diff options
Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/cp/except.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/gcc/cp/except.c | 1026 |
1 files changed, 1026 insertions, 0 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/cp/except.c b/gcc-4.2.1-5666.3/gcc/cp/except.c new file mode 100644 index 000000000..09cb288a3 --- /dev/null +++ b/gcc-4.2.1-5666.3/gcc/cp/except.c @@ -0,0 +1,1026 @@ +/* Handle exceptional things in C++. + Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, + 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. + Contributed by Michael Tiemann <tiemann@cygnus.com> + Rewritten by Mike Stump <mrs@cygnus.com>, based upon an + initial re-implementation courtesy Tad Hunt. + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GCC is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING. If not, write to +the Free Software Foundation, 51 Franklin Street, Fifth Floor, +Boston, MA 02110-1301, USA. */ + + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "rtl.h" +#include "expr.h" +#include "libfuncs.h" +#include "cp-tree.h" +#include "flags.h" +#include "output.h" +#include "except.h" +#include "toplev.h" +#include "tree-inline.h" +#include "tree-iterator.h" +#include "target.h" + +static void push_eh_cleanup (tree); +static tree prepare_eh_type (tree); +static tree build_eh_type_type (tree); +/* APPLE LOCAL radar 2848255 */ +static tree do_begin_catch (tree); +static int dtor_nothrow (tree); +static tree do_end_catch (tree); +static bool decl_is_java_type (tree decl, int err); +static void initialize_handler_parm (tree, tree); +static tree do_allocate_exception (tree); +static tree wrap_cleanups_r (tree *, int *, void *); +static int complete_ptr_ref_or_void_ptr_p (tree, tree); +static bool is_admissible_throw_operand (tree); +static int can_convert_eh (tree, tree); +static tree cp_protect_cleanup_actions (void); + +/* Sets up all the global eh stuff that needs to be initialized at the + start of compilation. */ + +void +init_exception_processing (void) +{ + tree tmp; + + /* void std::terminate (); */ + push_namespace (std_identifier); + tmp = build_function_type (void_type_node, void_list_node); + terminate_node = build_cp_library_fn_ptr ("terminate", tmp); + TREE_THIS_VOLATILE (terminate_node) = 1; + TREE_NOTHROW (terminate_node) = 1; + pop_namespace (); + + /* void __cxa_call_unexpected(void *); */ + tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node); + tmp = build_function_type (void_type_node, tmp); + call_unexpected_node + = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp); + + eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS + ? "__gxx_personality_sj0" + : "__gxx_personality_v0"); + if (targetm.arm_eabi_unwinder) + unwind_resume_libfunc = init_one_libfunc ("__cxa_end_cleanup"); + else + default_init_unwind_resume_libfunc (); + + lang_eh_runtime_type = build_eh_type_type; + lang_protect_cleanup_actions = &cp_protect_cleanup_actions; +} + +/* Returns an expression to be executed if an unhandled exception is + propagated out of a cleanup region. */ + +static tree +cp_protect_cleanup_actions (void) +{ + /* [except.terminate] + + When the destruction of an object during stack unwinding exits + using an exception ... void terminate(); is called. */ + return build_call (terminate_node, NULL_TREE); +} + +static tree +prepare_eh_type (tree type) +{ + if (type == NULL_TREE) + return type; + if (type == error_mark_node) + return error_mark_node; + + /* peel back references, so they match. */ + type = non_reference (type); + + /* Peel off cv qualifiers. */ + type = TYPE_MAIN_VARIANT (type); + + return type; +} + +/* Return the type info for TYPE as used by EH machinery. */ +tree +eh_type_info (tree type) +{ + tree exp; + + if (type == NULL_TREE || type == error_mark_node) + return type; + + if (decl_is_java_type (type, 0)) + exp = build_java_class_ref (TREE_TYPE (type)); + else + exp = get_tinfo_decl (type); + + return exp; +} + +/* Build the address of a typeinfo decl for use in the runtime + matching field of the exception model. */ + +static tree +build_eh_type_type (tree type) +{ + tree exp = eh_type_info (type); + + if (!exp) + return NULL; + + mark_used (exp); + + return convert (ptr_type_node, build_address (exp)); +} + +tree +build_exc_ptr (void) +{ + return build0 (EXC_PTR_EXPR, ptr_type_node); +} + +/* Build up a call to __cxa_get_exception_ptr so that we can build a + copy constructor for the thrown object. */ + +static tree +do_get_exception_ptr (void) +{ + tree fn; + + fn = get_identifier ("__cxa_get_exception_ptr"); + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void* __cxa_get_exception_ptr (void *). */ + tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node); + fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp)); + } + + return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (), + NULL_TREE)); +} + +/* APPLE LOCAL begin radar 2848255 */ +tree objcp_build_eh_type_type (tree type) +{ + return build_eh_type_type (type); +} +/* APPLE LOCAL end radar 2848255 */ + +/* Build up a call to __cxa_begin_catch, to tell the runtime that the + exception has been handled. */ + +static tree +/* APPLE LOCAL radar 2848255 */ +do_begin_catch (tree type) +{ + tree fn; + + /* APPLE LOCAL begin radar 2848255 */ + if (c_dialect_objc () && objc2_valid_objc_catch_type (type)) + fn = get_identifier ("objc_begin_catch"); + else + fn = get_identifier ("__cxa_begin_catch"); + /* APPLE LOCAL end radar 2848255 */ + + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void* __cxa_begin_catch (void *). */ + tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node); + fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp)); + } + + return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (), + NULL_TREE)); +} + +/* Returns nonzero if cleaning up an exception of type TYPE (which can be + NULL_TREE for a ... handler) will not throw an exception. */ + +static int +dtor_nothrow (tree type) +{ + if (type == NULL_TREE) + return 0; + + if (!CLASS_TYPE_P (type)) + return 1; + + if (CLASSTYPE_LAZY_DESTRUCTOR (type)) + lazily_declare_fn (sfk_destructor, type); + + return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type)); +} + +/* Build up a call to __cxa_end_catch, to destroy the exception object + for the current catch block if no others are currently using it. */ + +static tree +do_end_catch (tree type) +{ + tree fn, cleanup; + + /* APPLE LOCAL begin radar 2848255 */ + if (c_dialect_objc () && objc2_valid_objc_catch_type (type)) + fn = get_identifier ("objc_end_catch"); + else + fn = get_identifier ("__cxa_end_catch"); + /* APPLE LOCAL end radar 2848255 */ + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void __cxa_end_catch (). */ + fn = push_void_library_fn (fn, void_list_node); + /* This can throw if the destructor for the exception throws. */ + TREE_NOTHROW (fn) = 0; + } + + cleanup = build_function_call (fn, NULL_TREE); + TREE_NOTHROW (cleanup) = dtor_nothrow (type); + + return cleanup; +} + +/* This routine creates the cleanup for the current exception. */ + +static void +push_eh_cleanup (tree type) +{ + finish_decl_cleanup (NULL_TREE, do_end_catch (type)); +} + +/* Return nonzero value if DECL is a Java type suitable for catch or + throw. */ + +static bool +decl_is_java_type (tree decl, int err) +{ + bool r = (TREE_CODE (decl) == POINTER_TYPE + && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE + && TYPE_FOR_JAVA (TREE_TYPE (decl))); + + if (err) + { + if (TREE_CODE (decl) == REFERENCE_TYPE + && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE + && TYPE_FOR_JAVA (TREE_TYPE (decl))) + { + /* Can't throw a reference. */ + error ("type %qT is disallowed in Java %<throw%> or %<catch%>", + decl); + } + + if (r) + { + tree jthrow_node + = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable")); + + if (jthrow_node == NULL_TREE) + fatal_error + ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined"); + + jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node)); + + if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl))) + { + /* Thrown object must be a Throwable. */ + error ("type %qT is not derived from %<java::lang::Throwable%>", + TREE_TYPE (decl)); + } + } + } + + return r; +} + +/* Select the personality routine to be used for exception handling, + or issue an error if we need two different ones in the same + translation unit. + ??? At present eh_personality_libfunc is set to + __gxx_personality_(sj|v)0 in init_exception_processing - should it + be done here instead? */ +void +choose_personality_routine (enum languages lang) +{ + static enum { + chose_none, + chose_cpp, + chose_java, + gave_error + } state; + + switch (state) + { + case gave_error: + return; + + case chose_cpp: + if (lang != lang_cplusplus) + goto give_error; + return; + + case chose_java: + if (lang != lang_java) + goto give_error; + return; + + case chose_none: + ; /* Proceed to language selection. */ + } + + switch (lang) + { + case lang_cplusplus: + state = chose_cpp; + break; + + case lang_java: + state = chose_java; + eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS + ? "__gcj_personality_sj0" + : "__gcj_personality_v0"); + break; + + default: + gcc_unreachable (); + } + return; + + give_error: + error ("mixing C++ and Java catches in a single translation unit"); + state = gave_error; +} + +/* Initialize the catch parameter DECL. */ + +static void +initialize_handler_parm (tree decl, tree exp) +{ + tree init; + tree init_type; + + /* Make sure we mark the catch param as used, otherwise we'll get a + warning about an unused ((anonymous)). */ + TREE_USED (decl) = 1; + + /* Figure out the type that the initializer is. Pointers are returned + adjusted by value from __cxa_begin_catch. Others are returned by + reference. */ + init_type = TREE_TYPE (decl); + if (!POINTER_TYPE_P (init_type)) + init_type = build_reference_type (init_type); + + choose_personality_routine (decl_is_java_type (init_type, 0) + ? lang_java : lang_cplusplus); + + /* Since pointers are passed by value, initialize a reference to + pointer catch parm with the address of the temporary. */ + if (TREE_CODE (init_type) == REFERENCE_TYPE + && TYPE_PTR_P (TREE_TYPE (init_type))) + exp = build_unary_op (ADDR_EXPR, exp, 1); + + exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0); + + init = convert_from_reference (exp); + + /* If the constructor for the catch parm exits via an exception, we + must call terminate. See eh23.C. */ + if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl))) + { + /* Generate the copy constructor call directly so we can wrap it. + See also expand_default_init. */ + init = ocp_convert (TREE_TYPE (decl), init, + CONV_IMPLICIT|CONV_FORCE_TEMP, 0); + init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init); + } + + decl = pushdecl (decl); + + start_decl_1 (decl, true); + cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE, + LOOKUP_ONLYCONVERTING|DIRECT_BIND); +} + +/* Call this to start a catch block. DECL is the catch parameter. */ + +tree +expand_start_catch_block (tree decl) +{ + tree exp; + tree type; + + if (! doing_eh (1)) + return NULL_TREE; + + /* Make sure this declaration is reasonable. */ + if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE)) + decl = error_mark_node; + + if (decl) + type = prepare_eh_type (TREE_TYPE (decl)); + else + type = NULL_TREE; + + if (decl && decl_is_java_type (type, 1)) + { + /* Java only passes object via pointer and doesn't require + adjusting. The java object is immediately before the + generic exception header. */ + exp = build_exc_ptr (); + exp = build1 (NOP_EXPR, build_pointer_type (type), exp); + exp = build2 (MINUS_EXPR, TREE_TYPE (exp), exp, + TYPE_SIZE_UNIT (TREE_TYPE (exp))); + exp = build_indirect_ref (exp, NULL); + initialize_handler_parm (decl, exp); + return type; + } + + /* Call __cxa_end_catch at the end of processing the exception. */ + push_eh_cleanup (type); + + /* If there's no decl at all, then all we need to do is make sure + to tell the runtime that we've begun handling the exception. */ + if (decl == NULL || decl == error_mark_node) + /* APPLE LOCAL radar 2848255 */ + finish_expr_stmt (do_begin_catch (NULL_TREE)); + + /* If the C++ object needs constructing, we need to do that before + calling __cxa_begin_catch, so that