Fix use of boolean_true/false_node (PR 83979)

r255913 changed some constant_boolean_node calls to boolean_true_node
and boolean_false_node, which meant that the returned tree didn't
always have the right type.

2018-01-24  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	PR tree-optimization/83979
	* fold-const.c (fold_comparison): Use constant_boolean_node
	instead of boolean_{true,false}_node.

gcc/testsuite/
	PR tree-optimization/83979
	* g++.dg/pr83979.c: New test.

From-SVN: r257021

gcc/ChangeLog

+2018-01-24  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	PR tree-optimization/83979
+	* fold-const.c (fold_comparison): Use constant_boolean_node
+	instead of boolean_{true,false}_node.
+
 2018-01-24  Jan Hubicka  <hubicka@ucw.cz>
 
 	* ipa-profile.c (ipa_propagate_frequency_1): Fix logic skipping calls

gcc/fold-const.c

@@ -8572,39 +8572,39 @@ fold_comparison (location_t loc, enum tree_code code, tree type,
 		{
 		case EQ_EXPR:
 		  if (known_eq (bitpos0, bitpos1))
-		    return boolean_true_node;
+		    return constant_boolean_node (true, type);
 		  if (known_ne (bitpos0, bitpos1))
-		    return boolean_false_node;
+		    return constant_boolean_node (false, type);
 		  break;
 		case NE_EXPR:
 		  if (known_ne (bitpos0, bitpos1))
-		    return boolean_true_node;
+		    return constant_boolean_node (true, type);
 		  if (known_eq (bitpos0, bitpos1))
-		    return boolean_false_node;
+		    return constant_boolean_node (false, type);
 		  break;
 		case LT_EXPR:
 		  if (known_lt (bitpos0, bitpos1))
-		    return boolean_true_node;
+		    return constant_boolean_node (true, type);
 		  if (known_ge (bitpos0, bitpos1))
-		    return boolean_false_node;
+		    return constant_boolean_node (false, type);
 		  break;
 		case LE_EXPR:
 		  if (known_le (bitpos0, bitpos1))
-		    return boolean_true_node;
+		    return constant_boolean_node (true, type);
 		  if (known_gt (bitpos0, bitpos1))
-		    return boolean_false_node;
+		    return constant_boolean_node (false, type);
 		  break;
 		case GE_EXPR:
 		  if (known_ge (bitpos0, bitpos1))
-		    return boolean_true_node;
+		    return constant_boolean_node (true, type);
 		  if (known_lt (bitpos0, bitpos1))
-		    return boolean_false_node;
+		    return constant_boolean_node (false, type);
 		  break;
 		case GT_EXPR:
 		  if (known_gt (bitpos0, bitpos1))
-		    return boolean_true_node;
+		    return constant_boolean_node (true, type);
 		  if (known_le (bitpos0, bitpos1))
-		    return boolean_false_node;
+		    return constant_boolean_node (false, type);
 		  break;
 		default:;
 		}

gcc/testsuite/ChangeLog

+2018-01-24  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	PR tree-optimization/83979
+	* g++.dg/pr83979.c: New test.
+
 2018-01-24  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* gcc.dg/lto/20110201-1_0.c: Remove explicit -mfloat-abi=softfp

gcc/testsuite/g++.dg/pr83979.c

+/* { dg-compile } */
+
+int
+foo (char* p)
+{
+  return p + 1000 < p;
+}