8261008: Optimize Xor

Reviewed-by: thartmann, kvn

Author: Eric Liu

src/hotspot/share/opto/addnode.cpp

@@ -913,6 +913,22 @@ const Type *OrLNode::add_ring( const Type *t0, const Type *t1 ) const {
 }
 
 //=============================================================================
+
+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) {
+    return Type::TOP;
+  }
+  // x ^ x ==> 0
+  if (in1->eqv_uncast(in2)) {
+    return add_id();
+  }
+  return AddNode::Value(phase);
+}
+
 //------------------------------add_ring---------------------------------------
 // Supplied function returns the sum of the inputs IN THE CURRENT RING.  For
 // the logical operations the ring's ADD is really a logical OR function.
@@ -948,6 +964,20 @@ const Type *XorLNode::add_ring( const Type *t0, const Type *t1 ) const {
   return TypeLong::make( r0->get_con() ^ r1->get_con() );
 }
 
+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) {
+    return Type::TOP;
+  }
+  // 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) {
   bool is_int = gvn.type(a)->isa_int();

src/hotspot/share/opto/addnode.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -212,6 +212,7 @@ 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; }
 };
 
@@ -224,6 +225,7 @@ 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; }
 };