return type is @code{float}. -@end deftypefn - -@deftypefn {Built-in Function} {long double} __builtin_nanl (const char *str) -Similar to @code{__builtin_nan}, except the return type is @code{long double}. -@end deftypefn - -@deftypefn {Built-in Function} double __builtin_nans (const char *str) -Similar to @code{__builtin_nan}, except the significand is forced -to be a signaling NaN@. The @code{nans} function is proposed by -@uref{http://www.open-std.org/jtc1/sc22/wg14/www/docs/n965.htm,,WG14 N965}. -@end deftypefn - -@deftypefn {Built-in Function} float __builtin_nansf (const char *str) -Similar to @code{__builtin_nans}, except the return type is @code{float}. -@end deftypefn - -@deftypefn {Built-in Function} {long double} __builtin_nansl (const char *str) -Similar to @code{__builtin_nans}, except the return type is @code{long double}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_ffs (unsigned int x) -Returns one plus the index of the least significant 1-bit of @var{x}, or -if @var{x} is zero, returns zero. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_clz (unsigned int x) -Returns the number of leading 0-bits in @var{x}, starting at the most -significant bit position. If @var{x} is 0, the result is undefined. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_ctz (unsigned int x) -Returns the number of trailing 0-bits in @var{x}, starting at the least -significant bit position. If @var{x} is 0, the result is undefined. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_popcount (unsigned int x) -Returns the number of 1-bits in @var{x}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_parity (unsigned int x) -Returns the parity of @var{x}, i.e.@: the number of 1-bits in @var{x} -modulo 2. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_ffsl (unsigned long) -Similar to @code{__builtin_ffs}, except the argument type is -@code{unsigned long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_clzl (unsigned long) -Similar to @code{__builtin_clz}, except the argument type is -@code{unsigned long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_ctzl (unsigned long) -Similar to @code{__builtin_ctz}, except the argument type is -@code{unsigned long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_popcountl (unsigned long) -Similar to @code{__builtin_popcount}, except the argument type is -@code{unsigned long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_parityl (unsigned long) -Similar to @code{__builtin_parity}, except the argument type is -@code{unsigned long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_ffsll (unsigned long long) -Similar to @code{__builtin_ffs}, except the argument type is -@code{unsigned long long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_clzll (unsigned long long) -Similar to @code{__builtin_clz}, except the argument type is -@code{unsigned long long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_ctzll (unsigned long long) -Similar to @code{__builtin_ctz}, except the argument type is -@code{unsigned long long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_popcountll (unsigned long long) -Similar to @code{__builtin_popcount}, except the argument type is -@code{unsigned long long}. -@end deftypefn - -@deftypefn {Built-in Function} int __builtin_parityll (unsigned long long) -Similar to @code{__builtin_parity}, except the argument type is -@code{unsigned long long}. -@end deftypefn - -@deftypefn {Built-in Function} double __builtin_powi (double, int) -Returns the first argument raised to the power of the second. Unlike the -@code{pow} function no guarantees about precision and rounding are made. -@end deftypefn - -@deftypefn {Built-in Function} float __builtin_powif (float, int) -Similar to @code{__builtin_powi}, except the argument and return types -are @code{float}. -@end deftypefn - -@deftypefn {Built-in Function} {long double} __builtin_powil (long double, int) -Similar to @code{__builtin_powi}, except the argument and return types -are @code{long double}. -@end deftypefn -@c APPLE LOCAL begin mainline -@deftypefn {Built-in Function} int32_t __builtin_bswap32 (int32_t x) -Returns @var{x} with the order of the bytes reversed; for example, -@code{0xaabbccdd} becomes @code{0xddccbbaa}. Byte here always means -exactly 8 bits. -@end deftypefn - -@deftypefn {Built-in Function} int64_t __builtin_bswap64 (int64_t x) -Similar to @code{__builtin_bswap32}, except the argument and return types -are 64-bit. -@end deftypefn -@c APPLE LOCAL end mainline - -@node Target Builtins -@section Built-in Functions Specific to Particular Target Machines - -On some target machines, GCC supports many built-in functions specific -to those machines. Generally these generate calls to specific machine -instructions, but allow the compiler to schedule those calls. - -@c APPLE LOCAL begin ARM NEON support. Merge from Codesourcery -@menu -* Alpha Built-in Functions:: -* ARM Built-in Functions:: -* ARM NEON Intrinsics:: -* Blackfin Built-in Functions:: -* FR-V Built-in Functions:: -* X86 Built-in Functions:: -* MIPS DSP Built-in Functions:: -* MIPS Paired-Single Support:: -* PowerPC AltiVec Built-in Functions:: -* SPARC VIS Built-in Functions:: -@end menu -@c APPLE LOCAL end ARM NEON support. Merge from Codesourcery - -@node Alpha Built-in Functions -@subsection Alpha Built-in Functions - -These built-in functions are available for the Alpha family of -processors, depending on the command-line switches used. - -The following built-in functions are always available. They -all generate the machine instruction that is part of the name. - -@smallexample -long __builtin_alpha_implver (void) -long __builtin_alpha_rpcc (void) -long __builtin_alpha_amask (long) -long __builtin_alpha_cmpbge (long, long) -long __builtin_alpha_extbl (long, long) -long __builtin_alpha_extwl (long, long) -long __builtin_alpha_extll (long, long) -long __builtin_alpha_extql (long, long) -long __builtin_alpha_extwh (long, long) -long __builtin_alpha_extlh (long, long) -long __builtin_alpha_extqh (long, long) -long __builtin_alpha_insbl (long, long) -long __builtin_alpha_inswl (long, long) -long __builtin_alpha_insll (long, long) -long __builtin_alpha_insql (long, long) -long __builtin_alpha_inswh (long, long) -long __builtin_alpha_inslh (long, long) -long __builtin_alpha_insqh (long, long) -long __builtin_alpha_mskbl (long, long) -long __builtin_alpha_mskwl (long, long) -long __builtin_alpha_mskll (long, long) -long __builtin_alpha_mskql (long, long) -long __builtin_alpha_mskwh (long, long) -long __builtin_alpha_msklh (long, long) -long __builtin_alpha_mskqh (long, long) -long __builtin_alpha_umulh (long, long) -long __builtin_alpha_zap (long, long) -long __builtin_alpha_zapnot (long, long) -@end smallexample - -The following built-in functions are always with @option{-mmax} -or @option{-mcpu=@var{cpu}} where @var{cpu} is @code{pca56} or -later. They all generate the machine instruction that is part -of the name. - -@smallexample -long __builtin_alpha_pklb (long) -long __builtin_alpha_pkwb (long) -long __builtin_alpha_unpkbl (long) -long __builtin_alpha_unpkbw (long) -long __builtin_alpha_minub8 (long, long) -long __builtin_alpha_minsb8 (long, long) -long __builtin_alpha_minuw4 (long, long) -long __builtin_alpha_minsw4 (long, long) -long __builtin_alpha_maxub8 (long, long) -long __builtin_alpha_maxsb8 (long, long) -long __builtin_alpha_maxuw4 (long, long) -long __builtin_alpha_maxsw4 (long, long) -long __builtin_alpha_perr (long, long) -@end smallexample - -The following built-in functions are always with @option{-mcix} -or @option{-mcpu=@var{cpu}} where @var{cpu} is @code{ev67} or -later. They all generate the machine instruction that is part -of the name. - -@smallexample -long __builtin_alpha_cttz (long) -long __builtin_alpha_ctlz (long) -long __builtin_alpha_ctpop (long) -@end smallexample - -The following builtins are available on systems that use the OSF/1 -PALcode. Normally they invoke the @code{rduniq} and @code{wruniq} -PAL calls, but when invoked with @option{-mtls-kernel}, they invoke -@code{rdval} and @code{wrval}. - -@smallexample -void *__builtin_thread_pointer (void) -void __builtin_set_thread_pointer (void *) -@end smallexample - -@node ARM Built-in Functions -@subsection ARM Built-in Functions - -These built-in functions are available for the ARM family of -processors, when the @option{-mcpu=iwmmxt} switch is used: - -@smallexample -typedef int v2si __attribute__ ((vector_size (8))); -typedef short v4hi __attribute__ ((vector_size (8))); -typedef char v8qi __attribute__ ((vector_size (8))); - -int __builtin_arm_getwcx (int) -void __builtin_arm_setwcx (int, int) -int __builtin_arm_textrmsb (v8qi, int) -int __builtin_arm_textrmsh (v4hi, int) -int __builtin_arm_textrmsw (v2si, int) -int __builtin_arm_textrmub (v8qi, int) -int __builtin_arm_textrmuh (v4hi, int) -int __builtin_arm_textrmuw (v2si, int) -v8qi __builtin_arm_tinsrb (v8qi, int) -v4hi __builtin_arm_tinsrh (v4hi, int) -v2si __builtin_arm_tinsrw (v2si, int) -long long __builtin_arm_tmia (long long, int, int) -long long __builtin_arm_tmiabb (long long, int, int) -long long __builtin_arm_tmiabt (long long, int, int) -long long __builtin_arm_tmiaph (long long, int, int) -long long __builtin_arm_tmiatb (long long, int, int) -long long __builtin_arm_tmiatt (long long, int, int) -int __builtin_arm_tmovmskb (v8qi) -int __builtin_arm_tmovmskh (v4hi) -int __builtin_arm_tmovmskw (v2si) -long long __builtin_arm_waccb (v8qi) -long long __builtin_arm_wacch (v4hi) -long long __builtin_arm_waccw (v2si) -v8qi __builtin_arm_waddb (v8qi, v8qi) -v8qi __builtin_arm_waddbss (v8qi, v8qi) -v8qi __builtin_arm_waddbus (v8qi, v8qi) -v4hi __builtin_arm_waddh (v4hi, v4hi) -v4hi __builtin_arm_waddhss (v4hi, v4hi) -v4hi __builtin_arm_waddhus (v4hi, v4hi) -v2si __builtin_arm_waddw (v2si, v2si) -v2si __builtin_arm_waddwss (v2si, v2si) -v2si __builtin_arm_waddwus (v2si, v2si) -v8qi __builtin_arm_walign (v8qi, v8qi, int) -long long __builtin_arm_wand(long long, long long) -long long __builtin_arm_wandn (long long, long long) -v8qi __builtin_arm_wavg2b (v8qi, v8qi) -v8qi __builtin_arm_wavg2br (v8qi, v8qi) -v4hi __builtin_arm_wavg2h (v4hi, v4hi) -v4hi __builtin_arm_wavg2hr (v4hi, v4hi) -v8qi __builtin_arm_wcmpeqb (v8qi, v8qi) -v4hi __builtin_arm_wcmpeqh (v4hi, v4hi) -v2si __builtin_arm_wcmpeqw (v2si, v2si) -v8qi __builtin_arm_wcmpgtsb (v8qi, v8qi) -v4hi __builtin_arm_wcmpgtsh (v4hi, v4hi) -v2si __builtin_arm_wcmpgtsw (v2si, v2si) -v8qi __builtin_arm_wcmpgtub (v8qi, v8qi) -v4hi __builtin_arm_wcmpgtuh (v4hi, v4hi) -v2si __builtin_arm_wcmpgtuw (v2si, v2si) -long long __builtin_arm_wmacs (long long, v4hi, v4hi) -long long __builtin_arm_wmacsz (v4hi, v4hi) -long long __builtin_arm_wmacu (long long, v4hi, v4hi) -long long __builtin_arm_wmacuz (v4hi, v4hi) -v4hi __builtin_arm_wmadds (v4hi, v4hi) -v4hi __builtin_arm_wmaddu (v4hi, v4hi) -v8qi __builtin_arm_wmaxsb (v8qi, v8qi) -v4hi __builtin_arm_wmaxsh (v4hi, v4hi) -v2si __builtin_arm_wmaxsw (v2si, v2si) -v8qi __builtin_arm_wmaxub (v8qi, v8qi) -v4hi __builtin_arm_wmaxuh (v4hi, v4hi) -v2si __builtin_arm_wmaxuw (v2si, v2si) -v8qi __builtin_arm_wminsb (v8qi, v8qi) -v4hi __builtin_arm_wminsh (v4hi, v4hi) -v2si __builtin_arm_wminsw (v2si, v2si) -v8qi __builtin_arm_wminub (v8qi, v8qi) -v4hi __builtin_arm_wminuh (v4hi, v4hi) -v2si __builtin_arm_wminuw (v2si, v2si) -v4hi __builtin_arm_wmulsm (v4hi, v4hi) -v4hi __builtin_arm_wmulul (v4hi, v4hi) -v4hi __builtin_arm_wmulum (v4hi, v4hi) -long long __builtin_arm_wor (long long, long long) -v2si __builtin_arm_wpackdss (long long, long long) -v2si __builtin_arm_wpackdus (long long, long long) -v8qi __builtin_arm_wpackhss (v4hi, v4hi) -v8qi __builtin_arm_wpackhus (v4hi, v4hi) -v4hi __builtin_arm_wpackwss (v2si, v2si) -v4hi __builtin_arm_wpackwus (v2si, v2si) -long long __builtin_arm_wrord (long long, long long) -long long __builtin_arm_wrordi (long long, int) -v4hi __builtin_arm_wrorh (v4hi, long long) -v4hi __builtin_arm_wrorhi (v4hi, int) -v2si __builtin_arm_wrorw (v2si, long long) -v2si __builtin_arm_wrorwi (v2si, int) -v2si __builtin_arm_wsadb (v8qi, v8qi) -v2si __builtin_arm_wsadbz (v8qi, v8qi) -v2si __builtin_arm_wsadh (v4hi, v4hi) -v2si __builtin_arm_wsadhz (v4hi, v4hi) -v4hi __builtin_arm_wshufh (v4hi, int) -long long __builtin_arm_wslld (long long, long long) -long long __builtin_arm_wslldi (long long, int) -v4hi __builtin_arm_wsllh (v4hi, long long) -v4hi __builtin_arm_wsllhi (v4hi, int) -v2si __builtin_arm_wsllw (v2si, long long) -v2si __builtin_arm_wsllwi (v2si, int) -long long __builtin_arm_wsrad (long long, long long) -long long __builtin_arm_wsradi (long long, int) -v4hi __builtin_arm_wsrah (v4hi, long long) -v4hi __builtin_arm_wsrahi (v4hi, int) -v2si __builtin_arm_wsraw (v2si, long long) -v2si __builtin_arm_wsrawi (v2si, int) -long long __builtin_arm_wsrld (long long, long long) -long long __builtin_arm_wsrldi (long long, int) -v4hi __builtin_arm_wsrlh (v4hi, long long) -v4hi __builtin_arm_wsrlhi (v4hi, int) -v2si __builtin_arm_wsrlw (v2si, long long) -v2si __builtin_arm_wsrlwi (v2si, int) -v8qi __builtin_arm_wsubb (v8qi, v8qi) -v8qi __builtin_arm_wsubbss (v8qi, v8qi) -v8qi __builtin_arm_wsubbus (v8qi, v8qi) -v4hi __builtin_arm_wsubh (v4hi, v4hi) -v4hi __builtin_arm_wsubhss (v4hi, v4hi) -v4hi __builtin_arm_wsubhus (v4hi, v4hi) -v2si __builtin_arm_wsubw (v2si, v2si) -v2si __builtin_arm_wsubwss (v2si, v2si) -v2si __builtin_arm_wsubwus (v2si, v2si) -v4hi __builtin_arm_wunpckehsb (v8qi) -v2si __builtin_arm_wunpckehsh (v4hi) -long long __builtin_arm_wunpckehsw (v2si) -v4hi __builtin_arm_wunpckehub (v8qi) -v2si __builtin_arm_wunpckehuh (v4hi) -long long __builtin_arm_wunpckehuw (v2si) -v4hi __builtin_arm_wunpckelsb (v8qi) -v2si __builtin_arm_wunpckelsh (v4hi) -long long __builtin_arm_wunpckelsw (v2si) -v4hi __builtin_arm_wunpckelub (v8qi) -v2si __builtin_arm_wunpckeluh (v4hi) -long long __builtin_arm_wunpckeluw (v2si) -v8qi __builtin_arm_wunpckihb (v8qi, v8qi) -v4hi __builtin_arm_wunpckihh (v4hi, v4hi) -v2si __builtin_arm_wunpckihw (v2si, v2si) -v8qi __builtin_arm_wunpckilb (v8qi, v8qi) -v4hi __builtin_arm_wunpckilh (v4hi, v4hi) -v2si __builtin_arm_wunpckilw (v2si, v2si) -long long __builtin_arm_wxor (long long, long long) -long long __builtin_arm_wzero () -@end smallexample - -@c APPLE LOCAL begin ARM NEON support -@node ARM NEON Intrinsics -@subsection ARM NEON Intrinsics - -These built-in intrinsics for the ARM Advanced SIMD extension are available -when the @option{-mfpu=neon} switch is used: - -@include arm-neon-intrinsics.texi -@c APPLE LOCAL end ARM NEON support. Merge from Codesourcery. - -@node Blackfin Built-in Functions -@subsection Blackfin Built-in Functions - -Currently, there are two Blackfin-specific built-in functions. These are -used for generating @code{CSYNC} and @code{SSYNC} machine insns without -using inline assembly; by using these built-in functions the compiler can -automatically add workarounds for hardware errata involving these -instructions. These functions are named as follows: - -@smallexample -void __builtin_bfin_csync (void) -void __builtin_bfin_ssync (void) -@end smallexample - -@node FR-V Built-in Functions -@subsection FR-V Built-in Functions - -GCC provides many FR-V-specific built-in functions. In general, -these functions are intended to be compatible with those described -by @cite{FR-V Family, Softune C/C++ Compiler Manual (V6), Fujitsu -Semiconductor}. The two exceptions are @code{__MDUNPACKH} and -@code{__MBTOHE}, the gcc forms of which pass 128-bit values by -pointer rather than by value. - -Most of the functions are named after specific FR-V instructions. -Such functions are said to be ``directly mapped'' and are summarized -here in tabular form. - -@menu -* Argument Types:: -* Directly-mapped Integer Functions:: -* Directly-mapped Media Functions:: -* Raw read/write Functions:: -* Other Built-in Functions:: -@end menu - -@node Argument Types -@subsubsection Argument Types - -The arguments to the built-in functions can be divided into three groups: -register numbers, compile-time constants and run-time values. In order -to make this classification clear at a glance, the arguments and return -values are given the following pseudo types: - -@multitable @columnfractions .20 .30 .15 .35 -@item Pseudo type @tab Real C type @tab Constant? @tab Description -@item @code{uh} @tab @code{unsigned short} @tab No @tab an unsigned halfword -@item @code{uw1} @tab @code{unsigned int} @tab No @tab an unsigned word -@item @code{sw1} @tab @code{int} @tab No @tab a signed word -@item @code{uw2} @tab @code{unsigned long long} @tab No -@tab an unsigned doubleword -@item @code{sw2} @tab @code{long long} @tab No @tab a signed doubleword -@item @code{const} @tab @code{int} @tab Yes @tab an integer constant -@item @code{acc} @tab @code{int} @tab Yes @tab an ACC register number -@item @code{iacc} @tab @code{int} @tab Yes @tab an IACC register number -@end multitable - -These pseudo types are not defined by GCC, they are simply a notational -convenience used in this manual. - -Arguments of type @code{uh}, @code{uw1}, @code{sw1}, @code{uw2} -and @code{sw2} are evaluated at run time. They correspond to -register operands in the underlying FR-V instructions. - -@code{const} arguments represent immediate operands in the underlying -FR-V instructions. They must be compile-time constants. - -@code{acc} arguments are evaluated at compile time and specify the number -of an accumulator register. For example, an @code{acc} argument of 2 -will select the ACC2 register. - -@code{iacc} arguments are similar to @code{acc} arguments but specify the -number of an IACC register. See @pxref{Other Built-in Functions} -for more details. - -@node Directly-mapped Integer Functions -@subsubsection Directly-mapped Integer Functions - -The functions listed below map directly to FR-V I-type instructions. - -@multitable @columnfractions .45 .32 .23 -@item Function prototype @tab Example usage @tab Assembly output -@item @code{sw1 __ADDSS (sw1, sw1)} -@tab @code{@var{c} = __ADDSS (@var{a}, @var{b})} -@tab @code{ADDSS @var{a},@var{b},@var{c}} -@item @code{sw1 __SCAN (sw1, sw1)} -@tab @code{@var{c} = __SCAN (@var{a}, @var{b})} -@tab @code{SCAN @var{a},@var{b},@var{c}} -@item @code{sw1 __SCUTSS (sw1)} -@tab @code{@var{b} = __SCUTSS (@var{a})} -@tab @code{SCUTSS @var{a},@var{b}} -@item @code{sw1 __SLASS (sw1, sw1)} -@tab @code{@var{c} = __SLASS (@var{a}, @var{b})} -@tab @code{SLASS @var{a},@var{b},@var{c}} -@item @code{void __SMASS (sw1, sw1)} -@tab @code{__SMASS (@var{a}, @var{b})} -@tab @code{SMASS @var{a},@var{b}} -@item @code{void __SMSSS (sw1, sw1)} -@tab @code{__SMSSS (@var{a}, @var{b})} -@tab @code{SMSSS @var{a},@var{b}} -@item @code{void __SMU (sw1, sw1)} -@tab @code{__SMU (@var{a}, @var{b})} -@tab @code{SMU @var{a},@var{b}} -@item @code{sw2 __SMUL (sw1, sw1)} -@tab @code{@var{c} = __SMUL (@var{a}, @var{b})} -@tab @code{SMUL @var{a},@var{b},@var{c}} -@item @code{sw1 __SUBSS (sw1, sw1)} -@tab @code{@var{c} = __SUBSS (@var{a}, @var{b})} -@tab @code{SUBSS @var{a},@var{b},@var{c}} -@item @code{uw2 __UMUL (uw1, uw1)} -@tab @code{@var{c} = __UMUL (@var{a}, @var{b})} -@tab @code{UMUL @var{a},@var{b},@var{c}} -@end multitable - -@node Directly-mapped Media Functions -@subsubsection Directly-mapped Media Functions - -The functions listed below map directly to FR-V M-type instructions. - -@multitable @columnfractions .45 .32 .23 -@item Function prototype @tab Example usage @tab Assembly output -@item @code{uw1 __MABSHS (sw1)} -@tab @code{@var{b} = __MABSHS (@var{a})} -@tab @code{MABSHS @var{a},@var{b}} -@item @code{void __MADDACCS (acc, acc)} -@tab @code{__MADDACCS (@var{b}, @var{a})} -@tab @code{MADDACCS @var{a},@var{b}} -@item @code{sw1 __MADDHSS (sw1, sw1)} -@tab @code{@var{c} = __MADDHSS (@var{a}, @var{b})} -@tab @code{MADDHSS @var{a},@var{b},@var{c}} -@item @code{uw1 __MADDHUS (uw1, uw1)} -@tab @code{@var{c} = __MADDHUS (@var{a}, @var{b})} -@tab @code{MADDHUS @var{a},@var{b},@var{c}} -@item @code{uw1 __MAND (uw1, uw1)} -@tab @code{@var{c} = __MAND (@var{a}, @var{b})} -@tab @code{MAND @var{a},@var{b},@var{c}} -@item @code{void __MASACCS (acc, acc)} -@tab @code{__MASACCS (@var{b}, @var{a})} -@tab @code{MASACCS @var{a},@var{b}} -@item @code{uw1 __MAVEH (uw1, uw1)} -@tab @code{@var{c} = __MAVEH (@var{a}, @var{b})} -@tab @code{MAVEH @var{a},@var{b},@var{c}} -@item @code{uw2 __MBTOH (uw1)} -@tab @code{@var{b} = __MBTOH (@var{a})} -@tab @code{MBTOH @var{a},@var{b}} -@item @code{void __MBTOHE (uw1 *, uw1)} -@tab @code{__MBTOHE (&@var{b}, @var{a})} -@tab @code{MBTOHE @var{a},@var{b}} -@item @code{void __MCLRACC (acc)} -@tab @code{__MCLRACC (@var{a})} -@tab @code{MCLRACC @var{a}} -@item @code{void __MCLRACCA (void)} -@tab @code{__MCLRACCA ()} -@tab @code{MCLRACCA} -@item @code{uw1 __Mcop1 (uw1, uw1)} -@tab @code{@var{c} = __Mcop1 (@var{a}, @var{b})} -@tab @code{Mcop1 @var{a},@var{b},@var{c}} -@item @code{uw1 __Mcop2 (uw1, uw1)} -@tab @code{@var{c} = __Mcop2 (@var{a}, @var{b})} -@tab @code{Mcop2 @var{a},@var{b},@var{c}} -@item @code{uw1 __MCPLHI (uw2, const)} -@tab @code{@var{c} = __MCPLHI (@var{a}, @var{b})} -@tab @code{MCPLHI @var{a},#@var{b},@var{c}} -@item @code{uw1 __MCPLI (uw2, const)} -@tab @code{@var{c} = __MCPLI (@var{a}, @var{b})} -@tab @code{MCPLI @var{a},#@var{b},@var{c}} -@item @code{void __MCPXIS (acc, sw1, sw1)} -@tab @code{__MCPXIS (@var{c}, @var{a}, @var{b})} -@tab @code{MCPXIS @var{a},@var{b},@var{c}} -@item @code{void __MCPXIU (acc, uw1, uw1)} -@tab @code{__MCPXIU (@var{c}, @var{a}, @var{b})} -@tab @code{MCPXIU @var{a},@var{b},@var{c}} -@item @code{void __MCPXRS (acc, sw1, sw1)} -@tab @code{__MCPXRS (@var{c}, @var{a}, @var{b})} -@tab @code{MCPXRS @var{a},@var{b},@var{c}} -@item @code{void __MCPXRU (acc, uw1, uw1)} -@tab @code{__MCPXRU (@var{c}, @var{a}, @var{b})} -@tab @code{MCPXRU @var{a},@var{b},@var{c}} -@item @code{uw1 __MCUT (acc, uw1)} -@tab @code{@var{c} = __MCUT (@var{a}, @var{b})} -@tab @code{MCUT @var{a},@var{b},@var{c}} -@item @code{uw1 __MCUTSS (acc, sw1)} -@tab @code{@var{c} = __MCUTSS (@var{a}, @var{b})} -@tab @code{MCUTSS @var{a},@var{b},@var{c}} -@item @code{void __MDADDACCS (acc, acc)} -@tab @code{__MDADDACCS (@var{b}, @var{a})} -@tab @code{MDADDACCS @var{a},@var{b}} -@item @code{void __MDASACCS (acc, acc)} -@tab @code{__MDASACCS (@var{b}, @var{a})} -@tab @code{MDASACCS @var{a},@var{b}} -@item @code{uw2 __MDCUTSSI (acc, const)} -@tab @code{@var{c} = __MDCUTSSI (@var{a}, @var{b})} -@tab @code{MDCUTSSI @var{a},#@var{b},@var{c}} -@item @code{uw2 __MDPACKH (uw2, uw2)} -@tab @code{@var{c} = __MDPACKH (@var{a}, @var{b})} -@tab @code{MDPACKH @var{a},@var{b},@var{c}} -@item @code{uw2 __MDROTLI (uw2, const)} -@tab @code{@var{c} = __MDROTLI (@var{a}, @var{b})} -@tab @code{MDROTLI @var{a},#@var{b},@var{c}} -@item @code{void __MDSUBACCS (acc, acc)} -@tab @code{__MDSUBACCS (@var{b}, @var{a})} -@tab @code{MDSUBACCS @var{a},@var{b}} -@item @code{void __MDUNPACKH (uw1 *, uw2)} -@tab @code{__MDUNPACKH (&@var{b}, @var{a})} -@tab @code{MDUNPACKH @var{a},@var{b}} -@item @code{uw2 __MEXPDHD (uw1, const)} -@tab @code{@var{c} = __MEXPDHD (@var{a}, @var{b})} -@tab @code{MEXPDHD @var{a},#@var{b},@var{c}} -@item @code{uw1 __MEXPDHW (uw1, const)} -@tab @code{@var{c} = __MEXPDHW (@var{a}, @var{b})} -@tab @code{MEXPDHW @var{a},#@var{b},@var{c}} -@item @code{uw1 __MHDSETH (uw1, const)} -@tab @code{@var{c} = __MHDSETH (@var{a}, @var{b})} -@tab @code{MHDSETH @var{a},#@var{b},@var{c}} -@item @code{sw1 __MHDSETS (const)} -@tab @code{@var{b} = __MHDSETS (@var{a})} -@tab @code{MHDSETS #@var{a},@var{b}} -@item @code{uw1 __MHSETHIH (uw1, const)} -@tab @code{@var{b} = __MHSETHIH (@var{b}, @var{a})} -@tab @code{MHSETHIH #@var{a},@var{b}} -@item @code{sw1 __MHSETHIS (sw1, const)} -@tab @code{@var{b} = __MHSETHIS (@var{b}, @var{a})} -@tab @code{MHSETHIS #@var{a},@var{b}} -@item @code{uw1 __MHSETLOH (uw1, const)} -@tab @code{@var{b} = __MHSETLOH (@var{b}, @var{a})} -@tab @code{MHSETLOH #@var{a},@var{b}} -@item @code{sw1 __MHSETLOS (sw1, const)} -@tab @code{@var{b} = __MHSETLOS (@var{b}, @var{a})} -@tab @code{MHSETLOS #@var{a},@var{b}} -@item @code{uw1 __MHTOB (uw2)} -@tab @code{@var{b} = __MHTOB (@var{a})} -@tab @code{MHTOB @var{a},@var{b}} -@item @code{void __MMACHS (acc, sw1, sw1)} -@tab @code{__MMACHS (@var{c}, @var{a}, @var{b})} -@tab @code{MMACHS @var{a},@var{b},@var{c}} -@item @code{void __MMACHU (acc, uw1, uw1)} -@tab @code{__MMACHU (@var{c}, @var{a}, @var{b})} -@tab @code{MMACHU @var{a},@var{b},@var{c}} -@item @code{void __MMRDHS (acc, sw1, sw1)} -@tab @code{__MMRDHS (@var{c}, @var{a}, @var{b})} -@tab @code{MMRDHS @var{a},@var{b},@var{c}} -@item @code{void __MMRDHU (acc, uw1, uw1)} -@tab @code{__MMRDHU (@var{c}, @var{a}, @var{b})} -@tab @code{MMRDHU @var{a},@var{b},@var{c}} -@item @code{void __MMULHS (acc, sw1, sw1)} -@tab @code{__MMULHS (@var{c}, @var{a}, @var{b})} -@tab @code{MMULHS @var{a},@var{b},@var{c}} -@item @code{void __MMULHU (acc, uw1, uw1)} -@tab @code{__MMULHU (@var{c}, @var{a}, @var{b})} -@tab @code{MMULHU @var{a},@var{b},@var{c}} -@item @code{void __MMULXHS (acc, sw1, sw1)} -@tab @code{__MMULXHS (@var{c}, @var{a}, @var{b})} -@tab @code{MMULXHS @var{a},@var{b},@var{c}} -@item @code{void __MMULXHU (acc, uw1, uw1)} -@tab @code{__MMULXHU (@var{c}, @var{a}, @var{b})} -@tab @code{MMULXHU @var{a},@var{b},@var{c}} -@item @code{uw1 __MNOT (uw1)} -@tab @code{@var{b} = __MNOT (@var{a})} -@tab @code{MNOT @var{a},@var{b}} -@item @code{uw1 __MOR (uw1, uw1)} -@tab @code{@var{c} = __MOR (@var{a}, @var{b})} -@tab @code{MOR @var{a},@var{b},@var{c}} -@item @code{uw1 __MPACKH (uh, uh)} -@tab @code{@var{c} = __MPACKH (@var{a}, @var{b})} -@tab @code{MPACKH @var{a},@var{b},@var{c}} -@item @code{sw2 __MQADDHSS (sw2, sw2)} -@tab @code{@var{c} = __MQADDHSS (@var{a}, @var{b})} -@tab @code{MQADDHSS @var{a},@var{b},@var{c}} -@item @code{uw2 __MQADDHUS (uw2, uw2)} -@tab @code{@var{c} = __MQADDHUS (@var{a}, @var{b})} -@tab @code{MQADDHUS @var{a},@var{b},@var{c}} -@item @code{void __MQCPXIS (acc, sw2, sw2)} -@tab @code{__MQCPXIS (@var{c}, @var{a}, @var{b})} -@tab @code{MQCPXIS @var{a},@var{b},@var{c}} -@item @code{void __MQCPXIU (acc, uw2, uw2)} -@tab @code{__MQCPXIU (@var{c}, @var{a}, @var{b})} -@tab @code{MQCPXIU @var{a},@var{b},@var{c}} -@item @code{void __MQCPXRS (acc, sw2, sw2)} -@tab @code{__MQCPXRS (@var{c}, @var{a}, @var{b})} -@tab @code{MQCPXRS @var{a},@var{b},@var{c}} -@item @code{void __MQCPXRU (acc, uw2, uw2)} -@tab @code{__MQCPXRU (@var{c}, @var{a}, @var{b})} -@tab @code{MQCPXRU @var{a},@var{b},@var{c}} -@item @code{sw2 __MQLCLRHS (sw2, sw2)} -@tab @code{@var{c} = __MQLCLRHS (@var{a}, @var{b})} -@tab @code{MQLCLRHS @var{a},@var{b},@var{c}} -@item @code{sw2 __MQLMTHS (sw2, sw2)} -@tab @code{@var{c} = __MQLMTHS (@var{a}, @var{b})} -@tab @code{MQLMTHS @var{a},@var{b},@var{c}} -@item @code{void __MQMACHS (acc, sw2, sw2)} -@tab @code{__MQMACHS (@var{c}, @var{a}, @var{b})} -@tab @code{MQMACHS @var{a},@var{b},@var{c}} -@item @code{void __MQMACHU (acc, uw2, uw2)} -@tab @code{__MQMACHU (@var{c}, @var{a}, @var{b})} -@tab @code{MQMACHU @var{a},@var{b},@var{c}} -@item @code{void __MQMACXHS (acc, sw2, sw2)} -@tab @code{__MQMACXHS (@var{c}, @var{a}, @var{b})} -@tab @code{MQMACXHS @var{a},@var{b},@var{c}} -@item @code{void __MQMULHS (acc, sw2, sw2)} -@tab @code{__MQMULHS (@var{c}, @var{a}, @var{b})} -@tab @code{MQMULHS @var{a},@var{b},@var{c}} -@item @code{void __MQMULHU (acc, uw2, uw2)} -@tab @code{__MQMULHU (@var{c}, @var{a}, @var{b})} -@tab @code{MQMULHU @var{a},@var{b},@var{c}} -@item @code{void __MQMULXHS (acc, sw2, sw2)} -@tab @code{__MQMULXHS (@var{c}, @var{a}, @var{b})} -@tab @code{MQMULXHS @var{a},@var{b},@var{c}} -@item @code{void __MQMULXHU (acc, uw2, uw2)} -@tab @code{__MQMULXHU (@var{c}, @var{a}, @var{b})} -@tab @code{MQMULXHU @var{a},@var{b},@var{c}} -@item @code{sw2 __MQSATHS (sw2, sw2)} -@tab @code{@var{c} = __MQSATHS (@var{a}, @var{b})} -@tab @code{MQSATHS @var{a},@var{b},@var{c}} -@item @code{uw2 __MQSLLHI (uw2, int)} -@tab @code{@var{c} = __MQSLLHI (@var{a}, @var{b})} -@tab @code{MQSLLHI @var{a},@var{b},@var{c}} -@item @code{sw2 __MQSRAHI (sw2, int)} -@tab @code{@var{c} = __MQSRAHI (@var{a}, @var{b})} -@tab @code{MQSRAHI @var{a},@var{b},@var{c}} -@item @code{sw2 __MQSUBHSS (sw2, sw2)} -@tab @code{@var{c} = __MQSUBHSS (@var{a}, @var{b})} -@tab @code{MQSUBHSS @var{a},@var{b},@var{c}} -@item @code{uw2 __MQSUBHUS (uw2, uw2)} -@tab @code{@var{c} = __MQSUBHUS (@var{a}, @var{b})} -@tab @code{MQSUBHUS @var{a},@var{b},@var{c}} -@item @code{void __MQXMACHS (acc, sw2, sw2)} -@tab @code{__MQXMACHS (@var{c}, @var{a}, @var{b})} -@tab @code{MQXMACHS @var{a},@var{b},@var{c}} -@item @code{void __MQXMACXHS (acc, sw2, sw2)} -@tab @code{__MQXMACXHS (@var{c}, @var{a}, @var{b})} -@tab @code{MQXMACXHS @var{a},@var{b},@var{c}} -@item @code{uw1 __MRDACC (acc)} -@tab @code{@var{b} = __MRDACC (@var{a})} -@tab @code{MRDACC @var{a},@var{b}} -@item @code{uw1 __MRDACCG (acc)} -@tab @code{@var{b} = __MRDACCG (@var{a})} -@tab @code{MRDACCG @var{a},@var{b}} -@item @code{uw1 __MROTLI (uw1, const)} -@tab @code{@var{c} = __MROTLI (@var{a}, @var{b})} -@tab @code{MROTLI @var{a},#@var{b},@var{c}} -@item @code{uw1 __MROTRI (uw1, const)} -@tab @code{@var{c} = __MROTRI (@var{a}, @var{b})} -@tab @code{MROTRI @var{a},#@var{b},@var{c}} -@item @code{sw1 __MSATHS (sw1, sw1)} -@tab @code{@var{c} = __MSATHS (@var{a}, @var{b})} -@tab @code{MSATHS @var{a},@var{b},@var{c}} -@item @code{uw1 __MSATHU (uw1, uw1)} -@tab @code{@var{c} = __MSATHU (@var{a}, @var{b})} -@tab @code{MSATHU @var{a},@var{b},@var{c}} -@item @code{uw1 __MSLLHI (uw1, const)} -@tab @code{@var{c} = __MSLLHI (@var{a}, @var{b})} -@tab @code{MSLLHI @var{a},#@var{b},@var{c}} -@item @code{sw1 __MSRAHI (sw1, const)} -@tab @code{@var{c} = __MSRAHI (@var{a}, @var{b})} -@tab @code{MSRAHI @var{a},#@var{b},@var{c}} -@item @code{uw1 __MSRLHI (uw1, const)} -@tab @code{@var{c} = __MSRLHI (@var{a}, @var{b})} -@tab @code{MSRLHI @var{a},#@var{b},@var{c}} -@item @code{void __MSUBACCS (acc, acc)} -@tab @code{__MSUBACCS (@var{b}, @var{a})} -@tab @code{MSUBACCS @var{a},@var{b}} -@item @code{sw1 __MSUBHSS (sw1, sw1)} -@tab @code{@var{c} = __MSUBHSS (@var{a}, @var{b})} -@tab @code{MSUBHSS @var{a},@var{b},@var{c}} -@item @code{uw1 __MSUBHUS (uw1, uw1)} -@tab @code{@var{c} = __MSUBHUS (@var{a}, @var{b})} -@tab @code{MSUBHUS @var{a},@var{b},@var{c}} -@item @code{void __MTRAP (void)} -@tab @code{__MTRAP ()} -@tab @code{MTRAP} -@item @code{uw2 __MUNPACKH (uw1)} -@tab @code{@var{b} = __MUNPACKH (@var{a})} -@tab @code{MUNPACKH @var{a},@var{b}} -@item @code{uw1 __MWCUT (uw2, uw1)} -@tab @code{@var{c} = __MWCUT (@var{a}, @var{b})} -@tab @code{MWCUT @var{a},@var{b},@var{c}} -@item @code{void __MWTACC (acc, uw1)} -@tab @code{__MWTACC (@var{b}, @var{a})} -@tab @code{MWTACC @var{a},@var{b}} -@item @code{void __MWTACCG (acc, uw1)} -@tab @code{__MWTACCG (@var{b}, @var{a})} -@tab @code{MWTACCG @var{a},@var{b}} -@item @code{uw1 __MXOR (uw1, uw1)} -@tab @code{@var{c} = __MXOR (@var{a}, @var{b})} -@tab @code{MXOR @var{a},@var{b},@var{c}} -@end multitable - -@node Raw read/write Functions -@subsubsection Raw read/write Functions - -This sections describes built-in functions related to read and write -instructions to access memory. These functions generate -@code{membar} instructions to flush the I/O load and stores where -appropriate, as described in Fujitsu's manual described above. - -@table @code - -@item unsigned char __builtin_read8 (void *@var{data}) -@item unsigned short __builtin_read16 (void *@var{data}) -@item unsigned long __builtin_read32 (void *@var{data}) -@item unsigned long long __builtin_read64 (void *@var{data}) - -@item void __builtin_write8 (void *@var{data}, unsigned char @var{datum}) -@item void __builtin_write16 (void *@var{data}, unsigned short @var{datum}) -@item void __builtin_write32 (void *@var{data}, unsigned long @var{datum}) -@item void __builtin_write64 (void *@var{data}, unsigned long long @var{datum}) -@end table - -@node Other Built-in Functions -@subsubsection Other Built-in Functions - -This section describes built-in functions that are not named after -a specific FR-V instruction. - -@table @code -@item sw2 __IACCreadll (iacc @var{reg}) -Return the full 64-bit value of IACC0@. The @var{reg} argument is reserved -for future expansion and must be 0. - -@item sw1 __IACCreadl (iacc @var{reg}) -Return the value of IACC0H if @var{reg} is 0 and IACC0L if @var{reg} is 1. -Other values of @var{reg} are rejected as invalid. - -@item void __IACCsetll (iacc @var{reg}, sw2 @var{x}) -Set the full 64-bit value of IACC0 to @var{x}. The @var{reg} argument -is reserved for future expansion and must be 0. - -@item void __IACCsetl (iacc @var{reg}, sw1 @var{x}) -Set IACC0H to @var{x} if @var{reg} is 0 and IACC0L to @var{x} if @var{reg} -is 1. Other values of @var{reg} are rejected as invalid. - -@item void __data_prefetch0 (const void *@var{x}) -Use the @code{dcpl} instruction to load the contents of address @var{x} -into the data cache. - -@item void __data_prefetch (const void *@var{x}) -Use the @code{nldub} instruction to load the contents of address @var{x} -into the data cache. The instruction will be issued in slot I1@. -@end table - -@node X86 Built-in Functions -@subsection X86 Built-in Functions - -These built-in functions are available for the i386 and x86-64 family -of computers, depending on the command-line switches used. - -Note that, if you specify command-line switches such as @option{-msse}, -the compiler could use the extended instruction sets even if the built-ins -are not used explicitly in the program. For this reason, applications -which perform runtime CPU detection must compile separate files for each -supported architecture, using the appropriate flags. In particular, -the file containing the CPU detection code should be compiled without -these options. - -The following machine modes are available for use with MMX built-in functions -(@pxref{Vector Extensions}): @code{V2SI} for a vector of two 32-bit integers, -@code{V4HI} for a vector of four 16-bit integers, and @code{V8QI} for a -vector of eight 8-bit integers. Some of the built-in functions operate on -@c APPLE LOCAL begin 4656532 use V1DI for _m64 -MMX registers as a whole 64-bit entity, these use @code{V1DI} as their mode. - -If 3Dnow extensions are enabled, @code{V2SF} is used as a mode for a vector -of two 32-bit floating point values. - -If SSE extensions are enabled, @code{V4SF} is used for a vector of four 32-bit -floating point values. Some instructions use a vector of four 32-bit -integers, these use @code{V4SI}. Finally, some instructions operate on an -entire vector register, interpreting it as a 128-bit integer, these use mode -@code{TI}. - -The following built-in functions are made available by @option{-mmmx}. -All of them generate the machine instruction that is part of the name. - -@smallexample -v8qi __builtin_ia32_paddb (v8qi, v8qi) -v4hi __builtin_ia32_paddw (v4hi, v4hi) -v2si __builtin_ia32_paddd (v2si, v2si) -@c APPLE LOCAL begin radar 4395773 -v1di __builtin_ia32_paddq (v1di, v1di) -@c APPLE LOCAL end radar 4395773 -v8qi __builtin_ia32_psubb (v8qi, v8qi) -v4hi __builtin_ia32_psubw (v4hi, v4hi) -v2si __builtin_ia32_psubd (v2si, v2si) -@c APPLE LOCAL begin radar 4395773 -v1di __builtin_ia32_psubq (v1di, v1di) -@c APPLE LOCAL end radar 4395773 -v8qi __builtin_ia32_paddsb (v8qi, v8qi) -v4hi __builtin_ia32_paddsw (v4hi, v4hi) -v8qi __builtin_ia32_psubsb (v8qi, v8qi) -v4hi __builtin_ia32_psubsw (v4hi, v4hi) -v8qi __builtin_ia32_paddusb (v8qi, v8qi) -v4hi __builtin_ia32_paddusw (v4hi, v4hi) -v8qi __builtin_ia32_psubusb (v8qi, v8qi) -v4hi __builtin_ia32_psubusw (v4hi, v4hi) -v4hi __builtin_ia32_pmullw (v4hi, v4hi) -v4hi __builtin_ia32_pmulhw (v4hi, v4hi) -v1di __builtin_ia32_pand (v1di, v1di) -v1di __builtin_ia32_pandn (v1di,v1di) -v1di __builtin_ia32_por (v1di, v1di) -v1di __builtin_ia32_pxor (v1di, v1di) -v8qi __builtin_ia32_pcmpeqb (v8qi, v8qi) -v4hi __builtin_ia32_pcmpeqw (v4hi, v4hi) -v2si __builtin_ia32_pcmpeqd (v2si, v2si) -v8qi __builtin_ia32_pcmpgtb (v8qi, v8qi) -v4hi __builtin_ia32_pcmpgtw (v4hi, v4hi) -v2si __builtin_ia32_pcmpgtd (v2si, v2si) -v8qi __builtin_ia32_punpckhbw (v8qi, v8qi) -v4hi __builtin_ia32_punpckhwd (v4hi, v4hi) -v2si __builtin_ia32_punpckhdq (v2si, v2si) -v8qi __builtin_ia32_punpcklbw (v8qi, v8qi) -v4hi __builtin_ia32_punpcklwd (v4hi, v4hi) -v2si __builtin_ia32_punpckldq (v2si, v2si) -v8qi __builtin_ia32_packsswb (v4hi, v4hi) -v4hi __builtin_ia32_packssdw (v2si, v2si) -v8qi __builtin_ia32_packuswb (v4hi, v4hi) -@c APPLE LOCAL begin radar 4395773 -void __builtin_ia32_emms (void) -v4hi __builtin_ia32_psllw (v4hi, v1di) -v4hi __builtin_ia32_psllwi (v4hi, int) -v2si __builtin_ia32_pslld (v2si, v1di) -v2si __builtin_ia32_pslldi (v2si, int) -v1di __builtin_ia32_psllq (v1di, v1di) -@c APPLE LOCAL radar 4684674 -v1di __builtin_ia32_psllqi (v1di, int) -v4hi __builtin_ia32_psrlw (v4hi, v1di) -v4hi __builtin_ia32_psrlwi (v4hi, int) -v2si __builtin_ia32_psrld (v2si, v1di) -v2si __builtin_ia32_psrldi (v2si, int) -v1di __builtin_ia32_psrlq (v1di, v1di) -@c APPLE LOCAL radar 4684674 -v1di __builtin_ia32_psrlqi (v1di, int) -v4hi __builtin_ia32_psraw (v4hi, v1di) -v4hi __builtin_ia32_psrawi (v4hi, int) -v2si __builtin_ia32_psrad (v2si, v1di) -v2si __builtin_ia32_psradi (v2si, int) -v4hi __builtin_ia32_pshufw (v4hi, int) -v2si __builtin_ia32_pmaddwd (v4hi, v4hi) -v2si __builtin_ia32_vec_init_v2si (int, int) -v4hi __builtin_ia32_vec_init_v4hi (short, short, short, short) -v8qi __builtin_ia32_vec_init_v8qi (char, char, char, char, char, char, char, char) -int __builtin_ia32_vec_ext_v2si (v2si, int) -@c APPLE LOCAL end radar 4395773 -@end smallexample - -The following built-in functions are made available either with -@option{-msse}, or with a combination of @option{-m3dnow} and -@option{-march=athlon}. All of them generate the machine -instruction that is part of the name. - -@smallexample -v4hi __builtin_ia32_pmulhuw (v4hi, v4hi) -v8qi __builtin_ia32_pavgb (v8qi, v8qi) -v4hi __builtin_ia32_pavgw (v4hi, v4hi) -v4hi __builtin_ia32_psadbw (v8qi, v8qi) -v8qi __builtin_ia32_pmaxub (v8qi, v8qi) -v4hi __builtin_ia32_pmaxsw (v4hi, v4hi) -v8qi __builtin_ia32_pminub (v8qi, v8qi) -v4hi __builtin_ia32_pminsw (v4hi, v4hi) -int __builtin_ia32_pextrw (v4hi, int) -v4hi __builtin_ia32_pinsrw (v4hi, int, int) -int __builtin_ia32_pmovmskb (v8qi) -void __builtin_ia32_maskmovq (v8qi, v8qi, char *) -void __builtin_ia32_movntq (v1di *, v1di) -void __builtin_ia32_sfence (void) -@c APPLE LOCAL begin radar 4395773 -int __builtin_ia32_vec_ext_v4hi (v4hi, int) -v4hi __builtin_ia32_vec_set_v4hi (v4hi, int, int) -@c APPLE LOCAL end radar 4395773 -@end smallexample - -The following built-in functions are available when @option{-msse} is used. -All of them generate the machine instruction that is part of the name. - -@smallexample -int __builtin_ia32_comieq (v4sf, v4sf) -int __builtin_ia32_comineq (v4sf, v4sf) -int __builtin_ia32_comilt (v4sf, v4sf) -int __builtin_ia32_comile (v4sf, v4sf) -int __builtin_ia32_comigt (v4sf, v4sf) -int __builtin_ia32_comige (v4sf, v4sf) -int __builtin_ia32_ucomieq (v4sf, v4sf) -int __builtin_ia32_ucomineq (v4sf, v4sf) -int __builtin_ia32_ucomilt (v4sf, v4sf) -int __builtin_ia32_ucomile (v4sf, v4sf) -int __builtin_ia32_ucomigt (v4sf, v4sf) -int __builtin_ia32_ucomige (v4sf, v4sf) -v4sf __builtin_ia32_addps (v4sf, v4sf) -v4sf __builtin_ia32_subps (v4sf, v4sf) -v4sf __builtin_ia32_mulps (v4sf, v4sf) -v4sf __builtin_ia32_divps (v4sf, v4sf) -v4sf __builtin_ia32_addss (v4sf, v4sf) -v4sf __builtin_ia32_subss (v4sf, v4sf) -v4sf __builtin_ia32_mulss (v4sf, v4sf) -v4sf __builtin_ia32_divss (v4sf, v4sf) -v4si __builtin_ia32_cmpeqps (v4sf, v4sf) -v4si __builtin_ia32_cmpltps (v4sf, v4sf) -v4si __builtin_ia32_cmpleps (v4sf, v4sf) -v4si __builtin_ia32_cmpgtps (v4sf, v4sf) -v4si __builtin_ia32_cmpgeps (v4sf, v4sf) -v4si __builtin_ia32_cmpunordps (v4sf, v4sf) -v4si __builtin_ia32_cmpneqps (v4sf, v4sf) -v4si __builtin_ia32_cmpnltps (v4sf, v4sf) -v4si __builtin_ia32_cmpnleps (v4sf, v4sf) -v4si __builtin_ia32_cmpngtps (v4sf, v4sf) -v4si __builtin_ia32_cmpngeps (v4sf, v4sf) -v4si __builtin_ia32_cmpordps (v4sf, v4sf) -v4si __builtin_ia32_cmpeqss (v4sf, v4sf) -v4si __builtin_ia32_cmpltss (v4sf, v4sf) -v4si __builtin_ia32_cmpless (v4sf, v4sf) -v4si __builtin_ia32_cmpunordss (v4sf, v4sf) -v4si __builtin_ia32_cmpneqss (v4sf, v4sf) -v4si __builtin_ia32_cmpnlts (v4sf, v4sf) -v4si __builtin_ia32_cmpnless (v4sf, v4sf) -v4si __builtin_ia32_cmpordss (v4sf, v4sf) -v4sf __builtin_ia32_maxps (v4sf, v4sf) -v4sf __builtin_ia32_maxss (v4sf, v4sf) -v4sf __builtin_ia32_minps (v4sf, v4sf) -v4sf __builtin_ia32_minss (v4sf, v4sf) -v4sf __builtin_ia32_andps (v4sf, v4sf) -v4sf __builtin_ia32_andnps (v4sf, v4sf) -v4sf __builtin_ia32_orps (v4sf, v4sf) -v4sf __builtin_ia32_xorps (v4sf, v4sf) -v4sf __builtin_ia32_movss (v4sf, v4sf) -v4sf __builtin_ia32_movhlps (v4sf, v4sf) -v4sf __builtin_ia32_movlhps (v4sf, v4sf) -v4sf __builtin_ia32_unpckhps (v4sf, v4sf) -v4sf __builtin_ia32_unpcklps (v4sf, v4sf) -v4sf __builtin_ia32_cvtpi2ps (v4sf, v2si) -v4sf __builtin_ia32_cvtsi2ss (v4sf, int) -v2si __builtin_ia32_cvtps2pi (v4sf) -int __builtin_ia32_cvtss2si (v4sf) -v2si __builtin_ia32_cvttps2pi (v4sf) -int __builtin_ia32_cvttss2si (v4sf) -v4sf __builtin_ia32_rcpps (v4sf) -v4sf __builtin_ia32_rsqrtps (v4sf) -v4sf __builtin_ia32_sqrtps (v4sf) -v4sf __builtin_ia32_rcpss (v4sf) -v4sf __builtin_ia32_rsqrtss (v4sf) -v4sf __builtin_ia32_sqrtss (v4sf) -v4sf __builtin_ia32_shufps (v4sf, v4sf, int) -void __builtin_ia32_movntps (float *, v4sf) -int __builtin_ia32_movmskps (v4sf) -@c APPLE LOCAL begin radar 4395773 -void __builtin_ia32_ldmxcsr (unsigned) -unsigned __builtin_ia32_stmxcsr (void) -v2df __builtin_ia32_vec_ext_v2df (v2df, int) -v2di __builtin_ia32_vec_ext_v2di (v2di, int) -v4sf __builtin_ia32_vec_ext_v4sf (v4sf, int) -v4si __builtin_ia32_vec_ext_v4si (v4si, int) -v8hi __builtin_ia32_vec_set_v8hi (v8hi, int, int) -unsigned int __builtin_ia32_vec_ext_v8hi (v8hi, int) -@c APPLE LOCAL end radar 4395773 -@end smallexample - -The following built-in functions are available when @option{-msse} is used. - -@table @code -@item v4sf __builtin_ia32_loadaps (float *) -Generates the @code{movaps} machine instruction as a load from memory. -@item void __builtin_ia32_storeaps (float *, v4sf) -Generates the @code{movaps} machine instruction as a store to memory. -@item v4sf __builtin_ia32_loadups (float *) -Generates the @code{movups} machine instruction as a load from memory. -@item void __builtin_ia32_storeups (float *, v4sf) -Generates the @code{movups} machine instruction as a store to memory. -@item v4sf __builtin_ia32_loadsss (float *) -Generates the @code{movss} machine instruction as a load from memory. -@item void __builtin_ia32_storess (float *, v4sf) -Generates the @code{movss} machine instruction as a store to memory. -@item v4sf __builtin_ia32_loadhps (v4sf, v2si *) -Generates the @code{movhps} machine instruction as a load from memory. -@item v4sf __builtin_ia32_loadlps (v4sf, v2si *) -Generates the @code{movlps} machine instruction as a load from memory -@item void __builtin_ia32_storehps (v4sf, v2si *) -Generates the @code{movhps} machine instruction as a store to memory. -@item void __builtin_ia32_storelps (v4sf, v2si *) -Generates the @code{movlps} machine instruction as a store to memory. -@end table - -The following built-in functions are available when @option{-msse2} is used. -All of them generate the machine instruction that is part of the name. - -@smallexample -int __builtin_ia32_comisdeq (v2df, v2df) -int __builtin_ia32_comisdlt (v2df, v2df) -int __builtin_ia32_comisdle (v2df, v2df) -int __builtin_ia32_comisdgt (v2df, v2df) -int __builtin_ia32_comisdge (v2df, v2df) -int __builtin_ia32_comisdneq (v2df, v2df) -int __builtin_ia32_ucomisdeq (v2df, v2df) -int __builtin_ia32_ucomisdlt (v2df, v2df) -int __builtin_ia32_ucomisdle (v2df, v2df) -int __builtin_ia32_ucomisdgt (v2df, v2df) -int __builtin_ia32_ucomisdge (v2df, v2df) -int __builtin_ia32_ucomisdneq (v2df, v2df) -v2df __builtin_ia32_cmpeqpd (v2df, v2df) -v2df __builtin_ia32_cmpltpd (v2df, v2df) -v2df __builtin_ia32_cmplepd (v2df, v2df) -v2df __builtin_ia32_cmpgtpd (v2df, v2df) -v2df __builtin_ia32_cmpgepd (v2df, v2df) -v2df __builtin_ia32_cmpunordpd (v2df, v2df) -v2df __builtin_ia32_cmpneqpd (v2df, v2df) -v2df __builtin_ia32_cmpnltpd (v2df, v2df) -v2df __builtin_ia32_cmpnlepd (v2df, v2df) -v2df __builtin_ia32_cmpngtpd (v2df, v2df) -v2df __builtin_ia32_cmpngepd (v2df, v2df) -v2df __builtin_ia32_cmpordpd (v2df, v2df) -v2df __builtin_ia32_cmpeqsd (v2df, v2df) -v2df __builtin_ia32_cmpltsd (v2df, v2df) -v2df __builtin_ia32_cmplesd (v2df, v2df) -v2df __builtin_ia32_cmpunordsd (v2df, v2df) -v2df __builtin_ia32_cmpneqsd (v2df, v2df) -v2df __builtin_ia32_cmpnltsd (v2df, v2df) -v2df __builtin_ia32_cmpnlesd (v2df, v2df) -v2df __builtin_ia32_cmpordsd (v2df, v2df) -v2di __builtin_ia32_paddq (v2di, v2di) -v2di __builtin_ia32_psubq (v2di, v2di) -v2df __builtin_ia32_addpd (v2df, v2df) -v2df __builtin_ia32_subpd (v2df, v2df) -v2df __builtin_ia32_mulpd (v2df, v2df) -v2df __builtin_ia32_divpd (v2df, v2df) -v2df __builtin_ia32_addsd (v2df, v2df) -v2df __builtin_ia32_subsd (v2df, v2df) -v2df __builtin_ia32_mulsd (v2df, v2df) -v2df __builtin_ia32_divsd (v2df, v2df) -v2df __builtin_ia32_minpd (v2df, v2df) -v2df __builtin_ia32_maxpd (v2df, v2df) -v2df __builtin_ia32_minsd (v2df, v2df) -v2df __builtin_ia32_maxsd (v2df, v2df) -v2df __builtin_ia32_andpd (v2df, v2df) -v2df __builtin_ia32_andnpd (v2df, v2df) -v2df __builtin_ia32_orpd (v2df, v2df) -v2df __builtin_ia32_xorpd (v2df, v2df) -v2df __builtin_ia32_movsd (v2df, v2df) -v2df __builtin_ia32_unpckhpd (v2df, v2df) -v2df __builtin_ia32_unpcklpd (v2df, v2df) -v16qi __builtin_ia32_paddb128 (v16qi, v16qi) -v8hi __builtin_ia32_paddw128 (v8hi, v8hi) -v4si __builtin_ia32_paddd128 (v4si, v4si) -v2di __builtin_ia32_paddq128 (v2di, v2di) -v16qi __builtin_ia32_psubb128 (v16qi, v16qi) -v8hi __builtin_ia32_psubw128 (v8hi, v8hi) -v4si __builtin_ia32_psubd128 (v4si, v4si) -v2di __builtin_ia32_psubq128 (v2di, v2di) -v8hi __builtin_ia32_pmullw128 (v8hi, v8hi) -v8hi __builtin_ia32_pmulhw128 (v8hi, v8hi) -v2di __builtin_ia32_pand128 (v2di, v2di) -v2di __builtin_ia32_pandn128 (v2di, v2di) -v2di __builtin_ia32_por128 (v2di, v2di) -v2di __builtin_ia32_pxor128 (v2di, v2di) -v16qi __builtin_ia32_pavgb128 (v16qi, v16qi) -v8hi __builtin_ia32_pavgw128 (v8hi, v8hi) -v16qi __builtin_ia32_pcmpeqb128 (v16qi, v16qi) -v8hi __builtin_ia32_pcmpeqw128 (v8hi, v8hi) -v4si __builtin_ia32_pcmpeqd128 (v4si, v4si) -v16qi __builtin_ia32_pcmpgtb128 (v16qi, v16qi) -v8hi __builtin_ia32_pcmpgtw128 (v8hi, v8hi) -v4si __builtin_ia32_pcmpgtd128 (v4si, v4si) -v16qi __builtin_ia32_pmaxub128 (v16qi, v16qi) -v8hi __builtin_ia32_pmaxsw128 (v8hi, v8hi) -v16qi __builtin_ia32_pminub128 (v16qi, v16qi) -v8hi __builtin_ia32_pminsw128 (v8hi, v8hi) -v16qi __builtin_ia32_punpckhbw128 (v16qi, v16qi) -v8hi __builtin_ia32_punpckhwd128 (v8hi, v8hi) -v4si __builtin_ia32_punpckhdq128 (v4si, v4si) -v2di __builtin_ia32_punpckhqdq128 (v2di, v2di) -v16qi __builtin_ia32_punpcklbw128 (v16qi, v16qi) -v8hi __builtin_ia32_punpcklwd128 (v8hi, v8hi) -v4si __builtin_ia32_punpckldq128 (v4si, v4si) -v2di __builtin_ia32_punpcklqdq128 (v2di, v2di) -v16qi __builtin_ia32_packsswb128 (v16qi, v16qi) -v8hi __builtin_ia32_packssdw128 (v8hi, v8hi) -v16qi __builtin_ia32_packuswb128 (v16qi, v16qi) -v8hi __builtin_ia32_pmulhuw128 (v8hi, v8hi) -void __builtin_ia32_maskmovdqu (v16qi, v16qi) -v2df __builtin_ia32_loadupd (double *) -void __builtin_ia32_storeupd (double *, v2df) -v2df __builtin_ia32_loadhpd (v2df, double *) -v2df __builtin_ia32_loadlpd (v2df, double *) -int __builtin_ia32_movmskpd (v2df) -int __builtin_ia32_pmovmskb128 (v16qi) -void __builtin_ia32_movnti (int *, int) -void __builtin_ia32_movntpd (double *, v2df) -void __builtin_ia32_movntdq (v2df *, v2df) -v4si __builtin_ia32_pshufd (v4si, int) -v8hi __builtin_ia32_pshuflw (v8hi, int) -v8hi __builtin_ia32_pshufhw (v8hi, int) -v2di __builtin_ia32_psadbw128 (v16qi, v16qi) -v2df __builtin_ia32_sqrtpd (v2df) -v2df __builtin_ia32_sqrtsd (v2df) -v2df __builtin_ia32_shufpd (v2df, v2df, int) -v2df __builtin_ia32_cvtdq2pd (v4si) -v4sf __builtin_ia32_cvtdq2ps (v4si) -v4si __builtin_ia32_cvtpd2dq (v2df) -v2si __builtin_ia32_cvtpd2pi (v2df) -v4sf __builtin_ia32_cvtpd2ps (v2df) -v4si __builtin_ia32_cvttpd2dq (v2df) -v2si __builtin_ia32_cvttpd2pi (v2df) -v2df __builtin_ia32_cvtpi2pd (v2si) -int __builtin_ia32_cvtsd2si (v2df) -int __builtin_ia32_cvttsd2si (v2df) -long long __builtin_ia32_cvtsd2si64 (v2df) -long long __builtin_ia32_cvttsd2si64 (v2df) -v4si __builtin_ia32_cvtps2dq (v4sf) -v2df __builtin_ia32_cvtps2pd (v4sf) -v4si __builtin_ia32_cvttps2dq (v4sf) -v2df __builtin_ia32_cvtsi2sd (v2df, int) -v2df __builtin_ia32_cvtsi642sd (v2df, long long) -v4sf __builtin_ia32_cvtsd2ss (v4sf, v2df) -v2df __builtin_ia32_cvtss2sd (v2df, v4sf) -void __builtin_ia32_clflush (const void *) -void __builtin_ia32_lfence (void) -void __builtin_ia32_mfence (void) -v16qi __builtin_ia32_loaddqu (const char *) -void __builtin_ia32_storedqu (char *, v16qi) -unsigned long long __builtin_ia32_pmuludq (v2si, v2si) -v2di __builtin_ia32_pmuludq128 (v4si, v4si) -v8hi __builtin_ia32_psllw128 (v8hi, v2di) -v4si __builtin_ia32_pslld128 (v4si, v2di) -v2di __builtin_ia32_psllq128 (v4si, v2di) -v8hi __builtin_ia32_psrlw128 (v8hi, v2di) -v4si __builtin_ia32_psrld128 (v4si, v2di) -v2di __builtin_ia32_psrlq128 (v2di, v2di) -v8hi __builtin_ia32_psraw128 (v8hi, v2di) -v4si __builtin_ia32_psrad128 (v4si, v2di) -v2di __builtin_ia32_pslldqi128 (v2di, int) -v8hi __builtin_ia32_psllwi128 (v8hi, int) -v4si __builtin_ia32_pslldi128 (v4si, int) -v2di __builtin_ia32_psllqi128 (v2di, int) -v2di __builtin_ia32_psrldqi128 (v2di, int) -v8hi __builtin_ia32_psrlwi128 (v8hi, int) -v4si __builtin_ia32_psrldi128 (v4si, int) -v2di __builtin_ia32_psrlqi128 (v2di, int) -v8hi __builtin_ia32_psrawi128 (v8hi, int) -v4si __builtin_ia32_psradi128 (v4si, int) -v4si __builtin_ia32_pmaddwd128 (v8hi, v8hi) -@end smallexample - -The following built-in functions are available when @option{-msse3} is used. -All of them generate the machine instruction that is part of the name. - -@smallexample -v2df __builtin_ia32_addsubpd (v2df, v2df) -v4sf __builtin_ia32_addsubps (v4sf, v4sf) -v2df __builtin_ia32_haddpd (v2df, v2df) -v4sf __builtin_ia32_haddps (v4sf, v4sf) -v2df __builtin_ia32_hsubpd (v2df, v2df) -v4sf __builtin_ia32_hsubps (v4sf, v4sf) -v16qi __builtin_ia32_lddqu (char const *) -void __builtin_ia32_monitor (void *, unsigned int, unsigned int) -v2df __builtin_ia32_movddup (v2df) -v4sf __builtin_ia32_movshdup (v4sf) -v4sf __builtin_ia32_movsldup (v4sf) -void __builtin_ia32_mwait (unsigned int, unsigned int) -@end smallexample - -The following built-in functions are available when @option{-msse3} is used. - -@table @code -@item v2df __builtin_ia32_loadddup (double const *) -Generates the @code{movddup} machine instruction as a load from memory. -@end table - -@c APPLE LOCAL begin mainline -The following built-in functions are available when @option{-mssse3} is used. -All of them generate the machine instruction that is part of the name -with MMX registers. - -@smallexample -v2si __builtin_ia32_phaddd (v2si, v2si) -v4hi __builtin_ia32_phaddw (v4hi, v4hi) -v4hi __builtin_ia32_phaddsw (v4hi, v4hi) -v2si __builtin_ia32_phsubd (v2si, v2si) -v4hi __builtin_ia32_phsubw (v4hi, v4hi) -v4hi __builtin_ia32_phsubsw (v4hi, v4hi) -v8qi __builtin_ia32_pmaddubsw (v8qi, v8qi) -v4hi __builtin_ia32_pmulhrsw (v4hi, v4hi) -v8qi __builtin_ia32_pshufb (v8qi, v8qi) -v8qi __builtin_ia32_psignb (v8qi, v8qi) -v2si __builtin_ia32_psignd (v2si, v2si) -v4hi __builtin_ia32_psignw (v4hi, v4hi) -v1di __builtin_ia32_palignr (v1di, v1di, int) -v8qi __builtin_ia32_pabsb (v8qi) -v2si __builtin_ia32_pabsd (v2si) -v4hi __builtin_ia32_pabsw (v4hi) -@end smallexample -@c APPLE LOCAL end 4656532 use V1DI for _m64 - -The following built-in functions are available when @option{-mssse3} is used. -All of them generate the machine instruction that is part of the name -with SSE registers. - -@smallexample -v4si __builtin_ia32_phaddd128 (v4si, v4si) -v8hi __builtin_ia32_phaddw128 (v8hi, v8hi) -v8hi __builtin_ia32_phaddsw128 (v8hi, v8hi) -v4si __builtin_ia32_phsubd128 (v4si, v4si) -v8hi __builtin_ia32_phsubw128 (v8hi, v8hi) -v8hi __builtin_ia32_phsubsw128 (v8hi, v8hi) -v16qi __builtin_ia32_pmaddubsw128 (v16qi, v16qi) -v8hi __builtin_ia32_pmulhrsw128 (v8hi, v8hi) -v16qi __builtin_ia32_pshufb128 (v16qi, v16qi) -v16qi __builtin_ia32_psignb128 (v16qi, v16qi) -v4si __builtin_ia32_psignd128 (v4si, v4si) -v8hi __builtin_ia32_psignw128 (v8hi, v8hi) -v2di __builtin_ia32_palignr (v2di, v2di, int) -v16qi __builtin_ia32_pabsb128 (v16qi) -v4si __builtin_ia32_pabsd128 (v4si) -v8hi __builtin_ia32_pabsw128 (v8hi) -@end smallexample -@c APPLE LOCAL end mainline -The following built-in functions are available when @option{-m3dnow} is used. -All of them generate the machine instruction that is part of the name. - -@smallexample -void __builtin_ia32_femms (void) -v8qi __builtin_ia32_pavgusb (v8qi, v8qi) -v2si __builtin_ia32_pf2id (v2sf) -v2sf __builtin_ia32_pfacc (v2sf, v2sf) -v2sf __builtin_ia32_pfadd (v2sf, v2sf) -v2si __builtin_ia32_pfcmpeq (v2sf, v2sf) -v2si __builtin_ia32_pfcmpge (v2sf, v2sf) -v2si __builtin_ia32_pfcmpgt (v2sf, v2sf) -v2sf __builtin_ia32_pfmax (v2sf, v2sf) -v2sf __builtin_ia32_pfmin (v2sf, v2sf) -v2sf __builtin_ia32_pfmul (v2sf, v2sf) -v2sf __builtin_ia32_pfrcp (v2sf) -v2sf __builtin_ia32_pfrcpit1 (v2sf, v2sf) -v2sf __builtin_ia32_pfrcpit2 (v2sf, v2sf) -v2sf __builtin_ia32_pfrsqrt (v2sf) -v2sf __builtin_ia32_pfrsqrtit1 (v2sf, v2sf) -v2sf __builtin_ia32_pfsub (v2sf, v2sf) -v2sf __builtin_ia32_pfsubr (v2sf, v2sf) -v2sf __builtin_ia32_pi2fd (v2si) -v4hi __builtin_ia32_pmulhrw (v4hi, v4hi) -@end smallexample - -The following built-in functions are available when both @option{-m3dnow} -and @option{-march=athlon} are used. All of them generate the machine -instruction that is part of the name. - -@smallexample -v2si __builtin_ia32_pf2iw (v2sf) -v2sf __builtin_ia32_pfnacc (v2sf, v2sf) -v2sf __builtin_ia32_pfpnacc (v2sf, v2sf) -v2sf __builtin_ia32_pi2fw (v2si) -v2sf __builtin_ia32_pswapdsf (v2sf) -v2si __builtin_ia32_pswapdsi (v2si) -@end smallexample - -@node MIPS DSP Built-in Functions -@subsection MIPS DSP Built-in Functions - -The MIPS DSP Application-Specific Extension (ASE) includes new -instructions that are designed to improve the performance of DSP and -media