Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
DReturnTransformer |
|
| 1.0;1 | ||||
DReturnTransformer$1 |
|
| 1.0;1 | ||||
DReturnTransformer$LazyHolder |
|
| 1.0;1 |
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.automatic.instructions; | |
18 | ||
19 | import org.apache.commons.nabla.automatic.analysis.InstructionsTransformer; | |
20 | import org.apache.commons.nabla.automatic.analysis.MethodDifferentiator; | |
21 | import org.apache.commons.nabla.core.DifferentiationException; | |
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 | import org.objectweb.asm.tree.MethodInsnNode; | |
27 | import org.objectweb.asm.tree.TypeInsnNode; | |
28 | import org.objectweb.asm.tree.VarInsnNode; | |
29 | ||
30 | /** Differentiation transformer for DRETURN instructions. | |
31 | * <p>DRETURN instructions are replaced by instructions | |
32 | * that build a {@link org.apache.commons.nabla.core.DifferentialPair | |
33 | * DifferentialPair} instance from the expanded differential pair | |
34 | * on operand stack head and an ARETURN instruction returning this | |
35 | * instance.</p> | |
36 | */ | |
37 | 1 | public class DReturnTransformer implements InstructionsTransformer { |
38 | ||
39 | /** Holder for the singleton instance.*/ | |
40 | 65 | private static class LazyHolder { |
41 | /** The singleton instance. */ | |
42 | 1 | private static final InstructionsTransformer INSTANCE = new DReturnTransformer(); |
43 | } | |
44 | ||
45 | /** Hidden constructor. | |
46 | */ | |
47 | 1 | private DReturnTransformer() { |
48 | 1 | } |
49 | ||
50 | /** Get the singleton instance. | |
51 | * <p>We use here the Initialization on Demand Holder idiom.</p> | |
52 | * @return the singleton instance | |
53 | */ | |
54 | public static InstructionsTransformer getInstance() { | |
55 | 65 | return LazyHolder.INSTANCE; |
56 | } | |
57 | ||
58 | /** {@inheritDoc} */ | |
59 | public InsnList getReplacement(final AbstractInsnNode insn, | |
60 | final MethodDifferentiator methodDifferentiator) | |
61 | throws DifferentiationException { | |
62 | ||
63 | // reuse local variables slots 1, 2, 3 and 4 for temporary storage | |
64 | // (this may reduce the number of needed local variables) | |
65 | 65 | methodDifferentiator.useLocal(1, 4); |
66 | ||
67 | 65 | final InsnList list = new InsnList(); |
68 | // operand stack initial state: a0, a1 | |
69 | 65 | list.add(new VarInsnNode(Opcodes.DSTORE, 3)); // => a0 |
70 | 65 | list.add(new VarInsnNode(Opcodes.DSTORE, 1)); // => |
71 | 65 | list.add(new TypeInsnNode(Opcodes.NEW, |
72 | MethodDifferentiator.DP_NAME)); // => o, | |
73 | 65 | list.add(new InsnNode(Opcodes.DUP)); // => o, o |
74 | 65 | list.add(new VarInsnNode(Opcodes.DLOAD, 1)); // => o, o, a0 |
75 | 65 | list.add(new VarInsnNode(Opcodes.DLOAD, 3)); // => o, o, a0, a1 |
76 | 65 | list.add(new MethodInsnNode(Opcodes.INVOKESPECIAL, |
77 | MethodDifferentiator.DP_NAME, | |
78 | "<init>", "(DD)V")); // => dp | |
79 | 65 | list.add(new InsnNode(Opcodes.ARETURN)); // => |
80 | 65 | return list; |
81 | ||
82 | } | |
83 | ||
84 | } |