1 /* 2 * Copyright (C) 2023 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 public class Main { main(String[] args)18 public static void main(String[] args) { 19 assertEquals(0, $noinline$testRemoveAbsAndReturnConstant()); 20 } 21 22 // After LSE we know that some values are 0, making the Abs operation redundant. 23 24 /// CHECK-START: int Main.$noinline$testRemoveAbsAndReturnConstant() constant_folding$before_codegen (before) 25 /// CHECK: Abs 26 27 /// CHECK-START: int Main.$noinline$testRemoveAbsAndReturnConstant() constant_folding$before_codegen (after) 28 /// CHECK-NOT: Abs 29 30 // This enables DCE to know the return value at compile time. 31 32 /// CHECK-START: int Main.$noinline$testRemoveAbsAndReturnConstant() dead_code_elimination$before_codegen (before) 33 /// CHECK: <<ReturnPhi:i\d+>> Phi [<<Val1:i\d+>>,<<Val2:i\d+>>] 34 /// CHECK: Return [<<ReturnPhi>>] 35 36 /// CHECK-START: int Main.$noinline$testRemoveAbsAndReturnConstant() dead_code_elimination$before_codegen (after) 37 /// CHECK: <<Const0:i\d+>> IntConstant 0 38 /// CHECK: Return [<<Const0>>] 39 $noinline$testRemoveAbsAndReturnConstant()40 private static int $noinline$testRemoveAbsAndReturnConstant() { 41 final int ARRAY_SIZE = 10; 42 int[] result = new int[ARRAY_SIZE]; 43 int[] source = new int[ARRAY_SIZE]; 44 45 int value = 0; 46 for (int i = 0; i < ARRAY_SIZE; ++i) { 47 value += Math.abs(source[i]); 48 result[i] = value; 49 } 50 return value; 51 } 52 assertEquals(int expected, int result)53 public static void assertEquals(int expected, int result) { 54 if (expected != result) { 55 throw new Error("Expected: " + expected + ", found: " + result); 56 } 57 } 58 } 59