Implements Value() for XorNode.

Change-Id: Ic9fc01375801adc82c0a0289d9a11a5367031eb4

Author: Eric Liu

src/hotspot/share/opto/addnode.cpp

@@ -914,16 +914,19 @@ const Type *OrLNode::add_ring( const Type *t0, const Type *t1 ) const {
 
 //=============================================================================
 
-Node* XorINode::Ideal(PhaseGVN* phase, bool can_reshape) {
+const Type* XorINode::Value(PhaseGVN* phase) const {
   Node* in1 = in(1);
   Node* in2 = in(2);
   const Type* t1 = phase->type(in1);
   const Type* t2 = phase->type(in2);
-  if (t1 != Type::TOP && t2 != Type::TOP && in1 == in2) {
-    return new ConINode(TypeInt::ZERO);
+  if (t1 == Type::TOP || t2 == Type::TOP) {
+    return Type::TOP;
   }
-
-  return AddNode::Ideal(phase, can_reshape);
+  // x ^ x ==> 0
+  if (in1->eqv_uncast(in2)) {
+    return add_id();
+  }
+  return AddNode::Value(phase);
 }
 
 //------------------------------add_ring---------------------------------------
@@ -961,15 +964,19 @@ const Type *XorLNode::add_ring( const Type *t0, const Type *t1 ) const {
   return TypeLong::make( r0->get_con() ^ r1->get_con() );
 }
 
-Node* XorLNode::Ideal(PhaseGVN* phase, bool can_reshape) {
+const Type* XorLNode::Value(PhaseGVN* phase) const {
   Node* in1 = in(1);
   Node* in2 = in(2);
   const Type* t1 = phase->type(in1);
   const Type* t2 = phase->type(in2);
-  if (t1 != Type::TOP && t2 != Type::TOP && in1 == in2) {
-    return new ConLNode(TypeLong::ZERO);
+  if (t1 == Type::TOP || t2 == Type::TOP) {
+    return Type::TOP;
   }
-  return AddNode::Ideal(phase, can_reshape);
+  // x ^ x ==> 0
+  if (in1->eqv_uncast(in2)) {
+    return add_id();
+  }
+  return AddNode::Value(phase);
 }
 
 Node* MaxNode::build_min_max(Node* a, Node* b, bool is_max, bool is_unsigned, const Type* t, PhaseGVN& gvn) {

src/hotspot/share/opto/addnode.hpp

@@ -212,8 +212,8 @@ class XorINode : public AddNode {
   virtual const Type *add_ring( const Type *, const Type * ) const;
   virtual const Type *add_id() const { return TypeInt::ZERO; }
   virtual const Type *bottom_type() const { return TypeInt::INT; }
+  virtual const Type *Value(PhaseGVN *phase) const;
   virtual uint ideal_reg() const { return Op_RegI; }
-  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 };
 
 //------------------------------XorINode---------------------------------------
@@ -225,8 +225,8 @@ class XorLNode : public AddNode {
   virtual const Type *add_ring( const Type *, const Type * ) const;
   virtual const Type *add_id() const { return TypeLong::ZERO; }
   virtual const Type *bottom_type() const { return TypeLong::LONG; }
+  virtual const Type *Value(PhaseGVN *phase) const;
   virtual uint ideal_reg() const { return Op_RegL; }
-  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 };
 
 //------------------------------MaxNode----------------------------------------