001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.nabla.algorithmic.forward.arithmetic; 018 019 import org.apache.commons.nabla.algorithmic.forward.analysis.InstructionsTransformer; 020 import org.apache.commons.nabla.algorithmic.forward.analysis.MethodDifferentiator; 021 import org.apache.commons.nabla.core.DifferentiationException; 022 import org.objectweb.asm.Opcodes; 023 import org.objectweb.asm.tree.AbstractInsnNode; 024 import org.objectweb.asm.tree.InsnList; 025 import org.objectweb.asm.tree.InsnNode; 026 import org.objectweb.asm.tree.VarInsnNode; 027 028 /** Differentiation transformer for DREM instructions. 029 * <p>This transformer is used when only the first argument 030 * of DREM is an expanded differential pair. It is based on 031 * the identity: <code>a%b = a - q * b</code> where q is an 032 * integer.</p> 033 * @see DRemTransformer12 034 * @see DRemTransformer2 035 */ 036 public class DRemTransformer1 implements InstructionsTransformer { 037 038 // CHECKSTYLE: stop HideUtilityClassConstructor 039 /** Holder for the singleton instance.*/ 040 private static class LazyHolder { 041 /** The singleton instance. */ 042 private static final InstructionsTransformer INSTANCE = new DRemTransformer1(); 043 } 044 // CHECKSTYLE: resume HideUtilityClassConstructor 045 046 /** Hidden constructor. 047 */ 048 private DRemTransformer1() { 049 } 050 051 /** Get the singleton instance. 052 * <p>We use here the Initialization on Demand Holder idiom.</p> 053 * @return the singleton instance 054 */ 055 public static InstructionsTransformer getInstance() { 056 return LazyHolder.INSTANCE; 057 } 058 059 /** {@inheritDoc} */ 060 public InsnList getReplacement(final AbstractInsnNode insn, 061 final MethodDifferentiator methodDifferentiator) 062 throws DifferentiationException { 063 064 final int tmp = methodDifferentiator.getTmp(1); 065 final InsnList list = new InsnList(); 066 067 // operand stack initial state: a0, a1, b 068 list.add(new InsnNode(Opcodes.DUP2_X2)); // => a0, b, a1, b 069 list.add(new InsnNode(Opcodes.POP2)); // => a0, b, a1 070 list.add(new VarInsnNode(Opcodes.DSTORE, tmp)); // => a0, b 071 list.add(new InsnNode(Opcodes.DREM)); // => a0%b 072 list.add(new VarInsnNode(Opcodes.DLOAD, tmp)); // => a0%b, a1 073 074 return list; 075 076 } 077 078 }