applications. It provides instructions that operate on packed -8-bit integer data, Q15 fractional data and Q31 fractional data. - -GCC supports MIPS DSP operations using both the generic -vector extensions (@pxref{Vector Extensions}) and a collection of -MIPS-specific built-in functions. Both kinds of support are -enabled by the @option{-mdsp} command-line option. - -At present, GCC only provides support for operations on 32-bit -vectors. The vector type associated with 8-bit integer data is -usually called @code{v4i8} and the vector type associated with Q15 is -usually called @code{v2q15}. They can be defined in C as follows: - -@smallexample -typedef char v4i8 __attribute__ ((vector_size(4))); -typedef short v2q15 __attribute__ ((vector_size(4))); -@end smallexample - -@code{v4i8} and @code{v2q15} values are initialized in the same way as -aggregates. For example: - -@smallexample -v4i8 a = @{1, 2, 3, 4@}; -v4i8 b; -b = (v4i8) @{5, 6, 7, 8@}; - -v2q15 c = @{0x0fcb, 0x3a75@}; -v2q15 d; -d = (v2q15) @{0.1234 * 0x1.0p15, 0.4567 * 0x1.0p15@}; -@end smallexample - -@emph{Note:} The CPU's endianness determines the order in which values -are packed. On little-endian targets, the first value is the least -significant and the last value is the most significant. The opposite -order applies to big-endian targets. For example, the code above will -set the lowest byte of @code{a} to @code{1} on little-endian targets -and @code{4} on big-endian targets. - -@emph{Note:} Q15 and Q31 values must be initialized with their integer -representation. As shown in this example, the integer representation -of a Q15 value can be obtained by multiplying the fractional value by -@code{0x1.0p15}. The equivalent for Q31 values is to multiply by -@code{0x1.0p31}. - -The table below lists the @code{v4i8} and @code{v2q15} operations for which -hardware support exists. @code{a} and @code{b} are @code{v4i8} values, -and @code{c} and @code{d} are @code{v2q15} values. - -@multitable @columnfractions .50 .50 -@item C code @tab MIPS instruction -@item @code{a + b} @tab @code{addu.qb} -@item @code{c + d} @tab @code{addq.ph} -@item @code{a - b} @tab @code{subu.qb} -@item @code{c - d} @tab @code{subq.ph} -@end multitable - -It is easier to describe the DSP built-in functions if we first define -the following types: - -@smallexample -typedef int q31; -typedef int i32; -typedef long long a64; -@end smallexample - -@code{q31} and @code{i32} are actually the same as @code{int}, but we -use @code{q31} to indicate a Q31 fractional value and @code{i32} to -indicate a 32-bit integer value. Similarly, @code{a64} is the same as -@code{long long}, but we use @code{a64} to indicate values that will -be placed in one of the four DSP accumulators (@code{$ac0}, -@code{$ac1}, @code{$ac2} or @code{$ac3}). - -Also, some built-in functions prefer or require immediate numbers as -parameters, because the corresponding DSP instructions accept both immediate -numbers and register operands, or accept immediate numbers only. The -immediate parameters are listed as follows. - -@smallexample -imm0_7: 0 to 7. -imm0_15: 0 to 15. -imm0_31: 0 to 31. -imm0_63: 0 to 63. -imm0_255: 0 to 255. -imm_n32_31: -32 to 31. -imm_n512_511: -512 to 511. -@end smallexample - -The following built-in functions map directly to a particular MIPS DSP -instruction. Please refer to the architecture specification -for details on what each instruction does. - -@smallexample -v2q15 __builtin_mips_addq_ph (v2q15, v2q15) -v2q15 __builtin_mips_addq_s_ph (v2q15, v2q15) -q31 __builtin_mips_addq_s_w (q31, q31) -v4i8 __builtin_mips_addu_qb (v4i8, v4i8) -v4i8 __builtin_mips_addu_s_qb (v4i8, v4i8) -v2q15 __builtin_mips_subq_ph (v2q15, v2q15) -v2q15 __builtin_mips_subq_s_ph (v2q15, v2q15) -q31 __builtin_mips_subq_s_w (q31, q31) -v4i8 __builtin_mips_subu_qb (v4i8, v4i8) -v4i8 __builtin_mips_subu_s_qb (v4i8, v4i8) -i32 __builtin_mips_addsc (i32, i32) -i32 __builtin_mips_addwc (i32, i32) -i32 __builtin_mips_modsub (i32, i32) -i32 __builtin_mips_raddu_w_qb (v4i8) -v2q15 __builtin_mips_absq_s_ph (v2q15) -q31 __builtin_mips_absq_s_w (q31) -v4i8 __builtin_mips_precrq_qb_ph (v2q15, v2q15) -v2q15 __builtin_mips_precrq_ph_w (q31, q31) -v2q15 __builtin_mips_precrq_rs_ph_w (q31, q31) -v4i8 __builtin_mips_precrqu_s_qb_ph (v2q15, v2q15) -q31 __builtin_mips_preceq_w_phl (v2q15) -q31 __builtin_mips_preceq_w_phr (v2q15) -v2q15 __builtin_mips_precequ_ph_qbl (v4i8) -v2q15 __builtin_mips_precequ_ph_qbr (v4i8) -v2q15 __builtin_mips_precequ_ph_qbla (v4i8) -v2q15 __builtin_mips_precequ_ph_qbra (v4i8) -v2q15 __builtin_mips_preceu_ph_qbl (v4i8) -v2q15 __builtin_mips_preceu_ph_qbr (v4i8) -v2q15 __builtin_mips_preceu_ph_qbla (v4i8) -v2q15 __builtin_mips_preceu_ph_qbra (v4i8) -v4i8 __builtin_mips_shll_qb (v4i8, imm0_7) -v4i8 __builtin_mips_shll_qb (v4i8, i32) -v2q15 __builtin_mips_shll_ph (v2q15, imm0_15) -v2q15 __builtin_mips_shll_ph (v2q15, i32) -v2q15 __builtin_mips_shll_s_ph (v2q15, imm0_15) -v2q15 __builtin_mips_shll_s_ph (v2q15, i32) -q31 __builtin_mips_shll_s_w (q31, imm0_31) -q31 __builtin_mips_shll_s_w (q31, i32) -v4i8 __builtin_mips_shrl_qb (v4i8, imm0_7) -v4i8 __builtin_mips_shrl_qb (v4i8, i32) -v2q15 __builtin_mips_shra_ph (v2q15, imm0_15) -v2q15 __builtin_mips_shra_ph (v2q15, i32) -v2q15 __builtin_mips_shra_r_ph (v2q15, imm0_15) -v2q15 __builtin_mips_shra_r_ph (v2q15, i32) -q31 __builtin_mips_shra_r_w (q31, imm0_31) -q31 __builtin_mips_shra_r_w (q31, i32) -v2q15 __builtin_mips_muleu_s_ph_qbl (v4i8, v2q15) -v2q15 __builtin_mips_muleu_s_ph_qbr (v4i8, v2q15) -v2q15 __builtin_mips_mulq_rs_ph (v2q15, v2q15) -q31 __builtin_mips_muleq_s_w_phl (v2q15, v2q15) -q31 __builtin_mips_muleq_s_w_phr (v2q15, v2q15) -a64 __builtin_mips_dpau_h_qbl (a64, v4i8, v4i8) -a64 __builtin_mips_dpau_h_qbr (a64, v4i8, v4i8) -a64 __builtin_mips_dpsu_h_qbl (a64, v4i8, v4i8) -a64 __builtin_mips_dpsu_h_qbr (a64, v4i8, v4i8) -a64 __builtin_mips_dpaq_s_w_ph (a64, v2q15, v2q15) -a64 __builtin_mips_dpaq_sa_l_w (a64, q31, q31) -a64 __builtin_mips_dpsq_s_w_ph (a64, v2q15, v2q15) -a64 __builtin_mips_dpsq_sa_l_w (a64, q31, q31) -a64 __builtin_mips_mulsaq_s_w_ph (a64, v2q15, v2q15) -a64 __builtin_mips_maq_s_w_phl (a64, v2q15, v2q15) -a64 __builtin_mips_maq_s_w_phr (a64, v2q15, v2q15) -a64 __builtin_mips_maq_sa_w_phl (a64, v2q15, v2q15) -a64 __builtin_mips_maq_sa_w_phr (a64, v2q15, v2q15) -i32 __builtin_mips_bitrev (i32) -i32 __builtin_mips_insv (i32, i32) -v4i8 __builtin_mips_repl_qb (imm0_255) -v4i8 __builtin_mips_repl_qb (i32) -v2q15 __builtin_mips_repl_ph (imm_n512_511) -v2q15 __builtin_mips_repl_ph (i32) -void __builtin_mips_cmpu_eq_qb (v4i8, v4i8) -void __builtin_mips_cmpu_lt_qb (v4i8, v4i8) -void __builtin_mips_cmpu_le_qb (v4i8, v4i8) -i32 __builtin_mips_cmpgu_eq_qb (v4i8, v4i8) -i32 __builtin_mips_cmpgu_lt_qb (v4i8, v4i8) -i32 __builtin_mips_cmpgu_le_qb (v4i8, v4i8) -void __builtin_mips_cmp_eq_ph (v2q15, v2q15) -void __builtin_mips_cmp_lt_ph (v2q15, v2q15) -void __builtin_mips_cmp_le_ph (v2q15, v2q15) -v4i8 __builtin_mips_pick_qb (v4i8, v4i8) -v2q15 __builtin_mips_pick_ph (v2q15, v2q15) -v2q15 __builtin_mips_packrl_ph (v2q15, v2q15) -i32 __builtin_mips_extr_w (a64, imm0_31) -i32 __builtin_mips_extr_w (a64, i32) -i32 __builtin_mips_extr_r_w (a64, imm0_31) -i32 __builtin_mips_extr_s_h (a64, i32) -i32 __builtin_mips_extr_rs_w (a64, imm0_31) -i32 __builtin_mips_extr_rs_w (a64, i32) -i32 __builtin_mips_extr_s_h (a64, imm0_31) -i32 __builtin_mips_extr_r_w (a64, i32) -i32 __builtin_mips_extp (a64, imm0_31) -i32 __builtin_mips_extp (a64, i32) -i32 __builtin_mips_extpdp (a64, imm0_31) -i32 __builtin_mips_extpdp (a64, i32) -a64 __builtin_mips_shilo (a64, imm_n32_31) -a64 __builtin_mips_shilo (a64, i32) -a64 __builtin_mips_mthlip (a64, i32) -void __builtin_mips_wrdsp (i32, imm0_63) -i32 __builtin_mips_rddsp (imm0_63) -i32 __builtin_mips_lbux (void *, i32) -i32 __builtin_mips_lhx (void *, i32) -i32 __builtin_mips_lwx (void *, i32) -i32 __builtin_mips_bposge32 (void) -@end smallexample - -@node MIPS Paired-Single Support -@subsection MIPS Paired-Single Support - -The MIPS64 architecture includes a number of instructions that -operate on pairs of single-precision floating-point values. -Each pair is packed into a 64-bit floating-point register, -with one element being designated the ``upper half'' and -the other being designated the ``lower half''. - -GCC supports paired-single operations using both the generic -vector extensions (@pxref{Vector Extensions}) and a collection of -MIPS-specific built-in functions. Both kinds of support are -enabled by the @option{-mpaired-single} command-line option. - -The vector type associated with paired-single values is usually -called @code{v2sf}. It can be defined in C as follows: - -@smallexample -typedef float v2sf __attribute__ ((vector_size (8))); -@end smallexample - -@code{v2sf} values are initialized in the same way as aggregates. -For example: - -@smallexample -v2sf a = @{1.5, 9.1@}; -v2sf b; -float e, f; -b = (v2sf) @{e, f@}; -@end smallexample - -@emph{Note:} The CPU's endianness determines which value is stored in -the upper half of a register and which value is stored in the lower half. -On little-endian targets, the first value is the lower one and the second -value is the upper one. The opposite order applies to big-endian targets. -For example, the code above will set the lower half of @code{a} to -@code{1.5} on little-endian targets and @code{9.1} on big-endian targets. - -@menu -* Paired-Single Arithmetic:: -* Paired-Single Built-in Functions:: -* MIPS-3D Built-in Functions:: -@end menu - -@node Paired-Single Arithmetic -@subsubsection Paired-Single Arithmetic - -The table below lists the @code{v2sf} operations for which hardware -support exists. @code{a}, @code{b} and @code{c} are @code{v2sf} -values and @code{x} is an integral value. - -@multitable @columnfractions .50 .50 -@item C code @tab MIPS instruction -@item @code{a + b} @tab @code{add.ps} -@item @code{a - b} @tab @code{sub.ps} -@item @code{-a} @tab @code{neg.ps} -@item @code{a * b} @tab @code{mul.ps} -@item @code{a * b + c} @tab @code{madd.ps} -@item @code{a * b - c} @tab @code{msub.ps} -@item @code{-(a * b + c)} @tab @code{nmadd.ps} -@item @code{-(a * b - c)} @tab @code{nmsub.ps} -@item @code{x ? a : b} @tab @code{movn.ps}/@code{movz.ps} -@end multitable - -Note that the multiply-accumulate instructions can be disabled -using the command-line option @code{-mno-fused-madd}. - -@node Paired-Single Built-in Functions -@subsubsection Paired-Single Built-in Functions - -The following paired-single functions map directly to a particular -MIPS instruction. Please refer to the architecture specification -for details on what each instruction does. - -@table @code -@item v2sf __builtin_mips_pll_ps (v2sf, v2sf) -Pair lower lower (@code{pll.ps}). - -@item v2sf __builtin_mips_pul_ps (v2sf, v2sf) -Pair upper lower (@code{pul.ps}). - -@item v2sf __builtin_mips_plu_ps (v2sf, v2sf) -Pair lower upper (@code{plu.ps}). - -@item v2sf __builtin_mips_puu_ps (v2sf, v2sf) -Pair upper upper (@code{puu.ps}). - -@item v2sf __builtin_mips_cvt_ps_s (float, float) -Convert pair to paired single (@code{cvt.ps.s}). - -@item float __builtin_mips_cvt_s_pl (v2sf) -Convert pair lower to single (@code{cvt.s.pl}). - -@item float __builtin_mips_cvt_s_pu (v2sf) -Convert pair upper to single (@code{cvt.s.pu}). - -@item v2sf __builtin_mips_abs_ps (v2sf) -Absolute value (@code{abs.ps}). - -@item v2sf __builtin_mips_alnv_ps (v2sf, v2sf, int) -Align variable (@code{alnv.ps}). - -@emph{Note:} The value of the third parameter must be 0 or 4 -modulo 8, otherwise the result will be unpredictable. Please read the -instruction description for details. -@end table - -The following multi-instruction functions are also available. -In each case, @var{cond} can be any of the 16 floating-point conditions: -@code{f}, @code{un}, @code{eq}, @code{ueq}, @code{olt}, @code{ult}, -@code{ole}, @code{ule}, @code{sf}, @code{ngle}, @code{seq}, @code{ngl}, -@code{lt}, @code{nge}, @code{le} or @code{ngt}. - -@table @code -@item v2sf __builtin_mips_movt_c_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -@itemx v2sf __builtin_mips_movf_c_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -Conditional move based on floating point comparison (@code{c.@var{cond}.ps}, -@code{movt.ps}/@code{movf.ps}). - -The @code{movt} functions return the value @var{x} computed by: - -@smallexample -c.@var{cond}.ps @var{cc},@var{a},@var{b} -mov.ps @var{x},@var{c} -movt.ps @var{x},@var{d},@var{cc} -@end smallexample - -The @code{movf} functions are similar but use @code{movf.ps} instead -of @code{movt.ps}. - -@item int __builtin_mips_upper_c_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -@itemx int __builtin_mips_lower_c_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -Comparison of two paired-single values (@code{c.@var{cond}.ps}, -@code{bc1t}/@code{bc1f}). - -These functions compare @var{a} and @var{b} using @code{c.@var{cond}.ps} -and return either the upper or lower half of the result. For example: - -@smallexample -v2sf a, b; -if (__builtin_mips_upper_c_eq_ps (a, b)) - upper_halves_are_equal (); -else - upper_halves_are_unequal (); - -if (__builtin_mips_lower_c_eq_ps (a, b)) - lower_halves_are_equal (); -else - lower_halves_are_unequal (); -@end smallexample -@end table - -@node MIPS-3D Built-in Functions -@subsubsection MIPS-3D Built-in Functions - -The MIPS-3D Application-Specific Extension (ASE) includes additional -paired-single instructions that are designed to improve the performance -of 3D graphics operations. Support for these instructions is controlled -by the @option{-mips3d} command-line option. - -The functions listed below map directly to a particular MIPS-3D -instruction. Please refer to the architecture specification for -more details on what each instruction does. - -@table @code -@item v2sf __builtin_mips_addr_ps (v2sf, v2sf) -Reduction add (@code{addr.ps}). - -@item v2sf __builtin_mips_mulr_ps (v2sf, v2sf) -Reduction multiply (@code{mulr.ps}). - -@item v2sf __builtin_mips_cvt_pw_ps (v2sf) -Convert paired single to paired word (@code{cvt.pw.ps}). - -@item v2sf __builtin_mips_cvt_ps_pw (v2sf) -Convert paired word to paired single (@code{cvt.ps.pw}). - -@item float __builtin_mips_recip1_s (float) -@itemx double __builtin_mips_recip1_d (double) -@itemx v2sf __builtin_mips_recip1_ps (v2sf) -Reduced precision reciprocal (sequence step 1) (@code{recip1.@var{fmt}}). - -@item float __builtin_mips_recip2_s (float, float) -@itemx double __builtin_mips_recip2_d (double, double) -@itemx v2sf __builtin_mips_recip2_ps (v2sf, v2sf) -Reduced precision reciprocal (sequence step 2) (@code{recip2.@var{fmt}}). - -@item float __builtin_mips_rsqrt1_s (float) -@itemx double __builtin_mips_rsqrt1_d (double) -@itemx v2sf __builtin_mips_rsqrt1_ps (v2sf) -Reduced precision reciprocal square root (sequence step 1) -(@code{rsqrt1.@var{fmt}}). - -@item float __builtin_mips_rsqrt2_s (float, float) -@itemx double __builtin_mips_rsqrt2_d (double, double) -@itemx v2sf __builtin_mips_rsqrt2_ps (v2sf, v2sf) -Reduced precision reciprocal square root (sequence step 2) -(@code{rsqrt2.@var{fmt}}). -@end table - -The following multi-instruction functions are also available. -In each case, @var{cond} can be any of the 16 floating-point conditions: -@code{f}, @code{un}, @code{eq}, @code{ueq}, @code{olt}, @code{ult}, -@code{ole}, @code{ule}, @code{sf}, @code{ngle}, @code{seq}, -@code{ngl}, @code{lt}, @code{nge}, @code{le} or @code{ngt}. - -@table @code -@item int __builtin_mips_cabs_@var{cond}_s (float @var{a}, float @var{b}) -@itemx int __builtin_mips_cabs_@var{cond}_d (double @var{a}, double @var{b}) -Absolute comparison of two scalar values (@code{cabs.@var{cond}.@var{fmt}}, -@code{bc1t}/@code{bc1f}). - -These functions compare @var{a} and @var{b} using @code{cabs.@var{cond}.s} -or @code{cabs.@var{cond}.d} and return the result as a boolean value. -For example: - -@smallexample -float a, b; -if (__builtin_mips_cabs_eq_s (a, b)) - true (); -else - false (); -@end smallexample - -@item int __builtin_mips_upper_cabs_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -@itemx int __builtin_mips_lower_cabs_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -Absolute comparison of two paired-single values (@code{cabs.@var{cond}.ps}, -@code{bc1t}/@code{bc1f}). - -These functions compare @var{a} and @var{b} using @code{cabs.@var{cond}.ps} -and return either the upper or lower half of the result. For example: - -@smallexample -v2sf a, b; -if (__builtin_mips_upper_cabs_eq_ps (a, b)) - upper_halves_are_equal (); -else - upper_halves_are_unequal (); - -if (__builtin_mips_lower_cabs_eq_ps (a, b)) - lower_halves_are_equal (); -else - lower_halves_are_unequal (); -@end smallexample - -@item v2sf __builtin_mips_movt_cabs_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -@itemx v2sf __builtin_mips_movf_cabs_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -Conditional move based on absolute comparison (@code{cabs.@var{cond}.ps}, -@code{movt.ps}/@code{movf.ps}). - -The @code{movt} functions return the value @var{x} computed by: - -@smallexample -cabs.@var{cond}.ps @var{cc},@var{a},@var{b} -mov.ps @var{x},@var{c} -movt.ps @var{x},@var{d},@var{cc} -@end smallexample - -The @code{movf} functions are similar but use @code{movf.ps} instead -of @code{movt.ps}. - -@item int __builtin_mips_any_c_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -@itemx int __builtin_mips_all_c_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -@itemx int __builtin_mips_any_cabs_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -@itemx int __builtin_mips_all_cabs_@var{cond}_ps (v2sf @var{a}, v2sf @var{b}) -Comparison of two paired-single values -(@code{c.@var{cond}.ps}/@code{cabs.@var{cond}.ps}, -@code{bc1any2t}/@code{bc1any2f}). - -These functions compare @var{a} and @var{b} using @code{c.@var{cond}.ps} -or @code{cabs.@var{cond}.ps}. The @code{any} forms return true if either -result is true and the @code{all} forms return true if both results are true. -For example: - -@smallexample -v2sf a, b; -if (__builtin_mips_any_c_eq_ps (a, b)) - one_is_true (); -else - both_are_false (); - -if (__builtin_mips_all_c_eq_ps (a, b)) - both_are_true (); -else - one_is_false (); -@end smallexample - -@item int __builtin_mips_any_c_@var{cond}_4s (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -@itemx int __builtin_mips_all_c_@var{cond}_4s (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -@itemx int __builtin_mips_any_cabs_@var{cond}_4s (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -@itemx int __builtin_mips_all_cabs_@var{cond}_4s (v2sf @var{a}, v2sf @var{b}, v2sf @var{c}, v2sf @var{d}) -Comparison of four paired-single values -(@code{c.@var{cond}.ps}/@code{cabs.@var{cond}.ps}, -@code{bc1any4t}/@code{bc1any4f}). - -These functions use @code{c.@var{cond}.ps} or @code{cabs.@var{cond}.ps} -to compare @var{a} with @var{b} and to compare @var{c} with @var{d}. -The @code{any} forms return true if any of the four results are true -and the @code{all} forms return true if all four results are true. -For example: - -@smallexample -v2sf a, b, c, d; -if (__builtin_mips_any_c_eq_4s (a, b, c, d)) - some_are_true (); -else - all_are_false (); - -if (__builtin_mips_all_c_eq_4s (a, b, c, d)) - all_are_true (); -else - some_are_false (); -@end smallexample -@end table - -@node PowerPC AltiVec Built-in Functions -@subsection PowerPC AltiVec Built-in Functions - -GCC provides an interface for the PowerPC family of processors to access -the AltiVec operations described in Motorola's AltiVec Programming -Interface Manual. The interface is made available by including -@code{<altivec.h>} and using @option{-maltivec} and -@option{-mabi=altivec}. The interface supports the following vector -types. - -@smallexample -vector unsigned char -vector signed char -vector bool char - -vector unsigned short -vector signed short -vector bool short -vector pixel - -vector unsigned int -vector signed int -vector bool int -vector float -@end smallexample - -GCC's implementation of the high-level language interface available from -C and C++ code differs from Motorola's documentation in several ways. - -@itemize @bullet - -@item -A vector constant is a list of constant expressions within curly braces. - -@item -A vector initializer requires no cast if the vector constant is of the -same type as the variable it is initializing. - -@item -If @code{signed} or @code{unsigned} is omitted, the signedness of the -vector type is the default signedness of the base type. The default -varies depending on the operating system, so a portable program should -always specify the signedness. - -@item -Compiling with @option{-maltivec} adds keywords @code{__vector}, -@code{__pixel}, and @code{__bool}. Macros @option{vector}, -@code{pixel}, and @code{bool} are defined in @code{<altivec.h>} and can -be undefined. - -@item -GCC allows using a @code{typedef} name as the type specifier for a -vector type. - -@item -For C, overloaded functions are implemented with macros so the following -does not work: - -@smallexample - vec_add ((vector signed int)@{1, 2, 3, 4@}, foo); -@end smallexample - -Since @code{vec_add} is a macro, the vector constant in the example -is treated as four separate arguments. Wrap the entire argument in -parentheses for this to work. -@end itemize - -@emph{Note:} Only the @code{<altivec.h>} interface is supported. -Internally, GCC uses built-in functions to achieve the functionality in -the aforementioned header file, but they are not supported and are -subject to change without notice. - -The following interfaces are supported for the generic and specific -AltiVec operations and the AltiVec predicates. In cases where there -is a direct mapping between generic and specific operations, only the -generic names are shown here, although the specific operations can also -be used. - -Arguments that are documented as @code{const int} require literal -integral values within the range required for that operation. - -@smallexample -vector signed char vec_abs (vector signed char); -vector signed short vec_abs (vector signed short); -vector signed int vec_abs (vector signed int); -vector float vec_abs (vector float); - -vector signed char vec_abss (vector signed char); -vector signed short vec_abss (vector signed short); -vector signed int vec_abss (vector signed int); - -vector signed char vec_add (vector bool char, vector signed char); -vector signed char vec_add (vector signed char, vector bool char); -vector signed char vec_add (vector signed char, vector signed char); -vector unsigned char vec_add (vector bool char, vector unsigned char); -vector unsigned char vec_add (vector unsigned char, vector bool char); -vector unsigned char vec_add (vector unsigned char, - vector unsigned char); -vector signed short vec_add (vector bool short, vector signed short); -vector signed short vec_add (vector signed short, vector bool short); -vector signed short vec_add (vector signed short, vector signed short); -vector unsigned short vec_add (vector bool short, - vector unsigned short); -vector unsigned short vec_add (vector unsigned short, - vector bool short); -vector unsigned short vec_add (vector unsigned short, - vector unsigned short); -vector signed int vec_add (vector bool int, vector signed int); -vector signed int vec_add (vector signed int, vector bool int); -vector signed int vec_add (vector signed int, vector signed int); -vector unsigned int vec_add (vector bool int, vector unsigned int); -vector unsigned int vec_add (vector unsigned int, vector bool int); -vector unsigned int vec_add (vector unsigned int, vector unsigned int); -vector float vec_add (vector float, vector float); - -vector float vec_vaddfp (vector float, vector float); - -vector signed int vec_vadduwm (vector bool int, vector signed int); -vector signed int vec_vadduwm (vector signed int, vector bool int); -vector signed int vec_vadduwm (vector signed int, vector signed int); -vector unsigned int vec_vadduwm (vector bool int, vector unsigned int); -vector unsigned int vec_vadduwm (vector unsigned int, vector bool int); -vector unsigned int vec_vadduwm (vector unsigned int, - vector unsigned int); - -vector signed short vec_vadduhm (vector bool short, - vector signed short); -vector signed short vec_vadduhm (vector signed short, - vector bool short); -vector signed short vec_vadduhm (vector signed short, - vector signed short); -vector unsigned short vec_vadduhm (vector bool short, - vector unsigned short); -vector unsigned short vec_vadduhm (vector unsigned short, - vector bool short); -vector unsigned short vec_vadduhm (vector unsigned short, - vector unsigned short); - -vector signed char vec_vaddubm (vector bool char, vector signed char); -vector signed char vec_vaddubm (vector signed char, vector bool char); -vector signed char vec_vaddubm (vector signed char, vector signed char); -vector unsigned char vec_vaddubm (vector bool char, - vector unsigned char); -vector unsigned char vec_vaddubm (vector unsigned char, - vector bool char); -vector unsigned char vec_vaddubm (vector unsigned char, - vector unsigned char); - -vector unsigned int vec_addc (vector unsigned int, vector unsigned int); - -vector unsigned char vec_adds (vector bool char, vector unsigned char); -vector unsigned char vec_adds (vector unsigned char, vector bool char); -vector unsigned char vec_adds (vector unsigned char, - vector unsigned char); -vector signed char vec_adds (vector bool char, vector signed char); -vector signed char vec_adds (vector signed char, vector bool char); -vector signed char vec_adds (vector signed char, vector signed char); -vector unsigned short vec_adds (vector bool short, - vector unsigned short); -vector unsigned short vec_adds (vector unsigned short, - vector bool short); -vector unsigned short vec_adds (vector unsigned short, - vector unsigned short); -vector signed short vec_adds (vector bool short, vector signed short); -vector signed short vec_adds (vector signed short, vector bool short); -vector signed short vec_adds (vector signed short, vector signed short); -vector unsigned int vec_adds (vector bool int, vector unsigned int); -vector unsigned int vec_adds (vector unsigned int, vector bool int); -vector unsigned int vec_adds (vector unsigned int, vector unsigned int); -vector signed int vec_adds (vector bool int, vector signed int); -vector signed int vec_adds (vector signed int, vector bool int); -vector signed int vec_adds (vector signed int, vector signed int); - -vector signed int vec_vaddsws (vector bool int, vector signed int); -vector signed int vec_vaddsws (vector signed int, vector bool int); -vector signed int vec_vaddsws (vector signed int, vector signed int); - -vector unsigned int vec_vadduws (vector bool int, vector unsigned int); -vector unsigned int vec_vadduws (vector unsigned int, vector bool int); -vector unsigned int vec_vadduws (vector unsigned int, - vector unsigned int); - -vector signed short vec_vaddshs (vector bool short, - vector signed short); -vector signed short vec_vaddshs (vector signed short, - vector bool short); -vector signed short vec_vaddshs (vector signed short, - vector signed short); - -vector unsigned short vec_vadduhs (vector bool short, - vector unsigned short); -vector