[Bug tree-optimization/114787] New: wrong code at -O1 on x86_64-linux-gnu (the generated code hangs)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114787

            Bug ID: 114787
           Summary: wrong code at -O1 on x86_64-linux-gnu (the generated
                    code hangs)
           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: ---

It appears to be a recent regression and does not reproduce with 13.2 and
earlier. 

Compiler Explorer: https://godbolt.org/z/6sbh8Wr1e


[663] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/14.0.1/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 14.0.1 20240420 (experimental) (GCC) 
[664] % 
[664] % gcctk -O0 small.c; ./a.out
[665] % 
[665] % gcctk -O1 small.c
[666] % timeout -s 9 10 ./a.out
Killed
[667] % 
[667] % cat small.c
int a, b, c, d, e = -1, f, g, h, j, k, n, o, p;
int main() {
  int i, l = 2, m;
  for (b = 0; b < 1; b++)
    l = 0;
  for (; a >= 0; a--)
    for (m = 3; m; m--) {
      k = g;
      i = 0;
      for (; i < 1; i++)
        for (; f < 1; f++)
          h = g;
      n = 2 & ((e ^ d) | 1) * j;
      o = ~(e & n);
    q:
      if (c <= e)
        return 0;
      e = o;
    }
  p = l;
  l = 0;
  if (p)
    goto q;
  return 0;
}