[Bug tree-optimization/114552] New: wrong code at -O1 and above on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114552

            Bug ID: 114552
           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 is a regression from 12.3, and affects 13.* and the trunk. 

Compiler Explorer: https://godbolt.org/z/bznEs9bao

[656] % 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 20240401 (experimental) (GCC) 
[657] % 
[657] % gcctk -O0 small.c; ./a.out
[658] % 
[658] % gcctk -O1 small.c
[659] % ./a.out
Segmentation fault
[660] % 
[660] % cat small.c
#pragma pack(1)
struct a {
  short b;
  int c;
};
struct d {
  struct a b;
  int e;
};
short f, g, h;
int i, j, o;
const struct d k = {{1,0},0};
short *l = &h, *m = &g, *n = &f;
void p() { *n = (o > 0) > o; }
void q(struct a n) {
  j = 0;
  for (; j < 5; j++)
    i = *m = *l != 0;
  p();
}
int main() {
  q(k.b);
  return 0;
}