[Bug tree-optimization/121675] New: wrong code at -O3 on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121675

            Bug ID: 121675
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/MMjE5oeWG

Note:
- works: 8.5 and earlier
- fails: 9.1 and later
- -fno-tree-slsr and -fno-ivopts do not make it disappear

[519] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/16.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 16.0.0 20250825 (experimental) (GCC) 
[520] % 
[520] % gcctk -O3 small.c
[521] % ./a.out
Aborted
[522] % gcctk -O3 -fno-tree-slsr -fno-ivopts small.c
[523] % ./a.out
Aborted
[524] % cat small.c
int a, c, d, e;
int b(volatile int f, int g) {
  f = -2;
  if (!f)
    a = 1;
  c = 11 / f - g + 2;
  g = c + 2;
  if (!(1 / c + (g - 1)))
    a = 1;
  return a + f;
}
int main() {
  do {
    e = (b(1, -1) - 30885397) % 2 - 3;
    d = b(1, -1) - 1430885400;
  } while (a + 1 == 0);
  if (d + e != -1430885406)
    __builtin_abort();
  return 0;
}