[Bug tree-optimization/103458] New: [12 Regression] ICE in verify_loop_structure, at cfgloop.c:1736 (error: loop with header 4 not in loop tree)

[asolokha at gmx dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103458

            Bug ID: 103458
           Summary: [12 Regression] ICE in verify_loop_structure, at
                    cfgloop.c:1736 (error: loop with header 4 not in loop
                    tree)
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-12.0.0-alpha20211121 snapshot (g:da17c304e22ba256eba0b03710aa329115163b08)
ICEs when compiling the following testcase w/ -O2:

__attribute__ ((returns_twice)) int
bar (void);

void
foo (int *p, int x)
{
  *p = 0;
  while (*p < 1)
    {
      x = 0;
      while (x < 1)
        bar ();

      x /= 0;
    }

  foo (p, x);
}

% gcc-12.0.0 -O2 -w -c xiksrvsw.c
xiksrvsw.c: In function 'foo':
xiksrvsw.c:5:1: error: loop with header 4 not in loop tree
    5 | foo (int *p, int x)
      | ^~~
during GIMPLE pass: cddce
xiksrvsw.c:5:1: internal compiler error: in verify_loop_structure, at
cfgloop.c:1736
0x6816e7 verify_loop_structure()
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20211121/work/gcc-12-20211121/gcc/cfgloop.c:1736
0xdb8457 execute_function_todo
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20211121/work/gcc-12-20211121/gcc/passes.c:2058
0xdb8cbe execute_todo
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20211121/work/gcc-12-20211121/gcc/passes.c:2096