std::uncaught_exception gets + the right value during the copy constructor. */ + else if (flag_use_cxa_get_exception_ptr + && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl))) + { + exp = do_get_exception_ptr (); + initialize_handler_parm (decl, exp); + /* APPLE LOCAL radar 2848255 */ + finish_expr_stmt (do_begin_catch (type)); + } + + /* Otherwise the type uses a bitwise copy, and we don't have to worry + about the value of std::uncaught_exception and therefore can do the + copy with the return value of __cxa_end_catch instead. */ + else + { + /* APPLE LOCAL radar 2848255 */ + tree init = do_begin_catch (type); + tree init_type = type; + + /* Pointers are passed by values, everything else by reference. */ + if (!TYPE_PTR_P (type)) + init_type = build_pointer_type (type); + if (init_type != TREE_TYPE (init)) + init = build1 (NOP_EXPR, init_type, init); + exp = create_temporary_var (init_type); + DECL_REGISTER (exp) = 1; + cp_finish_decl (exp, init, /*init_const_expr=*/false, + NULL_TREE, LOOKUP_ONLYCONVERTING); + initialize_handler_parm (decl, exp); + } + + return type; +} + + +/* Call this to end a catch block. Its responsible for emitting the + code to handle jumping back to the correct place, and for emitting + the label to jump to if this catch block didn't match. */ + +void +expand_end_catch_block (void) +{ + if (! doing_eh (1)) + return; + + /* The exception being handled is rethrown if control reaches the end of + a handler of the function-try-block of a constructor or destructor. */ + if (in_function_try_handler + && (DECL_CONSTRUCTOR_P (current_function_decl) + || DECL_DESTRUCTOR_P (current_function_decl))) + finish_expr_stmt (build_throw (NULL_TREE)); +} + +tree +begin_eh_spec_block (void) +{ + tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE); + add_stmt (r); + EH_SPEC_STMTS (r) = push_stmt_list (); + return r; +} + +void +finish_eh_spec_block (tree raw_raises, tree eh_spec_block) +{ + tree raises; + + EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block)); + + /* Strip cv quals, etc, from the specification types. */ + for (raises = NULL_TREE; + raw_raises && TREE_VALUE (raw_raises); + raw_raises = TREE_CHAIN (raw_raises)) + { + tree type = prepare_eh_type (TREE_VALUE (raw_raises)); + tree tinfo = eh_type_info (type); + + mark_used (tinfo); + raises = tree_cons (NULL_TREE, type, raises); + } + + EH_SPEC_RAISES (eh_spec_block) = raises; +} + +/* Return a pointer to a buffer for an exception object of type TYPE. */ + +static tree +do_allocate_exception (tree type) +{ + tree fn; + + fn = get_identifier ("__cxa_allocate_exception"); + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void *__cxa_allocate_exception(size_t). */ + tree tmp = tree_cons (NULL_TREE, size_type_node, void_list_node); + fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp)); + } + + return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type), + NULL_TREE)); +} + +/* Call __cxa_free_exception from a cleanup. This is never invoked + directly, but see the comment for stabilize_throw_expr. */ + +static tree +do_free_exception (tree ptr) +{ + tree fn; + + fn = get_identifier ("__cxa_free_exception"); + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void __cxa_free_exception (void *). */ + fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node, + void_list_node)); + } + + return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE)); +} + +/* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR. + Called from build_throw via walk_tree_without_duplicates. */ + +static tree +wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, + void *data ATTRIBUTE_UNUSED) +{ + tree exp = *tp; + tree cleanup; + + /* Don't walk into types. */ + if (TYPE_P (exp)) + { + *walk_subtrees = 0; + return NULL_TREE; + } + if (TREE_CODE (exp) != TARGET_EXPR) + return NULL_TREE; + + cleanup = TARGET_EXPR_CLEANUP (exp); + if (cleanup) + { + cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup); + TARGET_EXPR_CLEANUP (exp) = cleanup; + } + + /* Keep iterating. */ + return NULL_TREE; +} + +/* Build a throw expression. */ + +tree +build_throw (tree exp) +{ + tree fn; + + if (exp == error_mark_node) + return exp; + + if (processing_template_decl) + { + if (cfun) + current_function_returns_abnormally = 1; + return build_min (THROW_EXPR, void_type_node, exp); + } + + if (exp == null_node) + warning (0, "throwing NULL, which has integral, not pointer type"); + + if (exp != NULL_TREE) + { + if (!is_admissible_throw_operand (exp)) + return error_mark_node; + } + + if (! doing_eh (1)) + return error_mark_node; + + if (exp && decl_is_java_type (TREE_TYPE (exp), 1)) + { + tree fn = get_identifier ("_Jv_Throw"); + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void _Jv_Throw (void *). */ + tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node); + tmp = build_function_type (ptr_type_node, tmp); + fn = push_throw_library_fn (fn, tmp); + } + else if (really_overloaded_fn (fn)) + { + error ("%qD should never be overloaded", fn); + return error_mark_node; + } + fn = OVL_CURRENT (fn); + exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE)); + } + /* APPLE LOCAL begin radar 2848255 */ + else if (c_dialect_objc () + && exp && objc2_valid_objc_catch_type (TREE_TYPE (exp))) + return objc2_build_throw_call (exp); + /* APPLE LOCAL end radar 2848255 */ + else if (exp) + { + tree throw_type; + tree temp_type; + tree cleanup; + tree object, ptr; + tree tmp; + tree temp_expr, allocate_expr; + bool elided; + + /* The CLEANUP_TYPE is the internal type of a destructor. */ + if (!cleanup_type) + { + tmp = void_list_node; + tmp = tree_cons (NULL_TREE, ptr_type_node, tmp); + tmp = build_function_type (void_type_node, tmp); + cleanup_type = build_pointer_type (tmp); + } + + fn = get_identifier ("__cxa_throw"); + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */ + /* ??? Second argument is supposed to be "std::type_info*". */ + tmp = void_list_node; + tmp = tree_cons (NULL_TREE, cleanup_type, tmp); + tmp = tree_cons (NULL_TREE, ptr_type_node, tmp); + tmp = tree_cons (NULL_TREE, ptr_type_node, tmp); + tmp = build_function_type (void_type_node, tmp); + fn = push_throw_library_fn (fn, tmp); + } + + /* [except.throw] + + A throw-expression initializes a temporary object, the type + of which is determined by removing any top-level + cv-qualifiers from the static type of the operand of throw + and adjusting the type from "array of T" or "function return + T" to "pointer to T" or "pointer to function returning T" + respectively. */ + temp_type = is_bitfield_expr_with_lowered_type (exp); + if (!temp_type) + temp_type = type_decays_to (TYPE_MAIN_VARIANT (TREE_TYPE (exp))); + + /* OK, this is kind of wacky. The standard says that we call + terminate when the exception handling mechanism, after + completing evaluation of the expression to be thrown but + before the exception is caught (_except.throw_), calls a + user function that exits via an uncaught exception. + + So we have to protect the actual initialization of the + exception object with terminate(), but evaluate the + expression first. Since there could be temps in the + expression, we need to handle that, too. We also expand + the call to __cxa_allocate_exception first (which doesn't + matter, since it can't throw). */ + + /* Allocate the space for the exception. */ + allocate_expr = do_allocate_exception (temp_type); + allocate_expr = get_target_expr (allocate_expr); + ptr = TARGET_EXPR_SLOT (allocate_expr); + object = build_nop (build_pointer_type (temp_type), ptr); + object = build_indirect_ref (object, NULL); + + elided = (TREE_CODE (exp) == TARGET_EXPR); + + /* And initialize the exception object. */ + if (CLASS_TYPE_P (temp_type)) + { + /* Call the copy constructor. */ + exp = (build_special_member_call + (object, complete_ctor_identifier, + build_tree_list (NULL_TREE, exp), + TREE_TYPE (object), + LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING)); + if (exp == error_mark_node) + { + error (" in thrown expression"); + return error_mark_node; + } + } + else + exp = build2 (INIT_EXPR, temp_type, object, + decay_conversion (exp)); + + /* Pre-evaluate the thrown expression first, since if we allocated + the space first