[Bug tree-optimization/84057] New: [8 Regression] ICE: Segmentation fault (in can_remove_branch_p)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84057

            Bug ID: 84057
           Summary: [8 Regression] ICE: Segmentation fault (in
                    can_remove_branch_p)
           Product: gcc
           Version: 8.0
            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-8.0.0-alpha20180121 snapshot (r256935) ICEs when compiling the following
snippet w/ -O2 -fgraphite -funroll-loops -fno-tree-ccp -fno-tree-dce:

int ue;

void
fr (int ct)
{
  int au = 0;
  int *ra = &au;

  while (au < 1)
    {
      au -= 0x7878788;
      if (au != ct && ue != 0)
        {
          while (au < 1)
            {
            }

 fc:
          while (ct != 0)
            {
            }
        }
    }

  for (au = 0; au < 2; ++au)
    if (ct != 0)
      goto fc;
}

% gcc-8.0.0-alpha20180121 -O2 -fgraphite -funroll-loops -fno-tree-ccp
-fno-tree-dce -c imaaek0k.c
during GIMPLE pass: cunroll
imaaek0k.c: In function 'fr':
imaaek0k.c:4:1: internal compiler error: Segmentation fault
 fr (int ct)
 ^~
0xc969ef crash_signal
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/toplev.c:325
0x8829e3 can_remove_branch_p(edge_def const*)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/cfghooks.c:389
0x891683 remove_path(edge_def*, bool*, bitmap_head*)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/cfgloopmanip.c:315
0xdd4b03 unloop_loops
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/tree-ssa-loop-ivcanon.c:668
0xdd7f01 unloop_loops
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/tree-ssa-loop-ivcanon.c:1450
0xdd7f01 tree_unroll_loops_completely
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/tree-ssa-loop-ivcanon.c:1450
0xdd83b4 execute
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180121/work/gcc-8-20180121/gcc/tree-ssa-loop-ivcanon.c:1599