https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103388
Bug ID: 103388 Summary: [12 Regression] missed optimization for dead code elimination at -O3 (vs. -O2) 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); void bar(void); static int b, d, e, *c, *f = &d, *h = &b; int main() { int **i = &c; if (e) { e = *f; bar(); if (!(((i && d) + *h >= 1 ^ d & b) <= 4 | d)) 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 e(%rip), %ecx testl %ecx, %ecx jne .L8 xorl %eax, %eax ret .L8: pushq %rax .cfi_def_cfa_offset 16 movl d(%rip), %eax movl %eax, e(%rip) call bar xorl %eax, %eax popq %rdx .cfi_def_cfa_offset 8 ret .cfi_endproc .LFE0: gcc-trunk -O3 -S -o /dev/stdout case.c main: .LFB0: .cfi_startproc movl e(%rip), %esi testl %esi, %esi jne .L10 xorl %eax, %eax ret .L10: pushq %rcx .cfi_def_cfa_offset 16 movl d(%rip), %eax movl %eax, e(%rip) call bar movl d(%rip), %edx movl b(%rip), %eax cmpl $1, %edx movl %eax, %ecx sbbl $-1, %ecx testl %ecx, %ecx setg %cl andl %edx, %eax movzbl %cl, %ecx xorl %ecx, %eax cmpl $4, %eax setle %al movzbl %al, %eax orl %edx, %eax je .L11 .L3: xorl %eax, %eax popq %rdx .cfi_remember_state .cfi_def_cfa_offset 8 ret .L11: .cfi_restore_state call foo jmp .L3 .cfi_endproc .LFE0: gcc-trunk -v Using built-in specs. Supported LTO compression algorithms: zlib zstd gcc version 12.0.0 20211123 (experimental) (GCC) Started with https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=4b3a325f07acebf47e82de227ce1d5ba62f5bcae