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8273021: C2: Improve Add and Xor ideal optimizations
Backport-of: a73c06de2ac47033503189140c0f8ee61fcbceae
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Yi Yang authored and Vladimir Kozlov committed Nov 5, 2021
1 parent dc93934 commit e829c856b738d03db3ab210d3bde24b83af633cb
Showing 3 changed files with 137 additions and 1 deletion.
@@ -363,6 +363,13 @@ Node *AddINode::Ideal(PhaseGVN *phase, bool can_reshape) {
}
}

// Convert (~x+1) into -x. Note there isn't a bitwise not bytecode,
// "~x" would typically represented as "x^(-1)", so (~x+1) will
// be (x^(-1))+1.
if (op1 == Op_XorI && phase->type(in2) == TypeInt::ONE &&
phase->type(in1->in(2)) == TypeInt::MINUS_1) {
return new SubINode(phase->makecon(TypeInt::ZERO), in1->in(1));
}
return AddNode::Ideal(phase, can_reshape);
}

@@ -486,7 +493,13 @@ Node *AddLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
}
}


// Convert (~x+1) into -x. Note there isn't a bitwise not bytecode,
// "~x" would typically represented as "x^(-1)", so (~x+1) will
// be (x^(-1))+1
if (op1 == Op_XorL && phase->type(in2) == TypeLong::ONE &&
phase->type(in1->in(2)) == TypeLong::MINUS_1) {
return new SubLNode(phase->makecon(TypeLong::ZERO), in1->in(1));
}
return AddNode::Ideal(phase, can_reshape);
}

@@ -899,6 +912,21 @@ const Type *OrLNode::add_ring( const Type *t0, const Type *t1 ) const {
}

//=============================================================================
//------------------------------Idealize---------------------------------------
Node* XorINode::Ideal(PhaseGVN* phase, bool can_reshape) {
Node* in1 = in(1);
Node* in2 = in(2);
int op1 = in1->Opcode();
// Convert ~(x-1) into -x. Note there isn't a bitwise not bytecode,
// "~x" would typically represented as "x^(-1)", and "x-c0" would
// convert into "x+ -c0" in SubXNode::Ideal. So ~(x-1) will eventually
// be (x+(-1))^-1.
if (op1 == Op_AddI && phase->type(in2) == TypeInt::MINUS_1 &&
phase->type(in1->in(2)) == TypeInt::MINUS_1) {
return new SubINode(phase->makecon(TypeInt::ZERO), in1->in(1));
}
return AddNode::Ideal(phase, can_reshape);
}

const Type* XorINode::Value(PhaseGVN* phase) const {
Node* in1 = in(1);
@@ -964,6 +992,21 @@ 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) {
Node* in1 = in(1);
Node* in2 = in(2);
int op1 = in1->Opcode();
// Convert ~(x-1) into -x. Note there isn't a bitwise not bytecode,
// "~x" would typically represented as "x^(-1)", and "x-c0" would
// convert into "x+ -c0" in SubXNode::Ideal. So ~(x-1) will eventually
// be (x+(-1))^-1.
if (op1 == Op_AddL && phase->type(in2) == TypeLong::MINUS_1 &&
phase->type(in1->in(2)) == TypeLong::MINUS_1) {
return new SubLNode(phase->makecon(TypeLong::ZERO), in1->in(1));
}
return AddNode::Ideal(phase, can_reshape);
}

const Type* XorLNode::Value(PhaseGVN* phase) const {
Node* in1 = in(1);
Node* in2 = in(2);
@@ -227,6 +227,7 @@ class XorINode : public AddNode {
public:
XorINode( Node *in1, Node *in2 ) : AddNode(in1,in2) {}
virtual int Opcode() const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
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; }
@@ -242,6 +243,7 @@ class XorLNode : public AddNode {
public:
XorLNode( Node *in1, Node *in2 ) : AddNode(in1,in2) {}
virtual int Opcode() const;
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
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; }
@@ -0,0 +1,91 @@
/*
* Copyright (c) 2021, Alibaba Group Holding Limited. 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
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/

/*
* @test
* @key randomness
* @bug 8273021
* @summary C2: Improve Add and Xor ideal optimizations
* @library /test/lib
* @run main/othervm -XX:-TieredCompilation
* -XX:CompileCommand=dontinline,compiler.c2.TestAddXorIdeal::test*
* compiler.c2.TestAddXorIdeal
*/
package compiler.c2;

import java.util.Random;

import jdk.test.lib.Asserts;
import jdk.test.lib.Utils;

public class TestAddXorIdeal {

public static int test1(int x) {
return ~x + 1;
}

public static int test2(int x) {
return ~(x - 1);
}

public static long test3(long x) {
return ~x + 1L;
}

public static long test4(long x) {
return ~(x - 1L);
}

public static int test5(int x) {
return 1 + ~x;
}

public static int test6(int x) {
return ~(-1 + x);
}

public static long test7(long x) {
return 1L + ~x;
}

public static long test8(long x) {
return ~(-1L + x);
}

public static void main(String... args) {
Random random = Utils.getRandomInstance();
for (int i = 0; i < 50_000; i++) {
int a = random.nextInt();
long b = random.nextLong();
Asserts.assertTrue(test1(a) == -a);
Asserts.assertTrue(test2(a) == -a);
Asserts.assertTrue(test3(b) == -b);
Asserts.assertTrue(test4(b) == -b);
Asserts.assertTrue(test5(a) == -a);
Asserts.assertTrue(test6(a) == -a);
Asserts.assertTrue(test7(b) == -b);
Asserts.assertTrue(test8(b) == -b);
}
}
}

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