/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2011 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.editor;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.preverification.*;
import proguard.classfile.attribute.preverification.visitor.*;
import proguard.classfile.attribute.visitor.*;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.SimplifiedVisitor;
import java.util.Arrays;
/**
* This AttributeVisitor accumulates specified changes to code, and then applies
* these accumulated changes to the code attributes that it visits.
*
* @author Eric Lafortune
*/
public class CodeAttributeEditor
extends SimplifiedVisitor
implements AttributeVisitor,
InstructionVisitor,
ExceptionInfoVisitor,
StackMapFrameVisitor,
VerificationTypeVisitor,
LineNumberInfoVisitor,
LocalVariableInfoVisitor,
LocalVariableTypeInfoVisitor
{
//*
private static final boolean DEBUG = false;
/*/
private static boolean DEBUG = true;
//*/
private boolean updateFrameSizes;
private int codeLength;
private boolean modified;
private boolean simple;
/*private*/public Instruction[] preInsertions = new Instruction[ClassConstants.TYPICAL_CODE_LENGTH];
/*private*/public Instruction[] replacements = new Instruction[ClassConstants.TYPICAL_CODE_LENGTH];
/*private*/public Instruction[] postInsertions = new Instruction[ClassConstants.TYPICAL_CODE_LENGTH];
/*private*/public boolean[] deleted = new boolean[ClassConstants.TYPICAL_CODE_LENGTH];
private int[] instructionOffsetMap = new int[ClassConstants.TYPICAL_CODE_LENGTH];
private int newOffset;
private boolean lengthIncreased;
private int expectedStackMapFrameOffset;
private final StackSizeUpdater stackSizeUpdater = new StackSizeUpdater();
private final VariableSizeUpdater variableSizeUpdater = new VariableSizeUpdater();
private final InstructionWriter instructionWriter = new InstructionWriter();
public CodeAttributeEditor()
{
this(true);
}
public CodeAttributeEditor(boolean updateFrameSizes)
{
this.updateFrameSizes = updateFrameSizes;
}
/**
* Resets the accumulated code changes.
* @param codeLength the length of the code that will be edited next.
*/
public void reset(int codeLength)
{
this.codeLength = codeLength;
// Try to reuse the previous arrays.
if (preInsertions.length < codeLength)
{
preInsertions = new Instruction[codeLength];
replacements = new Instruction[codeLength];
postInsertions = new Instruction[codeLength];
deleted = new boolean[codeLength];
}
else
{
Arrays.fill(preInsertions, 0, codeLength, null);
Arrays.fill(replacements, 0, codeLength, null);
Arrays.fill(postInsertions, 0, codeLength, null);
Arrays.fill(deleted, 0, codeLength, false);
}
modified = false;
simple = true;
}
/**
* Remembers to place the given instruction right before the instruction
* at the given offset.
* @param instructionOffset the offset of the instruction.
* @param instruction the new instruction.
*/
public void insertBeforeInstruction(int instructionOffset, Instruction instruction)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
preInsertions[instructionOffset] = instruction;
modified = true;
simple = false;
}
/**
* Remembers to place the given instructions right before the instruction
* at the given offset.
* @param instructionOffset the offset of the instruction.
* @param instructions the new instructions.
*/
public void insertBeforeInstruction(int instructionOffset, Instruction[] instructions)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
preInsertions[instructionOffset] = new CompositeInstruction(instructions);
modified = true;
simple = false;
}
/**
* Remembers to replace the instruction at the given offset by the given
* instruction.
* @param instructionOffset the offset of the instruction to be replaced.
* @param instruction the new instruction.
*/
public void replaceInstruction(int instructionOffset, Instruction instruction)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
replacements[instructionOffset] = instruction;
modified = true;
}
/**
* Remembers to replace the instruction at the given offset by the given
* instructions.
* @param instructionOffset the offset of the instruction to be replaced.
* @param instructions the new instructions.
*/
public void replaceInstruction(int instructionOffset, Instruction[] instructions)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
replacements[instructionOffset] = new CompositeInstruction(instructions);
modified = true;
}
/**
* Remembers to place the given instruction right after the instruction
* at the given offset.
* @param instructionOffset the offset of the instruction.
* @param instruction the new instruction.
*/
public void insertAfterInstruction(int instructionOffset, Instruction instruction)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
postInsertions[instructionOffset] = instruction;
modified = true;
simple = false;
}
/**
* Remembers to place the given instructions right after the instruction
* at the given offset.
