[Bug tree-optimization/68428] New: [6 Regression] [graphite] ICE in outermost_loop_in_sese w/ -O2 -floop-strip-mine or -O2 -floop-nest-optimize

["asolokha at gmx dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68428

            Bug ID: 68428
           Summary: [6 Regression] [graphite] ICE in
                    outermost_loop_in_sese w/ -O2 -floop-strip-mine or -O2
                    -floop-nest-optimize
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

At least gcc-6.0.0-alpha20151108 and gcc-6.0.0-alpha20151115 ICE when compiling
the following reduced case:

int au[4] = { 0 };

int
main(void)
{
  int dc;
  int m7;
  int lv;
  int f2;
  int uq[3] = { 1 };
  for (dc = 0; dc < 2; ++dc) {
    for (lv = 0; lv < 2; ++lv)
      for (m7 = 0; m7 < 3; ++m7) {
        if (uq[dc] == 0)
          continue;
        for (f2 = 0; f2 < 3; ++f2)
          au[dc+2] = uq[f2];
      }
  }
  return 0;
}

% gcc-6.0.0-alpha20151115 -O2 -floop-strip-mine y7cav5se.c 
y7cav5se.c: In function 'main':
y7cav5se.c:4:1: internal compiler error: in outermost_loop_in_sese, at
sese.c:1892
 main(void)
 ^~~~

I cannot reproduce it w/ gcc-6.0.0-alpha20150802, though.