[Bug tree-optimization/108351] New: Dead Code Elimination Regression at -O3 (trunk vs. 12.2.0)

[yann at ywg dot ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108351

            Bug ID: 108351
           Summary: Dead Code Elimination Regression at -O3 (trunk vs.
                    12.2.0)
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yann at ywg dot ch
  Target Milestone: ---

Created attachment 54226
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54226&action=edit
case file

cat case.c #51
struct a {
  int b;
} b;
static short c = 7, d, e, a, k;
int g;
struct a h;
int i;
int j;
void foo();
static struct a f(int l, unsigned short m) {
  a = e;
  k = d = j < i;
  if (m)
    return h;
  foo();
  return b;
}
int main() {
  for (; g;)
    f(1, c);
  f(7, 7);
  f(9, 7);
}

`gcc-cb93c5f8008b95743b741d6f1842f9be50c6985c (trunk) -O3` can not eliminate
`foo` but `gcc-releases/gcc-12.2.0 -O3` can.

`gcc-cb93c5f8008b95743b741d6f1842f9be50c6985c (trunk) -O3 -S -o /dev/stdout
case.c`
--------- OUTPUT ---------
f.isra.0:
.LFB3:
        .cfi_startproc
        testw   %di, %di
        je      .L4
        ret
        .p2align 4,,10
        .p2align 3
.L4:
        xorl    %eax, %eax
        jmp     foo
        .cfi_endproc
.LFE3:
        .size   f.isra.0, .-f.isra.0
        .section        .text.startup,"ax",@progbits
        .p2align 4
        .globl  main
        .type   main, @function
main:
.LFB1:
        .cfi_startproc
        movl    g(%rip), %eax
        testl   %eax, %eax
        je      .L6
.L7:
        jmp     .L7
        .p2align 4,,10
        .p2align 3
.L6:
        subq    $8, %rsp
        .cfi_def_cfa_offset 16
        movl    $7, %edi
        call    f.isra.0
        movl    $7, %edi
        call    f.isra.0
        xorl    %eax, %eax
        addq    $8, %rsp
        .cfi_def_cfa_offset 8
        ret
---------- END OUTPUT ---------


`gcc-releases/gcc-12.2.0 -O3 -S -o /dev/stdout case.c`
--------- OUTPUT ---------
main:
.LFB1:
        .cfi_startproc
        movl    g(%rip), %eax
        testl   %eax, %eax
        je      .L4
.L5:
        jmp     .L5
        .p2align 4,,10
        .p2align 3
.L4:
        xorl    %eax, %eax
        ret
---------- END OUTPUT ---------


Bisects to:
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=feeb0d68f1c7085199c3734e6517a3a4b58309ef