* @param instructionOffset the offset of the instruction.
* @param instructions the new instructions.
*/
public void insertAfterInstruction(int instructionOffset, Instruction[] instructions)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
postInsertions[instructionOffset] = new CompositeInstruction(instructions);
modified = true;
simple = false;
}
/**
* Remembers to delete the instruction at the given offset.
* @param instructionOffset the offset of the instruction to be deleted.
*/
public void deleteInstruction(int instructionOffset)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
deleted[instructionOffset] = true;
modified = true;
simple = false;
}
/**
* Remembers not to delete the instruction at the given offset.
* @param instructionOffset the offset of the instruction not to be deleted.
*/
public void undeleteInstruction(int instructionOffset)
{
if (instructionOffset < 0 ||
instructionOffset >= codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+instructionOffset+"] in code with length ["+codeLength+"]");
}
deleted[instructionOffset] = false;
}
/**
* Returns whether the instruction at the given offset has been modified
* in any way.
*/
public boolean isModified(int instructionOffset)
{
return preInsertions[instructionOffset] != null ||
replacements[instructionOffset] != null ||
postInsertions[instructionOffset] != null ||
deleted[instructionOffset];
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
// DEBUG =
// clazz.getName().equals("abc/Def") &&
// method.getName(clazz).equals("abc");
// TODO: Remove this when the code has stabilized.
// Catch any unexpected exceptions from the actual visiting method.
try
{
// Process the code.
visitCodeAttribute0(clazz, method, codeAttribute);
}
catch (RuntimeException ex)
{
System.err.println("Unexpected error while editing code:");
System.err.println(" Class = ["+clazz.getName()+"]");
System.err.println(" Method = ["+method.getName(clazz)+method.getDescriptor(clazz)+"]");
System.err.println(" Exception = ["+ex.getClass().getName()+"] ("+ex.getMessage()+")");
throw ex;
}
}
public void visitCodeAttribute0(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
if (DEBUG)
{
System.out.println("CodeAttributeEditor: "+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz));
}
// Do we have to update the code?
if (modified)
{
// Can we perform a faster simple replacement of instructions?
if (canPerformSimpleReplacements(codeAttribute))
{
if (DEBUG)
{
System.out.println(" Simple editing");
}
// Simply overwrite the instructions.
performSimpleReplacements(codeAttribute);
}
else
{
if (DEBUG)
{
System.out.println(" Full editing");
}
// Move and remap the instructions.
codeAttribute.u4codeLength =
updateInstructions(clazz, method, codeAttribute);
// Remap the exception table.
codeAttribute.exceptionsAccept(clazz, method, this);
// Remove exceptions with empty code blocks.
codeAttribute.u2exceptionTableLength =
removeEmptyExceptions(codeAttribute.exceptionTable,
codeAttribute.u2exceptionTableLength);
// Remap the line number table and the local variable tables.
codeAttribute.attributesAccept(clazz, method, this);
}
// Make sure instructions are widened if necessary.
instructionWriter.visitCodeAttribute(clazz, method, codeAttribute);
}
// Update the maximum stack size and local variable frame size.
if (updateFrameSizes)
{
stackSizeUpdater.visitCodeAttribute(clazz, method, codeAttribute);
variableSizeUpdater.visitCodeAttribute(clazz, method, codeAttribute);
}
}
public void visitStackMapAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, StackMapAttribute stackMapAttribute)
{
// Remap all stack map entries.
expectedStackMapFrameOffset = -1;
stackMapAttribute.stackMapFramesAccept(clazz, method, codeAttribute, this);
}
public void visitStackMapTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, StackMapTableAttribute stackMapTableAttribute)
{
// Remap all stack map table entries.
expectedStackMapFrameOffset = 0;
stackMapTableAttribute.stackMapFramesAccept(clazz, method, codeAttribute, this);
}
public void visitLineNumberTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LineNumberTableAttribute lineNumberTableAttribute)
{
// Remap all line number table entries.
lineNumberTableAttribute.lineNumbersAccept(clazz, method, codeAttribute, this);
// Remove line numbers with empty code blocks.
lineNumberTableAttribute.u2lineNumberTableLength =
removeEmptyLineNumbers(lineNumberTableAttribute.lineNumberTable,
lineNumberTableAttribute.u2lineNumberTableLength,
codeAttribute.u4codeLength);
}
public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute)
{
// Remap all local variable table entries.
localVariableTableAttribute.localVariablesAccept(clazz, method, codeAttribute, this);
}
public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute)
{
// Remap all local variable table entries.
localVariableTypeTableAttribute.localVariablesAccept(clazz, method, codeAttribute, this);
}
/**
* Checks if it is possible to modifies the given code without having to
* update any offsets.
