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8273454: C2: Transform (-a)*(-b) into a*b
Reviewed-by: thartmann, eliu, chagedorn
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zhengyu123 committed Sep 18, 2021
1 parent bb9d142 commit 7c9868c0b3c9bd3d305e71f91596190813cdccce
Showing 2 changed files with 120 additions and 1 deletion.
@@ -63,9 +63,24 @@ Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
const Type *t2 = phase->type( in(2) );
Node *progress = NULL; // Progress flag

// convert "max(a,b) * min(a,b)" into "a*b".
// convert "(-a)*(-b)" into "a*b"
Node *in1 = in(1);
Node *in2 = in(2);
if (in1->is_Sub() && in2->is_Sub()) {
if (phase->type(in1->in(1))->is_zero_type() &&
phase->type(in2->in(1))->is_zero_type()) {
set_req(1, in1->in(2));
set_req(2, in2->in(2));
PhaseIterGVN* igvn = phase->is_IterGVN();
if (igvn) {
igvn->_worklist.push(in1);
igvn->_worklist.push(in2);
}
progress = this;
}
}

// convert "max(a,b) * min(a,b)" into "a*b".
if ((in(1)->Opcode() == max_opcode() && in(2)->Opcode() == min_opcode())
|| (in(1)->Opcode() == min_opcode() && in(2)->Opcode() == max_opcode())) {
Node *in11 = in(1)->in(1);
@@ -0,0 +1,104 @@
/*
* Copyright (c) 2021, Red Hat, Inc. 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 8273454
* @summary Test transformation (-a)*(-b) = a*b
*
* @library /test/lib
*
* @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:CompileCommand="dontinline,TestNegMultiply::test*" TestNegMultiply
*
*/

import java.util.Random;
import jdk.test.lib.Utils;
import jdk.test.lib.Asserts;

public class TestNegMultiply {
private static final Random random = Utils.getRandomInstance();
// Enough cycles to ensure test methods are JIT-ed
private static final int TEST_COUNT = 20_000;

private static int testInt(int a, int b) {
return (-a) * (-b);
}
private static long testLong(long a, long b) {
return (-a) * (-b);
}
private static float testFloat(float a, float b) {
return (-a) * (-b);
}
private static double testDouble(double a, double b) {
return (-a) * (-b);
}

private static void runIntTests() {
for (int index = 0; index < TEST_COUNT; index ++) {
int a = random.nextInt();
int b = random.nextInt();
int expected = (-a) * (-b);
int res = testInt(a, b);
Asserts.assertEQ(res, expected);
}
}

private static void runLongTests() {
for (int index = 0; index < TEST_COUNT; index ++) {
long a = random.nextLong();
long b = random.nextLong();
long expected = (-a) * (-b);
long res = testLong(a, b);
Asserts.assertEQ(res, expected);
}
}

private static void runFloatTests() {
for (int index = 0; index < TEST_COUNT; index ++) {
float a = random.nextFloat();
float b = random.nextFloat();
float expected = (-a) * (-b);
float res = testFloat(a, b);
Asserts.assertEQ(res, expected);
}
}

private static void runDoubleTests() {
for (int index = 0; index < TEST_COUNT; index ++) {
double a = random.nextDouble();
double b = random.nextDouble();
double expected = (-a) * (-b);
double res = testDouble(a, b);
Asserts.assertEQ(res, expected);
}
}

public static void main(String[] args) {
runIntTests();
runLongTests();
runFloatTests();
runDoubleTests();
}
}

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