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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/102705] New: [12 Regression] Dead Code Elimination Regression at -O3 (trunk vs 11.2.0) Date: Tue, 12 Oct 2021 13:41:56 +0000 [thread overview] Message-ID: <bug-102705-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102705 Bug ID: 102705 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 void foo(void); static int b; static char c; static short a(short d, short e) { return e == 0 || d && e == 1 ? 0 : d % e; } int main() { b = c = b >= 2 ? 0 : 1 >> b; short f = a(0 >= 0 ^ c, 5); if (f == c) foo(); a(0, 9); } 11.2.0 at -O3 can eliminate the call to foo but trunk at -O3 cannot: gcc-11.2.0 test.c -S -O3 -o /dev/stdout main: .LFB1: .cfi_startproc movl b(%rip), %ecx movl $1, %eax sarl %cl, %eax movl %eax, %edx xorl %eax, %eax cmpl $2, %ecx cmovl %edx, %eax movsbl %al, %eax movl %eax, b(%rip) xorl %eax, %eax ret .cfi_endproc gcc-trunk test.c -S -O3 -o /dev/stdout main: .LFB1: .cfi_startproc movl b(%rip), %ecx cmpl $1, %ecx jle .L2 xorl %ecx, %ecx movl %ecx, b(%rip) .L5: xorl %eax, %eax ret .L2: movl $1, %eax sarl %cl, %eax movl %eax, %edx movl %eax, b(%rip) xorl $1, %edx movsbw %dl, %dx cmpw %ax, %dx jne .L5 pushq %rax .cfi_def_cfa_offset 16 call foo xorl %eax, %eax popq %rdx .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 20211012 (experimental) (GCC) It started with https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=145bc41dae7c7bfa093d61e77346f98e6a595a0e
next reply other threads:[~2021-10-12 13:41 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-12 13:41 theodort at inf dot ethz.ch [this message] 2021-10-12 13:51 ` [Bug tree-optimization/102705] [12 Regression] Dead Code Elimination Regression at -O3 since r12-2637-g145bc41dae7c7bfa093d61e77346f98e6a595a0e marxin at gcc dot gnu.org 2021-10-13 6:22 ` rguenth at gcc dot gnu.org 2021-10-13 19:25 ` amacleod at redhat dot com 2022-01-19 9:18 ` rguenth at gcc dot gnu.org 2022-05-06 8:31 ` [Bug tree-optimization/102705] [12/13 " jakub at gcc dot gnu.org 2022-10-19 9:35 ` rguenth at gcc dot gnu.org 2023-05-08 12:22 ` [Bug tree-optimization/102705] [12/13/14 " rguenth at gcc dot gnu.org 2024-02-21 7:00 ` pinskia at gcc dot gnu.org
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