re PR tree-optimization/70780 (wrong code at -O2 and -O3 on x86_64-linux-gnu)

2016-04-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/70780
	* tree-ssa-pre.c (compute_antic_aux): Also return true if the block
	wasn't visited yet.
	(compute_antic): Mark blocks with abnormal preds as visited as
	they have a final empty antic-in solution already.

	* gcc.dg/torture/pr70780.c: New testcase.

From-SVN: r235407

gcc/ChangeLog

+2016-04-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70780
+	* tree-ssa-pre.c (compute_antic_aux): Also return true if the block
+	wasn't visited yet.
+	(compute_antic): Mark blocks with abnormal preds as visited as
+	they have a final empty antic-in solution already.
+
 2016-04-25  Michael Collison  <michael.collison@linaro.org>
+
 	* ChangeLog(2016-04-25): Fix ChangeLog formatting.
 
 2016-04-25  Michael Collison  <michael.collison@linaro.org>

gcc/testsuite/ChangeLog

+2016-04-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70780
+	* gcc.dg/torture/pr70780.c: New testcase.
+
 2016-04-25  Michael Collison <michael.collison@arm.com>
 
 	* testsuite/gcc.target/arm/neon-vaddws16.c: New test.

gcc/testsuite/gcc.dg/torture/pr70780.c

+/* { dg-do run } */
+
+int a, b, c, *d, e;
+
+static int
+fn1 () 
+{
+  if (a)
+    goto l1;
+l2: while (b)
+      if (*d)
+	return c;
+    for (e = 0; e; e++)
+      {
+	goto l2;
+l1:;
+      }
+    return 0; 
+}
+
+int
+main ()
+{
+  fn1 ();
+  return 0; 
+}

gcc/tree-ssa-pre.c

@@ -2077,6 +2077,7 @@ compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge)
   unsigned int bii;
   edge e;
   edge_iterator ei;
+  bool was_visited = BB_VISITED (block);
 
   old = ANTIC_OUT = S = NULL;
   BB_VISITED (block) = 1;
@@ -2167,7 +2168,7 @@ compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge)
 
   clean (ANTIC_IN (block));
 
-  if (!bitmap_set_equal (old, ANTIC_IN (block)))
+  if (!was_visited || !bitmap_set_equal (old, ANTIC_IN (block)))
     changed = true;
 
  maybe_dump_sets: