001    /*
002     * Copyright 2010-2015 JetBrains s.r.o.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package org.jetbrains.kotlin.codegen.optimization.common;
018    
019    import org.jetbrains.annotations.NotNull;
020    import org.jetbrains.annotations.Nullable;
021    import org.jetbrains.org.objectweb.asm.Opcodes;
022    import org.jetbrains.org.objectweb.asm.Type;
023    import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode;
024    import org.jetbrains.org.objectweb.asm.tree.LdcInsnNode;
025    import org.jetbrains.org.objectweb.asm.tree.analysis.AnalyzerException;
026    import org.jetbrains.org.objectweb.asm.tree.analysis.BasicInterpreter;
027    import org.jetbrains.org.objectweb.asm.tree.analysis.BasicValue;
028    
029    public class OptimizationBasicInterpreter extends BasicInterpreter {
030        private static final BasicValue BOOLEAN_VALUE = new BasicValue(Type.BOOLEAN_TYPE);
031        private static final BasicValue CHAR_VALUE = new BasicValue(Type.CHAR_TYPE);
032        private static final BasicValue BYTE_VALUE = new BasicValue(Type.BYTE_TYPE);
033        private static final BasicValue SHORT_VALUE = new BasicValue(Type.SHORT_TYPE);
034    
035        @Override
036        @Nullable
037        public BasicValue newValue(@Nullable Type type) {
038            if (type == null) {
039                return super.newValue(null);
040            }
041    
042            switch (type.getSort()) {
043                case Type.VOID:
044                    return null;
045                case Type.BOOLEAN:
046                    return BOOLEAN_VALUE;
047                case Type.CHAR:
048                    return CHAR_VALUE;
049                case Type.BYTE:
050                    return BYTE_VALUE;
051                case Type.SHORT:
052                    return SHORT_VALUE;
053                case Type.OBJECT:
054                    return new BasicValue(type);
055                default:
056                    return super.newValue(type);
057            }
058        }
059    
060        @NotNull
061        @Override
062        public BasicValue merge(
063                @NotNull BasicValue v, @NotNull BasicValue w
064        ) {
065            if (v == BasicValue.UNINITIALIZED_VALUE || w == BasicValue.UNINITIALIZED_VALUE) {
066                return BasicValue.UNINITIALIZED_VALUE;
067            }
068            // Objects must be equal, others can just have the same sort
069            if (v.getType().getSort() == w.getType().getSort() && (v.getType().getSort() != Type.OBJECT || v.equals(w))) {
070                return v;
071            }
072    
073            // if merge of two references then `lub` is java/lang/Object
074            // arrays also are BasicValues with reference type's
075            if (v.getType().getSort() == Type.OBJECT && w.getType().getSort() == Type.OBJECT) {
076                return BasicValue.REFERENCE_VALUE;
077            }
078    
079            assert v.getType().getSort() != Type.ARRAY && w.getType().getSort() != Type.ARRAY : "There should not be arrays";
080    
081            // if merge of something can be stored in int var (int, char, boolean, byte, character)
082            if (v.getType().getOpcode(Opcodes.ISTORE) == Opcodes.ISTORE &&
083                w.getType().getOpcode(Opcodes.ISTORE) == Opcodes.ISTORE) {
084                return BasicValue.INT_VALUE;
085            }
086    
087            return BasicValue.UNINITIALIZED_VALUE;
088        }
089    }