[Bug tree-optimization/121378] New: wrong code at -O2 on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121378

            Bug ID: 121378
           Summary: wrong code at -O2 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/xnjGa3njq

Note:
* This is a recent regression as it doesn't reproduce with 15.1 and earlier.
* -fno-ivopts makes it disappear (but not -fno-tree-slsr)

[513] % 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 20250803 (experimental) (GCC) 
[514] % 
[514] % gcctk -O0 small.c
[515] % ./a.out
[516] % 
[516] % gcctk -O2 small.c
[517] % ./a.out
Aborted
[518] % cat small.c
int printf(const char *, ...);
int a, b, c, d, f, g, h, i, j, k, l;
int m(int n, int o[]) {
  for (int e = 0; e < n; ++e) {
    b = a ^ o[e];
    a = b;
  }
  return b;
}
static int p(int n, int o, int p3) {
  do {
    j = -p3 - 9;
    if (!(g + 9))
      break;
    g = -j;
    o = o - n;
  } while (g - 99 * o + c > 0);
  return m(12, (int[]){h, 0, l, i, c, d, f, g, o, j, p3, k});
}
void q() { p(5, 1, -2147483646); }
int main() {
  p(-2147483647, -2147483647, -2147483647);
  if (b != 2147483645)
    __builtin_abort();
  return 0;
}