[Bug tree-optimization/123416] New: wrong code at -O{s,2,3} with "-fno-tree-dse -fno-strict-aliasing" on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123416

            Bug ID: 123416
           Summary: wrong code at -O{s,2,3} with "-fno-tree-dse
                    -fno-strict-aliasing" 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: ---

Compiler Explorer: https://godbolt.org/z/MdMzj15xz

Note:
- fail: 12.5, 13.4, 14.3, 15.1, 15.2, trunk
- at -O{s,2,3}

[506] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/16.0.0/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 16.0.0 20260106 (experimental) (GCC) 
[507] % 
[507] % gcctk -O3 small.c; ./a.out
[508] % gcctk -O3 -fno-tree-dse -fno-strict-aliasing small.c
[509] % ./a.out
Aborted
[510] % cat small.c
struct a {
  int b;
} c;
int d;
static struct a g() {
  int a[2], b, f = 0;
  for (; f < 2; f++)
    a[f] = 1;
  b = a[0];
  if (b)
    return c;
}
int main() {
  c.b = 1;
  struct a e = g();
  c = g();
  if (!c.b)
    __builtin_abort();
  return 0;
}