* @param codeAttribute the code to be changed.
* @return the new code length.
*/
private boolean canPerformSimpleReplacements(CodeAttribute codeAttribute)
{
if (!simple)
{
return false;
}
byte[] code = codeAttribute.code;
int codeLength = codeAttribute.u4codeLength;
// Go over all replacement instructions.
for (int offset = 0; offset < codeLength; offset++)
{
// Check if the replacement instruction, if any, has a different
// length than the original instruction.
Instruction replacementInstruction = replacements[offset];
if (replacementInstruction != null &&
replacementInstruction.length(offset) !=
InstructionFactory.create(code, offset).length(offset))
{
return false;
}
}
return true;
}
/**
* Modifies the given code without updating any offsets.
* @param codeAttribute the code to be changed.
*/
private void performSimpleReplacements(CodeAttribute codeAttribute)
{
int codeLength = codeAttribute.u4codeLength;
// Go over all replacement instructions.
for (int offset = 0; offset < codeLength; offset++)
{
// Overwrite the original instruction with the replacement
// instruction if any.
Instruction replacementInstruction = replacements[offset];
if (replacementInstruction != null)
{
replacementInstruction.write(codeAttribute, offset);
if (DEBUG)
{
System.out.println(" Replaced "+replacementInstruction.toString(newOffset));
}
}
}
}
/**
* Modifies the given code based on the previously specified changes.
* @param clazz the class file of the code to be changed.
* @param method the method of the code to be changed.
* @param codeAttribute the code to be changed.
* @return the new code length.
*/
private int updateInstructions(Clazz clazz,
Method method,
CodeAttribute codeAttribute)
{
byte[] oldCode = codeAttribute.code;
int oldLength = codeAttribute.u4codeLength;
// Make sure there is a sufficiently large instruction offset map.
if (instructionOffsetMap.length < oldLength + 1)
{
instructionOffsetMap = new int[oldLength + 1];
}
// Fill out the instruction offset map.
int newLength = mapInstructions(oldCode,
oldLength);
// Create a new code array if necessary.
if (lengthIncreased)
{
codeAttribute.code = new byte[newLength];
}
// Prepare for possible widening of instructions.
instructionWriter.reset(newLength);
// Move the instructions into the new code array.
moveInstructions(clazz,
method,
codeAttribute,
oldCode,
oldLength);
// We can return the new length.
return newLength;
}
/**
* Fills out the instruction offset map for the given code block.
* @param oldCode the instructions to be moved.
* @param oldLength the code length.
* @return the new code length.
*/
private int mapInstructions(byte[] oldCode, int oldLength)
{
// Start mapping instructions at the beginning.
newOffset = 0;
lengthIncreased = false;
int oldOffset = 0;
do
{
// Get the next instruction.
Instruction instruction = InstructionFactory.create(oldCode, oldOffset);
// Compute the mapping of the instruction.
mapInstruction(oldOffset, instruction);
oldOffset += instruction.length(oldOffset);
if (newOffset > oldOffset)
{
lengthIncreased = true;
}
}
while (oldOffset < oldLength);
// Also add an entry for the first offset after the code.
instructionOffsetMap[oldOffset] = newOffset;
return newOffset;
}
/**
* Fills out the instruction offset map for the given instruction.
* @param oldOffset the instruction's old offset.
* @param instruction the instruction to be moved.
*/
private void mapInstruction(int oldOffset,
Instruction instruction)
{
instructionOffsetMap[oldOffset] = newOffset;
// Account for the pre-inserted instruction, if any.
Instruction preInstruction = preInsertions[oldOffset];
if (preInstruction != null)
{
newOffset += preInstruction.length(newOffset);
}
// Account for the replacement instruction, or for the current
// instruction, if it shouldn't be deleted.
Instruction replacementInstruction = replacements[oldOffset];
if (replacementInstruction != null)
{
newOffset += replacementInstruction.length(newOffset);
}
else if (!deleted[oldOffset])
{
// Note that the instruction's length may change at its new offset,
// e.g. if it is a switch instruction.
newOffset += instruction.length(newOffset);
}
// Account for the post-inserted instruction, if any.
