[Bug tree-optimization/89789] New: [9 Regression] Compile time hog during RPO VN

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89789

            Bug ID: 89789
           Summary: [9 Regression] Compile time hog during RPO VN
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          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-alpha20190317 snapshot (r269746) takes indefinite time when compiling
the following testcase at -O2 (-O3, -Ofast, -Os):

int x2;

void
m2 (void)
{
  goto gg;

  int fz, vh = 0;

  for (fz = 0; fz < 1; ++fz)
    {
      vh ^= x2;

      if (0)
        {
 gg:
          x2 %= 1;
          x2 += vh;
        }
    }
}

% timeout 10 gcc-9.0.0-alpha20190317 -O2 -c nzl2rb2h.c
zsh: exit 124   timeout 10 gcc-9.0.0-alpha20190317 -O2 -c nzl2rb2h.c