unsigned short vec_vadduhs (vector unsigned short, - vector bool short); -vector unsigned short vec_vadduhs (vector unsigned short, - vector unsigned short); - -vector signed char vec_vaddsbs (vector bool char, vector signed char); -vector signed char vec_vaddsbs (vector signed char, vector bool char); -vector signed char vec_vaddsbs (vector signed char, vector signed char); - -vector unsigned char vec_vaddubs (vector bool char, - vector unsigned char); -vector unsigned char vec_vaddubs (vector unsigned char, - vector bool char); -vector unsigned char vec_vaddubs (vector unsigned char, - vector unsigned char); - -vector float vec_and (vector float, vector float); -vector float vec_and (vector float, vector bool int); -vector float vec_and (vector bool int, vector float); -vector bool int vec_and (vector bool int, vector bool int); -vector signed int vec_and (vector bool int, vector signed int); -vector signed int vec_and (vector signed int, vector bool int); -vector signed int vec_and (vector signed int, vector signed int); -vector unsigned int vec_and (vector bool int, vector unsigned int); -vector unsigned int vec_and (vector unsigned int, vector bool int); -vector unsigned int vec_and (vector unsigned int, vector unsigned int); -vector bool short vec_and (vector bool short, vector bool short); -vector signed short vec_and (vector bool short, vector signed short); -vector signed short vec_and (vector signed short, vector bool short); -vector signed short vec_and (vector signed short, vector signed short); -vector unsigned short vec_and (vector bool short, - vector unsigned short); -vector unsigned short vec_and (vector unsigned short, - vector bool short); -vector unsigned short vec_and (vector unsigned short, - vector unsigned short); -vector signed char vec_and (vector bool char, vector signed char); -vector bool char vec_and (vector bool char, vector bool char); -vector signed char vec_and (vector signed char, vector bool char); -vector signed char vec_and (vector signed char, vector signed char); -vector unsigned char vec_and (vector bool char, vector unsigned char); -vector unsigned char vec_and (vector unsigned char, vector bool char); -vector unsigned char vec_and (vector unsigned char, - vector unsigned char); - -vector float vec_andc (vector float, vector float); -vector float vec_andc (vector float, vector bool int); -vector float vec_andc (vector bool int, vector float); -vector bool int vec_andc (vector bool int, vector bool int); -vector signed int vec_andc (vector bool int, vector signed int); -vector signed int vec_andc (vector signed int, vector bool int); -vector signed int vec_andc (vector signed int, vector signed int); -vector unsigned int vec_andc (vector bool int, vector unsigned int); -vector unsigned int vec_andc (vector unsigned int, vector bool int); -vector unsigned int vec_andc (vector unsigned int, vector unsigned int); -vector bool short vec_andc (vector bool short, vector bool short); -vector signed short vec_andc (vector bool short, vector signed short); -vector signed short vec_andc (vector signed short, vector bool short); -vector signed short vec_andc (vector signed short, vector signed short); -vector unsigned short vec_andc (vector bool short, - vector unsigned short); -vector unsigned short vec_andc (vector unsigned short, - vector bool short); -vector unsigned short vec_andc (vector unsigned short, - vector unsigned short); -vector signed char vec_andc (vector bool char, vector signed char); -vector bool char vec_andc (vector bool char, vector bool char); -vector signed char vec_andc (vector signed char, vector bool char); -vector signed char vec_andc (vector signed char, vector signed char); -vector unsigned char vec_andc (vector bool char, vector unsigned char); -vector unsigned char vec_andc (vector unsigned char, vector bool char); -vector unsigned char vec_andc (vector unsigned char, - vector unsigned char); - -vector unsigned char vec_avg (vector unsigned char, - vector unsigned char); -vector signed char vec_avg (vector signed char, vector signed char); -vector unsigned short vec_avg (vector unsigned short, - vector unsigned short); -vector signed short vec_avg (vector signed short, vector signed short); -vector unsigned int vec_avg (vector unsigned int, vector unsigned int); -vector signed int vec_avg (vector signed int, vector signed int); - -vector signed int vec_vavgsw (vector signed int, vector signed int); - -vector unsigned int vec_vavguw (vector unsigned int, - vector unsigned int); - -vector signed short vec_vavgsh (vector signed short, - vector signed short); - -vector unsigned short vec_vavguh (vector unsigned short, - vector unsigned short); - -vector signed char vec_vavgsb (vector signed char, vector signed char); - -vector unsigned char vec_vavgub (vector unsigned char, - vector unsigned char); - -vector float vec_ceil (vector float); - -vector signed int vec_cmpb (vector float, vector float); - -vector bool char vec_cmpeq (vector signed char, vector signed char); -vector bool char vec_cmpeq (vector unsigned char, vector unsigned char); -vector bool short vec_cmpeq (vector signed short, vector signed short); -vector bool short vec_cmpeq (vector unsigned short, - vector unsigned short); -vector bool int vec_cmpeq (vector signed int, vector signed int); -vector bool int vec_cmpeq (vector unsigned int, vector unsigned int); -vector bool int vec_cmpeq (vector float, vector float); - -vector bool int vec_vcmpeqfp (vector float, vector float); - -vector bool int vec_vcmpequw (vector signed int, vector signed int); -vector bool int vec_vcmpequw (vector unsigned int, vector unsigned int); - -vector bool short vec_vcmpequh (vector signed short, - vector signed short); -vector bool short vec_vcmpequh (vector unsigned short, - vector unsigned short); - -vector bool char vec_vcmpequb (vector signed char, vector signed char); -vector bool char vec_vcmpequb (vector unsigned char, - vector unsigned char); - -vector bool int vec_cmpge (vector float, vector float); - -vector bool char vec_cmpgt (vector unsigned char, vector unsigned char); -vector bool char vec_cmpgt (vector signed char, vector signed char); -vector bool short vec_cmpgt (vector unsigned short, - vector unsigned short); -vector bool short vec_cmpgt (vector signed short, vector signed short); -vector bool int vec_cmpgt (vector unsigned int, vector unsigned int); -vector bool int vec_cmpgt (vector signed int, vector signed int); -vector bool int vec_cmpgt (vector float, vector float); - -vector bool int vec_vcmpgtfp (vector float, vector float); - -vector bool int vec_vcmpgtsw (vector signed int, vector signed int); - -vector bool int vec_vcmpgtuw (vector unsigned int, vector unsigned int); - -vector bool short vec_vcmpgtsh (vector signed short, - vector signed short); - -vector bool short vec_vcmpgtuh (vector unsigned short, - vector unsigned short); - -vector bool char vec_vcmpgtsb (vector signed char, vector signed char); - -vector bool char vec_vcmpgtub (vector unsigned char, - vector unsigned char); - -vector bool int vec_cmple (vector float, vector float); - -vector bool char vec_cmplt (vector unsigned char, vector unsigned char); -vector bool char vec_cmplt (vector signed char, vector signed char); -vector bool short vec_cmplt (vector unsigned short, - vector unsigned short); -vector bool short vec_cmplt (vector signed short, vector signed short); -vector bool int vec_cmplt (vector unsigned int, vector unsigned int); -vector bool int vec_cmplt (vector signed int, vector signed int); -vector bool int vec_cmplt (vector float, vector float); - -vector float vec_ctf (vector unsigned int, const int); -vector float vec_ctf (vector signed int, const int); - -vector float vec_vcfsx (vector signed int, const int); - -vector float vec_vcfux (vector unsigned int, const int); - -vector signed int vec_cts (vector float, const int); - -vector unsigned int vec_ctu (vector float, const int); - -void vec_dss (const int); - -void vec_dssall (void); - -void vec_dst (const vector unsigned char *, int, const int); -void vec_dst (const vector signed char *, int, const int); -void vec_dst (const vector bool char *, int, const int); -void vec_dst (const vector unsigned short *, int, const int); -void vec_dst (const vector signed short *, int, const int); -void vec_dst (const vector bool short *, int, const int); -void vec_dst (const vector pixel *, int, const int); -void vec_dst (const vector unsigned int *, int, const int); -void vec_dst (const vector signed int *, int, const int); -void vec_dst (const vector bool int *, int, const int); -void vec_dst (const vector float *, int, const int); -void vec_dst (const unsigned char *, int, const int); -void vec_dst (const signed char *, int, const int); -void vec_dst (const unsigned short *, int, const int); -void vec_dst (const short *, int, const int); -void vec_dst (const unsigned int *, int, const int); -void vec_dst (const int *, int, const int); -void vec_dst (const unsigned long *, int, const int); -void vec_dst (const long *, int, const int); -void vec_dst (const float *, int, const int); - -void vec_dstst (const vector unsigned char *, int, const int); -void vec_dstst (const vector signed char *, int, const int); -void vec_dstst (const vector bool char *, int, const int); -void vec_dstst (const vector unsigned short *, int, const int); -void vec_dstst (const vector signed short *, int, const int); -void vec_dstst (const vector bool short *, int, const int); -void vec_dstst (const vector pixel *, int, const int); -void vec_dstst (const vector unsigned int *, int, const int); -void vec_dstst (const vector signed int *, int, const int); -void vec_dstst (const vector bool int *, int, const int); -void vec_dstst (const vector float *, int, const int); -void vec_dstst (const unsigned char *, int, const int); -void vec_dstst (const signed char *, int, const int); -void vec_dstst (const unsigned short *, int, const int); -void vec_dstst (const short *, int, const int); -void vec_dstst (const unsigned int *, int, const int); -void vec_dstst (const int *, int, const int); -void vec_dstst (const unsigned long *, int, const int); -void vec_dstst (const long *, int, const int); -void vec_dstst (const float *, int, const int); - -void vec_dststt (const vector unsigned char *, int, const int); -void vec_dststt (const vector signed char *, int, const int); -void vec_dststt (const vector bool char *, int, const int); -void vec_dststt (const vector unsigned short *, int, const int); -void vec_dststt (const vector signed short *, int, const int); -void vec_dststt (const vector bool short *, int, const int); -void vec_dststt (const vector pixel *, int, const int); -void vec_dststt (const vector unsigned int *, int, const int); -void vec_dststt (const vector signed int *, int, const int); -void vec_dststt (const vector bool int *, int, const int); -void vec_dststt (const vector float *, int, const int); -void vec_dststt (const unsigned char *, int, const int); -void vec_dststt (const signed char *, int, const int); -void vec_dststt (const unsigned short *, int, const int); -void vec_dststt (const short *, int, const int); -void vec_dststt (const unsigned int *, int, const int); -void vec_dststt (const int *, int, const int); -void vec_dststt (const unsigned long *, int, const int); -void vec_dststt (const long *, int, const int); -void vec_dststt (const float *, int, const int); - -void vec_dstt (const vector unsigned char *, int, const int); -void vec_dstt (const vector signed char *, int, const int); -void vec_dstt (const vector bool char *, int, const int); -void vec_dstt (const vector unsigned short *, int, const int); -void vec_dstt (const vector signed short *, int, const int); -void vec_dstt (const vector bool short *, int, const int); -void vec_dstt (const vector pixel *, int, const int); -void vec_dstt (const vector unsigned int *, int, const int); -void vec_dstt (const vector signed int *, int, const int); -void vec_dstt (const vector bool int *, int, const int); -void vec_dstt (const vector float *, int, const int); -void vec_dstt (const unsigned char *, int, const int); -void vec_dstt (const signed char *, int, const int); -void vec_dstt (const unsigned short *, int, const int); -void vec_dstt (const short *, int, const int); -void vec_dstt (const unsigned int *, int, const int); -void vec_dstt (const int *, int, const int); -void vec_dstt (const unsigned long *, int, const int); -void vec_dstt (const long *, int, const int); -void vec_dstt (const float *, int, const int); - -vector float vec_expte (vector float); - -vector float vec_floor (vector float); - -vector float vec_ld (int, const vector float *); -vector float vec_ld (int, const float *); -vector bool int vec_ld (int, const vector bool int *); -vector signed int vec_ld (int, const vector signed int *); -vector signed int vec_ld (int, const int *); -vector signed int vec_ld (int, const long *); -vector unsigned int vec_ld (int, const vector unsigned int *); -vector unsigned int vec_ld (int, const unsigned int *); -vector unsigned int vec_ld (int, const unsigned long *); -vector bool short vec_ld (int, const vector bool short *); -vector pixel vec_ld (int, const vector pixel *); -vector signed short vec_ld (int, const vector signed short *); -vector signed short vec_ld (int, const short *); -vector unsigned short vec_ld (int, const vector unsigned short *); -vector unsigned short vec_ld (int, const unsigned short *); -vector bool char vec_ld (int, const vector bool char *); -vector signed char vec_ld (int, const vector signed char *); -vector signed char vec_ld (int, const signed char *); -vector unsigned char vec_ld (int, const vector unsigned char *); -vector unsigned char vec_ld (int, const unsigned char *); - -vector signed char vec_lde (int, const signed char *); -vector unsigned char vec_lde (int, const unsigned char *); -vector signed short vec_lde (int, const short *); -vector unsigned short vec_lde (int, const unsigned short *); -vector float vec_lde (int, const float *); -vector signed int vec_lde (int, const int *); -vector unsigned int vec_lde (int, const unsigned int *); -vector signed int vec_lde (int, const long *); -vector unsigned int vec_lde (int, const unsigned long *); - -vector float vec_lvewx (int, float *); -vector signed int vec_lvewx (int, int *); -vector unsigned int vec_lvewx (int, unsigned int *); -vector signed int vec_lvewx (int, long *); -vector unsigned int vec_lvewx (int, unsigned long *); - -vector signed short vec_lvehx (int, short *); -vector unsigned short vec_lvehx (int, unsigned short *); - -vector signed char vec_lvebx (int, char *); -vector unsigned char vec_lvebx (int, unsigned char *); - -vector float vec_ldl (int, const vector float *); -vector float vec_ldl (int, const float *); -vector bool int vec_ldl (int, const vector bool int *); -vector signed int vec_ldl (int, const vector signed int *); -vector signed int vec_ldl (int, const int *); -vector signed int vec_ldl (int, const long *); -vector unsigned int vec_ldl (int, const vector unsigned int *); -vector unsigned int vec_ldl (int, const unsigned int *); -vector unsigned int vec_ldl (int, const unsigned long *); -vector bool short vec_ldl (int, const vector bool short *); -vector pixel vec_ldl (int, const vector pixel *); -vector signed short vec_ldl (int, const vector signed short *); -vector signed short vec_ldl (int, const short *); -vector unsigned short vec_ldl (int, const vector unsigned short *); -vector unsigned short vec_ldl (int, const unsigned short *); -vector bool char vec_ldl (int, const vector bool char *); -vector signed char vec_ldl (int, const vector signed char *); -vector signed char vec_ldl (int, const signed char *); -vector unsigned char vec_ldl (int, const vector unsigned char *); -vector unsigned char vec_ldl (int, const unsigned char *); - -vector float vec_loge (vector float); - -vector unsigned char vec_lvsl (int, const volatile unsigned char *); -vector unsigned char vec_lvsl (int, const volatile signed char *); -vector unsigned char vec_lvsl (int, const volatile unsigned short *); -vector unsigned char vec_lvsl (int, const volatile short *); -vector unsigned char vec_lvsl (int, const volatile unsigned int *); -vector unsigned char vec_lvsl (int, const volatile int *); -vector unsigned char vec_lvsl (int, const volatile unsigned long *); -vector unsigned char vec_lvsl (int, const volatile long *); -vector unsigned char vec_lvsl (int, const volatile float *); - -vector unsigned char vec_lvsr (int, const volatile unsigned char *); -vector unsigned char vec_lvsr (int, const volatile signed char *); -vector unsigned char vec_lvsr (int, const volatile unsigned short *); -vector unsigned char vec_lvsr (int, const volatile short *); -vector unsigned char vec_lvsr (int, const volatile unsigned int *); -vector unsigned char vec_lvsr (int, const volatile int *); -vector unsigned char vec_lvsr (int, const volatile unsigned long *); -vector unsigned char vec_lvsr (int, const volatile long *); -vector unsigned char vec_lvsr (int, const volatile float *); - -vector float vec_madd (vector float, vector float, vector float); - -vector signed short vec_madds (vector signed short, - vector signed short, - vector signed short); - -vector unsigned char vec_max (vector bool char, vector unsigned char); -vector unsigned char vec_max (vector unsigned char, vector bool char); -vector unsigned char vec_max (vector unsigned char, - vector unsigned char); -vector signed char vec_max (vector bool char, vector signed char); -vector signed char vec_max (vector signed char, vector bool char); -vector signed char vec_max (vector signed char, vector signed char); -vector unsigned short vec_max (vector bool short, - vector unsigned short); -vector unsigned short vec_max (vector unsigned short, - vector bool short); -vector unsigned short vec_max (vector unsigned short, - vector unsigned short); -vector signed short vec_max (vector bool short, vector signed short); -vector signed short vec_max (vector signed short, vector bool short); -vector signed short vec_max (vector signed short, vector signed short); -vector unsigned int vec_max (vector bool int, vector unsigned int); -vector unsigned int vec_max (vector unsigned int, vector bool int); -vector unsigned int vec_max (vector unsigned int, vector unsigned int); -vector signed int vec_max (vector bool int, vector signed int); -vector signed int vec_max (vector signed int, vector bool int); -vector signed int vec_max (vector signed int, vector signed int); -vector float vec_max (vector float, vector float); - -vector float vec_vmaxfp (vector float, vector float); - -vector signed int vec_vmaxsw (vector bool int, vector signed int); -vector signed int vec_vmaxsw (vector signed int, vector bool int); -vector signed int vec_vmaxsw (vector signed int, vector signed int); - -vector unsigned int vec_vmaxuw (vector bool int, vector unsigned int); -vector unsigned int vec_vmaxuw (vector unsigned int, vector bool int); -vector unsigned int vec_vmaxuw (vector unsigned int, - vector unsigned int); - -vector signed short vec_vmaxsh (vector bool short, vector signed short); -vector signed short vec_vmaxsh (vector signed short, vector bool short); -vector signed short vec_vmaxsh (vector signed short, - vector signed short); - -vector unsigned short vec_vmaxuh (vector bool short, - vector unsigned short); -vector unsigned short vec_vmaxuh (vector unsigned short, - vector bool short); -vector unsigned short vec_vmaxuh (vector unsigned short, - vector unsigned short); - -vector signed char vec_vmaxsb (vector bool char, vector signed char); -vector signed char vec_vmaxsb (vector signed char, vector bool char); -vector signed char vec_vmaxsb (vector signed char, vector signed char); - -vector unsigned char vec_vmaxub (vector bool char, - vector unsigned char); -vector unsigned char vec_vmaxub (vector unsigned char, - vector bool char); -vector unsigned char vec_vmaxub (vector unsigned char, - vector unsigned char); - -vector bool char vec_mergeh (vector bool char, vector bool char); -vector signed char vec_mergeh (vector signed char, vector signed char); -vector unsigned char vec_mergeh (vector unsigned char, - vector unsigned char); -vector bool short vec_mergeh (vector bool short, vector bool short); -vector pixel vec_mergeh (vector pixel, vector pixel); -vector signed short vec_mergeh (vector signed short, - vector signed short); -vector unsigned short vec_mergeh (vector unsigned short, - vector unsigned short); -vector float vec_mergeh (vector float, vector float); -vector bool int vec_mergeh (vector bool int, vector bool int); -vector signed int vec_mergeh (vector signed int, vector signed int); -vector unsigned int vec_mergeh (vector unsigned int, - vector unsigned int); - -vector float vec_vmrghw (vector float, vector float); -vector bool int vec_vmrghw (vector bool int, vector bool int); -vector signed int vec_vmrghw (vector signed int, vector signed int); -vector unsigned int vec_vmrghw (vector unsigned int, - vector unsigned int); - -vector bool short vec_vmrghh (vector bool short, vector bool short); -vector signed short vec_vmrghh (vector signed short, - vector signed short); -vector unsigned short vec_vmrghh (vector unsigned short, - vector unsigned short); -vector pixel vec_vmrghh (vector pixel, vector pixel); - -vector bool char vec_vmrghb (vector bool char, vector bool char); -vector signed char vec_vmrghb (vector signed char, vector signed char); -vector unsigned char vec_vmrghb (vector unsigned char, - vector unsigned char); - -vector bool char vec_mergel (vector bool char, vector bool char); -vector signed char vec_mergel (vector signed char, vector signed char); -vector unsigned char vec_mergel (vector unsigned char, - vector unsigned char); -vector bool short vec_mergel (vector bool short, vector bool short); -vector pixel vec_mergel (vector pixel, vector pixel); -vector signed short vec_mergel (vector signed short, - vector signed short); -vector unsigned short vec_mergel (vector unsigned short, - vector unsigned short); -vector float vec_mergel (vector float, vector float); -vector bool int vec_mergel (vector bool int, vector bool int); -vector signed int vec_mergel (vector signed int, vector signed int); -vector unsigned int vec_mergel (vector unsigned int, - vector unsigned int); - -vector float vec_vmrglw (vector float, vector float); -vector signed int vec_vmrglw (vector signed int, vector signed int); -vector unsigned int vec_vmrglw (vector unsigned int, - vector unsigned int); -vector bool int vec_vmrglw (vector bool int, vector bool int); - -vector bool short vec_vmrglh (vector bool short, vector bool short); -vector signed short vec_vmrglh (vector signed short, - vector signed short); -vector unsigned short vec_vmrglh (vector unsigned short, - vector unsigned short); -vector pixel vec_vmrglh (vector pixel, vector pixel); - -vector bool char vec_vmrglb (vector bool char, vector bool char); -vector signed char vec_vmrglb (vector signed char, vector signed char); -vector unsigned char vec_vmrglb (vector unsigned char, - vector unsigned char); - -vector unsigned short vec_mfvscr (void); - -vector unsigned char vec_min (vector bool char, vector unsigned char); -vector unsigned char vec_min (vector unsigned char, vector bool char); -vector unsigned char vec_min (vector unsigned char, - vector unsigned char); -vector signed char vec_min (vector bool char, vector signed char); -vector signed char vec_min (vector signed char, vector bool char); -vector signed char vec_min (vector signed char, vector signed char); -vector unsigned short vec_min (vector bool short, - vector unsigned short); -vector unsigned short vec_min (vector unsigned short, - vector bool short); -vector unsigned short vec_min (vector unsigned short, - vector unsigned short); -vector signed short vec_min (vector bool short, vector signed short); -vector signed short vec_min (vector signed short, vector bool short); -vector signed short vec_min (vector signed short, vector signed short); -vector unsigned int vec_min (vector bool int, vector unsigned int); -vector unsigned int vec_min (vector unsigned int, vector bool int); -vector unsigned int vec_min (vector unsigned int, vector unsigned int); -vector signed int vec_min (vector bool int, vector signed int); -vector signed int vec_min (vector signed int, vector bool int); -vector signed int vec_min (vector signed int, vector signed int); -vector float vec_min (vector float, vector float); - -vector float vec_vminfp (vector float, vector float); - -vector signed int vec_vminsw (vector bool int, vector signed int); -vector signed int vec_vminsw (vector signed int, vector bool int); -vector signed int vec_vminsw (vector signed int, vector signed int); - -vector unsigned int vec_vminuw (vector bool int, vector unsigned int); -vector unsigned int vec_vminuw (vector unsigned int, vector bool int); -vector unsigned int vec_vminuw (vector unsigned int, - vector unsigned int); - -vector signed short vec_vminsh (vector bool short, vector signed short); -vector signed short vec_vminsh (vector signed short, vector bool short); -vector signed short vec_vminsh (vector signed short, - vector signed short); - -vector unsigned short vec_vminuh (vector bool short, - vector unsigned short); -vector unsigned short vec_vminuh (vector unsigned short, - vector bool short); -vector unsigned short vec_vminuh (vector unsigned short, - vector unsigned short); - -vector signed char vec_vminsb (vector bool char, vector signed char); -vector signed char vec_vminsb (vector signed char, vector bool char); -vector signed char vec_vminsb (vector signed char, vector signed char); - -vector unsigned char vec_vminub (vector bool char, - vector unsigned char); -vector unsigned char vec_vminub (vector unsigned char, - vector bool char); -vector unsigned char vec_vminub (vector unsigned char, - vector unsigned char); - -vector signed short vec_mladd (vector signed short, - vector signed short, - vector signed short); -vector signed short vec_mladd (vector signed short, - vector unsigned short, - vector unsigned short); -vector signed short vec_mladd (vector unsigned short, - vector signed short, - vector signed short); -vector unsigned short vec_mladd (vector unsigned short, - vector unsigned short, - vector unsigned short); - -vector signed short vec_mradds (vector signed short, - vector signed short, - vector signed short); - -vector unsigned int vec_msum (vector unsigned char, - vector unsigned char, - vector unsigned int); -vector signed int vec_msum (vector signed char, - vector unsigned char, - vector signed int); -vector unsigned int vec_msum (vector unsigned short, - vector unsigned short, - vector unsigned int); -vector signed int vec_msum (vector signed short, - vector signed short, - vector signed int); - -vector signed int vec_vmsumshm (vector signed short, - vector signed short, - vector signed int); - -vector unsigned int vec_vmsumuhm (vector unsigned short, - vector unsigned short, - vector unsigned int); - -vector signed int vec_vmsummbm (vector signed char, - vector unsigned char, - vector signed int); - -vector unsigned int vec_vmsumubm (vector unsigned char, - vector unsigned char, - vector unsigned int); - -vector unsigned int vec_msums (vector unsigned short, - vector unsigned short, - vector unsigned int); -vector signed int vec_msums (vector signed short, - vector signed short, - vector signed int); - -vector signed int vec_vmsumshs (vector signed short, - vector signed short, - vector signed int); - -vector unsigned int vec_vmsumuhs (vector unsigned short, - vector unsigned short, - vector unsigned int); - -void vec_mtvscr (vector signed int); -void vec_mtvscr (vector unsigned int); -void vec_mtvscr (vector bool int); -void vec_mtvscr (vector signed short); -void vec_mtvscr (vector unsigned short); -void vec_mtvscr (vector bool short); -void vec_mtvscr (vector pixel); -void vec_mtvscr (vector signed char); -void vec_mtvscr (vector unsigned char); -void vec_mtvscr (vector bool char); - -vector unsigned short vec_mule (vector unsigned char, - vector unsigned char); -vector signed short vec_mule (vector signed char, - vector signed char); -vector unsigned int vec_mule (vector unsigned short, - vector unsigned short); -vector signed int vec_mule (vector signed short, vector signed short); - -vector signed int vec_vmulesh (vector signed short, - vector signed short); - -vector unsigned int vec_vmuleuh (vector unsigned short, - vector unsigned short); - -vector signed short vec_vmulesb (vector signed char, - vector signed char); - -vector unsigned short vec_vmuleub (vector unsigned char, - vector unsigned char); - -vector unsigned short vec_mulo (vector unsigned char, - vector unsigned char); -vector signed short vec_mulo (vector signed char, vector signed char); -vector unsigned int vec_mulo (vector unsigned short, - vector unsigned short); -vector signed int vec_mulo (vector signed short, vector signed short); - -vector signed int vec_vmulosh (vector signed short, - vector signed short); - -vector unsigned int vec_vmulouh (vector unsigned short, - vector unsigned short); - -vector signed short vec_vmulosb (vector signed char, - vector signed char); - -vector unsigned short vec_vmuloub (vector unsigned char, - vector unsigned char); - -vector float vec_nmsub (vector float, vector float, vector float); -@c APPLE LOCAL begin fixhtml --mrs -@end smallexample - -@smallexample -@c APPLE LOCAL end fixhtml --mrs -vector float vec_nor (vector float, vector float); -vector signed int vec_nor (vector signed int, vector signed int); -vector unsigned int vec_nor (vector unsigned int, vector unsigned int); -vector bool int vec_nor (vector bool int, vector bool int); -vector signed short vec_nor (vector signed short, vector signed short); -vector unsigned short vec_nor (vector unsigned short, - vector unsigned short); -vector bool short vec_nor (vector bool short, vector bool short); -vector signed char vec_nor (vector signed char, vector signed char); -vector unsigned char vec_nor (vector unsigned char, - vector unsigned char); -vector bool char vec_nor (vector bool char, vector bool char); - -vector float vec_or (vector float, vector float); -vector float vec_or (vector float, vector bool int); -vector float vec_or (vector bool int, vector float); -vector bool int vec_or (vector bool int, vector bool int); -vector signed int vec_or (vector bool int, vector signed int); -vector signed int vec_or (vector signed int, vector bool int); -vector signed int vec_or (vector signed int, vector signed int); -vector unsigned int vec_or (vector bool int, vector unsigned int); -vector unsigned int vec_or (vector unsigned int, vector bool int); -vector unsigned int vec_or (vector unsigned int, vector unsigned int); -vector bool short vec_or (vector bool short, vector bool short); -vector signed short vec_or (vector bool short, vector signed short); -vector signed short vec_or (vector signed short, vector bool short); -vector signed short vec_or (vector signed short, vector signed short); -vector unsigned short vec_or (vector bool short, vector unsigned short); -vector unsigned short vec_or (vector unsigned short, vector bool short); -vector unsigned short vec_or (vector unsigned short, - vector unsigned short); -vector signed char vec_or (vector bool char, vector signed char); -vector bool char vec_or (vector bool char, vector bool char); -vector signed char vec_or (vector signed char, vector bool char); -vector signed char vec_or (vector signed char, vector signed char); -vector unsigned char vec_or (vector bool char, vector unsigned char); -vector unsigned char vec_or (vector unsigned char, vector bool char); -vector unsigned char vec_or (vector unsigned char, - vector unsigned char); - -vector signed char vec_pack (vector signed short, vector signed short); -vector unsigned char vec_pack (vector unsigned short, - vector unsigned short); -vector bool char vec_pack (vector bool short, vector bool short); -vector signed short vec_pack (vector signed int, vector signed int); -vector unsigned short vec_pack (vector unsigned int, - vector unsigned int); -vector bool short vec_pack (vector bool int, vector bool int); - -vector bool short vec_vpkuwum (vector bool int, vector bool int); -vector signed short vec_vpkuwum (vector signed int, vector signed int); -vector unsigned short vec_vpkuwum (vector unsigned int, - vector unsigned int); - -vector bool char vec_vpkuhum (vector bool short, vector bool short); -vector signed char vec_vpkuhum (vector signed short, - vector signed short); -vector unsigned char vec_vpkuhum (vector unsigned short, - vector unsigned short); - -vector pixel vec_packpx (vector unsigned int, vector unsigned int); - -vector unsigned char vec_packs (vector unsigned short, - vector unsigned short); -vector signed char vec_packs (vector signed short, vector signed short); -vector unsigned short vec_packs (vector unsigned int, - vector unsigned int); -vector signed short vec_packs (vector signed int, vector signed int); - -vector signed short vec_vpkswss (vector signed int, vector signed int); - -vector unsigned short vec_vpkuwus (vector unsigned int, - vector unsigned int); - -vector signed char vec_vpkshss (vector signed short, - vector signed short); - -vector unsigned char vec_vpkuhus (vector unsigned short, - vector unsigned short); - -vector unsigned char vec_packsu (vector unsigned short, - vector unsigned short); -vector unsigned char vec_packsu (vector signed short, - vector signed short); -vector unsigned short vec_packsu (vector unsigned int, - vector unsigned int); -vector unsigned short vec_packsu (vector signed int, vector signed int); - -vector unsigned short vec_vpkswus (vector signed int, - vector signed int); - -vector unsigned char vec_vpkshus (vector signed short, - vector signed short); - -vector float vec_perm (vector float, - vector float, - vector unsigned char); -vector signed int vec_perm (vector signed int, - vector signed int, - vector unsigned char); -vector unsigned int vec_perm (vector unsigned int, - vector unsigned int, - vector unsigned char); -vector bool int vec_perm (vector bool int, - vector bool int, - vector unsigned char); -vector signed short vec_perm (vector signed short, - vector signed short, - vector unsigned char); -vector unsigned short vec_perm (vector unsigned short, - vector unsigned short, - vector unsigned char); -vector bool short vec_perm (vector bool short, - vector bool short, - vector unsigned char); -vector pixel vec_perm (vector pixel, - vector pixel, - vector unsigned char); -vector signed char vec_perm (vector signed char, - vector signed char, - vector unsigned char); -vector unsigned char vec_perm (vector unsigned char, - vector unsigned char, - vector unsigned char); -vector bool char vec_perm (vector bool char, - vector bool char, - vector unsigned char); - -vector float vec_re (vector float); - -vector signed char vec_rl (vector signed char, - vector unsigned char); -vector unsigned char vec_rl (vector unsigned char, - vector unsigned char); -vector signed short vec_rl (vector signed short, vector unsigned short); -vector unsigned short vec_rl (vector unsigned short, - vector unsigned short); -vector signed int vec_rl (vector signed int, vector unsigned int); -vector unsigned int vec_rl (vector unsigned int, vector unsigned int); - -vector signed int vec_vrlw (vector signed int, vector unsigned int); -vector unsigned int vec_vrlw (vector unsigned int, vector unsigned int); - -vector signed short vec_vrlh (vector signed short, - vector unsigned short); -vector unsigned short vec_vrlh (vector unsigned short, - vector unsigned short); - -vector signed char vec_vrlb (vector signed char, vector unsigned char); -vector unsigned char vec_vrlb (vector unsigned char, - vector unsigned char); - -vector float vec_round (vector float); - -vector float vec_rsqrte (vector float); - -vector float vec_sel (vector float, vector float, vector bool int); -vector float vec_sel (vector float, vector float, vector unsigned int); -vector signed int vec_sel (vector signed int, - vector signed int, - vector bool int); -vector signed int vec_sel (vector signed int, - vector signed int, - vector unsigned int); -vector unsigned int vec_sel (vector unsigned int, - vector unsigned int, - vector bool int); -vector unsigned int vec_sel (vector unsigned int, - vector unsigned int, - vector unsigned int); -vector bool int vec_sel (vector bool int, - vector bool int, - vector bool int); -vector bool int vec_sel (vector bool int, - vector bool int, - vector unsigned int); -vector signed short vec_sel (vector signed short, - vector signed short, - vector bool short); -vector signed short vec_sel (vector signed short, - vector signed short, - vector unsigned short); -vector unsigned short vec_sel (vector unsigned short, - vector unsigned short, - vector bool short); -vector unsigned short vec_sel (vector unsigned short, - vector unsigned short, - vector unsigned short); -vector bool short vec_sel (vector bool short, - vector bool short, - vector bool short); -vector bool short vec_sel (vector bool short, - vector bool short, - vector unsigned short); -vector signed char vec_sel (vector signed char, - vector signed char, - vector bool char); -vector signed char vec_sel (vector signed char, - vector signed char, - vector unsigned char); -vector unsigned char vec_sel (vector unsigned char, - vector unsigned char, - vector bool char); -vector unsigned char vec_sel (vector unsigned char, - vector unsigned char, - vector unsigned char); -vector bool char vec_sel (vector bool char, - vector bool char, - vector bool char); -vector bool char vec_sel (vector bool char, - vector bool char, - vector unsigned char); - -vector signed char vec_sl (vector signed char, - vector unsigned char); -vector unsigned char vec_sl (vector unsigned char, - vector unsigned char); -vector signed short vec_sl (vector signed short, vector unsigned short); -vector unsigned short vec_sl (vector unsigned short, - vector unsigned short); -vector signed int vec_sl (vector signed int, vector unsigned int); -vector unsigned int vec_sl (vector unsigned int, vector unsigned int); - -vector signed int vec_vslw (vector signed int, vector unsigned int); -vector unsigned int vec_vslw (vector unsigned int, vector unsigned int); - -vector signed short vec_vslh (vector signed short, - vector unsigned short); -vector unsigned short vec_vslh (vector unsigned short, - vector unsigned short); - -vector signed char vec_vslb (vector signed char, vector unsigned char); -vector unsigned char vec_vslb (vector unsigned char, - vector unsigned char); - -vector float vec_sld (vector float, vector float, const int); -vector signed int vec_sld (vector signed int, - vector signed int, - const int); -vector unsigned int vec_sld (vector unsigned int, - vector unsigned int, - const int); -vector bool int vec_sld (vector bool int, - vector bool int, - const int); -vector signed short vec_sld (vector signed short, - vector signed short, - const int); -vector unsigned short vec_sld (vector unsigned short, - vector unsigned short, - const int); -vector bool short vec_sld (vector bool short, - vector bool short, - const int); -vector pixel vec_sld (vector pixel, - vector pixel, - const int); -vector signed char vec_sld (vector signed char, - vector signed char, - const int); -vector unsigned char vec_sld (vector unsigned char, - vector unsigned char, - const int); -vector bool char vec_sld (vector bool char, - vector bool char, - const int); - -vector signed int vec_sll (vector signed int, - vector unsigned int); -vector signed int vec_sll (vector signed int, - vector unsigned short); -vector signed int vec_sll (vector signed int, - vector unsigned char); -vector unsigned int vec_sll (vector unsigned int, - vector unsigned int); -vector unsigned int vec_sll (vector unsigned int, - vector unsigned short); -vector unsigned int vec_sll (vector unsigned int, - vector unsigned char); -vector bool int vec_sll (vector bool int, - vector unsigned int); -vector bool int vec_sll (vector bool int, - vector unsigned short); -vector bool int vec_sll (vector bool int, - vector unsigned char); -vector signed short vec_sll (vector signed short, - vector unsigned int); -vector signed short vec_sll (vector signed short, - vector unsigned short); -vector signed short vec_sll (vector signed short, - vector unsigned char); -vector unsigned short vec_sll (vector unsigned short, - vector unsigned int); -vector unsigned short vec_sll (vector unsigned short, - vector unsigned short); -vector unsigned short vec_sll (vector unsigned short, - vector unsigned char); -vector bool short vec_sll (vector bool short, vector unsigned int); -vector bool short vec_sll (vector bool short, vector unsigned short); -vector bool short vec_sll (vector bool short, vector unsigned char); -vector pixel vec_sll (vector pixel, vector unsigned int); -vector pixel vec_sll (vector pixel, vector unsigned short); -vector pixel vec_sll (vector pixel, vector unsigned char); -vector signed char vec_sll (vector signed char, vector unsigned int); -vector signed char vec_sll (vector signed char, vector unsigned short); -vector signed char vec_sll (vector signed char, vector unsigned char); -vector unsigned char vec_sll (vector unsigned char, - vector unsigned int); -vector unsigned char vec_sll (vector unsigned char, - vector unsigned short); -vector unsigned char vec_sll (vector unsigned char, - vector unsigned char); -vector bool char vec_sll (vector bool char, vector unsigned int); -vector bool char vec_sll (vector bool char, vector unsigned short); -vector bool char vec_sll (vector bool char, vector unsigned char); - -vector float vec_slo (vector float, vector signed char); -vector float vec_slo (vector float, vector unsigned char); -vector signed int vec_slo (vector signed int, vector signed char); -vector signed int vec_slo (vector signed int, vector unsigned char); -vector unsigned int vec_slo (vector unsigned int, vector signed char); -vector unsigned int vec_slo (vector unsigned int, vector unsigned char); -vector signed short vec_slo (vector signed short, vector signed char); -vector signed short vec_slo (vector signed short, vector unsigned char); -vector unsigned short vec_slo (vector unsigned short, - vector signed char); -vector unsigned short vec_slo (vector unsigned short, - vector unsigned char); -vector pixel vec_slo (vector pixel, vector signed char); -vector pixel vec_slo (vector pixel, vector unsigned char); -vector signed char vec_slo (vector signed char, vector signed char); -vector signed char vec_slo (vector signed char, vector unsigned char); -vector unsigned char vec_slo (vector unsigned char, vector signed char); -vector unsigned char vec_slo (vector unsigned char, - vector unsigned char); - -vector signed char vec_splat (vector signed char, const int); -vector unsigned char vec_splat (vector unsigned char, const int); -vector bool char vec_splat (vector bool char, const int); -vector signed short vec_splat (vector signed short, const int); -vector unsigned short vec_splat (vector unsigned short, const int); -vector bool short vec_splat (vector bool short, const int); -vector pixel vec_splat (vector pixel, const int); -vector float vec_splat (vector float, const int); -vector signed int vec_splat (vector signed int, const int); -vector unsigned int vec_splat (vector unsigned int, const int); -vector bool int vec_splat (vector bool int, const int); - -vector float vec_vspltw (vector float, const int); -vector signed int vec_vspltw (vector signed int, const int); -vector unsigned int vec_vspltw (vector unsigned int, const int); -vector bool int vec_vspltw (vector bool int, const int); - -vector bool short vec_vsplth (vector bool short, const int); -vector signed short vec_vsplth (vector signed short, const int); -vector unsigned short vec_vsplth (vector unsigned short, const int); -vector pixel vec_vsplth (vector pixel, const int); - -vector signed char vec_vspltb (vector signed char, const int); -vector unsigned char vec_vspltb (vector unsigned char, const int); -vector bool char vec_vspltb (vector bool char, const int); - -vector signed char vec_splat_s8 (const int); - -vector signed short vec_splat_s16 (const int); - -vector signed int vec_splat_s32 (const int); - -vector unsigned char vec_splat_u8 (const int); - -vector unsigned short vec_splat_u16 (const int); - -vector unsigned int vec_splat_u32 (const int); - -vector signed char vec_sr (vector signed char, vector unsigned char); -vector unsigned char vec_sr (vector unsigned char, - vector unsigned char); -vector signed short vec_sr (vector signed short, - vector unsigned short); -vector unsigned short vec_sr (vector unsigned short, - vector unsigned short); -vector signed int vec_sr (vector signed int, vector unsigned int); -vector unsigned int vec_sr (vector unsigned int, vector unsigned int); - -vector signed int vec_vsrw (vector signed int, vector unsigned int); -vector unsigned int vec_vsrw (vector unsigned int, vector unsigned int); - -vector signed short vec_vsrh (vector signed short, - vector unsigned short); -vector unsigned short vec_vsrh (vector unsigned short, - vector unsigned short); - -vector signed char vec_vsrb (vector signed char, vector unsigned char); -vector unsigned char vec_vsrb (vector unsigned char, - vector unsigned char); - -vector signed char vec_sra (vector signed char, vector unsigned char); -vector unsigned char vec_sra (vector unsigned char, - vector unsigned char); -vector signed short vec_sra (vector signed short, - vector unsigned short); -vector unsigned short vec_sra (vector unsigned short, - vector unsigned short); -vector signed int vec_sra (vector signed int, vector unsigned int); -vector unsigned int vec_sra (vector unsigned int, vector unsigned int); - -vector signed int vec_vsraw (vector signed int, vector unsigned int); -vector unsigned int vec_vsraw (vector unsigned int, - vector unsigned int); - -vector signed short vec_vsrah (vector signed short, - vector unsigned short); -vector unsigned short vec_vsrah (vector unsigned short, - vector unsigned short); - -vector signed char vec_vsrab (vector signed char, vector unsigned char); -vector unsigned char vec_vsrab (vector unsigned char, - vector unsigned char); - -vector signed int vec_srl (vector signed int, vector unsigned int); -vector signed int vec_srl (vector signed int, vector unsigned short); -vector signed int vec_srl (vector signed int, vector unsigned char); -vector unsigned int vec_srl (vector unsigned int, vector unsigned int); -vector unsigned int vec_srl (vector unsigned int, - vector unsigned short); -vector unsigned int vec_srl (vector unsigned int, vector unsigned char); -vector bool int vec_srl (vector bool int, vector unsigned int); -vector bool int vec_srl (vector bool int, vector unsigned short); -vector bool int vec_srl (vector bool int, vector unsigned char); -vector signed short vec_srl (vector signed short, vector unsigned int); -vector signed short vec_srl (vector signed short, - vector unsigned short); -vector signed short vec_srl (vector signed short, vector unsigned char); -vector unsigned short vec_srl (vector unsigned short, - vector unsigned int); -vector unsigned short vec_srl (vector unsigned short, - vector unsigned short); -vector unsigned short vec_srl (vector unsigned short, - vector unsigned char); -vector bool short vec_srl (vector bool short, vector unsigned int); -vector bool short vec_srl (vector bool short, vector unsigned short); -vector bool short vec_srl (vector bool short, vector unsigned char); -vector pixel vec_srl (vector pixel, vector unsigned int); -vector pixel vec_srl (vector pixel, vector unsigned short); -vector pixel vec_srl (vector pixel, vector unsigned char); -vector signed char vec_srl (vector signed char, vector unsigned int); -vector signed char vec_srl (vector signed char, vector unsigned short); -vector signed char vec_srl (vector signed char, vector unsigned char); -vector unsigned char vec_srl (vector unsigned char, - vector unsigned int); -vector unsigned char vec_srl (vector unsigned char, - vector unsigned short); -vector unsigned char vec_srl (vector unsigned char, - vector unsigned char); -vector bool char vec_srl (vector bool char, vector unsigned int); -vector bool char vec_srl (vector bool char, vector unsigned short); -vector bool char vec_srl (vector bool char, vector unsigned char); - -vector float vec_sro (vector float, vector signed char); -vector float vec_sro (vector float, vector unsigned char); -vector signed int vec_sro (vector signed int, vector signed char); -vector signed int vec_sro (vector signed int, vector unsigned char); -vector unsigned int vec_sro (vector unsigned int, vector signed char); -vector unsigned int vec_sro (vector unsigned int, vector unsigned char); -vector signed short vec_sro (vector signed short, vector signed char); -vector signed short vec_sro (vector signed short, vector unsigned char); -vector unsigned short vec_sro (vector unsigned short, - vector signed char); -vector unsigned short vec_sro (vector unsigned short, - vector unsigned char); -vector pixel vec_sro (vector pixel, vector signed char); -vector pixel vec_sro (vector pixel, vector unsigned char); -vector signed char vec_sro (vector signed char, vector signed char); -vector signed char vec_sro (vector signed char, vector unsigned char); -vector unsigned char vec_sro (vector unsigned char, vector signed char); -vector unsigned char vec_sro (vector unsigned char, - vector unsigned char); - -void vec_st (vector float, int, vector float *); -void vec_st (vector float, int, float *); -void vec_st (vector signed int, int, vector signed int *); -void vec_st (vector signed int, int, int *); -void vec_st (vector unsigned int, int, vector unsigned int *); -void vec_st (vector unsigned int, int, unsigned int *); -void vec_st (vector bool int, int, vector bool int *); -void vec_st (vector bool int, int, unsigned int *); -void vec_st (vector bool int, int, int *); -void vec_st (vector signed short, int, vector signed short *); -void vec_st (vector signed short, int, short *); -void vec_st (vector unsigned short, int, vector unsigned short *); -void vec_st (vector unsigned short, int, unsigned short *); -void vec_st (vector bool short, int, vector bool short *); -void vec_st (vector bool short, int, unsigned short *); -void vec_st (vector pixel, int, vector pixel *); -void vec_st (vector pixel, int, unsigned short *); -void vec_st (vector pixel, int, short *); -void vec_st (vector bool short, int, short *); -void vec_st (vector signed char, int, vector signed char *); -void vec_st (vector signed char, int, signed char *); -void vec_st (vector unsigned char, int, vector unsigned char *); -void vec_st (vector unsigned char, int, unsigned char *); -void vec_st (vector bool char, int, vector bool char *); -void vec_st (vector bool char, int, unsigned char *); -void vec_st (vector bool char, int, signed char *); - -void vec_ste (vector signed char, int, signed char *); -void vec_ste (vector unsigned char, int, unsigned char *); -void vec_ste (vector bool char, int, signed char *); -void vec_ste (vector bool char, int, unsigned char *); -void vec_ste (vector signed short, int, short *); -void vec_ste (vector unsigned short, int, unsigned short *); -void vec_ste (vector bool short, int, short *); -void vec_ste (vector bool short, int, unsigned short *); -void vec_ste (vector pixel, int, short *); -void vec_ste (vector pixel, int, unsigned short *); -void vec_ste (vector float, int, float *); -void vec_ste (vector signed int, int, int *); -void vec_ste (vector unsigned int, int, unsigned int *); -void vec_ste (vector bool int, int, int *); -void vec_ste (vector bool int, int, unsigned int *); - -void vec_stvewx (vector float, int, float *); -void vec_stvewx (vector signed int, int, int *); -void vec_stvewx (vector unsigned int, int, unsigned int *); -void vec_stvewx (vector bool int, int, int *); -void vec_stvewx (vector bool int, int, unsigned int *); - -void vec_stvehx (vector signed short, int, short *); -void vec_stvehx (vector unsigned short, int, unsigned short *); -void vec_stvehx (vector bool short, int, short *); -void vec_stvehx (vector bool short, int, unsigned short *); -void vec_stvehx (vector pixel, int, short *); -void vec_stvehx (vector pixel, int, unsigned short *); - -void vec_stvebx (vector signed char, int, signed char *); -void vec_stvebx (vector unsigned char, int, unsigned char *); -void vec_stvebx (vector bool char, int, signed char *); -void vec_stvebx (vector bool char, int, unsigned char *); - -void vec_stl (vector float, int, vector float *); -void vec_stl (vector float, int, float *); -void vec_stl (vector signed int, int, vector signed int *); -void vec_stl (vector signed int, int, int *); -void vec_stl (vector unsigned int, int, vector unsigned int *); -void vec_stl (vector unsigned int, int, unsigned int *); -void vec_stl (vector bool int, int, vector bool int *); -void vec_stl (vector bool int, int, unsigned int *); -void vec_stl (vector bool int, int, int *); -void vec_stl (vector signed short, int, vector signed short *); -void vec_stl (vector signed short, int, short *); -void vec_stl (vector unsigned short, int, vector unsigned short *); -void vec_stl (vector unsigned short, int, unsigned short *); -void vec_stl (vector bool short, int, vector bool short *); -void vec_stl (vector bool short, int, unsigned short *); -void vec_stl (vector bool short, int, short *); -void vec_stl (vector pixel, int, vector pixel *); -void vec_stl (vector pixel, int, unsigned short *); -void vec_stl (vector pixel, int, short *); -void vec_stl (vector signed char, int, vector signed char *); -void vec_stl (vector signed char, int, signed char *); -void vec_stl (vector unsigned char, int, vector unsigned char *); -void vec_stl (vector unsigned char, int, unsigned char *); -void vec_stl (vector bool char, int, vector bool char *); -void vec_stl (vector bool char, int, unsigned char *); -void vec_stl (vector bool char, int, signed char *); - -vector signed char vec_sub (vector bool char, vector signed char); -vector signed char vec_sub (vector signed char, vector bool char); -vector signed char vec_sub (vector signed char, vector signed char); -vector unsigned char vec_sub (vector bool char, vector unsigned char); -vector unsigned char vec_sub (vector unsigned char, vector bool char); -vector unsigned char vec_sub (vector unsigned char, - vector unsigned char); -vector signed