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Diffstat (limited to 'src/proguard/classfile/instruction/ConstantInstruction.java')
-rw-r--r-- | src/proguard/classfile/instruction/ConstantInstruction.java | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/src/proguard/classfile/instruction/ConstantInstruction.java b/src/proguard/classfile/instruction/ConstantInstruction.java new file mode 100644 index 0000000..6c2d1a3 --- /dev/null +++ b/src/proguard/classfile/instruction/ConstantInstruction.java @@ -0,0 +1,303 @@ +/* + * 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.constant.*; +import proguard.classfile.constant.visitor.ConstantVisitor; +import proguard.classfile.instruction.visitor.InstructionVisitor; +import proguard.classfile.util.ClassUtil; + +/** + * This Instruction represents an instruction that refers to an entry in the + * constant pool. + * + * @author Eric Lafortune + */ +public class ConstantInstruction extends Instruction +implements ConstantVisitor +{ + public int constantIndex; + public int constant; + + + // Fields acting as return parameters for the ConstantVisitor methods. + private int parameterStackDelta; + private int typeStackDelta; + + + /** + * Creates an uninitialized ConstantInstruction. + */ + public ConstantInstruction() {} + + + /** + * Creates a new ConstantInstruction with the given opcode and constant pool + * index. + */ + public ConstantInstruction(byte opcode, int constantIndex) + { + this(opcode, constantIndex, 0); + } + + + /** + * Creates a new ConstantInstruction with the given opcode, constant pool + * index, and constant. + */ + public ConstantInstruction(byte opcode, int constantIndex, int constant) + { + this.opcode = opcode; + this.constantIndex = constantIndex; + this.constant = constant; + } + + + /** + * Copies the given instruction into this instruction. + * @param constantInstruction the instruction to be copied. + * @return this instruction. + */ + public ConstantInstruction copy(ConstantInstruction constantInstruction) + { + this.opcode = constantInstruction.opcode; + this.constantIndex = constantInstruction.constantIndex; + this.constant = constantInstruction.constant; + + return this; + } + + + // Implementations for Instruction. + + public byte canonicalOpcode() + { + // Remove the _w extension, if any. + switch (opcode) + { + case InstructionConstants.OP_LDC_W: + case InstructionConstants.OP_LDC2_W: return InstructionConstants.OP_LDC; + + default: return opcode; + } + } + + public Instruction shrink() + { + // Do we need a short index or a long index? + if (requiredConstantIndexSize() == 1) + { + // Can we replace the long instruction by a short instruction? + if (opcode == InstructionConstants.OP_LDC_W) + { + opcode = InstructionConstants.OP_LDC; + } + } + else + { + // Should we replace the short instruction by a long instruction? + if (opcode == InstructionConstants.OP_LDC) + { + opcode = InstructionConstants.OP_LDC_W; + } + } + + return this; + } + + protected void readInfo(byte[] code, int offset) + { + int constantIndexSize = constantIndexSize(); + int constantSize = constantSize(); + + constantIndex = readValue(code, offset, constantIndexSize); offset += constantIndexSize; + constant = readValue(code, offset, constantSize); + } + + + protected void writeInfo(byte[] code, int offset) + { + int constantIndexSize = constantIndexSize(); + int constantSize = constantSize(); + + if (requiredConstantIndexSize() > constantIndexSize) + { + throw new IllegalArgumentException("Instruction has invalid constant index size ("+this.toString(offset)+")"); + } + + writeValue(code, offset, constantIndex, constantIndexSize); offset += constantIndexSize; + writeValue(code, offset, constant, constantSize); + } + + + public int length(int offset) + { + return 1 + constantIndexSize() + constantSize(); + } + + + public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, InstructionVisitor