re PR tree-optimization/57083 (Wrong constant folding)

	PR tree-optimization/57083
	* tree-vrp.c (extract_range_from_binary_expr_1): For LSHIFT_EXPR with
	non-singleton shift count range, zero extend low_bound for uns case.

	* gcc.dg/torture/pr57083.c: New test.

From-SVN: r198388

gcc/ChangeLog

 2013-04-29  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/57083
+	* tree-vrp.c (extract_range_from_binary_expr_1): For LSHIFT_EXPR with
+	non-singleton shift count range, zero extend low_bound for uns case.
+
 	* config/i386/predicates.md (general_vector_operand): New predicate.
 	* config/i386/i386.c (const_vector_equal_evenodd_p): New function.
 	(ix86_expand_mul_widen_evenodd): Force op1 resp. op2 into register

gcc/testsuite/ChangeLog

+2013-04-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/57083
+	* gcc.dg/torture/pr57083.c: New test.
+
 2013-04-28  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/56450

gcc/testsuite/gcc.dg/torture/pr57083.c

+/* PR tree-optimization/57083 */
+/* { dg-do run { target int32plus } } */
+
+extern void abort (void);
+short x = 1;
+int y = 0;
+
+int
+main ()
+{
+  unsigned t = (0x7fff8001U - x) << (y == 0);
+  if (t != 0xffff0000U)
+    abort ();
+  return 0;
+}

gcc/tree-vrp.c

@@ -2837,7 +2837,7 @@ extract_range_from_binary_expr_1 (value_range_t *vr,
 
 	      if (uns)
 		{
-		  low_bound = bound;
+		  low_bound = bound.zext (prec);
 		  high_bound = complement.zext (prec);
 		  if (tree_to_double_int (vr0.max).ult (low_bound))
 		    {