[Bug tree-optimization/100453] New: wrong code at -O1 and above

[zhendong.su at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100453

            Bug ID: 100453
           Summary: wrong code at -O1 and above
           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 a recent regression.

[513] % 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 20210506 (experimental) [master revision
1698f496c5e:27b373b33d4:a1ac9ffb5a7f44b2e2633b7265c21ce803c8e854] (GCC) 
[514] % 
[514] % gcctk -O0 small.c; ./a.out
[515] % gcc110 -O1 small.c; ./a.out
[516] % 
[516] % gcctk -O1 small.c
[517] % ./a.out
Segmentation fault
[518] % 
[518] % cat small.c
struct a {
  int b : 4;
} d;
static int c, e;
static const struct a f;
static void g(const struct a h) {
  for (; c < 1; c++)
    d = h;
  e = h.b;
  c = h.b;
}
int main() {
  g(f);
  return 0;
}