Instruction postInstruction = postInsertions[oldOffset];
if (postInstruction != null)
{
newOffset += postInstruction.length(newOffset);
}
}
/**
* Moves the given code block to the new offsets.
* @param clazz the class file of the code to be changed.
* @param method the method of the code to be changed.
* @param codeAttribute the code to be changed.
* @param oldCode the original code to be moved.
* @param oldLength the original code length.
*/
private void moveInstructions(Clazz clazz,
Method method,
CodeAttribute codeAttribute,
byte[] oldCode,
int oldLength)
{
// Start writing instructions at the beginning.
newOffset = 0;
int oldOffset = 0;
do
{
// Get the next instruction.
Instruction instruction = InstructionFactory.create(oldCode, oldOffset);
// Move the instruction to its new offset.
moveInstruction(clazz,
method,
codeAttribute,
oldOffset,
instruction);
oldOffset += instruction.length(oldOffset);
}
while (oldOffset < oldLength);
}
/**
* Moves the given instruction to its new offset.
* @param clazz the class file of the code to be changed.
* @param method the method of the code to be changed.
* @param codeAttribute the code to be changed.
* @param oldOffset the original instruction offset.
* @param instruction the original instruction.
*/
private void moveInstruction(Clazz clazz,
Method method,
CodeAttribute codeAttribute,
int oldOffset,
Instruction instruction)
{
// Remap and insert the pre-inserted instruction, if any.
Instruction preInstruction = preInsertions[oldOffset];
if (preInstruction != null)
{
if (DEBUG)
{
System.out.println(" Pre-inserted "+preInstruction.toString(newOffset));
}
// Remap the instruction.
preInstruction.accept(clazz, method, codeAttribute, oldOffset, this);
}
// Remap and insert the replacement instruction, or the current
// instruction, if it shouldn't be deleted.
Instruction replacementInstruction = replacements[oldOffset];
if (replacementInstruction != null)
{
if (DEBUG)
{
System.out.println(" Replaced "+replacementInstruction.toString(newOffset));
}
// Remap the instruction.
replacementInstruction.accept(clazz, method, codeAttribute, oldOffset, this);
}
else if (!deleted[oldOffset])
{
if (DEBUG)
{
System.out.println(" Copied "+instruction.toString(newOffset));
}
// Remap the instruction.
instruction.accept(clazz, method, codeAttribute, oldOffset, this);
}
// Remap and insert the post-inserted instruction, if any.
Instruction postInstruction = postInsertions[oldOffset];
if (postInstruction != null)
{
if (DEBUG)
{
System.out.println(" Post-inserted "+postInstruction.toString(newOffset));
}
// Remap the instruction.
postInstruction.accept(clazz, method, codeAttribute, oldOffset, this);
}
}
// Implementations for InstructionVisitor.
public void visitSimpleInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SimpleInstruction simpleInstruction)
{
// Write out the instruction.
instructionWriter.visitSimpleInstruction(clazz,
method,
codeAttribute,
newOffset,
simpleInstruction);
newOffset += simpleInstruction.length(newOffset);
}
public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction)
{
// Write out the instruction.
instructionWriter.visitConstantInstruction(clazz,
method,
codeAttribute,
newOffset,
constantInstruction);
newOffset += constantInstruction.length(newOffset);
}
public void visitVariableInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, VariableInstruction variableInstruction)
{
// Write out the instruction.
instructionWriter.visitVariableInstruction(clazz,
method,
codeAttribute,
newOffset,
variableInstruction);
newOffset += variableInstruction.length(newOffset);
}
public void visitBranchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, BranchInstruction branchInstruction)
{
// Adjust the branch offset.
branchInstruction.branchOffset = remapBranchOffset(offset,
branchInstruction.branchOffset);
// Write out the instruction.
instructionWriter.visitBranchInstruction(clazz,
method,
codeAttribute,
newOffset,
branchInstruction);
newOffset += branchInstruction.length(newOffset);
}
public void visitTableSwitchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, TableSwitchInstruction tableSwitchInstruction)
{
// Adjust the default jump offset.
tableSwitchInstruction.defaultOffset = remapBranchOffset(offset,
tableSwitchInstruction.defaultOffset);
// Adjust the jump offsets.
