[Bug tree-optimization/88105] New: Possibly infinite loop in pass_dominator::execute

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88105

            Bug ID: 88105
           Summary: Possibly infinite loop in pass_dominator::execute
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: compile-time-hog, openmp
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-9.0.0-alpha20181118 snapshot (r266255), 8.2, 7.3, 6.3, 5.4, 4.9.4, 4.8.5
all take indefinite time compiling the following snippet at any optimization
level (except -Og) and w/ -fexceptions -fnon-call-exceptions -fopenmp
-fno-tree-fre:

int
s0 (void)
{
  int g6, oh = 0;
  int *a6 = &g6;

  (void) a6;

#pragma omp parallel for
  for (g6 = 0; g6 < 1; ++g6)
    {
      int zk;

      for (zk = 0; zk < 1; ++zk)
        {
          oh += zk / (zk + 1);

          for (;;)
            {
            }
        }

      a6 = &zk;
    }

  return oh;
}

% timeout 10 gcc-9.0.0-alpha20181118 -O1 -fexceptions -fnon-call-exceptions
-fopenmp -fno-tree-fre -c eusbqkjq.c
zsh: exit 124   timeout 10 gcc-9.0.0-alpha20181118 -O1 -fexceptions
-fnon-call-exceptions   -