If a function definition is present, except.c:set_nothrow_function_flags marks functions as nothrow depending on analysis of the function definition. This is incorrect when the function does not bind locally (compare with other function analysis in PR tree-optimization/27781).
Created attachment 12370 [details] test case - main file
Created attachment 12371 [details] test case - actual definition of function foo
While except.c:set_nothrow_function_flags analyzes rtl, the DECL_NOTHROW flag it computes is a tree bit. via calls.c:flags_from_decl_or_type -> calls.c:call_expr_flags -> tree-eh.c:tree_could_throw_p makes this information is made available to the tree optimizers.
http://gcc.gnu.org/ml/gcc-patches/2000-03/msg00354.html So this is a regression from 2.95.3.
The frontend marks foo () TREE_STATIC in start_preparsed_function () and later TREE_NOTHROW in finish_function () because /* If this function can't throw any exceptions, remember that. */ if (!processing_template_decl && !cp_function_chain->can_throw && !flag_non_call_exceptions) TREE_NOTHROW (fndecl) = 1; where cp_function_chain->can_throw is 0 (its initial value(?)). Fixing that and the RTL problem fixes the testcase. I am, of course, not sure if the C++ frontend fix is ok. Index: except.c =================================================================== --- except.c (revision 117569) +++ except.c (working copy) @@ -2787,6 +2787,9 @@ set_nothrow_function_flags (void) { rtx insn; + if (!targetm.binds_local_p (current_function_decl)) + return 0; + TREE_NOTHROW (current_function_decl) = 1; /* Assume cfun->all_throwers_are_sibcalls until we encounter Index: cp/decl.c =================================================================== --- cp/decl.c (revision 117569) +++ cp/decl.c (working copy) @@ -11081,7 +11081,8 @@ finish_function (int flags) /* If this function can't throw any exceptions, remember that. */ if (!processing_template_decl && !cp_function_chain->can_throw - && !flag_non_call_exceptions) + && !flag_non_call_exceptions + && targetm.binds_local_p (fndecl)) TREE_NOTHROW (fndecl) = 1; /* This must come after expand_function_end because cleanups might
Subject: Bug number PR29323 A patch for this bug has been added to the patch tracker. The mailing list url for the patch is http://gcc.gnu.org/ml/gcc-patches/2006-10/msg00458.html
Subject: Bug 29323 Author: rguenth Date: Tue Oct 10 08:27:02 2006 New Revision: 117598 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=117598 Log: 2006-10-10 Richard Guenther <rguenther@suse.de> PR rtl-optimization/29323 * except.c (set_nothrow_function_flags): For functions that do not bind local bail out early. * decl.c (finish_function): Set TREE_NOTHROW only for functions that bind local. Modified: trunk/gcc/ChangeLog trunk/gcc/cp/ChangeLog trunk/gcc/cp/decl.c trunk/gcc/except.c
Fixed on the mainline.
Subject: Bug 29323 Author: rguenth Date: Sat Oct 14 09:13:43 2006 New Revision: 117727 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=117727 Log: 2006-10-14 Richard Guenther <rguenther@suse.de> PR rtl-optimization/29323 * except.c (set_nothrow_function_flags): For functions that do not bind local bail out early. * decl.c (finish_function): Set TREE_NOTHROW only for functions that bind local. Modified: branches/gcc-4_1-branch/gcc/ChangeLog branches/gcc-4_1-branch/gcc/cp/ChangeLog branches/gcc-4_1-branch/gcc/cp/decl.c branches/gcc-4_1-branch/gcc/except.c
Fixed for 4.1.2.
Fixed in GCC-4.1.2.