remapJumpOffsets(offset,
tableSwitchInstruction.jumpOffsets);
// Write out the instruction.
instructionWriter.visitTableSwitchInstruction(clazz,
method,
codeAttribute,
newOffset,
tableSwitchInstruction);
newOffset += tableSwitchInstruction.length(newOffset);
}
public void visitLookUpSwitchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, LookUpSwitchInstruction lookUpSwitchInstruction)
{
// Adjust the default jump offset.
lookUpSwitchInstruction.defaultOffset = remapBranchOffset(offset,
lookUpSwitchInstruction.defaultOffset);
// Adjust the jump offsets.
remapJumpOffsets(offset,
lookUpSwitchInstruction.jumpOffsets);
// Write out the instruction.
instructionWriter.visitLookUpSwitchInstruction(clazz,
method,
codeAttribute,
newOffset,
lookUpSwitchInstruction);
newOffset += lookUpSwitchInstruction.length(newOffset);
}
// Implementations for ExceptionInfoVisitor.
public void visitExceptionInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, ExceptionInfo exceptionInfo)
{
// Remap the code offsets. Note that the instruction offset map also has
// an entry for the first offset after the code, for u2endPC.
exceptionInfo.u2startPC = remapInstructionOffset(exceptionInfo.u2startPC);
exceptionInfo.u2endPC = remapInstructionOffset(exceptionInfo.u2endPC);
exceptionInfo.u2handlerPC = remapInstructionOffset(exceptionInfo.u2handlerPC);
}
// Implementations for StackMapFrameVisitor.
public void visitAnyStackMapFrame(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, StackMapFrame stackMapFrame)
{
// Remap the stack map frame offset.
int stackMapFrameOffset = remapInstructionOffset(offset);
int offsetDelta = stackMapFrameOffset;
// Compute the offset delta if the frame is part of a stack map frame
// table (for JDK 6.0) instead of a stack map (for Java Micro Edition).
if (expectedStackMapFrameOffset >= 0)
{
offsetDelta -= expectedStackMapFrameOffset;
expectedStackMapFrameOffset = stackMapFrameOffset + 1;
}
stackMapFrame.u2offsetDelta = offsetDelta;
}
public void visitSameOneFrame(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SameOneFrame sameOneFrame)
{
// Remap the stack map frame offset.
visitAnyStackMapFrame(clazz, method, codeAttribute, offset, sameOneFrame);
// Remap the verification type offset.
sameOneFrame.stackItemAccept(clazz, method, codeAttribute, offset, this);
}
public void visitMoreZeroFrame(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, MoreZeroFrame moreZeroFrame)
{
// Remap the stack map frame offset.
visitAnyStackMapFrame(clazz, method, codeAttribute, offset, moreZeroFrame);
// Remap the verification type offsets.
moreZeroFrame.additionalVariablesAccept(clazz, method, codeAttribute, offset, this);
}
public void visitFullFrame(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, FullFrame fullFrame)
{
// Remap the stack map frame offset.
visitAnyStackMapFrame(clazz, method, codeAttribute, offset, fullFrame);
// Remap the verification type offsets.
fullFrame.variablesAccept(clazz, method, codeAttribute, offset, this);
fullFrame.stackAccept(clazz, method, codeAttribute, offset, this);
}
// Implementations for VerificationTypeVisitor.
public void visitAnyVerificationType(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, VerificationType verificationType) {}
public void visitUninitializedType(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, UninitializedType uninitializedType)
{
// Remap the offset of the 'new' instruction.
uninitializedType.u2newInstructionOffset = remapInstructionOffset(uninitializedType.u2newInstructionOffset);
}
// Implementations for LineNumberInfoVisitor.
public void visitLineNumberInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LineNumberInfo lineNumberInfo)
{
// Remap the code offset.
lineNumberInfo.u2startPC = remapInstructionOffset(lineNumberInfo.u2startPC);
}
// Implementations for LocalVariableInfoVisitor.
public void visitLocalVariableInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableInfo localVariableInfo)
{
// Remap the code offset and length.
int newStartPC = remapInstructionOffset(localVariableInfo.u2startPC);
int newEndPC = remapInstructionOffset(localVariableInfo.u2startPC +
localVariableInfo.u2length);
localVariableInfo.u2length = newEndPC - newStartPC;
localVariableInfo.u2startPC = newStartPC;
}
// Implementations for LocalVariableTypeInfoVisitor.
public void visitLocalVariableTypeInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeInfo localVariableTypeInfo)
{
// Remap the code offset and length.
int newStartPC = remapInstructionOffset(localVariableTypeInfo.u2startPC);
int newEndPC = remapInstructionOffset(localVariableTypeInfo.u2startPC +
localVariableTypeInfo.u2length);
localVariableTypeInfo.u2length = newEndPC - newStartPC;
localVariableTypeInfo.u2startPC = newStartPC;
}
// Small utility methods.
