mirror of
https://github.com/openjdk/jdk.git
synced 2026-02-09 09:58:43 +00:00
75 lines
2.3 KiB
Java
75 lines
2.3 KiB
Java
/*
|
|
* Copyright (c) 2025 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.
|
|
*/
|
|
|
|
package org.openjdk.bench.vm.compiler;
|
|
|
|
import org.openjdk.jmh.annotations.*;
|
|
|
|
import java.util.concurrent.TimeUnit;
|
|
import java.util.concurrent.ThreadLocalRandom;
|
|
|
|
@BenchmarkMode(Mode.AverageTime)
|
|
@OutputTimeUnit(TimeUnit.NANOSECONDS)
|
|
@Fork(value = 3)
|
|
@Warmup(iterations = 10, time = 1)
|
|
@Measurement(iterations = 5, time = 1)
|
|
@State(Scope.Thread)
|
|
public class CountLeadingZeros {
|
|
private long[] longArray = new long[1000];
|
|
|
|
@Setup
|
|
public void setup() {
|
|
for (int i = 0; i < longArray.length; i++) {
|
|
longArray[i] = ThreadLocalRandom.current().nextLong();
|
|
}
|
|
}
|
|
|
|
@Benchmark
|
|
public int benchNumberOfNibbles() {
|
|
int sum = 0;
|
|
for (long l : longArray) {
|
|
sum += numberOfNibbles((int) l);
|
|
}
|
|
return sum;
|
|
}
|
|
|
|
public static int numberOfNibbles(int i) {
|
|
int mag = Integer.SIZE - Integer.numberOfLeadingZeros(i);
|
|
return Math.max((mag + 3) / 4, 1);
|
|
}
|
|
|
|
@Benchmark
|
|
public int benchClzLongConstrained() {
|
|
int sum = 0;
|
|
for (long l : longArray) {
|
|
sum += clzLongConstrained(l);
|
|
}
|
|
return sum;
|
|
}
|
|
|
|
public static int clzLongConstrained(long param) {
|
|
long constrainedParam = Math.min(175, Math.max(param, 160));
|
|
return Long.numberOfLeadingZeros(constrainedParam);
|
|
}
|
|
}
|