[Bug tree-optimization/103257] New: [12 Regression] Dead Code Elimination Regression at -O3 (trunk vs 11.2.0)

["theodort at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103257

            Bug ID: 103257
           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);
unsigned b, c;
static short a(short e, short f) { return e * f; }
int main() {
  if (a(1  ^ ((0, 0) ^ 1 && b) <= b, c))
    foo();
  c = 0;
}

11.2.0 at -O3 can eliminate the call to foo but trunk at -O3 cannot:

gcc11  case.c -S -O3 -o /dev/stdout
main:
.LFB1:
        .cfi_startproc
        movl    b(%rip), %eax
        xorl    %edx, %edx
        testl   %eax, %eax
        setne   %dl
        cmpl    %edx, %eax
        movl    $0, %eax
        cmovb   c(%rip), %ax
        testw   %ax, %ax
        jne     .L11
        movl    $0, c(%rip)
        xorl    %eax, %eax
        ret
.L11:
        pushq   %rax
        .cfi_def_cfa_offset 16
        call    foo
        xorl    %edx, %edx
        xorl    %eax, %eax
        movl    %edx, c(%rip)
        popq    %rcx
        .cfi_def_cfa_offset 8
        ret
        .cfi_endproc


gcc-trunk -v
Target: x86_64-pc-linux-gnu
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20211115 (experimental) (GCC)

It started with
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=0288527f47cec6698b31ccb3210816415506009e