short vec_sub (vector bool short, vector signed short); -vector signed short vec_sub (vector signed short, vector bool short); -vector signed short vec_sub (vector signed short, vector signed short); -vector unsigned short vec_sub (vector bool short, - vector unsigned short); -vector unsigned short vec_sub (vector unsigned short, - vector bool short); -vector unsigned short vec_sub (vector unsigned short, - vector unsigned short); -vector signed int vec_sub (vector bool int, vector signed int); -vector signed int vec_sub (vector signed int, vector bool int); -vector signed int vec_sub (vector signed int, vector signed int); -vector unsigned int vec_sub (vector bool int, vector unsigned int); -vector unsigned int vec_sub (vector unsigned int, vector bool int); -vector unsigned int vec_sub (vector unsigned int, vector unsigned int); -vector float vec_sub (vector float, vector float); - -vector float vec_vsubfp (vector float, vector float); - -vector signed int vec_vsubuwm (vector bool int, vector signed int); -vector signed int vec_vsubuwm (vector signed int, vector bool int); -vector signed int vec_vsubuwm (vector signed int, vector signed int); -vector unsigned int vec_vsubuwm (vector bool int, vector unsigned int); -vector unsigned int vec_vsubuwm (vector unsigned int, vector bool int); -vector unsigned int vec_vsubuwm (vector unsigned int, - vector unsigned int); - -vector signed short vec_vsubuhm (vector bool short, - vector signed short); -vector signed short vec_vsubuhm (vector signed short, - vector bool short); -vector signed short vec_vsubuhm (vector signed short, - vector signed short); -vector unsigned short vec_vsubuhm (vector bool short, - vector unsigned short); -vector unsigned short vec_vsubuhm (vector unsigned short, - vector bool short); -vector unsigned short vec_vsubuhm (vector unsigned short, - vector unsigned short); - -vector signed char vec_vsububm (vector bool char, vector signed char); -vector signed char vec_vsububm (vector signed char, vector bool char); -vector signed char vec_vsububm (vector signed char, vector signed char); -vector unsigned char vec_vsububm (vector bool char, - vector unsigned char); -vector unsigned char vec_vsububm (vector unsigned char, - vector bool char); -vector unsigned char vec_vsububm (vector unsigned char, - vector unsigned char); - -vector unsigned int vec_subc (vector unsigned int, vector unsigned int); - -vector unsigned char vec_subs (vector bool char, vector unsigned char); -vector unsigned char vec_subs (vector unsigned char, vector bool char); -vector unsigned char vec_subs (vector unsigned char, - vector unsigned char); -vector signed char vec_subs (vector bool char, vector signed char); -vector signed char vec_subs (vector signed char, vector bool char); -vector signed char vec_subs (vector signed char, vector signed char); -vector unsigned short vec_subs (vector bool short, - vector unsigned short); -vector unsigned short vec_subs (vector unsigned short, - vector bool short); -vector unsigned short vec_subs (vector unsigned short, - vector unsigned short); -vector signed short vec_subs (vector bool short, vector signed short); -vector signed short vec_subs (vector signed short, vector bool short); -vector signed short vec_subs (vector signed short, vector signed short); -vector unsigned int vec_subs (vector bool int, vector unsigned int); -vector unsigned int vec_subs (vector unsigned int, vector bool int); -vector unsigned int vec_subs (vector unsigned int, vector unsigned int); -vector signed int vec_subs (vector bool int, vector signed int); -vector signed int vec_subs (vector signed int, vector bool int); -vector signed int vec_subs (vector signed int, vector signed int); - -vector signed int vec_vsubsws (vector bool int, vector signed int); -vector signed int vec_vsubsws (vector signed int, vector bool int); -vector signed int vec_vsubsws (vector signed int, vector signed int); - -vector unsigned int vec_vsubuws (vector bool int, vector unsigned int); -vector unsigned int vec_vsubuws (vector unsigned int, vector bool int); -vector unsigned int vec_vsubuws (vector unsigned int, - vector unsigned int); - -vector signed short vec_vsubshs (vector bool short, - vector signed short); -vector signed short vec_vsubshs (vector signed short, - vector bool short); -vector signed short vec_vsubshs (vector signed short, - vector signed short); - -vector unsigned short vec_vsubuhs (vector bool short, - vector unsigned short); -vector unsigned short vec_vsubuhs (vector unsigned short, - vector bool short); -vector unsigned short vec_vsubuhs (vector unsigned short, - vector unsigned short); - -vector signed char vec_vsubsbs (vector bool char, vector signed char); -vector signed char vec_vsubsbs (vector signed char, vector bool char); -vector signed char vec_vsubsbs (vector signed char, vector signed char); - -vector unsigned char vec_vsububs (vector bool char, - vector unsigned char); -vector unsigned char vec_vsububs (vector unsigned char, - vector bool char); -vector unsigned char vec_vsububs (vector unsigned char, - vector unsigned char); - -vector unsigned int vec_sum4s (vector unsigned char, - vector unsigned int); -vector signed int vec_sum4s (vector signed char, vector signed int); -vector signed int vec_sum4s (vector signed short, vector signed int); - -vector signed int vec_vsum4shs (vector signed short, vector signed int); - -vector signed int vec_vsum4sbs (vector signed char, vector signed int); - -vector unsigned int vec_vsum4ubs (vector unsigned char, - vector unsigned int); - -vector signed int vec_sum2s (vector signed int, vector signed int); - -vector signed int vec_sums (vector signed int, vector signed int); - -vector float vec_trunc (vector float); - -vector signed short vec_unpackh (vector signed char); -vector bool short vec_unpackh (vector bool char); -vector signed int vec_unpackh (vector signed short); -vector bool int vec_unpackh (vector bool short); -vector unsigned int vec_unpackh (vector pixel); - -vector bool int vec_vupkhsh (vector bool short); -vector signed int vec_vupkhsh (vector signed short); - -vector unsigned int vec_vupkhpx (vector pixel); - -vector bool short vec_vupkhsb (vector bool char); -vector signed short vec_vupkhsb (vector signed char); - -vector signed short vec_unpackl (vector signed char); -vector bool short vec_unpackl (vector bool char); -vector unsigned int vec_unpackl (vector pixel); -vector signed int vec_unpackl (vector signed short); -vector bool int vec_unpackl (vector bool short); - -vector unsigned int vec_vupklpx (vector pixel); - -vector bool int vec_vupklsh (vector bool short); -vector signed int vec_vupklsh (vector signed short); - -vector bool short vec_vupklsb (vector bool char); -vector signed short vec_vupklsb (vector signed char); - -vector float vec_xor (vector float, vector float); -vector float vec_xor (vector float, vector bool int); -vector float vec_xor (vector bool int, vector float); -vector bool int vec_xor (vector bool int, vector bool int); -vector signed int vec_xor (vector bool int, vector signed int); -vector signed int vec_xor (vector signed int, vector bool int); -vector signed int vec_xor (vector signed int, vector signed int); -vector unsigned int vec_xor (vector bool int, vector unsigned int); -vector unsigned int vec_xor (vector unsigned int, vector bool int); -vector unsigned int vec_xor (vector unsigned int, vector unsigned int); -vector bool short vec_xor (vector bool short, vector bool short); -vector signed short vec_xor (vector bool short, vector signed short); -vector signed short vec_xor (vector signed short, vector bool short); -vector signed short vec_xor (vector signed short, vector signed short); -vector unsigned short vec_xor (vector bool short, - vector unsigned short); -vector unsigned short vec_xor (vector unsigned short, - vector bool short); -vector unsigned short vec_xor (vector unsigned short, - vector unsigned short); -vector signed char vec_xor (vector bool char, vector signed char); -vector bool char vec_xor (vector bool char, vector bool char); -vector signed char vec_xor (vector signed char, vector bool char); -vector signed char vec_xor (vector signed char, vector signed char); -vector unsigned char vec_xor (vector bool char, vector unsigned char); -vector unsigned char vec_xor (vector unsigned char, vector bool char); -vector unsigned char vec_xor (vector unsigned char, - vector unsigned char); - -int vec_all_eq (vector signed char, vector bool char); -int vec_all_eq (vector signed char, vector signed char); -int vec_all_eq (vector unsigned char, vector bool char); -int vec_all_eq (vector unsigned char, vector unsigned char); -int vec_all_eq (vector bool char, vector bool char); -int vec_all_eq (vector bool char, vector unsigned char); -int vec_all_eq (vector bool char, vector signed char); -int vec_all_eq (vector signed short, vector bool short); -int vec_all_eq (vector signed short, vector signed short); -int vec_all_eq (vector unsigned short, vector bool short); -int vec_all_eq (vector unsigned short, vector unsigned short); -int vec_all_eq (vector bool short, vector bool short); -int vec_all_eq (vector bool short, vector unsigned short); -int vec_all_eq (vector bool short, vector signed short); -int vec_all_eq (vector pixel, vector pixel); -int vec_all_eq (vector signed int, vector bool int); -int vec_all_eq (vector signed int, vector signed int); -int vec_all_eq (vector unsigned int, vector bool int); -int vec_all_eq (vector unsigned int, vector unsigned int); -int vec_all_eq (vector bool int, vector bool int); -int vec_all_eq (vector bool int, vector unsigned int); -int vec_all_eq (vector bool int, vector signed int); -int vec_all_eq (vector float, vector float); - -int vec_all_ge (vector bool char, vector unsigned char); -int vec_all_ge (vector unsigned char, vector bool char); -int vec_all_ge (vector unsigned char, vector unsigned char); -int vec_all_ge (vector bool char, vector signed char); -int vec_all_ge (vector signed char, vector bool char); -int vec_all_ge (vector signed char, vector signed char); -int vec_all_ge (vector bool short, vector unsigned short); -int vec_all_ge (vector unsigned short, vector bool short); -int vec_all_ge (vector unsigned short, vector unsigned short); -int vec_all_ge (vector signed short, vector signed short); -int vec_all_ge (vector bool short, vector signed short); -int vec_all_ge (vector signed short, vector bool short); -int vec_all_ge (vector bool int, vector unsigned int); -int vec_all_ge (vector unsigned int, vector bool int); -int vec_all_ge (vector unsigned int, vector unsigned int); -int vec_all_ge (vector bool int, vector signed int); -int vec_all_ge (vector signed int, vector bool int); -int vec_all_ge (vector signed int, vector signed int); -int vec_all_ge (vector float, vector float); - -int vec_all_gt (vector bool char, vector unsigned char); -int vec_all_gt (vector unsigned char, vector bool char); -int vec_all_gt (vector unsigned char, vector unsigned char); -int vec_all_gt (vector bool char, vector signed char); -int vec_all_gt (vector signed char, vector bool char); -int vec_all_gt (vector signed char, vector signed char); -int vec_all_gt (vector bool short, vector unsigned short); -int vec_all_gt (vector unsigned short, vector bool short); -int vec_all_gt (vector unsigned short, vector unsigned short); -int vec_all_gt (vector bool short, vector signed short); -int vec_all_gt (vector signed short, vector bool short); -int vec_all_gt (vector signed short, vector signed short); -int vec_all_gt (vector bool int, vector unsigned int); -int vec_all_gt (vector unsigned int, vector bool int); -int vec_all_gt (vector unsigned int, vector unsigned int); -int vec_all_gt (vector bool int, vector signed int); -int vec_all_gt (vector signed int, vector bool int); -int vec_all_gt (vector signed int, vector signed int); -int vec_all_gt (vector float, vector float); - -int vec_all_in (vector float, vector float); - -int vec_all_le (vector bool char, vector unsigned char); -int vec_all_le (vector unsigned char, vector bool char); -int vec_all_le (vector unsigned char, vector unsigned char); -int vec_all_le (vector bool char, vector signed char); -int vec_all_le (vector signed char, vector bool char); -int vec_all_le (vector signed char, vector signed char); -int vec_all_le (vector bool short, vector unsigned short); -int vec_all_le (vector unsigned short, vector bool short); -int vec_all_le (vector unsigned short, vector unsigned short); -int vec_all_le (vector bool short, vector signed short); -int vec_all_le (vector signed short, vector bool short); -int vec_all_le (vector signed short, vector signed short); -int vec_all_le (vector bool int, vector unsigned int); -int vec_all_le (vector unsigned int, vector bool int); -int vec_all_le (vector unsigned int, vector unsigned int); -int vec_all_le (vector bool int, vector signed int); -int vec_all_le (vector signed int, vector bool int); -int vec_all_le (vector signed int, vector signed int); -int vec_all_le (vector float, vector float); - -int vec_all_lt (vector bool char, vector unsigned char); -int vec_all_lt (vector unsigned char, vector bool char); -int vec_all_lt (vector unsigned char, vector unsigned char); -int vec_all_lt (vector bool char, vector signed char); -int vec_all_lt (vector signed char, vector bool char); -int vec_all_lt (vector signed char, vector signed char); -int vec_all_lt (vector bool short, vector unsigned short); -int vec_all_lt (vector unsigned short, vector bool short); -int vec_all_lt (vector unsigned short, vector unsigned short); -int vec_all_lt (vector bool short, vector signed short); -int vec_all_lt (vector signed short, vector bool short); -int vec_all_lt (vector signed short, vector signed short); -int vec_all_lt (vector bool int, vector unsigned int); -int vec_all_lt (vector unsigned int, vector bool int); -int vec_all_lt (vector unsigned int, vector unsigned int); -int vec_all_lt (vector bool int, vector signed int); -int vec_all_lt (vector signed int, vector bool int); -int vec_all_lt (vector signed int, vector signed int); -int vec_all_lt (vector float, vector float); - -int vec_all_nan (vector float); - -int vec_all_ne (vector signed char, vector bool char); -int vec_all_ne (vector signed char, vector signed char); -int vec_all_ne (vector unsigned char, vector bool char); -int vec_all_ne (vector unsigned char, vector unsigned char); -int vec_all_ne (vector bool char, vector bool char); -int vec_all_ne (vector bool char, vector unsigned char); -int vec_all_ne (vector bool char, vector signed char); -int vec_all_ne (vector signed short, vector bool short); -int vec_all_ne (vector signed short, vector signed short); -int vec_all_ne (vector unsigned short, vector bool short); -int vec_all_ne (vector unsigned short, vector unsigned short); -int vec_all_ne (vector bool short, vector bool short); -int vec_all_ne (vector bool short, vector unsigned short); -int vec_all_ne (vector bool short, vector signed short); -int vec_all_ne (vector pixel, vector pixel); -int vec_all_ne (vector signed int, vector bool int); -int vec_all_ne (vector signed int, vector signed int); -int vec_all_ne (vector unsigned int, vector bool int); -int vec_all_ne (vector unsigned int, vector unsigned int); -int vec_all_ne (vector bool int, vector bool int); -int vec_all_ne (vector bool int, vector unsigned int); -int vec_all_ne (vector bool int, vector signed int); -int vec_all_ne (vector float, vector float); - -int vec_all_nge (vector float, vector float); - -int vec_all_ngt (vector float, vector float); - -int vec_all_nle (vector float, vector float); - -int vec_all_nlt (vector float, vector float); - -int vec_all_numeric (vector float); - -int vec_any_eq (vector signed char, vector bool char); -int vec_any_eq (vector signed char, vector signed char); -int vec_any_eq (vector unsigned char, vector bool char); -int vec_any_eq (vector unsigned char, vector unsigned char); -int vec_any_eq (vector bool char, vector bool char); -int vec_any_eq (vector bool char, vector unsigned char); -int vec_any_eq (vector bool char, vector signed char); -int vec_any_eq (vector signed short, vector bool short); -int vec_any_eq (vector signed short, vector signed short); -int vec_any_eq (vector unsigned short, vector bool short); -int vec_any_eq (vector unsigned short, vector unsigned short); -int vec_any_eq (vector bool short, vector bool short); -int vec_any_eq (vector bool short, vector unsigned short); -int vec_any_eq (vector bool short, vector signed short); -int vec_any_eq (vector pixel, vector pixel); -int vec_any_eq (vector signed int, vector bool int); -int vec_any_eq (vector signed int, vector signed int); -int vec_any_eq (vector unsigned int, vector bool int); -int vec_any_eq (vector unsigned int, vector unsigned int); -int vec_any_eq (vector bool int, vector bool int); -int vec_any_eq (vector bool int, vector unsigned int); -int vec_any_eq (vector bool int, vector signed int); -int vec_any_eq (vector float, vector float); - -int vec_any_ge (vector signed char, vector bool char); -int vec_any_ge (vector unsigned char, vector bool char); -int vec_any_ge (vector unsigned char, vector unsigned char); -int vec_any_ge (vector signed char, vector signed char); -int vec_any_ge (vector bool char, vector unsigned char); -int vec_any_ge (vector bool char, vector signed char); -int vec_any_ge (vector unsigned short, vector bool short); -int vec_any_ge (vector unsigned short, vector unsigned short); -int vec_any_ge (vector signed short, vector signed short); -int vec_any_ge (vector signed short, vector bool short); -int vec_any_ge (vector bool short, vector unsigned short); -int vec_any_ge (vector bool short, vector signed short); -int vec_any_ge (vector signed int, vector bool int); -int vec_any_ge (vector unsigned int, vector bool int); -int vec_any_ge (vector unsigned int, vector unsigned int); -int vec_any_ge (vector signed int, vector signed int); -int vec_any_ge (vector bool int, vector unsigned int); -int vec_any_ge (vector bool int, vector signed int); -int vec_any_ge (vector float, vector float); - -int vec_any_gt (vector bool char, vector unsigned char); -int vec_any_gt (vector unsigned char, vector bool char); -int vec_any_gt (vector unsigned char, vector unsigned char); -int vec_any_gt (vector bool char, vector signed char); -int vec_any_gt (vector signed char, vector bool char); -int vec_any_gt (vector signed char, vector signed char); -int vec_any_gt (vector bool short, vector unsigned short); -int vec_any_gt (vector unsigned short, vector bool short); -int vec_any_gt (vector unsigned short, vector unsigned short); -int vec_any_gt (vector bool short, vector signed short); -int vec_any_gt (vector signed short, vector bool short); -int vec_any_gt (vector signed short, vector signed short); -int vec_any_gt (vector bool int, vector unsigned int); -int vec_any_gt (vector unsigned int, vector bool int); -int vec_any_gt (vector unsigned int, vector unsigned int); -int vec_any_gt (vector bool int, vector signed int); -int vec_any_gt (vector signed int, vector bool int); -int vec_any_gt (vector signed int, vector signed int); -int vec_any_gt (vector float, vector float); - -int vec_any_le (vector bool char, vector unsigned char); -int vec_any_le (vector unsigned char, vector bool char); -int vec_any_le (vector unsigned char, vector unsigned char); -int vec_any_le (vector bool char, vector signed char); -int vec_any_le (vector signed char, vector bool char); -int vec_any_le (vector signed char, vector signed char); -int vec_any_le (vector bool short, vector unsigned short); -int vec_any_le (vector unsigned short, vector bool short); -int vec_any_le (vector unsigned short, vector unsigned short); -int vec_any_le (vector bool short, vector signed short); -int vec_any_le (vector signed short, vector bool short); -int vec_any_le (vector signed short, vector signed short); -int vec_any_le (vector bool int, vector unsigned int); -int vec_any_le (vector unsigned int, vector bool int); -int vec_any_le (vector unsigned int, vector unsigned int); -int vec_any_le (vector bool int, vector signed int); -int vec_any_le (vector signed int, vector bool int); -int vec_any_le (vector signed int, vector signed int); -int vec_any_le (vector float, vector float); - -int vec_any_lt (vector bool char, vector unsigned char); -int vec_any_lt (vector unsigned char, vector bool char); -int vec_any_lt (vector unsigned char, vector unsigned char); -int vec_any_lt (vector bool char, vector signed char); -int vec_any_lt (vector signed char, vector bool char); -int vec_any_lt (vector signed char, vector signed char); -int vec_any_lt (vector bool short, vector unsigned short); -int vec_any_lt (vector unsigned short, vector bool short); -int vec_any_lt (vector unsigned short, vector unsigned short); -int vec_any_lt (vector bool short, vector signed short); -int vec_any_lt (vector signed short, vector bool short); -int vec_any_lt (vector signed short, vector signed short); -int vec_any_lt (vector bool int, vector unsigned int); -int vec_any_lt (vector unsigned int, vector bool int); -int vec_any_lt (vector unsigned int, vector unsigned int); -int vec_any_lt (vector bool int, vector signed int); -int vec_any_lt (vector signed int, vector bool int); -int vec_any_lt (vector signed int, vector signed int); -int vec_any_lt (vector float, vector float); - -int vec_any_nan (vector float); - -int vec_any_ne (vector signed char, vector bool char); -int vec_any_ne (vector signed char, vector signed char); -int vec_any_ne (vector unsigned char, vector bool char); -int vec_any_ne (vector unsigned char, vector unsigned char); -int vec_any_ne (vector bool char, vector bool char); -int vec_any_ne (vector bool char, vector unsigned char); -int vec_any_ne (vector bool char, vector signed char); -int vec_any_ne (vector signed short, vector bool short); -int vec_any_ne (vector signed short, vector signed short); -int vec_any_ne (vector unsigned short, vector bool short); -int vec_any_ne (vector unsigned short, vector unsigned short); -int vec_any_ne (vector bool short, vector bool short); -int vec_any_ne (vector bool short, vector unsigned short); -int vec_any_ne (vector bool short, vector signed short); -int vec_any_ne (vector pixel, vector pixel); -int vec_any_ne (vector signed int, vector bool int); -int vec_any_ne (vector signed int, vector signed int); -int vec_any_ne (vector unsigned int, vector bool int); -int vec_any_ne (vector unsigned int, vector unsigned int); -int vec_any_ne (vector bool int, vector bool int); -int vec_any_ne (vector bool int, vector unsigned int); -int vec_any_ne (vector bool int, vector signed int); -int vec_any_ne (vector float, vector float); - -int vec_any_nge (vector float, vector float); - -int vec_any_ngt (vector float, vector float); - -int vec_any_nle (vector float, vector float); - -int vec_any_nlt (vector float, vector float); - -int vec_any_numeric (vector float); - -int vec_any_out (vector float, vector float); -@end smallexample - -@node SPARC VIS Built-in Functions -@subsection SPARC VIS Built-in Functions - -GCC supports SIMD operations on the SPARC using both the generic vector -extensions (@pxref{Vector Extensions}) as well as built-in functions for -the SPARC Visual Instruction Set (VIS). When you use the @option{-mvis} -switch, the VIS extension is exposed as the following built-in functions: - -@smallexample -typedef int v2si __attribute__ ((vector_size (8))); -typedef short v4hi __attribute__ ((vector_size (8))); -typedef short v2hi __attribute__ ((vector_size (4))); -typedef char v8qi __attribute__ ((vector_size (8))); -typedef char v4qi __attribute__ ((vector_size (4))); - -void * __builtin_vis_alignaddr (void *, long); -int64_t __builtin_vis_faligndatadi (int64_t, int64_t); -v2si __builtin_vis_faligndatav2si (v2si, v2si); -v4hi __builtin_vis_faligndatav4hi (v4si, v4si); -v8qi __builtin_vis_faligndatav8qi (v8qi, v8qi); - -v4hi __builtin_vis_fexpand (v4qi); - -v4hi __builtin_vis_fmul8x16 (v4qi, v4hi); -v4hi __builtin_vis_fmul8x16au (v4qi, v4hi); -v4hi __builtin_vis_fmul8x16al (v4qi, v4hi); -v4hi __builtin_vis_fmul8sux16 (v8qi, v4hi); -v4hi __builtin_vis_fmul8ulx16 (v8qi, v4hi); -v2si __builtin_vis_fmuld8sux16 (v4qi, v2hi); -v2si __builtin_vis_fmuld8ulx16 (v4qi, v2hi); - -v4qi __builtin_vis_fpack16 (v4hi); -v8qi __builtin_vis_fpack32 (v2si, v2si); -v2hi __builtin_vis_fpackfix (v2si); -v8qi __builtin_vis_fpmerge (v4qi, v4qi); - -int64_t __builtin_vis_pdist (v8qi, v8qi, int64_t); -@end smallexample - -@node Target Format Checks -@section Format Checks Specific to Particular Target Machines - -For some target machines, GCC supports additional options to the -format attribute -(@pxref{Function Attributes,,Declaring Attributes of Functions}). - -@menu -* Solaris Format Checks:: -@end menu - -@node Solaris Format Checks -@subsection Solaris Format Checks - -Solaris targets support the @code{cmn_err} (or @code{__cmn_err__}) format -check. @code{cmn_err} accepts a subset of the standard @code{printf} -conversions, and the two-argument @code{%b} conversion for displaying -bit-fields. See the Solaris man page for @code{cmn_err} for more information. - -@node Pragmas -@section Pragmas Accepted by GCC -@cindex pragmas -@cindex #pragma - -GCC supports several types of pragmas, primarily in order to compile -code originally written for other compilers. Note that in general -we do not recommend the use of pragmas; @xref{Function Attributes}, -for further explanation. - -@menu -* ARM Pragmas:: -* M32C Pragmas:: -* RS/6000 and PowerPC Pragmas:: -* Darwin Pragmas:: -* Solaris Pragmas:: -* Symbol-Renaming Pragmas:: -* Structure-Packing Pragmas:: -* Weak Pragmas:: -* Diagnostic Pragmas:: -* Visibility Pragmas:: -@end menu - -@node ARM Pragmas -@subsection ARM Pragmas - -The ARM target defines pragmas for controlling the default addition of -@code{long_call} and @code{short_call} attributes to functions. -@xref{Function Attributes}, for information about the effects of these -attributes. - -@table @code -@item long_calls -@cindex pragma, long_calls -Set all subsequent functions to have the @code{long_call} attribute. - -@item no_long_calls -@cindex pragma, no_long_calls -Set all subsequent functions to have the @code{short_call} attribute. - -@item long_calls_off -@cindex pragma, long_calls_off -Do not affect the @code{long_call} or @code{short_call} attributes of -subsequent functions. -@end table - -@node M32C Pragmas -@subsection M32C Pragmas - -@table @code -@item memregs @var{number} -@cindex pragma, memregs -Overrides the command line option @code{-memregs=} for the current -file. Use with care! This pragma must be before any function in the -file, and mixing different memregs values in different objects may -make them incompatible. This pragma is useful when a -performance-critical function uses a memreg for temporary values, -as it may allow you to reduce the number of memregs used. - -@end table - -@node RS/6000 and PowerPC Pragmas -@subsection RS/6000 and PowerPC Pragmas - -The RS/6000 and PowerPC targets define one pragma for controlling -whether or not the @code{longcall} attribute is added to function -declarations by default. This pragma overrides the @option{-mlongcall} -option, but not the @code{longcall} and @code{shortcall} attributes. -@xref{RS/6000 and PowerPC Options}, for more information about when long -calls are and are not necessary. - -@table @code -@item longcall (1) -@cindex pragma, longcall -Apply the @code{longcall} attribute to all subsequent function -declarations. - -@item longcall (0) -Do not apply the @code{longcall} attribute to subsequent function -declarations. -@end table - -@c Describe c4x pragmas here. -@c Describe h8300 pragmas here. -@c Describe sh pragmas here. -@c Describe v850 pragmas here. - -@node Darwin Pragmas -@subsection Darwin Pragmas - -The following pragmas are available for all architectures running the -Darwin operating system. These are useful for compatibility with other -Mac OS compilers. - -@table @code -@item mark @var{tokens}@dots{} -@cindex pragma, mark -This pragma is accepted, but has no effect. - -@item options align=@var{alignment} -@cindex pragma, options align -This pragma sets the alignment of fields in structures. The values of -@var{alignment} may be @code{mac68k}, to emulate m68k alignment, or -@code{power}, to emulate PowerPC alignment. Uses of this pragma nest -properly; to restore the previous setting, use @code{reset} for the -@var{alignment}. - -@c APPLE LOCAL begin radar 4827197 -The @code{power} setting, when compiling for the Intel target, does not -fully emulate the alignments on native PowerPC targets. When the first -field within a struct is of type @code{double}, this causes the struct -to be 8-byte aligned on PowerPC target, but only 4-byte aligned on -Intel target. When such a struct is nested within another aggregate, -differing layouts on the two targets can occur. In such a case, a dummy -field @code{char : 0;} can be inserted before the @code{double} to achieve -the same layout on both targets. -@c APPLE LOCAL end radar 4827197 - -@item segment @var{tokens}@dots{} -@cindex pragma, segment -This pragma is accepted, but has no effect. - -@item unused (@var{var} [, @var{var}]@dots{}) -@cindex pragma, unused -This pragma declares variables to be possibly unused. GCC will not -produce warnings for the listed variables. The effect is similar to -that of the @code{unused} attribute, except that this pragma may appear -anywhere within the variables' scopes. - -@c APPLE LOCAL begin optimization pragmas 3124235/3420242 -@item optimization_level @{ 0 | 1 | 2 | 3 | reset @} -@item optimize_for_size @{ on | off | reset @} -@item GCC optimization_level @{ 0 | 1 | 2 | 3 | reset @} -@item GCC optimize_for_size @{ on | off | reset @} -@cindex pragma, optimization_level -(These pragmas are APPLE ONLY.) - -These pragmas set the current optimization level, similar but not identical -to -O0 through -O3, or -Os, on the command line. These pragmas form a -stack; the "reset" argument pops the stack, restoring the optimization level -to what it was before the previous optimization pragma. The optimization -level in effect at the beginning of each function definition is applied to -that function. Currently, the pragmas will not affect optimizations whose -implementation is based on whole-file analysis; this notably includes -inlining and strict aliasing. Also, the feature currently doesn't apply -to functions whose body is within a class definition (that is, such -functions are compiled with the command line options). - -The versions without "GCC" have the same syntax and similar effect as -CodeWarrior pragmas (although since the optimizations performed by -the compilers are not identical, the effect of the options won't be -either). These may be convenient for existing code. The versions -with "GCC" are recommended for new code. -@end table -@c APPLE LOCAL end optimization pragmas 3124235/3420242 - -@node Solaris Pragmas -@subsection Solaris Pragmas - -The Solaris target supports @code{#pragma redefine_extname} -(@pxref{Symbol-Renaming Pragmas}). It also supports additional -@code{#pragma} directives for compatibility with the system compiler. - -@table @code -@item align @var{alignment} (@var{variable} [, @var{variable}]...) -@cindex pragma, align - -Increase the minimum alignment of each @var{variable} to @var{alignment}. -This is the same as GCC's @code{aligned} attribute @pxref{Variable -Attributes}). Macro expansion occurs on the arguments to this pragma -when compiling C and Objective-C. It does not currently occur when -compiling C++, but this is a bug which may be fixed in a future -release. - -@item fini (@var{function} [, @var{function}]...) -@cindex pragma, fini - -This pragma causes each listed @var{function} to be called after -main, or during shared module unloading, by adding a call to the -@code{.fini} section. - -@item init (@var{function} [, @var{function}]...) -@cindex pragma, init - -This pragma causes each listed @var{function} to be called during -initialization (before @code{main}) or during shared module loading, by -adding a call to the @code{.init} section. - -@end table - -@node Symbol-Renaming Pragmas -@subsection Symbol-Renaming Pragmas - -For compatibility with the Solaris and Tru64 UNIX system headers, GCC -supports two @code{#pragma} directives which change the name used in -assembly for a given declaration. These pragmas are only available on -platforms whose system headers need them. To get this effect on all -platforms supported by GCC, use the asm labels extension (@pxref{Asm -Labels}). - -@table @code -@item redefine_extname @var{oldname} @var{newname} -@cindex pragma, redefine_extname - -This pragma gives the C function @var{oldname} the assembly symbol -@var{newname}. The preprocessor macro @code{__PRAGMA_REDEFINE_EXTNAME} -will be defined if this pragma is available (currently only on -Solaris). - -@item extern_prefix @var{string} -@cindex pragma, extern_prefix - -This pragma causes all subsequent external function and variable -declarations to have @var{string} prepended to their assembly symbols. -This effect may be terminated with another @code{extern_prefix} pragma -whose argument is an empty string. The preprocessor macro -@code{__PRAGMA_EXTERN_PREFIX} will be defined if this pragma is -available (currently only on Tru64 UNIX)@. -@end table - -These pragmas and the asm labels extension interact in a complicated -manner. Here are some corner cases you may want to be aware of. - -@enumerate -@item Both pragmas silently apply only to declarations with external -linkage. Asm labels do not have this restriction. - -@item In C++, both pragmas silently apply only to declarations with -``C'' linkage. Again, asm labels do not have this restriction. - -@item If any of the three ways of changing the assembly name of a -declaration is applied to a declaration whose assembly name has -already been determined (either by a previous use of one of these -features, or because the compiler needed the assembly name in order to -generate code), and the new name is different, a warning issues and -the name does not change. - -@item The @var{oldname} used by @code{#pragma redefine_extname} is -always the C-language name. - -@item If @code{#pragma extern_prefix} is in effect, and a declaration -occurs with an asm label attached, the prefix is silently ignored for -that declaration. - -@item If @code{#pragma extern_prefix} and @code{#pragma redefine_extname} -apply to the same declaration, whichever triggered first wins, and a -warning issues if they contradict each other. (We would like to have -@code{#pragma redefine_extname} always win, for consistency with asm -labels, but if @code{#pragma extern_prefix} triggers first we have no -way of knowing that that happened.) -@end enumerate - -@node Structure-Packing Pragmas -@subsection Structure-Packing Pragmas - -@c APPLE LOCAL begin radar 4679943 -For compatibility with Win32, GCC supports a set of @code{#pragma} -directives which change the maximum alignment of members of structures -(other than zero-width bitfields), unions, and classes subsequently -defined. The @var{n} value below always is required to be a small power -of two and specifies the new maximum alignment in bytes. - -@enumerate -@c APPLE LOCAL prune man page -@ignore -@item @code{#pragma pack(@var{n})} simply sets the new alignment. -@item @code{#pragma pack()} sets the alignment to the one that was in -effect when compilation started (see also command line option -@option{-fpack-struct[=<n>]} @pxref{Code Gen Options}). -@item @code{#pragma pack(push[,@var{n}])} pushes the current alignment -setting on an internal stack and then optionally sets the new alignment. -@item @code{#pragma pack(pop)} restores the alignment setting to the one -saved at the top of the internal stack (and removes that stack entry). -Note that @code{#pragma pack([@var{n}])} does not influence this internal -stack; thus it is possible to have @code{#pragma pack(push)} followed by -multiple @code{#pragma pack(@var{n})} instances and finalized by a single -@code{#pragma pack(pop)}. -@c APPLE LOCAL prune man page -@end ignore - -@item @code{#pragma pack(@var{n})} pushes the current maximum alignment setting -onto an internal stack and then sets the new maximum alignment. (APPLE ONLY) -@item @code{#pragma pack()} acts like a @code{#pragma pack(pop)} directive. -(APPLE ONLY) -@item @code{#pragma pack(push[,@var{n}])} pushes the current maximum alignment -setting onto an internal stack and then optionally sets the new maximum -alignment. -@item @code{#pragma pack(pop)} restores the maximum alignment setting to the -one saved at the top of the internal stack (and removes that stack entry). -@end enumerate -@c APPLE LOCAL end radar 4679943 - -Some targets, e.g. i386 and powerpc, support the @code{ms_struct} -@code{#pragma} which lays out a structure as the documented -@code{__attribute__ ((ms_struct))}. -@enumerate -@item @code{#pragma ms_struct on} turns on the layout for structures -declared. -@item @code{#pragma ms_struct off} turns off the layout for structures -declared. -@item @code{#pragma ms_struct reset} goes back to the default layout. -@end enumerate - -@node Weak Pragmas -@subsection Weak Pragmas - -For compatibility with SVR4, GCC supports a set of @code{#pragma} -directives for declaring symbols to be weak, and defining weak -aliases. - -@table @code -@item #pragma weak @var{symbol} -@cindex pragma, weak -This pragma declares @var{symbol} to be weak, as if the declaration -had the attribute of the same name. The pragma may appear before -or after the declaration of @var{symbol}, but must appear before -either its first use or its definition. It is not an error for -@var{symbol} to never be defined at all. - -@item #pragma weak @var{symbol1} = @var{symbol2} -This pragma declares @var{symbol1} to be a weak alias of @var{symbol2}. -It is an error if @var{symbol2} is not defined in the current -translation unit. -@end table - -@node Diagnostic Pragmas -@subsection Diagnostic Pragmas - -GCC allows the user to selectively enable or disable certain types of -diagnostics, and change the kind of the diagnostic. For example, a -project's policy might require that all sources compile with -@option{-Werror} but certain files might have exceptions allowing -specific types of warnings. Or, a project might selectively enable -diagnostics and treat them as errors depending on which preprocessor -macros are defined. - -@table @code -@item #pragma GCC diagnostic @var{kind} @var{option} -@cindex pragma, diagnostic - -Modifies the disposition of a diagnostic. Note that not all -diagnostics are modifiable; at the moment only warnings (normally -controlled by @samp{-W...}) can be controlled, and not all of them. -Use @option{-fdiagnostics-show-option} to determine which diagnostics -are controllable and which option controls them. - -@var{kind} is @samp{error} to treat this diagnostic as an error, -@samp{warning} to treat it like a warning (even if @option{-Werror} is -in effect), or @samp{ignored} if the diagnostic is to be ignored. -@var{option} is a double quoted string which matches the command line -option. - -@example -#pragma GCC diagnostic warning "-Wformat" -#pragma GCC diagnostic error "-Wformat" -#pragma GCC diagnostic ignored "-Wformat" -@end example - -Note that these pragmas override any command line options. Also, -while it is syntactically valid to put these pragmas anywhere in your -sources, the only supported location for them is before any data or -functions are defined. Doing otherwise may result in unpredictable -results depending on how the optimizer manages your sources. If the -same option is listed multiple times, the last one specified is the -one that is in effect. This pragma is not intended to be a general -purpose replacement for command line options, but for implementing -strict control over project policies. - -@end table - -@node Visibility Pragmas -@subsection Visibility Pragmas - -@table @code -@item #pragma GCC visibility push(@var{visibility}) -@itemx #pragma GCC visibility pop -@cindex pragma, visibility - -This pragma allows the user to set the visibility for multiple -declarations without having to give each a visibility attribute -@xref{Function Attributes}, for more information about visibility and -the attribute syntax. - -In C++, @samp{#pragma GCC visibility} affects only namespace-scope -declarations. Class members and template specializations are not -affected; if you want to override the visibility for a particular -member or instantiation, you must use an attribute. - -@end table - -@node Unnamed Fields -@section Unnamed struct/union fields within structs/unions -@cindex struct -@cindex union - -For compatibility with other compilers, GCC allows you to define -a structure or union that contains, as fields, structures and unions -without names. For example: - -@smallexample -struct @{ - int a; - union @{ - int b; - float c; - @}; - int d; -@} foo; -@end smallexample - -In this example, the user would be able to access members of the unnamed -union with code like @samp{foo.b}. Note that only unnamed structs and -unions are allowed, you may not have, for example, an unnamed -@code{int}. - -You must never create such structures that cause ambiguous field definitions. -For example, this structure: - -@smallexample -struct @{ - int a; - struct @{ - int a; - @}; -@} foo; -@end smallexample - -It is ambiguous which @code{a} is being referred to with @samp{foo.a}. -Such constructs are not supported and must be avoided. In the future, -such constructs may be detected and treated as compilation errors. - -@opindex fms-extensions -Unless @option{-fms-extensions} is used, the unnamed field must be a -structure or union definition without a tag (for example, @samp{struct -@{ int a; @};}). If @option{-fms-extensions} is used, the field may -also be a definition with a tag such as @samp{struct foo @{ int a; -@};}, a reference to a previously defined structure or union such as -@samp{struct foo;}, or a reference to a @code{typedef} name for a -previously defined structure or union type. - -@node Thread-Local -@section Thread-Local Storage -@cindex Thread-Local Storage -@cindex @acronym{TLS} -@cindex __thread - -Thread-local storage (@acronym{TLS}) is a mechanism by which variables -are allocated such that there is one instance of the variable per extant -thread. The run-time model GCC uses to implement this originates -in the IA-64 processor-specific ABI, but has since been migrated -to other processors as well. It requires significant support from -the linker (@command{ld}), dynamic linker (@command{ld.so}), and -system libraries (@file{libc.so} and @file{libpthread.so}), so it -is not available everywhere. - -At the user level, the extension is visible with a new storage -class keyword: @code{__thread}. For example: - -@smallexample -__thread int i; -extern __thread struct state s; -static __thread char *p; -@end smallexample - -The @code{__thread} specifier may be used alone, with the @code{extern} -or @code{static} specifiers, but with no other storage class specifier. -When used with @code{extern} or @code{static}, @code{__thread} must appear -immediately after the other storage class specifier. - -The @code{__thread} specifier may be applied to any global, file-scoped -static, function-scoped static, or static data member of a class. It may -not be applied to block-scoped automatic or non-static data member. - -When the address-of operator is applied to a thread-local variable, it is -evaluated at run-time and returns the address of the current thread's -instance of that variable. An address so obtained may be used by any -thread. When a thread terminates, any pointers to thread-local variables -in that thread become invalid. - -No static initialization may refer to the address of a thread-local variable. - -In C++, if an initializer is present for a thread-local variable, it must -be a @var{constant-expression}, as defined in 5.19.2 of the ANSI/ISO C++ -standard. - -See @uref{http://people.redhat.com/drepper/tls.pdf, -ELF Handling For Thread-Local Storage} for a detailed explanation of -the four thread-local storage addressing models, and how the run-time -is expected to function. - -@menu -* C99 Thread-Local Edits:: -* C++98 Thread-Local Edits:: -@end menu - -@node C99 Thread-Local Edits -@subsection ISO/IEC 9899:1999 Edits for Thread-Local Storage - -The following are a set of changes to ISO/IEC 9899:1999 (aka C99) -that document the exact semantics of the language extension. - -@itemize @bullet -@item -@cite{5.1.2 Execution environments} - -Add new text after paragraph 1 - -@quotation -Within either execution environment, a @dfn{thread} is a flow of -control within a program. It is implementation defined whether -or not there may be more than one thread associated with a program. -It is implementation defined how threads beyond the first are -created, the name and type of the function called at thread -startup, and how threads may be terminated. However, objects -with thread storage duration shall be initialized before thread -startup. -@end quotation - -@item -@cite{6.2.4 Storage durations of objects} - -Add new text before paragraph 3 - -@quotation -An object whose identifier is declared with the storage-class -specifier @w{@code{__thread}} has @dfn{thread storage duration}. -Its lifetime is the entire execution of the thread, and its -stored value is initialized only once, prior to thread startup. -@end quotation - -@item -@cite{6.4.1 Keywords} - -Add @code{__thread}. - -@item -@cite{6.7.1 Storage-class specifiers} - -Add @code{__thread} to the list of storage class specifiers in -paragraph 1. - -Change paragraph 2 to - -@quotation -With the exception of @code{__thread}, at most one storage-class -specifier may be given [@dots{}]. The @code{__thread} specifier may -be used alone, or immediately following @code{extern} or -@code{static}. -@end quotation - -Add new text after paragraph 6 - -@quotation -The declaration of an identifier for a variable that has -block scope that specifies @code{__thread} shall also -specify either @code{extern} or @code{static}. - -The @code{__thread} specifier shall be used only with -variables. -@end quotation -@end itemize - -@node C++98 Thread-Local Edits -@subsection ISO/IEC 14882:1998 Edits for Thread-Local Storage - -The following are a set of changes to ISO/IEC 14882:1998 (aka C++98) -that document the exact semantics of the language extension. - -@itemize @bullet -@item -@b{[intro.execution]} - -New text after paragraph 4 - -@quotation -A @dfn{thread} is a flow of control within the abstract machine. -It is implementation defined whether or not there may be more than -one thread. -@end quotation - -New text after paragraph 7 - -@quotation -It is unspecified whether additional action must be taken to -ensure when and whether side effects are visible to other threads. -@end quotation - -@item -@b{[lex.key]} - -Add @code{__thread}. - -@item -@b{[basic.start.main]} - -Add after paragraph 5 - -@quotation -The thread that begins execution at the @code{main} function is called -the @dfn{main thread}. It is implementation defined how functions -beginning threads other than the main thread are designated or typed. -A function so designated, as well as the @code{main} function, is called -a @dfn{thread startup function}. It is implementation defined what -happens if a thread startup function returns. It is implementation -defined what happens to other threads when any thread calls @code{exit}. -@end quotation - -@item -@b{[basic.start.init]} - -Add after paragraph 4 - -@quotation -The storage for an object of thread storage duration shall be -statically initialized before the first statement of the thread startup -function. An object of thread storage duration shall not require -dynamic initialization. -@end quotation - -@item -@b{[basic.start.term]} - -Add after paragraph 3 - -@quotation -The type of an object with thread storage duration shall not have a -non-trivial destructor, nor shall it be an array type whose elements -(directly or indirectly) have non-trivial destructors. -@end quotation - -@item -@b{[basic.stc]} - -Add ``thread storage duration'' to the list in paragraph 1. - -Change paragraph 2 - -@quotation -Thread, static, and automatic storage durations are associated with -objects introduced by declarations [@dots{}]. -@end quotation - -Add @code{__thread} to the list of specifiers in paragraph 3. - -@item -@b{[basic.stc.thread]} - -New section before @b{[basic.stc.static]} - -@quotation -The keyword @code{__thread} applied to a non-local object gives the -object thread storage duration. - -A local variable or class data member declared both @code{static} -and @code{__thread} gives the variable or member thread storage -duration. -@end quotation - -@item -@b{[basic.stc.static]} - -Change paragraph 1 - -@quotation -All objects which have neither thread storage duration, dynamic -storage duration nor are local [@dots{}]. -@end quotation - -@item -@b{[dcl.stc]} - -Add @code{__thread} to the list in paragraph 1. - -Change paragraph 1 - -@quotation -With the exception of @code{__thread}, at most one -@var{storage-class-specifier} shall appear in a given -@var{decl-specifier-seq}. The @code{__thread} specifier may -be used alone, or immediately following the @code{extern} or -@code{static} specifiers. [@dots{}] -@end quotation - -Add after paragraph 5 - -@quotation -The @code{__thread} specifier can be applied only to the names of objects -and to anonymous unions. -@end quotation - -@item -@b{[class.mem]} - -Add after paragraph 6 - -@quotation -Non-@code{static} members shall not be @code{__thread}. -@end quotation -@end itemize - -@c APPLE LOCAL begin blocks 7205047 5811887 -@node Blocks -@section Blocks -@cindex Blocks -@cindex __block - -Blocks is a language feature that allows one to create anonymous -functions. The feature is also known as lambdas or closures in other -languages. The feature is controlled by @option{-fblocks}. -See @uref{http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/Blocks/Articles/00_Introduction.html} for additional details. -@c APPLE LOCAL end blocks 7205047 5811887 - -@node C++ Extensions -@chapter Extensions to the C++ Language -@cindex extensions, C++ language -@cindex C++ language extensions - -The GNU compiler provides these extensions to the C++ language (and you -can also use most of the C language extensions in your C++ programs). If you -want to write code that checks whether these features are available, you can -test for the GNU compiler the same way as for C programs: check for a -predefined macro @code{__GNUC__}. You can also use @code{__GNUG__} to -test specifically for GNU C++ (@pxref{Common Predefined Macros,, -Predefined Macros,cpp,The GNU C Preprocessor}). - -@menu -* Volatiles:: What constitutes an access to a volatile object. -* Restricted Pointers:: C99 restricted pointers and references. -* Vague Linkage:: Where G++ puts inlines, vtables and such. -* C++ Interface:: You can use a single C++ header file for both - declarations and definitions. -* Template Instantiation:: Methods for ensuring that exactly one copy of - each needed template instantiation is emitted. -* Bound member functions:: You can extract a function pointer to the - method denoted by a @samp{->*} or @samp{.