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8222029: Optimize Math.floorMod

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Reviewed-by: aph, darcy
This commit is contained in:
Claes Redestad 2019-04-10 20:03:07 +02:00
parent 0f4b0947ff
commit 8ee30d4fbe
3 changed files with 120 additions and 3 deletions
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16
src/java.base/share/classes/java/lang/Math.java
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@ -1274,7 +1274,12 @@ public final class Math {
* @since 1.8
*/
public static int floorMod(int x, int y) {
return x - floorDiv(x, y) * y;
int mod = x % y;
// if the signs are different and modulo not zero, adjust result
if ((mod ^ y) < 0 && mod != 0) {
mod += y;
}
return mod;
}
/**
@ -1301,7 +1306,7 @@ public final class Math {
*/
public static int floorMod(long x, int y) {
// Result cannot overflow the range of int.
return (int)(x - floorDiv(x, y) * y);
return (int)floorMod(x, (long)y);
}
/**
@ -1327,7 +1332,12 @@ public final class Math {
* @since 1.8
*/
public static long floorMod(long x, long y) {
return x - floorDiv(x, y) * y;
long mod = x % y;
// if the signs are different and modulo not zero, adjust result
if ((x ^ y) < 0 && mod != 0) {
mod += y;
}
return mod;
}
/**

12
test/jdk/java/lang/Math/DivModTests.java
View File

@ -91,6 +91,10 @@ public class DivModTests {
testIntFloorDivMod(Integer.MIN_VALUE, 3, -715827883, 1);
testIntFloorDivMod(Integer.MIN_VALUE + 1, 3, -715827883, 2);
testIntFloorDivMod(Integer.MIN_VALUE + 1, -1, Integer.MAX_VALUE, 0);
testIntFloorDivMod(Integer.MAX_VALUE, Integer.MAX_VALUE, 1, 0);
testIntFloorDivMod(Integer.MAX_VALUE, Integer.MIN_VALUE, -1, -1);
testIntFloorDivMod(Integer.MIN_VALUE, Integer.MIN_VALUE, 1, 0);
testIntFloorDivMod(Integer.MIN_VALUE, Integer.MAX_VALUE, -2, 2147483646);
// Special case of integer overflow
testIntFloorDivMod(Integer.MIN_VALUE, -1, Integer.MIN_VALUE, 0);
}
@ -179,6 +183,10 @@ public class DivModTests {
testLongFloorDivMod(Long.MIN_VALUE, 3L, Long.MIN_VALUE / 3L - 1L, 1L);
testLongFloorDivMod(Long.MIN_VALUE + 1L, 3L, Long.MIN_VALUE / 3L - 1L, 2L);
testLongFloorDivMod(Long.MIN_VALUE + 1, -1, Long.MAX_VALUE, 0L);
testLongFloorDivMod(Long.MAX_VALUE, Long.MAX_VALUE, 1L, 0L);
testLongFloorDivMod(Long.MAX_VALUE, Long.MIN_VALUE, -1L, -1L);
testLongFloorDivMod(Long.MIN_VALUE, Long.MIN_VALUE, 1L, 0L);
testLongFloorDivMod(Long.MIN_VALUE, Long.MAX_VALUE, -2L, 9223372036854775806L);
// Special case of integer overflow
testLongFloorDivMod(Long.MIN_VALUE, -1, Long.MIN_VALUE, 0L);
}
@ -283,6 +291,10 @@ public class DivModTests {
testLongIntFloorDivMod(Long.MIN_VALUE, 3, Long.MIN_VALUE / 3L - 1L, 1L);
testLongIntFloorDivMod(Long.MIN_VALUE + 1L, 3, Long.MIN_VALUE / 3L - 1L, 2L);
testLongIntFloorDivMod(Long.MIN_VALUE + 1, -1, Long.MAX_VALUE, 0L);
testLongIntFloorDivMod(Long.MAX_VALUE, Integer.MAX_VALUE, 4294967298L, 1);
testLongIntFloorDivMod(Long.MAX_VALUE, Integer.MIN_VALUE, -4294967296L, -1);
testLongIntFloorDivMod(Long.MIN_VALUE, Integer.MIN_VALUE, 4294967296L, 0);
testLongIntFloorDivMod(Long.MIN_VALUE, Integer.MAX_VALUE, -4294967299L, 2147483645);
// Special case of integer overflow
testLongIntFloorDivMod(Long.MIN_VALUE, -1, Long.MIN_VALUE, 0L);
}

95
test/micro/org/openjdk/bench/java/lang/MathBench.java Normal file
View File

@ -0,0 +1,95 @@
/*
* Copyright (c) 2014 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
* 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.
*/
package org.openjdk.bench.java.lang;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.CompilerControl;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import java.util.Random;
import java.util.concurrent.TimeUnit;
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
public class MathBench {
@Param("0")
public long seed;
public int dividend;
public int divisor;
public long longDividend;
public long longDivisor;
@Setup
public void setupValues() {
Random random = new Random(seed);
dividend = Math.abs(random.nextInt() + 4711);
divisor = Math.abs(random.nextInt(dividend) + 17);
longDividend = Math.abs(random.nextLong() + 4711L);
longDivisor = Math.abs(random.nextLong() + longDividend);
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public int floorModIntIntPositive() {
return Math.floorMod(dividend, divisor);
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public int floorModIntInt() {
return Math.floorMod( dividend, divisor) +
Math.floorMod( dividend, -divisor) +
Math.floorMod(-dividend, divisor) +
Math.floorMod(-dividend, -divisor);
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public int floorModLongInt() {
return Math.floorMod( longDividend, divisor) +
Math.floorMod( longDividend, -divisor) +
Math.floorMod(-longDividend, divisor) +
Math.floorMod(-longDividend, -divisor);
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public long floorModLongLong() {
return Math.floorMod( longDividend, longDivisor) +
Math.floorMod( longDividend, -longDivisor) +
Math.floorMod(-longDividend, longDivisor) +
Math.floorMod(-longDividend, -longDivisor);
}
}