[Bug tree-optimization/121194] New: ICE on valid code at -O3: in quick_push, at vec.h:1050

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121194

            Bug ID: 121194
           Summary: ICE on valid code at -O3: in quick_push, at vec.h:1050
           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/895xeMPYe

It appears to be a recent regression as it doesn't reproduce with 15.1 and
earlier. 

[515] % 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 20250720 (experimental) (GCC) 
[516] % 
[516] % gcctk -O3 small.c
during GIMPLE pass: vect
small.c: In function ‘main’:
small.c:10:5: internal compiler error: in quick_push, at vec.h:1050
   10 | int main() {
      |     ^~~~
0x2564dd6 internal_error(char const*, ...)
        ../../gcc-trunk/gcc/diagnostic-global-context.cc:517
0xa02678 fancy_abort(char const*, int, char const*)
        ../../gcc-trunk/gcc/diagnostic.cc:1818
0x907fb6 vec<int, va_heap, vl_embed>::quick_push(int const&)
        ../../gcc-trunk/gcc/vec.h:1050
0x908648 vec<tree_node*, va_heap, vl_embed>::quick_push(tree_node* const&)
        ../../gcc-trunk/gcc/gimple.h:2619
0x908648 vec<tree_node*, va_heap, vl_ptr>::quick_push(tree_node* const&)
        ../../gcc-trunk/gcc/vec.h:2081
0x908648 _slp_tree::push_vec_def(gimple*)
        ../../gcc-trunk/gcc/tree-vect-slp.cc:162
0x148d5c1 vect_transform_lc_phi(_loop_vec_info*, _stmt_vec_info*, _slp_tree*)
        ../../gcc-trunk/gcc/tree-vect-loop.cc:8789
0x1484d48 vect_transform_stmt(vec_info*, _stmt_vec_info*,
gimple_stmt_iterator*, _slp_tree*, _slp_instance*)
        ../../gcc-trunk/gcc/tree-vect-stmts.cc:13514
0x14ccd3d vect_schedule_slp_node
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11503
0x14e679f vect_schedule_slp_node
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11270
0x14e679f vect_schedule_scc
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11756
0x14e6e97 vect_schedule_slp(vec_info*, vec<_slp_instance*, va_heap, vl_ptr>
const&)
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11901
0x14ac0aa vect_transform_loop(_loop_vec_info*, gimple*)
        ../../gcc-trunk/gcc/tree-vect-loop.cc:11556
0x14f86cb vect_transform_loops
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1044
0x14f8db3 try_vectorize_loop_1
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1193
0x14f8db3 try_vectorize_loop
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1223
0x14f942c execute
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1339
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
[517] % 
[517] % cat small.c
int a, b, c, d;
void e() {
  int *f = &b;
  for (a = 0; a < 8; a++) {
    *f = 0;
    for (c = 0; c < 2; c++)
      *f = *f == 0;
  }
}
int main() {
  e();
  int *g = &b;
  *g = *g == (d == 0);
  return 0;
}