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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/103281] New: [12 Regression] Dead Code Elimination Regression at -O3 (trunk vs 11.2.0) Date: Tue, 16 Nov 2021 18:31:51 +0000 [thread overview] Message-ID: <bug-103281-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103281 Bug ID: 103281 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 case.c void foo(void); static unsigned b; int main() { for (; b < 3; b++) { char c = b; char a = c ? c : c << 1; if (!(a < 1 ^ b)) foo(); } } trunk cannot eliminate the call to foo but 11.2.0 can: gcc-11.2.0 -O3 -S -o /dev/stdout case.c main: .LFB0: .cfi_startproc movl b(%rip), %eax cmpl $2, %eax ja .L6 testl %eax, %eax movl $1, %edx cmove %edx, %eax .L8: addl $1, %eax movl %eax, b(%rip) cmpl $2, %eax je .L8 .L6: xorl %eax, %eax ret .cfi_endproc gcc-trunk -O3 -S -o /dev/stdout case.c main: .LFB0: .cfi_startproc movl b(%rip), %eax cmpl $2, %eax ja .L13 .p2align 4,,10 .p2align 3 .L12: xorl %edx, %edx testb %al, %al setle %dl cmpl %eax, %edx je .L16 addl $1, %eax movl %eax, b(%rip) cmpl $3, %eax jne .L12 .L13: xorl %eax, %eax ret .p2align 4,,10 .p2align 3 .L16: subq $8, %rsp .cfi_def_cfa_offset 16 .L14: call foo movl b(%rip), %eax addl $1, %eax movl %eax, b(%rip) cmpl $2, %eax ja .L7 .L2: xorl %edx, %edx testb %al, %al setle %dl cmpl %eax, %edx je .L14 addl $1, %eax movl %eax, b(%rip) cmpl $3, %eax jne .L2 .L7: xorl %eax, %eax popq %rdx .cfi_def_cfa_offset 8 ret .cfi_endproc gcc-trunk -v Using built-in specs. Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 12.0.0 20211116 (experimental) (GCC) Started with https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=7d6979197274a662da7bdc564314afe8415865c1
next reply other threads:[~2021-11-16 18:31 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-16 18:31 theodort at inf dot ethz.ch [this message] 2021-11-16 20:51 ` [Bug tree-optimization/103281] [9/12 " pinskia at gcc dot gnu.org 2021-11-16 20:52 ` [Bug tree-optimization/103281] [9/10/12 " pinskia at gcc dot gnu.org 2021-11-16 21:03 ` pinskia at gcc dot gnu.org 2021-11-16 21:16 ` pinskia at gcc dot gnu.org 2021-11-18 10:31 ` marxin at gcc dot gnu.org 2022-01-18 14:28 ` rguenth at gcc dot gnu.org 2022-05-27 9:46 ` [Bug tree-optimization/103281] [10/12/13 " rguenth at gcc dot gnu.org 2022-06-28 10:46 ` jakub at gcc dot gnu.org 2023-05-01 23:49 ` [Bug tree-optimization/103281] [10/12/13/14 " pinskia at gcc dot gnu.org 2023-08-07 5:47 ` [Bug tree-optimization/103281] [12/13/14 " pinskia at gcc dot gnu.org 2023-08-07 6:34 ` pinskia at gcc dot gnu.org 2023-08-07 6:34 ` pinskia at gcc dot gnu.org 2023-08-08 15:42 ` cvs-commit at gcc dot gnu.org 2023-08-08 15:43 ` pinskia at gcc dot gnu.org 2023-08-08 15:46 ` pinskia at gcc dot gnu.org
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