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From: "theodort at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/102892] New: [12 Regression] Dead Code Elimination Regression at -O3 (trunk vs 11.2.0) Date: Fri, 22 Oct 2021 09:39:03 +0000 [thread overview] Message-ID: <bug-102892-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102892 Bug ID: 102892 Summary: [12 Regression] Dead Code Elimination Regression at -O3 (trunk vs 11.2.0) Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: theodort at inf dot ethz.ch Target Milestone: --- cat test.c static long b[2][1] = {0}; void bar(void); void foo(void); int main() { long c = 0; for (long a; a < 1; ++a) for (; c <= 1; c++) { bar(); if (1 == b[c][0]) foo(); } } 11.2.0 at -O3 can eliminate the call to foo but trunk at -O3 cannot: gcc-11 -O3 -S test.c -o /dev/stdout ... main: .LFB0: .cfi_startproc subq $8, %rsp .cfi_def_cfa_offset 16 call bar call bar xorl %eax, %eax addq $8, %rsp .cfi_def_cfa_offset 8 ret .cfi_endproc gcc-trunk-O3 -S test.c -o /dev/stdout main: .LFB0: .cfi_startproc pushq %rbx .cfi_def_cfa_offset 16 .cfi_offset 3, -16 xorl %ebx, %ebx call bar cmpq $1, b(,%rbx,8) je .L11 .p2align 4,,10 .p2align 3 .L3: cmpq $1, %rbx je .L12 .L5: call bar movl $1, %ebx cmpq $1, b(,%rbx,8) jne .L3 .L11: call foo cmpq $1, %rbx jne .L5 .L12: xorl %eax, %eax popq %rbx .cfi_def_cfa_offset 8 ret .cfi_endproc gcc-trunk -v Using built-in specs. Target: x86_64-pc-linux-gnu Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 12.0.0 20211022 (experimental) (GCC) Introduced with https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=01b5038718056b024b370b74a874fbd92c5bbab3
next reply other threads:[~2021-10-22 9:39 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-22 9:39 theodort at inf dot ethz.ch [this message] 2021-10-22 9:48 ` [Bug tree-optimization/102892] " aldyh at gcc dot gnu.org 2021-10-22 21:19 ` pinskia at gcc dot gnu.org 2021-10-23 9:29 ` aldyh at gcc dot gnu.org 2021-11-10 14:24 ` marxin at gcc dot gnu.org 2021-11-10 15:42 ` aldyh at gcc dot gnu.org 2021-11-10 15:46 ` marxin at gcc dot gnu.org 2021-11-10 15:52 ` aldyh at gcc dot gnu.org 2021-11-10 19:27 ` cvs-commit at gcc dot gnu.org 2022-03-28 9:18 ` ebotcazou at gcc dot gnu.org 2022-03-28 14:37 ` aldyh at gcc dot gnu.org 2022-03-28 14:55 ` jakub at gcc dot gnu.org 2022-04-22 3:04 ` jiawei at iscas dot ac.cn 2022-05-04 0:50 ` [Bug tree-optimization/102892] [12/13 " palmer at gcc dot gnu.org 2022-05-04 0:50 ` palmer at gcc dot gnu.org 2022-05-04 11:58 ` jiawei at iscas dot ac.cn 2022-05-06 8:31 ` jakub at gcc dot gnu.org 2022-07-26 13:21 ` rguenth at gcc dot gnu.org 2022-09-29 22:34 ` cvs-commit at gcc dot gnu.org 2022-10-19 9:42 ` cvs-commit at gcc dot gnu.org 2022-10-19 9:43 ` rguenth at gcc dot gnu.org
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