[Bug tree-optimization/112303] New: ICE on valid code at -O3 on x86_64-linux-gnu: verify_flow_info failed

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112303

            Bug ID: 112303
           Summary: ICE on valid code at -O3 on x86_64-linux-gnu:
                    verify_flow_info failed
           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: ---

This appears to be a recent regression.

Compiler Explorer: https://godbolt.org/z/9h7K8eqs8

[578] % 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/14.0.0/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 14.0.0 20231030 (experimental) (GCC)
[579] %
[579] % gcctk -O2 -c small.c
[580] %
[580] % gcctk -O3 -c small.c
small.c: In function ‘j’:
small.c:3:6: error: count of bb 228 not initialized
    3 | int *j() {
      |      ^
during GIMPLE pass: cunroll
small.c:3:6: internal compiler error: verify_flow_info failed
0xbafcaf verify_flow_info()
        ../../gcc-trunk/gcc/cfghooks.cc:287
0x11718ff checking_verify_flow_info()
        ../../gcc-trunk/gcc/cfghooks.h:214
0x11718ff cleanup_tree_cfg_noloop
        ../../gcc-trunk/gcc/tree-cfgcleanup.cc:1154
0x11718ff cleanup_tree_cfg(unsigned int)
        ../../gcc-trunk/gcc/tree-cfgcleanup.cc:1205
0x1295dbd tree_unroll_loops_completely
        ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.cc:1565
0x1295ed3 execute
        ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.cc:1673
0x1295ed3 execute
        ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.cc:1663
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.
[581] %
[581] % cat small.c
int a, b, d, e, f, **g, h;
char c;
int *j() {
  for (int i = 0; i < 3; i++) {
    for (h = 0; h < 2; h++)
      ;
    if (!b)
      break;
  }
  while (f)
    while (e) {
      c = 0;
      while (d)
        while (a)
          *g = j();
    }
  return 0;
}