/**
* Adjusts the given jump offsets for the instruction at the given offset.
*/
private void remapJumpOffsets(int offset, int[] jumpOffsets)
{
for (int index = 0; index < jumpOffsets.length; index++)
{
jumpOffsets[index] = remapBranchOffset(offset, jumpOffsets[index]);
}
}
/**
* Computes the new branch offset for the instruction at the given offset
* with the given branch offset.
*/
private int remapBranchOffset(int offset, int branchOffset)
{
return remapInstructionOffset(offset + branchOffset) - newOffset;
}
/**
* Computes the new instruction offset for the instruction at the given offset.
*/
private int remapInstructionOffset(int offset)
{
if (offset < 0 ||
offset > codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+offset+"] in code with length ["+codeLength+"]");
}
return instructionOffsetMap[offset];
}
/**
* Returns the given list of exceptions, without the ones that have empty
* code blocks.
*/
private int removeEmptyExceptions(ExceptionInfo[] exceptionInfos,
int exceptionInfoCount)
{
// Overwrite all empty exceptions.
int newIndex = 0;
for (int index = 0; index < exceptionInfoCount; index++)
{
ExceptionInfo exceptionInfo = exceptionInfos[index];
if (exceptionInfo.u2startPC < exceptionInfo.u2endPC)
{
exceptionInfos[newIndex++] = exceptionInfo;
}
}
return newIndex;
}
/**
* Returns the given list of line numbers, without the ones that have empty
* code blocks or that exceed the code size.
*/
private int removeEmptyLineNumbers(LineNumberInfo[] lineNumberInfos,
int lineNumberInfoCount,
int codeLength)
{
// Overwrite all empty line number entries.
int newIndex = 0;
for (int index = 0; index < lineNumberInfoCount; index++)
{
LineNumberInfo lineNumberInfo = lineNumberInfos[index];
int startPC = lineNumberInfo.u2startPC;
if (startPC < codeLength &&
(index == 0 || startPC > lineNumberInfos[index-1].u2startPC))
{
lineNumberInfos[newIndex++] = lineNumberInfo;
}
}
return newIndex;
}
private class CompositeInstruction
extends Instruction
{
private Instruction[] instructions;
private CompositeInstruction(Instruction[] instructions)
{
this.instructions = instructions;
}
// Implementations for Instruction.
public Instruction shrink()
{
for (int index = 0; index < instructions.length; index++)
{
instructions[index] = instructions[index].shrink();
}
return this;
}
public void write(byte[] code, int offset)
{
for (int index = 0; index < instructions.length; index++)
{
Instruction instruction = instructions[index];
instruction.write(code, offset);
offset += instruction.length(offset);
}
}
protected void readInfo(byte[] code, int offset)
{
throw new UnsupportedOperationException("Can't read composite instruction");
}
protected void writeInfo(byte[] code, int offset)
{
throw new UnsupportedOperationException("Can't write composite instruction");
}
public int length(int offset)
{
int newOffset = offset;
for (int index = 0; index < instructions.length; index++)
{
newOffset += instructions[index].length(newOffset);
}
return newOffset - offset;
}
public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, InstructionVisitor instructionVisitor)
{
if (instructionVisitor != CodeAttributeEditor.this)
{
throw new UnsupportedOperationException("Unexpected visitor ["+instructionVisitor+"]");
}
for (int index = 0; index < instructions.length; index++)
{
Instruction instruction = instructions[index];
instruction.accept(clazz, method, codeAttribute, offset, CodeAttributeEditor.this);
offset += instruction.length(offset);
}
}
// Implementations for Object.
public String toString()
{
StringBuffer stringBuffer = new StringBuffer();
for (int index = 0; index < instructions.length; index++)
{
stringBuffer.append(instructions[index].toString()).append("; ");
}
return stringBuffer.toString();
}
}
}