we would have to deal with cleaning it up if + evaluating this expression throws. + + The case where EXP the initializer is a cast or a function + returning a class is a bit of a grey area in the standard; it's + unclear whether or not it should be allowed to throw. We used to + say no, as that allowed us to optimize this case without worrying + about deallocating the exception object if it does. But that + conflicted with expectations (PR 13944) and the EDG compiler; now + we wrap the initialization in a TRY_CATCH_EXPR to call + do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this + case only. + + BUT: Issue 475 may do away with this inconsistency by removing the + terminate() in this situation. + + Note that we don't check the return value from stabilize_init + because it will only return false in cases where elided is true, + and therefore we don't need to work around the failure to + preevaluate. */ + temp_expr = NULL_TREE; + stabilize_init (exp, &temp_expr); + + /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups + for temporaries within the initialization are run before the one + for the exception object, preserving LIFO order. */ + exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp); + + if (elided) + exp = build2 (TRY_CATCH_EXPR, void_type_node, exp, + do_free_exception (ptr)); + else + exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp); + + /* Prepend the allocation. */ + exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp); + if (temp_expr) + { + /* Prepend the calculation of the throw expression. Also, force + any cleanups from the expression to be evaluated here so that + we don't have to do them during unwinding. But first wrap + them in MUST_NOT_THROW_EXPR, since they are run after the + exception object is initialized. */ + walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0); + exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp); + exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp); + } + + throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object))); + + if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object))) + { + cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)), + complete_dtor_identifier, 0); + cleanup = BASELINK_FUNCTIONS (cleanup); + mark_used (cleanup); + cxx_mark_addressable (cleanup); + /* Pretend it's a normal function. */ + cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup); + } + else + cleanup = build_int_cst (cleanup_type, 0); + + tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE); + tmp = tree_cons (NULL_TREE, throw_type, tmp); + tmp = tree_cons (NULL_TREE, ptr, tmp); + /* ??? Indicate that this function call throws throw_type. */ + tmp = build_function_call (fn, tmp); + + /* Tack on the initialization stuff. */ + exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp); + } + else + { + /* Rethrow current exception. */ + + tree fn = get_identifier ("__cxa_rethrow"); + if (!get_global_value_if_present (fn, &fn)) + { + /* Declare void __cxa_rethrow (void). */ + fn = push_throw_library_fn + (fn, build_function_type (void_type_node, void_list_node)); + } + + /* ??? Indicate that this function call allows exceptions of the type + of the enclosing catch block (if known). */ + exp = build_function_call (fn, NULL_TREE); + } + + exp = build1 (THROW_EXPR, void_type_node, exp); + + return exp; +} + +/* Make sure TYPE is complete, pointer to complete, reference to + complete, or pointer to cv void. Issue diagnostic on failure. + Return the zero on failure and nonzero on success. FROM can be + the expr or decl from whence TYPE came, if available. */ + +static int +complete_ptr_ref_or_void_ptr_p (tree type, tree from) +{ + int is_ptr; + + /* Check complete. */ + type = complete_type_or_else (type, from); + if (!type) + return 0; + + /* Or a pointer or ref to one, or cv void *. */ + is_ptr = TREE_CODE (type) == POINTER_TYPE; + if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE) + { + tree core = TREE_TYPE (type); + + if (is_ptr && VOID_TYPE_P (core)) + /* OK */; + else if (!complete_type_or_else (core, from)) + return 