Fix bb-reorder problem with degenerate cond_jump (PR68182)

The code mistakenly thinks any cond_jump has two successors.  This is
not true if both destinations are the same, as can happen with weird
patterns as in the PR.


	PR rtl-optimization/68182
	* gcc/bb-reorder.c (reorder_basic_blocks_simple): Treat a conditional
	branch with only one successor just like unconditional branches.

From-SVN: r229983

gcc/ChangeLog

-2015-11-08  Jeff Law <jeff@redhat.com>
+2015-11-09  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/68182
+	* gcc/bb-reorder.c (reorder_basic_blocks_simple): Treat a conditional
+	branch with only one successor just like unconditional branches.
+
+2015-11-08  Jeff Law  <jeff@redhat.com>
 
 	* tree-ssa-threadupdate.c (register_jump_thraed): Assert that a
 	non-FSM path has no edges marked with EDGE_DFS_BACK.

gcc/bb-reorder.c

@@ -2304,7 +2304,9 @@ reorder_basic_blocks_simple (void)
       if (JUMP_P (end) && extract_asm_operands (end))
 	continue;
 
-      if (any_condjump_p (end))
+      if (single_succ_p (bb))
+	edges[n++] = EDGE_SUCC (bb, 0);
+      else if (any_condjump_p (end))
 	{
 	  edge e0 = EDGE_SUCC (bb, 0);
 	  edge e1 = EDGE_SUCC (bb, 1);
@@ -2315,8 +2317,6 @@ reorder_basic_blocks_simple (void)
 	  edges[n++] = e0;
 	  edges[n++] = e1;
 	}
-      else if (single_succ_p (bb))
-	edges[n++] = EDGE_SUCC (bb, 0);
     }
 
   /* Sort the edges, the most desirable first.  When optimizing for size