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diff --git a/gcc-4.2.1-5666.3/gcc/doc/interface.texi b/gcc-4.2.1-5666.3/gcc/doc/interface.texi deleted file mode 100644 index f6fdc329e..000000000 --- a/gcc-4.2.1-5666.3/gcc/doc/interface.texi +++ /dev/null @@ -1,71 +0,0 @@ -@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, -@c 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. -@c This is part of the GCC manual. -@c For copying conditions, see the file gcc.texi. - -@node Interface -@chapter Interfacing to GCC Output -@cindex interfacing to GCC output -@cindex run-time conventions -@cindex function call conventions -@cindex conventions, run-time - -GCC is normally configured to use the same function calling convention -normally in use on the target system. This is done with the -machine-description macros described (@pxref{Target Macros}). - -@cindex unions, returning -@cindex structures, returning -@cindex returning structures and unions -However, returning of structure and union values is done differently on -some target machines. As a result, functions compiled with PCC -returning such types cannot be called from code compiled with GCC, -and vice versa. This does not cause trouble often because few Unix -library routines return structures or unions. - -GCC code returns structures and unions that are 1, 2, 4 or 8 bytes -long in the same registers used for @code{int} or @code{double} return -values. (GCC typically allocates variables of such types in -registers also.) Structures and unions of other sizes are returned by -storing them into an address passed by the caller (usually in a -register). The target hook @code{TARGET_STRUCT_VALUE_RTX} -tells GCC where to pass this address. - -By contrast, PCC on most target machines returns structures and unions -of any size by copying the data into an area of static storage, and then -returning the address of that storage as if it were a pointer value. -The caller must copy the data from that memory area to the place where -the value is wanted. This is slower than the method used by GCC, and -fails to be reentrant. - -On some target machines, such as RISC machines and the 80386, the -standard system convention is to pass to the subroutine the address of -where to return the value. On these machines, GCC has been -configured to be compatible with the standard compiler, when this method -is used. It may not be compatible for structures of 1, 2, 4 or 8 bytes. - -@cindex argument passing -@cindex passing arguments -GCC uses the system's standard convention for passing arguments. On -some machines, the first few arguments are passed in registers; in -others, all are passed on the stack. It would be possible to use -registers for argument passing on any machine, and this would probably -result in a significant speedup. But the result would be complete -incompatibility with code that follows the standard convention. So this -change is practical only if you are switching to GCC as the sole C -compiler for the system. We may implement register argument passing on -certain machines once we have a complete GNU system so that we can -compile the libraries with GCC@. - -On some machines (particularly the SPARC), certain types of arguments -are passed ``by invisible reference''. This means that the value is -stored in memory, and the address of the memory location is passed to -the subroutine. - -@cindex @code{longjmp} and automatic variables -If you use @code{longjmp}, beware of automatic variables. ISO C says that -automatic variables that are not declared @code{volatile} have undefined -values after a @code{longjmp}. And this is all GCC promises to do, -because it is very difficult to restore register variables correctly, and -one of GCC's features is that it can put variables in registers without -your asking it to. |