instructionVisitor) + { + instructionVisitor.visitConstantInstruction(clazz, method, codeAttribute, offset, this); + } + + + public int stackPopCount(Clazz clazz) + { + int stackPopCount = super.stackPopCount(clazz); + + // Some special cases. + switch (opcode) + { + case InstructionConstants.OP_MULTIANEWARRAY: + // For each dimension, an integer size is popped from the stack. + stackPopCount += constant; + break; + + case InstructionConstants.OP_PUTSTATIC: + case InstructionConstants.OP_PUTFIELD: + // The field value is be popped from the stack. + clazz.constantPoolEntryAccept(constantIndex, this); + stackPopCount += typeStackDelta; + break; + + case InstructionConstants.OP_INVOKEVIRTUAL: + case InstructionConstants.OP_INVOKESPECIAL: + case InstructionConstants.OP_INVOKESTATIC: + case InstructionConstants.OP_INVOKEINTERFACE: + // The some parameters may be popped from the stack. + clazz.constantPoolEntryAccept(constantIndex, this); + stackPopCount += parameterStackDelta; + break; + } + + return stackPopCount; + } + + + public int stackPushCount(Clazz clazz) + { + int stackPushCount = super.stackPushCount(clazz); + + // Some special cases. + switch (opcode) + { + case InstructionConstants.OP_GETSTATIC: + case InstructionConstants.OP_GETFIELD: + case InstructionConstants.OP_INVOKEVIRTUAL: + case InstructionConstants.OP_INVOKESPECIAL: + case InstructionConstants.OP_INVOKESTATIC: + case InstructionConstants.OP_INVOKEINTERFACE: + // The field value or a return value may be pushed onto the stack. + clazz.constantPoolEntryAccept(constantIndex, this); + stackPushCount += typeStackDelta; + break; + } + + return stackPushCount; + } + + + // Implementations for ConstantVisitor. + + public void visitIntegerConstant(Clazz clazz, IntegerConstant integerConstant) {} + public void visitLongConstant(Clazz clazz, LongConstant longConstant) {} + public void visitFloatConstant(Clazz clazz, FloatConstant floatConstant) {} + public void visitDoubleConstant(Clazz clazz, DoubleConstant doubleConstant) {} + public void visitStringConstant(Clazz clazz, StringConstant stringConstant) {} + public void visitUtf8Constant(Clazz clazz, Utf8Constant utf8Constant) {} + public void visitClassConstant(Clazz clazz, ClassConstant classConstant) {} + public void visitNameAndTypeConstant(Clazz clazz, NameAndTypeConstant nameAndTypeConstant) {} + + + public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant) + { + String type = fieldrefConstant.getType(clazz); + + typeStackDelta = ClassUtil.internalTypeSize(ClassUtil.internalMethodReturnType(type)); + } + + + public void visitInterfaceMethodrefConstant(Clazz clazz, InterfaceMethodrefConstant interfaceMethodrefConstant) + { + visitRefConstant(clazz, interfaceMethodrefConstant); + } + + + public void visitMethodrefConstant(Clazz clazz, MethodrefConstant methodrefConstant) + { + visitRefConstant(clazz, methodrefConstant); + } + + + private void visitRefConstant(Clazz clazz, RefConstant methodrefConstant) + { + String type = methodrefConstant.getType(clazz); + + parameterStackDelta = ClassUtil.internalMethodParameterSize(type); + typeStackDelta = ClassUtil.internalTypeSize(ClassUtil.internalMethodReturnType(type)); + } + + + // Implementations for Object. + + public String toString() + { + return getName()+" #"+constantIndex; + } + + + // Small utility methods. + + /** + * Returns the constant pool index size for this instruction. + */ + private int constantIndexSize() + { + return opcode == InstructionConstants.OP_LDC ? 1 : + 2; + } + + + /** + * Returns the constant size for this instruction. + */ + private int constantSize() + { + return opcode == InstructionConstants.OP_MULTIANEWARRAY ? 1 : + opcode == InstructionConstants.OP_INVOKEINTERFACE ? 2 : + 0; + } + + + /** + * Computes the required constant pool index size for this instruction's + * constant pool index. + */ + private int requiredConstantIndexSize() + { + return (constantIndex & 0xff) == constantIndex ? 1 : + (constantIndex & 0xffff) == constantIndex ? 2 : + 4; + } +} |