[Bug tree-optimization/121202] New: ICE on valid code at -O3 with -fno-tree-copy-prop on x86_64-linux-gnu: in vect_schedule_slp_node, at tree-vect-slp.cc:11381

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121202

            Bug ID: 121202
           Summary: ICE on valid code at -O3 with -fno-tree-copy-prop on
                    x86_64-linux-gnu: in vect_schedule_slp_node, at
                    tree-vect-slp.cc:11381
           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/McYd5M8Mq

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

[523] % 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 20250721 (experimental) (GCC) 
[524] % 
[524] % gcctk -O3 -fno-tree-copy-prop small.c
during GIMPLE pass: vect
small.c: In function ‘main’:
small.c:4:5: internal compiler error: in vect_schedule_slp_node, at
tree-vect-slp.cc:11380
    4 | int main() {
      |     ^~~~
0x25699e6 internal_error(char const*, ...)
        ../../gcc-trunk/gcc/diagnostic-global-context.cc:517
0xa014ca fancy_abort(char const*, int, char const*)
        ../../gcc-trunk/gcc/diagnostic.cc:1818
0x9097d2 vect_schedule_slp_node
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11380
0x14e702f vect_schedule_slp_node
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11269
0x14e702f vect_schedule_scc
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11755
0x14e7727 vect_schedule_slp(vec_info*, vec<_slp_instance*, va_heap, vl_ptr>
const&)
        ../../gcc-trunk/gcc/tree-vect-slp.cc:11900
0x14ac93a vect_transform_loop(_loop_vec_info*, gimple*)
        ../../gcc-trunk/gcc/tree-vect-loop.cc:11564
0x14f8f1b vect_transform_loops
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1044
0x14f9603 try_vectorize_loop_1
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1193
0x14f9603 try_vectorize_loop
        ../../gcc-trunk/gcc/tree-vectorizer.cc:1223
0x14f9c7c 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.
[525] % 
[525] % cat small.c
int a, b, c;
int e(int f, int g) { return f >> g; }
int h(int f) { return a > 1 ? 0 : f << a; }
int main() {
  while (c--)
    b = e(h(1), a);
  return 0;
}