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.functions;
018    
019    import org.apache.commons.nabla.algorithmic.forward.analysis.MethodDifferentiator;
020    import org.apache.commons.nabla.core.DifferentiationException;
021    import org.objectweb.asm.Opcodes;
022    import org.objectweb.asm.tree.InsnList;
023    import org.objectweb.asm.tree.InsnNode;
024    import org.objectweb.asm.tree.MethodInsnNode;
025    import org.objectweb.asm.tree.VarInsnNode;
026    
027    /** Differentiation transformer for the hypot function invocation instructions.
028     */
029    public class HypotTransformer2 implements MathInvocationTransformer {
030    
031        /** {@inheritDoc} */
032        public InsnList getReplacementList(final String owner, final MethodDifferentiator methodDifferentiator)
033            throws DifferentiationException {
034    
035            final int tmp1 = methodDifferentiator.getTmp(1);
036    
037            // generate differential code
038            // ... x, y0, y1  --> ...  hypot(x,y0), y0*y1/hypot(x,y0)
039            final InsnList list = new InsnList();
040            list.add(new VarInsnNode(Opcodes.DSTORE, tmp1)); // => x, y0
041            list.add(new InsnNode(Opcodes.DUP2_X2));         // => y0, x, y0
042            list.add(new MethodInsnNode(Opcodes.INVOKESTATIC, owner, "hypot", DD_RETURN_D_DESCRIPTOR)); // => y0, hypot(x,y0)
043            list.add(new InsnNode(Opcodes.DUP2_X2));         // => hypot(x,y0), y0, hypot(x,y0)
044            list.add(new InsnNode(Opcodes.DDIV));            // => hypot(x,y0), y0/hypot(x,y0)
045            list.add(new VarInsnNode(Opcodes.DLOAD,  tmp1)); // => hypot(x,y0), y0/hypot(x,y0), y1
046            list.add(new InsnNode(Opcodes.DMUL));            // => hypot(x,y0), y0*y1/hypot(x,y0)
047            return list;
048    
049        }
050    
051    }