[Bug tree-optimization/71142] New: [6/7 Regression] ICE: Segmentation fault in ssa_default_def

["ktkachov at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71142

            Bug ID: 71142
           Summary: [6/7 Regression] ICE: Segmentation fault in
                    ssa_default_def
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64

The testcase:

int a, b, d, e;
int c[10];
short f;
unsigned g;

void
fn1 ()
{
  int *h = &d;
  for (; f; f--)
    {
      a = 0;
      for (; a <= 1; a++)
        {
          d = 1;
          for (; d >= 0; d--)
            {
              b = 0;
              for (; b < 7; b++)
                c[b] = b;
            }
          *h ^= g;
        }
    }
  *h = *h & e;
}

ICEs on aarch64-none-linux-gnu with -Ofast -floop-interchange:

mycrash.c: In function 'fn1':
mycrash.c:7:1: internal compiler error: Segmentation fault
 fn1 ()
 ^~~
0xb02b4f crash_signal
        $SRC/gcc/toplev.c:335
0xb58db5 ssa_default_def(function*, tree_node*)
        $SRC/gcc/tree-dfa.c:305
0xb5b9c4 get_or_create_ssa_default_def(function*, tree_node*)
        $SRC/gcc/tree-dfa.c:357
0xb9665f get_reaching_def
        $SRC/gcc/tree-into-ssa.c:1168
0xb9b6b4 rewrite_update_phi_arguments
        $SRC/gcc/tree-into-ssa.c:2017
0xb9b6b4 rewrite_update_dom_walker::before_dom_children(basic_block_def*)
        $SRC/gcc/tree-into-ssa.c:2137
0x1063b49 dom_walker::walk(basic_block_def*)
        $SRC/gcc/domwalk.c:265
0xb9427c rewrite_blocks
        $SRC/gcc/tree-into-ssa.c:2194
0xb9cccf update_ssa(unsigned int)
        $SRC/gcc/tree-into-ssa.c:3356
0x1091de5 graphite_regenerate_ast_isl(scop*)
        $SRC/gcc/graphite-isl-ast-to-gimple.c:3204
0x1088995 graphite_transform_loops()
        $SRC/gcc/graphite.c:329
0x1088b34 graphite_transforms
        $SRC/gcc/graphite.c:356
0x1088b34 execute
        $SRC/gcc/graphite.c:433
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