0; + } + return 1; +} + +/* Return truth-value if EXPRESSION is admissible in throw-expression, + i.e. if it is not of incomplete type or a pointer/reference to such + a type or of an abstract class type. */ + +static bool +is_admissible_throw_operand (tree expr) +{ + tree type = TREE_TYPE (expr); + + /* 15.1/4 [...] The type of the throw-expression shall not be an + incomplete type, or a pointer or a reference to an incomplete + type, other than void*, const void*, volatile void*, or + const volatile void*. Except for these restriction and the + restrictions on type matching mentioned in 15.3, the operand + of throw is treated exactly as a function argument in a call + (5.2.2) or the operand of a return statement. */ + if (!complete_ptr_ref_or_void_ptr_p (type, expr)) + return false; + + /* 10.4/3 An abstract class shall not be used as a parameter type, + as a function return type or as type of an explicit + conversion. */ + else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type)) + { + error ("expression %qE of abstract class type %qT cannot " + "be used in throw-expression", expr, type); + return false; + } + + return true; +} + +/* Returns nonzero if FN is a declaration of a standard C library + function which is known not to throw. + + [lib.res.on.exception.handling]: None of the functions from the + Standard C library shall report an error by throwing an + exception, unless it calls a program-supplied function that + throws an exception. */ + +#include "cfns.h" + +int +nothrow_libfn_p (tree fn) +{ + tree id; + + if (TREE_PUBLIC (fn) + && DECL_EXTERNAL (fn) + && DECL_NAMESPACE_SCOPE_P (fn) + && DECL_EXTERN_C_P (fn)) + /* OK */; + else + /* Can't be a C library function. */ + return 0; + + /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME + unless the system headers are playing rename tricks, and if + they are, we don't want to be confused by them. */ + id = DECL_NAME (fn); + return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id)); +} + +/* Returns nonzero if an exception of type FROM will be caught by a + handler for type TO, as per [except.handle]. */ + +static int +can_convert_eh (tree to, tree from) +{ + to = non_reference (to); + from = non_reference (from); + + if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE) + { + to = TREE_TYPE (to); + from = TREE_TYPE (from); + + if (! at_least_as_qualified_p (to, from)) + return 0; + + if (TREE_CODE (to) == VOID_TYPE) + return 1; + + /* Else fall through. */ + } + + if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from) + && PUBLICLY_UNIQUELY_DERIVED_P (to, from)) + return 1; + + return 0; +} + +/* Check whether any of the handlers in I are shadowed by another handler + accepting TYPE. Note that the shadowing may not be complete; even if + an exception of type B would be caught by a handler for A, there could + be a derived class C for which A is an ambiguous base but B is not, so + the handler for B would catch an exception of type C. */ + +static void +check_handlers_1 (tree master, tree_stmt_iterator i) +{ + tree type = TREE_TYPE (master); + + for (; !tsi_end_p (i); tsi_next (&i)) + { + tree handler = tsi_stmt (i); + if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler))) + { + warning (0, "%Hexception of type %qT will be caught", + EXPR_LOCUS (handler), TREE_TYPE (handler)); + warning (0, "%H by earlier handler for %qT", + EXPR_LOCUS (master), type); + break; + } + } +} + +/* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */ + +void +check_handlers (tree handlers) +{ + tree_stmt_iterator i; + + /* If we don't have a STATEMENT_LIST, then we've just got one + handler, and thus nothing to warn about. */ + if (TREE_CODE (handlers) != STATEMENT_LIST) + return; + + i = tsi_start (handlers); + if (!tsi_end_p (i)) + while (1) + { + tree handler = tsi_stmt (i); + tsi_next (&i); + + /* No more handlers; nothing to shadow. */ + if (tsi_end_p (i)) + break; + if (TREE_TYPE (handler) == NULL_TREE) + pedwarn ("%H%<...%> handler must be the last handler for" + " its try block", EXPR_LOCUS (handler)); + else + check_handlers_1 (handler, i); + } +} |