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Diffstat (limited to 'src/proguard/classfile/instruction/SimpleInstruction.java')
| -rw-r--r-- | src/proguard/classfile/instruction/SimpleInstruction.java | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/src/proguard/classfile/instruction/SimpleInstruction.java b/src/proguard/classfile/instruction/SimpleInstruction.java new file mode 100644 index 0000000..84e6344 --- /dev/null +++ b/src/proguard/classfile/instruction/SimpleInstruction.java @@ -0,0 +1,255 @@ +/* + * ProGuard -- shrinking, optimization, obfuscation, and preverification + * of Java bytecode. + * + * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu) + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +package proguard.classfile.instruction; + +import proguard.classfile.*; +import proguard.classfile.attribute.CodeAttribute; +import proguard.classfile.instruction.visitor.InstructionVisitor; + +/** + * This Instruction represents a simple instruction without variable arguments + * or constant pool references. + * + * @author Eric Lafortune + */ +public class SimpleInstruction extends Instruction +{ + public int constant; + + + /** + * Creates an uninitialized SimpleInstruction. + */ + public SimpleInstruction() {} + + + /** + * Creates a new SimpleInstruction with the given opcode. + */ + public SimpleInstruction(byte opcode) + { + this(opcode, embeddedConstant(opcode)); + } + + + /** + * Creates a new SimpleInstruction with the given opcode and constant. + */ + public SimpleInstruction(byte opcode, int constant) + { + this.opcode = opcode; + this.constant = constant; + } + + + /** + * Copies the given instruction into this instruction. + * @param simpleInstruction the instruction to be copied. + * @return this instruction. + */ + public SimpleInstruction copy(SimpleInstruction simpleInstruction) + { + this.opcode = simpleInstruction.opcode; + this.constant = simpleInstruction.constant; + + return this; + } + + + /** + * Return the embedded constant of the given opcode, or 0 if the opcode + * doesn't have one. + */ + private static int embeddedConstant(byte opcode) + { + switch (opcode) + { + case InstructionConstants.OP_ICONST_M1: return -1; + + case InstructionConstants.OP_ICONST_1: + case InstructionConstants.OP_LCONST_1: + case InstructionConstants.OP_FCONST_1: + case InstructionConstants.OP_DCONST_1: return 1; + + case InstructionConstants.OP_ICONST_2: + case InstructionConstants.OP_FCONST_2: return 2; + + case InstructionConstants.OP_ICONST_3: return 3; + + case InstructionConstants.OP_ICONST_4: return 4; + + case InstructionConstants.OP_ICONST_5: return 5; + + default: return 0; + } + } + + + // Implementations for Instruction. + + public byte canonicalOpcode() + { + // Replace any _1, _2, _3,... extension by _0. + switch (opcode) + { + case InstructionConstants.OP_ICONST_M1: + case InstructionConstants.OP_ICONST_0: + case InstructionConstants.OP_ICONST_1: + case InstructionConstants.OP_ICONST_2: + case InstructionConstants.OP_ICONST_3: + case InstructionConstants.OP_ICONST_4: + case InstructionConstants.OP_ICONST_5: + case InstructionConstants.OP_BIPUSH: + case InstructionConstants.OP_SIPUSH: return InstructionConstants.OP_ICONST_0; + + case InstructionConstants.OP_LCONST_0: + case InstructionConstants.OP_LCONST_1: return InstructionConstants.OP_LCONST_0; + + case InstructionConstants.OP_FCONST_0: + case InstructionConstants.OP_FCONST_1: + case InstructionConstants.OP_FCONST_2: return InstructionConstants.OP_FCONST_0; + + case InstructionConstants.OP_DCONST_0: + case InstructionConstants.OP_DCONST_1: return InstructionConstants.OP_DCONST_0; + + default: return opcode; + } + } + + public Instruction shrink() + { + // Reconstruct the opcode of the shortest instruction, if there are + // any alternatives. + switch (opcode) + { + case InstructionConstants.OP_ICONST_M1: + case InstructionConstants.OP_ICONST_0: + case InstructionConstants.OP_ICONST_1: + case InstructionConstants.OP_ICONST_2: + case InstructionConstants.OP_ICONST_3: + case InstructionConstants.OP_ICONST_4: + case InstructionConstants.OP_ICONST_5: + case InstructionConstants.OP_BIPUSH: + case InstructionConstants.OP_SIPUSH: + switch (requiredConstantSize()) + { + case 0: + opcode = (byte)(InstructionConstants.OP_ICONST_0 + constant); + break; + case 1: + opcode = InstructionConstants.OP_BIPUSH; + break; + case 2: + opcode = InstructionConstants.OP_SIPUSH; + break; + } + break; + + case InstructionConstants.OP_LCONST_0: + case InstructionConstants.OP_LCONST_1: + opcode = (byte)(InstructionConstants.OP_LCONST_0 + constant); + break; + + case InstructionConstants.OP_FCONST_0: + case InstructionConstants.OP_FCONST_1: + case InstructionConstants.OP_FCONST_2: + opcode = (byte)(InstructionConstants.OP_FCONST_0 + constant); + break; + + case InstructionConstants.OP_DCONST_0: + case InstructionConstants.OP_DCONST_1: + opcode = (byte)(InstructionConstants.OP_DCONST_0 + constant); + break; + } + + return this; + } + + protected void readInfo(byte[] code, int offset) + { + int constantSize = constantSize(); + + // Also initialize embedded constants that are different from 0. + constant = constantSize == 0 ? + embeddedConstant(opcode) : + readSignedValue(code, offset, constantSize); + } + + + protected void writeInfo(byte[] code, int offset) + { + int constantSize = constantSize(); + + if (requiredConstantSize() > constantSize) + { + throw new IllegalArgumentException("Instruction has invalid constant size ("+this.toString(offset)+")"); + } + + writeSignedValue(code, offset, constant, constantSize); + } + + + public int length(int offset) + { + return 1 + constantSize(); + } + + + public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, InstructionVisitor instructionVisitor) + { + instructionVisitor.visitSimpleInstruction(clazz, method, codeAttribute, offset, this); + } + + + // Implementations for Object. + + public String toString() + { + return getName() + + (constantSize() > 0 ? " "+constant : ""); + } + + + // Small utility methods. + + /** + * Returns the constant size for this instruction. + */ + private int constantSize() + { + return opcode == InstructionConstants.OP_BIPUSH || + opcode == InstructionConstants.OP_NEWARRAY ? 1 : + opcode == InstructionConstants.OP_SIPUSH ? 2 : + 0; + } + + + /** + * Computes the required constant size for this instruction. + */ + private int requiredConstantSize() + { + return constant >= -1 && constant <= 5 ? 0 : + constant << 24 >> 24 == constant ? 1 : + constant << 16 >> 16 == constant ? 2 : + 4; + } +} |