[Bug tree-optimization/121648] New: wrong code at -O{s,2,3} with "-fno-tree-loop-im -fno-gcse -fno-code-hoisting -fno-tree-fre -fno-tree-pre -fno-tree-dominator-opts" on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121648

            Bug ID: 121648
           Summary: wrong code at -O{s,2,3} with "-fno-tree-loop-im
                    -fno-gcse -fno-code-hoisting -fno-tree-fre
                    -fno-tree-pre -fno-tree-dominator-opts" 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/KPKbdhbKb

Note:
- works: 10.5 and earlier
- fails: 11.1 and later
- -fno-tree-slsr and -fno-ivopts do not make it disappear

[992] % 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 20250823 (experimental) (GCC) 
[993] % 
[993] % gcctk -O3 small.c; ./a.out
[994] % gcctk -O3 -fno-tree-loop-im -fno-gcse -fno-code-hoisting -fno-tree-fre
-fno-tree-pre -fno-tree-dominator-opts small.c
[995] % ./a.out
Aborted
[996] % cat small.c
int a = -2;
int main() {
  int b = -2, c = 12 / a;
  do {
    if (3 / c)
      b = 0;
  } while (3 / c);
  int d[] = {b, -2, 1 - 3 % c};
  for (int e = 0; e < 3; e++)
    if (d[e] != a)
      __builtin_abort();
  return 0;
}