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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/107115] Wrong codegen from TBAA under stores that change effective type? Date: Thu, 06 Oct 2022 09:44:52 +0000 [thread overview] Message-ID: <bug-107115-4-rezUAo9uFY@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-107115-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107115 --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- So possibly expand_assignment is eliding the store somewhere downthread (it's operand_equal_p check shouldn't fire). It's rtx store_expr (tree exp, rtx target, int call_param_p, bool nontemporal, bool reverse) { ... if ((! rtx_equal_p (temp, target) || (temp != target && (side_effects_p (temp) || side_effects_p (target)))) which doesn't fire. We have (gdb) p debug_rtx (temp) (mem:DI (reg/f:DI 87 [ _11 ]) [2 *_11+0 S8 A64]) (gdb) p debug_rtx (target) (mem:DI (reg/f:DI 87 [ _11 ]) [1 MEM[(long int *)_11]+0 S8 A64]) Note that even just matching up MEM_ALIAS_SET isn't enough. I'd call the above optimization premature at least. (gdb) p mems_same_for_tbaa_p (temp, target) $13 = false so diff --git a/gcc/expr.cc b/gcc/expr.cc index 80bb1b8a4c5..71a7fc19c42 100644 --- a/gcc/expr.cc +++ b/gcc/expr.cc @@ -6207,7 +6207,8 @@ store_expr (tree exp, rtx target, int call_param_p, if ((! rtx_equal_p (temp, target) || (temp != target && (side_effects_p (temp) - || side_effects_p (target)))) + || side_effects_p (target) + || !mems_same_for_tbaa_p (temp, target)))) && TREE_CODE (exp) != ERROR_MARK /* If store_expr stores a DECL whose DECL_RTL(exp) == TARGET, but TARGET is not valid memory reference, TEMP will differ fixes this mistake. But then we run into the sched issue which -fno-schedule-insns2 "fixes".
next prev parent reply other threads:[~2022-10-06 9:44 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-10-01 20:00 [Bug middle-end/107115] New: " bugdal at aerifal dot cx 2022-10-01 23:34 ` [Bug rtl-optimization/107115] " pinskia at gcc dot gnu.org 2022-10-01 23:51 ` [Bug middle-end/107115] " pinskia at gcc dot gnu.org 2022-10-06 9:44 ` rguenth at gcc dot gnu.org [this message] 2022-10-06 12:20 ` cvs-commit at gcc dot gnu.org 2022-10-06 12:24 ` rguenth at gcc dot gnu.org 2022-10-06 15:19 ` amonakov at gcc dot gnu.org 2022-10-06 15:32 ` jakub at gcc dot gnu.org 2022-10-06 15:39 ` amonakov at gcc dot gnu.org 2022-10-06 19:04 ` pinskia at gcc dot gnu.org 2022-10-07 7:41 ` rguenth at gcc dot gnu.org 2022-10-07 7:44 ` rguenth at gcc dot gnu.org 2022-10-07 13:19 ` amonakov at gcc dot gnu.org 2022-12-27 22:19 ` gabravier at gmail dot com 2022-12-27 22:21 ` gabravier at gmail dot com
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