*} expression. -* C++ Attributes:: Variable, function, and type attributes for C++ only. -* Namespace Association:: Strong using-directives for namespace association. -* Java Exceptions:: Tweaking exception handling to work with Java. -* Deprecated Features:: Things will disappear from g++. -* Backwards Compatibility:: Compatibilities with earlier definitions of C++. -@end menu - -@node Volatiles -@section When is a Volatile Object Accessed? -@cindex accessing volatiles -@cindex volatile read -@cindex volatile write -@cindex volatile access - -Both the C and C++ standard have the concept of volatile objects. These -are normally accessed by pointers and used for accessing hardware. The -standards encourage compilers to refrain from optimizations concerning -accesses to volatile objects. The C standard leaves it implementation -defined as to what constitutes a volatile access. The C++ standard omits -to specify this, except to say that C++ should behave in a similar manner -to C with respect to volatiles, where possible. The minimum either -standard specifies is that at a sequence point all previous accesses to -volatile objects have stabilized and no subsequent accesses have -occurred. Thus an implementation is free to reorder and combine -volatile accesses which occur between sequence points, but cannot do so -for accesses across a sequence point. The use of volatiles does not -allow you to violate the restriction on updating objects multiple times -within a sequence point. - -@xref{Qualifiers implementation, , Volatile qualifier and the C compiler}. - -The behavior differs slightly between C and C++ in the non-obvious cases: - -@smallexample -volatile int *src = @var{somevalue}; -*src; -@end smallexample - -With C, such expressions are rvalues, and GCC interprets this either as a -read of the volatile object being pointed to or only as request to evaluate -the side-effects. The C++ standard specifies that such expressions do not -undergo lvalue to rvalue conversion, and that the type of the dereferenced -object may be incomplete. The C++ standard does not specify explicitly -that it is this lvalue to rvalue conversion which may be responsible for -causing an access. However, there is reason to believe that it is, -because otherwise certain simple expressions become undefined. However, -because it would surprise most programmers, G++ treats dereferencing a -pointer to volatile object of complete type when the value is unused as -GCC would do for an equivalent type in C. When the object has incomplete -type, G++ issues a warning; if you wish to force an error, you must -force a conversion to rvalue with, for instance, a static cast. - -When using a reference to volatile, G++ does not treat equivalent -expressions as accesses to volatiles, but instead issues a warning that -no volatile is accessed. The rationale for this is that otherwise it -becomes difficult to determine where volatile access occur, and not -possible to ignore the return value from functions returning volatile -references. Again, if you wish to force a read, cast the reference to -an rvalue. - -@node Restricted Pointers -@section Restricting Pointer Aliasing -@cindex restricted pointers -@cindex restricted references -@cindex restricted this pointer - -As with the C front end, G++ understands the C99 feature of restricted pointers, -specified with the @code{__restrict__}, or @code{__restrict} type -qualifier. Because you cannot compile C++ by specifying the @option{-std=c99} -language flag, @code{restrict} is not a keyword in C++. - -In addition to allowing restricted pointers, you can specify restricted -references, which indicate that the reference is not aliased in the local -context. - -@smallexample -void fn (int *__restrict__ rptr, int &__restrict__ rref) -@{ - /* @r{@dots{}} */ -@} -@end smallexample - -@noindent -In the body of @code{fn}, @var{rptr} points to an unaliased integer and -@var{rref} refers to a (different) unaliased integer. - -You may also specify whether a member function's @var{this} pointer is -unaliased by using @code{__restrict__} as a member function qualifier. - -@smallexample -void T::fn () __restrict__ -@{ - /* @r{@dots{}} */ -@} -@end smallexample - -@noindent -Within the body of @code{T::fn}, @var{this} will have the effective -definition @code{T *__restrict__ const this}. Notice that the -interpretation of a @code{__restrict__} member function qualifier is -different to that of @code{const} or @code{volatile} qualifier, in that it -is applied to the pointer rather than the object. This is consistent with -other compilers which implement restricted pointers. - -As with all outermost parameter qualifiers, @code{__restrict__} is -ignored in function definition matching. This means you only need to -specify @code{__restrict__} in a function definition, rather than -in a function prototype as well. - -@node Vague Linkage -@section Vague Linkage -@cindex vague linkage - -There are several constructs in C++ which require space in the object -file but are not clearly tied to a single translation unit. We say that -these constructs have ``vague linkage''. Typically such constructs are -emitted wherever they are needed, though sometimes we can be more -clever. - -@table @asis -@item Inline Functions -Inline functions are typically defined in a header file which can be -included in many different compilations. Hopefully they can usually be -inlined, but sometimes an out-of-line copy is necessary, if the address -of the function is taken or if inlining fails. In general, we emit an -out-of-line copy in all translation units where one is needed. As an -exception, we only emit inline virtual functions with the vtable, since -it will always require a copy. - -Local static variables and string constants used in an inline function -are also considered to have vague linkage, since they must be shared -between all inlined and out-of-line instances of the function. - -@item VTables -@cindex vtable -C++ virtual functions are implemented in most compilers using a lookup -table, known as a vtable. The vtable contains pointers to the virtual -functions provided by a class, and each object of the class contains a -pointer to its vtable (or vtables, in some multiple-inheritance -situations). If the class declares any non-inline, non-pure virtual -functions, the first one is chosen as the ``key method'' for the class, -and the vtable is only emitted in the translation unit where the key -method is defined. - -@emph{Note:} If the chosen key method is later defined as inline, the -vtable will still be emitted in every translation unit which defines it. -Make sure that any inline virtuals are declared inline in the class -body, even if they are not defined there. - -@item type_info objects -@cindex type_info -@cindex RTTI -C++ requires information about types to be written out in order to -implement @samp{dynamic_cast}, @samp{typeid} and exception handling. -For polymorphic classes (classes with virtual functions), the type_info -object is written out along with the vtable so that @samp{dynamic_cast} -can determine the dynamic type of a class object at runtime. For all -other types, we write out the type_info object when it is used: when -applying @samp{typeid} to an expression, throwing an object, or -referring to a type in a catch clause or exception specification. - -@item Template Instantiations -Most everything in this section also applies to template instantiations, -but there are other options as well. -@xref{Template Instantiation,,Where's the Template?}. - -@end table - -When used with GNU ld version 2.8 or later on an ELF system such as -GNU/Linux or Solaris 2, or on Microsoft Windows, duplicate copies of -these constructs will be discarded at link time. This is known as -COMDAT support. - -On targets that don't support COMDAT, but do support weak symbols, GCC -will use them. This way one copy will override all the others, but -the unused copies will still take up space in the executable. - -For targets which do not support either COMDAT or weak symbols, -most entities with vague linkage will be emitted as local symbols to -avoid duplicate definition errors from the linker. This will not happen -for local statics in inlines, however, as having multiple copies will -almost certainly break things. - -@xref{C++ Interface,,Declarations and Definitions in One Header}, for -another way to control placement of these constructs. - -@node C++ Interface -@section #pragma interface and implementation - -@cindex interface and implementation headers, C++ -@cindex C++ interface and implementation headers -@cindex pragmas, interface and implementation - -@code{#pragma interface} and @code{#pragma implementation} provide the -user with a way of explicitly directing the compiler to emit entities -with vague linkage (and debugging information) in a particular -translation unit. - -@emph{Note:} As of GCC 2.7.2, these @code{#pragma}s are not useful in -most cases, because of COMDAT support and the ``key method'' heuristic -mentioned in @ref{Vague Linkage}. Using them can actually cause your -program to grow due to unnecessary out-of-line copies of inline -functions. Currently (3.4) the only benefit of these -@code{#pragma}s is reduced duplication of debugging information, and -that should be addressed soon on DWARF 2 targets with the use of -COMDAT groups. - -@table @code -@item #pragma interface -@itemx #pragma interface "@var{subdir}/@var{objects}.h" -@kindex #pragma interface -Use this directive in @emph{header files} that define object classes, to save -space in most of the object files that use those classes. Normally, -local copies of certain information (backup copies of inline member -functions, debugging information, and the internal tables that implement -virtual functions) must be kept in each object file that includes class -definitions. You can use this pragma to avoid such duplication. When a -header file containing @samp{#pragma interface} is included in a -compilation, this auxiliary information will not be generated (unless -the main input source file itself uses @samp{#pragma implementation}). -Instead, the object files will contain references to be resolved at link -time. - -The second form of this directive is useful for the case where you have -multiple headers with the same name in different directories. If you -use this form, you must specify the same string to @samp{#pragma -implementation}. - -@item #pragma implementation -@itemx #pragma implementation "@var{objects}.h" -@kindex #pragma implementation -Use this pragma in a @emph{main input file}, when you want full output from -included header files to be generated (and made globally visible). The -included header file, in turn, should use @samp{#pragma interface}. -Backup copies of inline member functions, debugging information, and the -internal tables used to implement virtual functions are all generated in -implementation files. - -@cindex implied @code{#pragma implementation} -@cindex @code{#pragma implementation}, implied -@cindex naming convention, implementation headers -If you use @samp{#pragma implementation} with no argument, it applies to -an include file with the same basename@footnote{A file's @dfn{basename} -was the name stripped of all leading path information and of trailing -suffixes, such as @samp{.h} or @samp{.C} or @samp{.cc}.} as your source -file. For example, in @file{allclass.cc}, giving just -@samp{#pragma implementation} -by itself is equivalent to @samp{#pragma implementation "allclass.h"}. - -In versions of GNU C++ prior to 2.6.0 @file{allclass.h} was treated as -an implementation file whenever you would include it from -@file{allclass.cc} even if you never specified @samp{#pragma -implementation}. This was deemed to be more trouble than it was worth, -however, and disabled. - -Use the string argument if you want a single implementation file to -include code from multiple header files. (You must also use -@samp{#include} to include the header file; @samp{#pragma -implementation} only specifies how to use the file---it doesn't actually -include it.) - -There is no way to split up the contents of a single header file into -multiple implementation files. -@end table - -@cindex inlining and C++ pragmas -@cindex C++ pragmas, effect on inlining -@cindex pragmas in C++, effect on inlining -@samp{#pragma implementation} and @samp{#pragma interface} also have an -effect on function inlining. - -If you define a class in a header file marked with @samp{#pragma -interface}, the effect on an inline function defined in that class is -similar to an explicit @code{extern} declaration---the compiler emits -no code at all to define an independent version of the function. Its -definition is used only for inlining with its callers. - -@opindex fno-implement-inlines -Conversely, when you include the same header file in a main source file -that declares it as @samp{#pragma implementation}, the compiler emits -code for the function itself; this defines a version of the function -that can be found via pointers (or by callers compiled without -inlining). If all calls to the function can be inlined, you can avoid -emitting the function by compiling with @option{-fno-implement-inlines}. -If any calls were not inlined, you will get linker errors. - -@node Template Instantiation -@section Where's the Template? -@cindex template instantiation - -C++ templates are the first language feature to require more -intelligence from the environment than one usually finds on a UNIX -system. Somehow the compiler and linker have to make sure that each -template instance occurs exactly once in the executable if it is needed, -and not at all otherwise. There are two basic approaches to this -problem, which are referred to as the Borland model and the Cfront model. - -@table @asis -@item Borland model -Borland C++ solved the template instantiation problem by adding the code -equivalent of common blocks to their linker; the compiler emits template -instances in each translation unit that uses them, and the linker -collapses them together. The advantage of this model is that the linker -only has to consider the object files themselves; there is no external -complexity to worry about. This disadvantage is that compilation time -is increased because the template code is being compiled repeatedly. -Code written for this model tends to include definitions of all -templates in the header file, since they must be seen to be -instantiated. - -@item Cfront model -The AT&T C++ translator, Cfront, solved the template instantiation -problem by creating the notion of a template repository, an -automatically maintained place where template instances are stored. A -more modern version of the repository works as follows: As individual -object files are built, the compiler places any template definitions and -instantiations encountered in the repository. At link time, the link -wrapper adds in the objects in the repository and compiles any needed -instances that were not previously emitted. The advantages of this -model are more optimal compilation speed and the ability to use the -system linker; to implement the Borland model a compiler vendor also -needs to replace the linker. The disadvantages are vastly increased -complexity, and thus potential for error; for some code this can be -just as transparent, but in practice it can been very difficult to build -multiple programs in one directory and one program in multiple -directories. Code written for this model tends to separate definitions -of non-inline member templates into a separate file, which should be -compiled separately. -@end table - -When used with GNU ld version 2.8 or later on an ELF system such as -GNU/Linux or Solaris 2, or on Microsoft Windows, G++ supports the -Borland model. On other systems, G++ implements neither automatic -model. - -A future version of G++ will support a hybrid model whereby the compiler -will emit any instantiations for which the template definition is -included in the compile, and store template definitions and -instantiation context information into the object file for the rest. -The link wrapper will extract that information as necessary and invoke -the compiler to produce the remaining instantiations. The linker will -then combine duplicate instantiations. - -In the mean time, you have the following options for dealing with -template instantiations: - -@enumerate -@item -@opindex frepo -Compile your template-using code with @option{-frepo}. The compiler will -generate files with the extension @samp{.rpo} listing all of the -template instantiations used in the corresponding object files which -could be instantiated there; the link wrapper, @samp{collect2}, will -then update the @samp{.rpo} files to tell the compiler where to place -those instantiations and rebuild any affected object files. The -link-time overhead is negligible after the first pass, as the compiler -will continue to place the instantiations in the same files. - -This is your best option for application code written for the Borland -model, as it will just work. Code written for the Cfront model will -need to be modified so that the template definitions are available at -one or more points of instantiation; usually this is as simple as adding -@code{#include <tmethods.cc>} to the end of each template header. - -For library code, if you want the library to provide all of the template -instantiations it needs, just try to link all of its object files -together; the link will fail, but cause the instantiations to be -generated as a side effect. Be warned, however, that this may cause -conflicts if multiple libraries try to provide the same instantiations. -For greater control, use explicit instantiation as described in the next -option. - -@item -@opindex fno-implicit-templates -Compile your code with @option{-fno-implicit-templates} to disable the -implicit generation of template instances, and explicitly instantiate -all the ones you use. This approach requires more knowledge of exactly -which instances you need than do the others, but it's less -mysterious and allows greater control. You can scatter the explicit -instantiations throughout your program, perhaps putting them in the -translation units where the instances are used or the translation units -that define the templates themselves; you can put all of the explicit -instantiations you need into one big file; or you can create small files -like - -@smallexample -#include "Foo.h" -#include "Foo.cc" - -template class Foo<int>; -template ostream& operator << - (ostream&, const Foo<int>&); -@end smallexample - -for each of the instances you need, and create a template instantiation -library from those. - -If you are using Cfront-model code, you can probably get away with not -using @option{-fno-implicit-templates} when compiling files that don't -@samp{#include} the member template definitions. - -If you use one big file to do the instantiations, you may want to -compile it without @option{-fno-implicit-templates} so you get all of the -instances required by your explicit instantiations (but not by any -other files) without having to specify them as well. - -G++ has extended the template instantiation syntax given in the ISO -standard to allow forward declaration of explicit instantiations -(with @code{extern}), instantiation of the compiler support data for a -template class (i.e.@: the vtable) without instantiating any of its -members (with @code{inline}), and instantiation of only the static data -members of a template class, without the support data or member -functions (with (@code{static}): - -@smallexample -extern template int max (int, int); -inline template class Foo<int>; -static template class Foo<int>; -@end smallexample - -@item -Do nothing. Pretend G++ does implement automatic instantiation -management. Code written for the Borland model will work fine, but -each translation unit will contain instances of each of the templates it -uses. In a large program, this can lead to an unacceptable amount of code -duplication. -@end enumerate - -@node Bound member functions -@section Extracting the function pointer from a bound pointer to member function -@cindex pmf -@cindex pointer to member function -@cindex bound pointer to member function - -In C++, pointer to member functions (PMFs) are implemented using a wide -pointer of sorts to handle all the possible call mechanisms; the PMF -needs to store information about how to adjust the @samp{this} pointer, -and if the function pointed to is virtual, where to find the vtable, and -where in the vtable to look for the member function. If you are using -PMFs in an inner loop, you should really reconsider that decision. If -that is not an option, you can extract the pointer to the function that -would be called for a given object/PMF pair and call it directly inside -the inner loop, to save a bit of time. - -Note that you will still be paying the penalty for the call through a -function pointer; on most modern architectures, such a call defeats the -branch prediction features of the CPU@. This is also true of normal -virtual function calls. - -The syntax for this extension is - -@smallexample -extern A a; -extern int (A::*fp)(); -typedef int (*fptr)(A *); - -fptr p = (fptr)(a.*fp); -@end smallexample - -For PMF constants (i.e.@: expressions of the form @samp{&Klasse::Member}), -no object is needed to obtain the address of the function. They can be -converted to function pointers directly: - -@smallexample -fptr p1 = (fptr)(&A::foo); -@end smallexample - -@opindex Wno-pmf-conversions -You must specify @option{-Wno-pmf-conversions} to use this extension. - -@node C++ Attributes -@section C++-Specific Variable, Function, and Type Attributes - -Some attributes only make sense for C++ programs. - -@table @code -@item init_priority (@var{priority}) -@cindex init_priority attribute - - -In Standard C++, objects defined at namespace scope are guaranteed to be -initialized in an order in strict accordance with that of their definitions -@emph{in a given translation unit}. No guarantee is made for initializations -across translation units. However, GNU C++ allows users to control the -order of initialization of objects defined at namespace scope with the -@code{init_priority} attribute by specifying a relative @var{priority}, -a constant integral expression currently bounded between 101 and 65535 -inclusive. Lower numbers indicate a higher priority. - -In the following example, @code{A} would normally be created before -@code{B}, but the @code{init_priority} attribute has reversed that order: - -@smallexample -Some_Class A __attribute__ ((init_priority (2000))); -Some_Class B __attribute__ ((init_priority (543))); -@end smallexample - -@noindent -Note that the particular values of @var{priority} do not matter; only their -relative ordering. - -@item java_interface -@cindex java_interface attribute - -This type attribute informs C++ that the class is a Java interface. It may -only be applied to classes declared within an @code{extern "Java"} block. -Calls to methods declared in this interface will be dispatched using GCJ's -interface table mechanism, instead of regular virtual table dispatch. - -@end table - -See also @xref{Namespace Association}. - -@node Namespace Association -@section Namespace Association - -@strong{Caution:} The semantics of this extension are not fully -defined. Users should refrain from using this extension as its -semantics may change subtly over time. It is possible that this -extension will be removed in future versions of G++. - -A using-directive with @code{__attribute ((strong))} is stronger -than a normal using-directive in two ways: - -@itemize @bullet -@item -Templates from the used namespace can be specialized and explicitly -instantiated as though they were members of the using namespace. - -@item -The using namespace is considered an associated namespace of all -templates in the used namespace for purposes of argument-dependent -name lookup. -@end itemize - -The used namespace must be nested within the using namespace so that -normal unqualified lookup works properly. - -This is useful for composing a namespace transparently from -implementation namespaces. For example: - -@smallexample -namespace std @{ - namespace debug @{ - template <class T> struct A @{ @}; - @} - using namespace debug __attribute ((__strong__)); - template <> struct A<int> @{ @}; // @r{ok to specialize} - - template <class T> void f (A<T>); -@} - -int main() -@{ - f (std::A<float>()); // @r{lookup finds} std::f - f (std::A<int>()); -@} -@end smallexample - -@node Java Exceptions -@section Java Exceptions - -The Java language uses a slightly different exception handling model -from C++. Normally, GNU C++ will automatically detect when you are -writing C++ code that uses Java exceptions, and handle them -appropriately. However, if C++ code only needs to execute destructors -when Java exceptions are thrown through it, GCC will guess incorrectly. -Sample problematic code is: - -@smallexample - struct S @{ ~S(); @}; - extern void bar(); // @r{is written in Java, and may throw exceptions} - void foo() - @{ - S s; - bar(); - @} -@end smallexample - -@noindent -The usual effect of an incorrect guess is a link failure, complaining of -a missing routine called @samp{__gxx_personality_v0}. - -You can inform the compiler that Java exceptions are to be used in a -translation unit, irrespective of what it might think, by writing -@samp{@w{#pragma GCC java_exceptions}} at the head of the file. This -@samp{#pragma} must appear before any functions that throw or catch -exceptions, or run destructors when exceptions are thrown through them. - -You cannot mix Java and C++ exceptions in the same translation unit. It -is believed to be safe to throw a C++ exception from one file through -another file compiled for the Java exception model, or vice versa, but -there may be bugs in this area. - -@node Deprecated Features -@section Deprecated Features - -In the past, the GNU C++ compiler was extended to experiment with new -features, at a time when the C++ language was still evolving. Now that -the C++ standard is complete, some of those features are superseded by -superior alternatives. Using the old features might cause a warning in -some cases that the feature will be dropped in the future. In other -cases, the feature might be gone already. - -While the list below is not exhaustive, it documents some of the options -that are now deprecated: - -@table @code -@item -fexternal-templates -@itemx -falt-external-templates -These are two of the many ways for G++ to implement template -instantiation. @xref{Template Instantiation}. The C++ standard clearly -defines how template definitions have to be organized across -implementation units. G++ has an implicit instantiation mechanism that -should work just fine for standard-conforming code. - -@item -fstrict-prototype -@itemx -fno-strict-prototype -Previously it was possible to use an empty prototype parameter list to -indicate an unspecified number of parameters (like C), rather than no -parameters, as C++ demands. This feature has been removed, except where -it is required for backwards compatibility @xref{Backwards Compatibility}. -@end table - -G++ allows a virtual function returning @samp{void *} to be overridden -by one returning a different pointer type. This extension to the -covariant return type rules is now deprecated and will be removed from a -future version. - -The G++ minimum and maximum operators (@samp{<?} and @samp{>?}) and -their compound forms (@samp{<?=}) and @samp{>?=}) have been deprecated -@c APPLE LOCAL begin for-fsf-4_4 5482863 -and are now removed from G++. Code using these operators should be -modified to use @code{std::min} and @code{std::max} instead. - -@c APPLE LOCAL end for-fsf-4_4 5482863 -The named return value extension has been deprecated, and is now -removed from G++. - -The use of initializer lists with new expressions has been deprecated, -and is now removed from G++. - -Floating and complex non-type template parameters have been deprecated, -and are now removed from G++. - -The implicit typename extension has been deprecated and is now -removed from G++. - -The use of default arguments in function pointers, function typedefs -and other places where they are not permitted by the standard is -deprecated and will be removed from a future version of G++. - -G++ allows floating-point literals to appear in integral constant expressions, -e.g. @samp{ enum E @{ e = int(2.2 * 3.7) @} } -This extension is deprecated and will be removed from a future version. - -G++ allows static data members of const floating-point type to be declared -with an initializer in a class definition. The standard only allows -initializers for static members of const integral types and const -enumeration types so this extension has been deprecated and will be removed -from a future version. - -@node Backwards Compatibility -@section Backwards Compatibility -@cindex Backwards Compatibility -@cindex ARM [Annotated C++ Reference Manual] - -Now that there is a definitive ISO standard C++, G++ has a specification -to adhere to. The C++ language evolved over time, and features that -used to be acceptable in previous drafts of the standard, such as the ARM -[Annotated C++ Reference Manual], are no longer accepted. In order to allow -compilation of C++ written to such drafts, G++ contains some backwards -compatibilities. @emph{All such backwards compatibility features are -liable to disappear in future versions of G++.} They should be considered -deprecated @xref{Deprecated Features}. - -@table @code -@item For scope -If a variable is declared at for scope, it used to remain in scope until -the end of the scope which contained the for statement (rather than just -within the for scope). G++ retains this, but issues a warning, if such a -variable is accessed outside the for scope. - -@item Implicit C language -Old C system header files did not contain an @code{extern "C" @{@dots{}@}} -scope to set the language. On such systems, all header files are -implicitly scoped inside a C language scope. Also, an empty prototype -@code{()} will be treated as an unspecified number of arguments, rather -than no arguments, as C++ demands. -@end table |