re PR tree-optimization/70190 (ICE (segfault) at -O2 and -O3 on x86_64-linux-gnu)

	PR tree-optimization/70190
	* tree-ssa-threadbackward.c (fsm_find_control_statement_thread_paths):
	Handle cases where we can not extract the taken edge, even though we
	found a constant value.

	PR tree-optimization/70190
	* gcc.c-torture/compile/pr70190.c: New test.

From-SVN: r234151

gcc/ChangeLog

 2016-03-11  Jeff Law  <law@redhat.com>
 
+	PR tree-optimization/70190
+	* tree-ssa-threadbackward.c (fsm_find_control_statement_thread_paths):
+	Handle cases where we can not extract the taken edge, even though we
+	found a constant value.
+
 	PR tree-optimization/64058
 	* tree-ssa-coalesce.c (struct coalesce_pair): Add new field INDEX.
 	(num_coalesce_pairs): Move up earlier in file.

gcc/testsuite/ChangeLog

+2016-03-11  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/70190
+	* gcc.c-torture/compile/pr70190.c: New test.
+
 2016-03-11  David Malcolm  <dmalcolm@redhat.com>
 
 	PR c/68187

gcc/testsuite/gcc.c-torture/compile/pr70190.c

+/* { dg-require-effective-target indirect_jumps } */
+/* { dg-require-effective-target label_values } */
+
+
+int
+fn1 ()
+{
+  static char a[] = "foo";
+  static void *b[] = { &&l1, &&l2 };
+  goto *(b[1]);
+ l1: goto *(a[0]);
+ l2: return 0;
+}
+

gcc/tree-ssa-threadbackward.c

@@ -385,6 +385,16 @@ fsm_find_control_statement_thread_paths (tree name,
 
 	     We have to know the outgoing edge to figure this out.  */
 	  edge taken_edge = find_taken_edge ((*path)[0], arg);
+
+	  /* There are cases where we may not be able to extract the
+	     taken edge.  For example, a computed goto to an absolute
+	     address.  Handle those cases gracefully.  */
+	  if (taken_edge == NULL)
+	    {
+	      path->pop ();
+	      continue;
+	    }
+
 	  bool creates_irreducible_loop = false;
 	  if (threaded_through_latch
 	      && loop == taken_edge->dest->loop_father