[Bug tree-optimization/116796] New: ICE on valid code at -O3 with "-fno-tree-dominator-opts -fno-tree-vrp -fno-tree-ch" on x86_64-linux-gnu: in check_loop_closed_ssa_def, at tree-ssa-loop-manip.cc:647

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116796

            Bug ID: 116796
           Summary: ICE on valid code at -O3 with
                    "-fno-tree-dominator-opts -fno-tree-vrp -fno-tree-ch"
                    on x86_64-linux-gnu: in check_loop_closed_ssa_def, at
                    tree-ssa-loop-manip.cc:647
           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 appears to be a recent regression (it doesn't reproduce with 14.2 and
earlier).

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

[541] % 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/15.0.0/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 15.0.0 20240921 (experimental) (GCC) 
[542] % 
[542] % gcctk -O3 -c small.c
[543] % gcctk -O3 -c -fno-tree-dominator-opts -fno-tree-vrp -fno-tree-ch
small.c
during GIMPLE pass: cunroll
small.c: In function ‘main’:
small.c:4:5: internal compiler error: in check_loop_closed_ssa_def, at
tree-ssa-loop-manip.cc:647
    4 | int main() {
      |     ^~~~
0x25b5ae5 internal_error(char const*, ...)
        ../../gcc-trunk/gcc/diagnostic-global-context.cc:517
0xa6f6e0 fancy_abort(char const*, int, char const*)
        ../../gcc-trunk/gcc/diagnostic.cc:1512
0x8bebeb check_loop_closed_ssa_def
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:647
0x1356e54 check_loop_closed_ssa_bb
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:661
0x1358a3e verify_loop_closed_ssa(bool, loop*)
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:697
0x1358a3e verify_loop_closed_ssa(bool, loop*)
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:681
0x133f441 tree_unroll_loops_completely
        ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.cc:1576
0x133f4c3 execute
        ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.cc:1680
0x133f4c3 execute
        ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.cc:1670
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.
[544] % 
[544] % cat small.c
volatile int a;
extern void b();
int c;
int main() {
 L1:
  if (c) {
    int f;
  L2:
    for (f = 0; f < 6; f++) {
      b();
      if (f)
        goto L2;
      a;
    }
  }
  if (c)
    goto L1;
  return 0;
}