1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.nabla.forward.instructions; 18 19 import org.apache.commons.nabla.DifferentiationException; 20 import org.apache.commons.nabla.forward.analysis.InstructionsTransformer; 21 import org.apache.commons.nabla.forward.analysis.MethodDifferentiator; 22 import org.objectweb.asm.Opcodes; 23 import org.objectweb.asm.tree.AbstractInsnNode; 24 import org.objectweb.asm.tree.InsnList; 25 import org.objectweb.asm.tree.InsnNode; 26 27 /** Differentiation transformer for DRETURN instructions. 28 * <p>DRETURN instructions are replaced by ARETURN instructions 29 * as a reference to a {@link 30 * org.apache.commons.math3.analysis.differentiation.DerivativeStructure} 31 * instance uses only one stack slot instead of two.</p> 32 * @version $Id$ 33 */ 34 public class DReturnTransformer implements InstructionsTransformer { 35 36 /** Indicator for top stack element conversion. */ 37 private final boolean stack0Converted; 38 39 /** Simple constructor. 40 * @param stack0Converted if true, the top level stack element has already been converted 41 */ 42 public DReturnTransformer(final boolean stack0Converted) { 43 this.stack0Converted = stack0Converted; 44 } 45 46 /** {@inheritDoc} */ 47 public InsnList getReplacement(final AbstractInsnNode insn, 48 final MethodDifferentiator methodDifferentiator) 49 throws DifferentiationException { 50 51 final InsnList list = new InsnList(); 52 53 if (!stack0Converted) { 54 // add conversion for top level stack element 55 list.add(methodDifferentiator.doubleToDerivativeStructureConversion()); 56 } 57 58 // add the return instruction for a reference type 59 list.add(new InsnNode(Opcodes.ARETURN)); 60 61 return list; 62 63 } 64 65 }