re PR tree-optimization/70725 (Internal compiler error (ICE) on valid code)

	PR tree-optimization/70725
	* tree-if-conv.c (is_false_predicate): New function.
	(predicate_mem_writes): Use it.

	* gcc.dg/pr70725.c: New test.

From-SVN: r235250

gcc/ChangeLog

+2016-04-20  Marek Polacek  <polacek@redhat.com>
+
+	PR tree-optimization/70725
+	* tree-if-conv.c (is_false_predicate): New function.
+	(predicate_mem_writes): Use it.
+
 2016-04-20  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/70726

gcc/testsuite/ChangeLog

+2016-04-20  Marek Polacek  <polacek@redhat.com>
+
+	PR tree-optimization/70725
+	* gcc.dg/pr70725.c: New test.
+
 2016-04-20  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/70726

gcc/testsuite/gcc.dg/pr70725.c

+/* PR tree-optimization/70725 */
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+/* { dg-additional-options "-march=skylake-avx512" { target { i?86-*-* x86_64-*-* } } } */
+
+extern short a;
+extern int b, d;
+extern int c[100];
+extern int e;
+extern int f;
+
+void
+fn1 ()
+{
+  for (; e < 2; e = e + 1)
+    d = a;
+  for (;;)
+    for (int g = 0; g < 5; g = g + 1)
+      for (int h = 0; h < 2; h = h + 1)
+	for (int i = 0; i < 3; i = i + 1)
+	  c[f + i] = a && b;
+}

gcc/tree-if-conv.c

@@ -262,6 +262,16 @@ ifc_temp_var (tree type, tree expr, gimple_stmt_iterator *gsi)
   return new_name;
 }
 
+/* Return true when COND is a false predicate.  */
+
+static inline bool
+is_false_predicate (tree cond)
+{
+  return (cond == NULL_TREE
+	  || cond == boolean_false_node
+	  || integer_zerop (cond));
+}
+
 /* Return true when COND is a true predicate.  */
 
 static inline bool
@@ -1988,7 +1998,7 @@ predicate_mem_writes (loop_p loop)
       gimple *stmt;
       int index;
 
-      if (is_true_predicate (cond))
+      if (is_true_predicate (cond) || is_false_predicate (cond))
 	continue;
 
       swap = false;