[Bug tree-optimization/105665] New: wrong code at -Os 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=105665

            Bug ID: 105665
           Summary: wrong code at -Os 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: ---

This appears to be a regression from 11.3.

[599] % 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/13.0.0/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 13.0.0 20220519 (experimental) [master r13-673-gd863ba23fb1] (GCC) 
[600] % 
[600] % gcctk -O1 small.c; ./a.out
[601] % 
[601] % gcctk -Os small.c
[602] % ./a.out
Segmentation fault
[603] % 
[603] % cat small.c
int a, b, c[1], d[2], *e = c;
int main() {
  int f = 0;
  for (; b < 2; b++) {
    int g;
    if (f)
      b = 40;
    a = d[b * b];
    for (f = 0; f < 3; f++) {
      if (e)
        break;
      g--;
      if (a)
        a = g;
    }
  }
  return 0;
}