[Bug tree-optimization/57592] New: ICE in tree_unroll_loops_completely at -O3

[dhazeghi at yahoo dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57592

            Bug ID: 57592
           Summary: ICE in tree_unroll_loops_completely at -O3
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dhazeghi at yahoo dot com

With current gcc trunk on x86_64-linux, the following code causes an ICE when
compiled at -O3.  This is a regression from 4.8.x.

$ gcc-trunk -v
gcc version 4.9.0 20130611 (experimental) [trunk revision 199947] (GCC) 
$ gcc-trunk -m32 -O2 -c ice.c 
$ gcc-4.8 -m32 -O3 -c ice.c 
$ gcc-trunk -m32 -O3 -c ice.c 
ice.c: In function ‘f’:
ice.c:4:1: internal compiler error: Segmentation fault
 f ()
 ^
0x7d419f crash_signal
    ../../gcc-trunk/gcc/toplev.c:333
0x7fc29b ssa_default_def(function*, tree_node*)
    ../../gcc-trunk/gcc/tree-dfa.c:314
0x7fc560 get_or_create_ssa_default_def(function*, tree_node*)
    ../../gcc-trunk/gcc/tree-dfa.c:362
0x81585a get_reaching_def
    ../../gcc-trunk/gcc/tree-into-ssa.c:1184
0x81b9db maybe_replace_use
    ../../gcc-trunk/gcc/tree-into-ssa.c:1784
0x81b9db rewrite_update_stmt
    ../../gcc-trunk/gcc/tree-into-ssa.c:1967
0x81b9db rewrite_update_enter_block
    ../../gcc-trunk/gcc/tree-into-ssa.c:2136
0xb3561a walk_dominator_tree(dom_walk_data*, basic_block_def*)
    ../../gcc-trunk/gcc/domwalk.c:210
0x814563 rewrite_blocks
    ../../gcc-trunk/gcc/tree-into-ssa.c:2216
0x81ac8e update_ssa(unsigned int)
    ../../gcc-trunk/gcc/tree-into-ssa.c:3303
0xb99fe4 tree_unroll_loops_completely(bool, bool)
    ../../gcc-trunk/gcc/tree-ssa-loop-ivcanon.c:1207
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

---------------------
int a, b, c;

void
f ()
{
  int d, e;
  a = 0;
  for (; a <= 1; a++)
    {
      e = 4;
      for (; e; e--)
    {
      d |= c < b++;
      c = 0;
    }
    }
  g (d);
}