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.forward.instructions;
018    
019    import org.apache.commons.nabla.DifferentiationException;
020    import org.apache.commons.nabla.forward.analysis.InstructionsTransformer;
021    import org.apache.commons.nabla.forward.analysis.MethodDifferentiator;
022    import org.objectweb.asm.Opcodes;
023    import org.objectweb.asm.Type;
024    import org.objectweb.asm.tree.AbstractInsnNode;
025    import org.objectweb.asm.tree.InsnList;
026    import org.objectweb.asm.tree.InsnNode;
027    import org.objectweb.asm.tree.MethodInsnNode;
028    
029    /** Differentiation transformer for DCMPx instructions.
030     * @version $Id$
031     */
032    public class DcmpTransformer implements InstructionsTransformer {
033    
034        /** Name of the {@link org.apache.commons.math3.analysis.differentiation.DerivativeStructure} method corresponding to the value getter. */
035        private static final String VALUE_GETTER_METHOD = "getValue";
036    
037        /** Indicator for top stack element conversion. */
038        private final boolean stack0Converted;
039    
040        /** Indicator for next to top stack element conversion. */
041        private final boolean stack1Converted;
042    
043        /** Simple constructor.
044         * @param stack0Converted if true, the top level stack element has already been converted
045         * @param stack1Converted if true, the next to top level stack element has already been converted
046         */
047        public DcmpTransformer(final boolean stack0Converted, final boolean stack1Converted) {
048            this.stack0Converted = stack0Converted;
049            this.stack1Converted = stack1Converted;
050        }
051    
052        /** {@inheritDoc} */
053        public InsnList getReplacement(final AbstractInsnNode insn,
054                                       final MethodDifferentiator methodDifferentiator)
055            throws DifferentiationException {
056            final InsnList list = new InsnList();
057    
058            if (stack1Converted) {
059                if (stack0Converted) {
060                    // operand stack initial state: ds_a, ds_b
061                    list.add(new InsnNode(Opcodes.SWAP));                                              // => ds_b, ds_a
062                    list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
063                                                VALUE_GETTER_METHOD,
064                                                Type.getMethodDescriptor(Type.DOUBLE_TYPE)));          // => ds_b, a0
065                    list.add(new InsnNode(Opcodes.DUP2_X2));                                           // => a0, ds_b, a0
066                    list.add(new InsnNode(Opcodes.POP2));                                              // => a0, ds_b
067                    list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
068                                                VALUE_GETTER_METHOD,
069                                                Type.getMethodDescriptor(Type.DOUBLE_TYPE)));          // => a0, b0
070                } else {
071                    // operand stack initial state: ds_a, b0
072                    list.add(new InsnNode(Opcodes.DUP2_X2));                                           // => b0, ds_a, b0
073                    list.add(new InsnNode(Opcodes.POP2));                                              // => b0, ds_a
074                    list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
075                                                VALUE_GETTER_METHOD,
076                                                Type.getMethodDescriptor(Type.DOUBLE_TYPE)));          // => b0, a0
077                    list.add(new InsnNode(Opcodes.DUP2_X2));                                           // => a0, b0, a0
078                    list.add(new InsnNode(Opcodes.POP2));                                              // => a0, b0
079                }
080            } else {
081                // operand stack initial state: a, ds_b
082                list.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, DS_TYPE.getInternalName(),
083                                            VALUE_GETTER_METHOD,
084                                            Type.getMethodDescriptor(Type.DOUBLE_TYPE)));              // => a0, b0
085            }
086    
087            list.add(new InsnNode(insn.getOpcode()));                                                  // => bool
088    
089            return list;
090    
091        }
092    
093    }