| /* |
| * Copyright (C) 2009 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package examples; |
| |
| import com.google.caliper.Benchmark; |
| |
| /** |
| * Measures several candidate implementations for mod(). |
| */ |
| @SuppressWarnings("SameParameterValue") |
| public class IntModBenchmark { |
| private static final int M = (1 << 16) - 1; |
| |
| @Benchmark int conditional(int reps) { |
| int dummy = 5; |
| for (int i = 0; i < reps; i++) { |
| dummy += Integer.MAX_VALUE + conditionalMod(dummy, M); |
| } |
| return dummy; |
| } |
| |
| private static int conditionalMod(int a, int m) { |
| int r = a % m; |
| return r < 0 ? r + m : r; |
| } |
| |
| @Benchmark int doubleRemainder(int reps) { |
| int dummy = 5; |
| for (int i = 0; i < reps; i++) { |
| dummy += Integer.MAX_VALUE + doubleRemainderMod(dummy, M); |
| } |
| return dummy; |
| } |
| |
| @SuppressWarnings("NumericCastThatLosesPrecision") // result of % by an int must be in int range |
| private static int doubleRemainderMod(int a, int m) { |
| return (int) ((a % m + (long) m) % m); |
| } |
| |
| @Benchmark int rightShiftingMod(int reps) { |
| int dummy = 5; |
| for (int i = 0; i < reps; i++) { |
| dummy += Integer.MAX_VALUE + rightShiftingMod(dummy, M); |
| } |
| return dummy; |
| } |
| |
| @SuppressWarnings("NumericCastThatLosesPrecision") // must be in int range |
| private static int rightShiftingMod(int a, int m) { |
| long r = a % m; |
| return (int) (r + (r >> 63 & m)); |
| } |
| |
| @Benchmark int leftShiftingMod(int reps) { |
| int dummy = 5; |
| for (int i = 0; i < reps; i++) { |
| dummy += Integer.MAX_VALUE + leftShiftingMod(dummy, M); |
| } |
| return dummy; |
| } |
| |
| @SuppressWarnings("NumericCastThatLosesPrecision") // result of % by an int must be in int range |
| private static int leftShiftingMod(int a, int m) { |
| return (int) ((a + ((long) m << 32)) % m); |
| } |
| |
| @Benchmark int wrongMod(int reps) { |
| int dummy = 5; |
| for (int i = 0; i < reps; i++) { |
| dummy += Integer.MAX_VALUE + dummy % M; |
| } |
| return dummy; |
| } |
| } |