[Bug tree-optimization/85964] New: [8/9 Regression] Compile time hog w/ -O3 -ftracer -fno-guess-branch-probability

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85964

            Bug ID: 85964
           Summary: [8/9 Regression] Compile time hog w/ -O3 -ftracer
                    -fno-guess-branch-probability
           Product: gcc
           Version: 8.1.0
            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-alpha20180527 snapshot (r260810) and gcc 8.1 both take inordinate
time when compiling the following snippet w/ -O3 (-Ofast) -ftracer
-fno-guess-branch-probability:

int
px (int t8)
{
  int sw;

#pragma GCC unroll 128
  for (sw = 0; sw < 128; ++sw)
    {
      int uu = 8;

      do
        {
          int yq = 8;

          do
            {
              t8 /= (t8 < 2) ? 1 : 3;
              --yq;
            }
          while (yq > 0);

          --uu;
        }
      while (uu > 0);
    }

  return t8;
}

% timeout 30 gcc-9.0.0-alpha20180527 -O3 -ftracer -fno-guess-branch-probability
-c tzihxwey.c
zsh: exit 124   timeout 30 gcc-9.0.0-alpha20180527 -O3 -ftracer
-fno-guess-branch-probability

Not sure if it is a duplicate of PR69580 or not.