[Bug tree-optimization/102769] New: wrong code at -O1 and above on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102769

            Bug ID: 102769
           Summary: wrong code at -O1 and above 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: ---

It seems to be very long-latent regression (since at least as early as GCC
4.7.* according to Compiler Explorer).

[581] % 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/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-languages=c,c++
--disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20211015 (experimental) [master r12-4426-gf7571527a44] (GCC) 
[582] % 
[582] % gcctk -O0 small.c; ./a.out
[583] % 
[583] % gcctk -O1 small.c
[584] % ./a.out
Aborted
[585] % 
[585] % cat small.c
int a, *b, **c = &b, *d, e, f = 1;
int main() {
  int g[20];
  for (; e < 2; e++) {
    if (a == f && *b)
      break;
    int h;
    f = h = 0;
    *c = &h;
  }
  d = &g[4];
  if (e != 2)
    __builtin_abort();
  return 0;
}