| /* |
| * Copyright (c) 2017, 2020, Oracle and/or its affiliates. All rights reserved. |
| */ |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package com.sun.org.apache.bcel.internal.generic; |
| |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| |
| import com.sun.org.apache.bcel.internal.Const; |
| import com.sun.org.apache.bcel.internal.util.ByteSequence; |
| |
| /** |
| * Abstract super class for instructions dealing with local variables. |
| * |
| * @LastModified: Jan 2020 |
| */ |
| public abstract class LocalVariableInstruction extends Instruction implements TypedInstruction, |
| IndexedInstruction { |
| |
| private int n = -1; // index of referenced variable |
| private short c_tag = -1; // compact version, such as ILOAD_0 |
| private short canon_tag = -1; // canonical tag such as ILOAD |
| |
| |
| private boolean wide() { |
| return n > Const.MAX_BYTE; |
| } |
| |
| |
| /** |
| * Empty constructor needed for Instruction.readInstruction. |
| * Not to be used otherwise. |
| * tag and length are defined in readInstruction and initFromFile, respectively. |
| */ |
| LocalVariableInstruction(final short canon_tag, final short c_tag) { |
| super(); |
| this.canon_tag = canon_tag; |
| this.c_tag = c_tag; |
| } |
| |
| |
| /** |
| * Empty constructor needed for Instruction.readInstruction. |
| * Also used by IINC()! |
| */ |
| LocalVariableInstruction() { |
| } |
| |
| |
| /** |
| * @param opcode Instruction opcode |
| * @param c_tag Instruction number for compact version, ALOAD_0, e.g. |
| * @param n local variable index (unsigned short) |
| */ |
| protected LocalVariableInstruction(final short opcode, final short c_tag, final int n) { |
| super(opcode, (short) 2); |
| this.c_tag = c_tag; |
| canon_tag = opcode; |
| setIndex(n); |
| } |
| |
| |
| /** |
| * Dump instruction as byte code to stream out. |
| * @param out Output stream |
| */ |
| @Override |
| public void dump( final DataOutputStream out ) throws IOException { |
| if (wide()) { |
| out.writeByte(Const.WIDE); |
| } |
| out.writeByte(super.getOpcode()); |
| if (super.getLength() > 1) { // Otherwise ILOAD_n, instruction, e.g. |
| if (wide()) { |
| out.writeShort(n); |
| } else { |
| out.writeByte(n); |
| } |
| } |
| } |
| |
| |
| /** |
| * Long output format: |
| * |
| * <name of opcode> "["<opcode number>"]" |
| * "("<length of instruction>")" "<"< local variable index>">" |
| * |
| * @param verbose long/short format switch |
| * @return mnemonic for instruction |
| */ |
| @Override |
| public String toString( final boolean verbose ) { |
| final short _opcode = super.getOpcode(); |
| if (((_opcode >= Const.ILOAD_0) && (_opcode <= Const.ALOAD_3)) |
| || ((_opcode >= Const.ISTORE_0) && (_opcode <= Const.ASTORE_3))) { |
| return super.toString(verbose); |
| } |
| return super.toString(verbose) + " " + n; |
| } |
| |
| |
| /** |
| * Read needed data (e.g. index) from file. |
| * <pre> |
| * (ILOAD <= tag <= ALOAD_3) || (ISTORE <= tag <= ASTORE_3) |
| * </pre> |
| */ |
| @Override |
| protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException { |
| if (wide) { |
| n = bytes.readUnsignedShort(); |
| super.setLength(4); |
| } else { |
| final short _opcode = super.getOpcode(); |
| if (((_opcode >= Const.ILOAD) && (_opcode <= Const.ALOAD)) |
| || ((_opcode >= Const.ISTORE) && (_opcode <= Const.ASTORE))) { |
| n = bytes.readUnsignedByte(); |
| super.setLength(2); |
| } else if (_opcode <= Const.ALOAD_3) { // compact load instruction such as ILOAD_2 |
| n = (_opcode - Const.ILOAD_0) % 4; |
| super.setLength(1); |
| } else { // Assert ISTORE_0 <= tag <= ASTORE_3 |
| n = (_opcode - Const.ISTORE_0) % 4; |
| super.setLength(1); |
| } |
| } |
| } |
| |
| |
| /** |
| * @return local variable index (n) referred by this instruction. |
| */ |
| @Override |
| public final int getIndex() { |
| return n; |
| } |
| |
| |
| /** |
| * Set the local variable index. |
| * also updates opcode and length |
| * TODO Why? |
| * @see #setIndexOnly(int) |
| */ |
| @Override |
| public void setIndex( final int n ) { // TODO could be package-protected? |
| if ((n < 0) || (n > Const.MAX_SHORT)) { |
| throw new ClassGenException("Illegal value: " + n); |
| } |
| this.n = n; |
| // Cannot be < 0 as this is checked above |
| if (n <= 3) { // Use more compact instruction xLOAD_n |
| super.setOpcode((short) (c_tag + n)); |
| super.setLength(1); |
| } else { |
| super.setOpcode(canon_tag); |
| if (wide()) { |
| super.setLength(4); |
| } else { |
| super.setLength(2); |
| } |
| } |
| } |
| |
| |
| /** @return canonical tag for instruction, e.g., ALOAD for ALOAD_0 |
| */ |
| public short getCanonicalTag() { |
| return canon_tag; |
| } |
| |
| |
| /** |
| * Returns the type associated with the instruction - |
| * in case of ALOAD or ASTORE Type.OBJECT is returned. |
| * This is just a bit incorrect, because ALOAD and ASTORE |
| * may work on every ReferenceType (including Type.NULL) and |
| * ASTORE may even work on a ReturnaddressType . |
| * @return type associated with the instruction |
| */ |
| @Override |
| public Type getType( final ConstantPoolGen cp ) { |
| switch (canon_tag) { |
| case Const.ILOAD: |
| case Const.ISTORE: |
| return Type.INT; |
| case Const.LLOAD: |
| case Const.LSTORE: |
| return Type.LONG; |
| case Const.DLOAD: |
| case Const.DSTORE: |
| return Type.DOUBLE; |
| case Const.FLOAD: |
| case Const.FSTORE: |
| return Type.FLOAT; |
| case Const.ALOAD: |
| case Const.ASTORE: |
| return Type.OBJECT; |
| default: |
| throw new ClassGenException("Oops: unknown case in switch" + canon_tag); |
| } |
| } |
| |
| /** |
| * Sets the index of the referenced variable (n) only |
| * @since 6.0 |
| * @see #setIndex(int) |
| */ |
| final void setIndexOnly(final int n) { |
| this.n = n; |
| } |
| } |