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/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2019 Guardsquare NV
*
* 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.annotation.*;
import proguard.classfile.attribute.annotation.target.*;
import proguard.classfile.attribute.annotation.target.visitor.*;
import proguard.classfile.attribute.annotation.visitor.TypeAnnotationVisitor;
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 proguard.classfile.visitor.ClassPrinter;
import proguard.util.ArrayUtil;
import java.util.Arrays;
/**
* This AttributeVisitor accumulates instructions and exceptions, and then
* copies them into code attributes that it visits.
*
* @author Eric Lafortune
*/
public class CodeAttributeComposer
extends SimplifiedVisitor
implements AttributeVisitor,
InstructionVisitor,
ExceptionInfoVisitor,
StackMapFrameVisitor,
VerificationTypeVisitor,
LineNumberInfoVisitor,
LocalVariableInfoVisitor,
LocalVariableTypeInfoVisitor,
TypeAnnotationVisitor,
TargetInfoVisitor,
LocalVariableTargetElementVisitor
{
//*
private static final boolean DEBUG = false;
/*/
public static boolean DEBUG = false;
//*/
private static final int MAXIMUM_LEVELS = 32;
private static final int INVALID = -1;
private final boolean allowExternalBranchTargets;
private final boolean allowExternalExceptionHandlers;
private final boolean shrinkInstructions;
private int maximumCodeLength;
private int codeLength;
private int exceptionTableLength;
private int lineNumberTableLength;
private int level = -1;
private byte[] code = new byte[ClassConstants.TYPICAL_CODE_LENGTH];
private int[] oldInstructionOffsets = new int[ClassConstants.TYPICAL_CODE_LENGTH];
private final int[] codeFragmentOffsets = new int[MAXIMUM_LEVELS];
private final int[] codeFragmentLengths = new int[MAXIMUM_LEVELS];
private final int[][] instructionOffsetMap = new int[MAXIMUM_LEVELS][ClassConstants.TYPICAL_CODE_LENGTH + 1];
private ExceptionInfo[] exceptionTable = new ExceptionInfo[ClassConstants.TYPICAL_EXCEPTION_TABLE_LENGTH];
private LineNumberInfo[] lineNumberTable = new LineNumberInfo[ClassConstants.TYPICAL_LINE_NUMBER_TABLE_LENGTH];
private int expectedStackMapFrameOffset;
private final StackSizeUpdater stackSizeUpdater = new StackSizeUpdater();
private final VariableSizeUpdater variableSizeUpdater = new VariableSizeUpdater();
private final InstructionWriter instructionWriter = new InstructionWriter();
/**
* Creates a new CodeAttributeComposer that doesn't allow external branch
* targets or exception handlers and that automatically shrinks
* instructions.
*/
public CodeAttributeComposer()
{
this(false, false, true);
}
/**
* Creates a new CodeAttributeComposer.
* @param allowExternalBranchTargets specifies whether branch targets
* can lie outside the code fragment
* of the branch instructions.
* @param allowExternalExceptionHandlers specifies whether exception
* handlers can lie outside the code
* fragment in which exceptions are
* defined.
* @param shrinkInstructions specifies whether instructions
* should automatically be shrunk
* before being written.
*/
public CodeAttributeComposer(boolean allowExternalBranchTargets,
boolean allowExternalExceptionHandlers,
boolean shrinkInstructions)
{
this.allowExternalBranchTargets = allowExternalBranchTargets;
this.allowExternalExceptionHandlers = allowExternalExceptionHandlers;
this.shrinkInstructions = shrinkInstructions;
}
/**
* Starts a new code definition.
*/
public void reset()
{
maximumCodeLength = 0;
codeLength = 0;
exceptionTableLength = 0;
lineNumberTableLength = 0;
level = -1;
// Make sure the instruction writer has at least the same buffer size
// as the local arrays.
instructionWriter.reset(code.length);
}
/**
* Starts a new code fragment. Branch instructions that are added are
* assumed to be relative within such code fragments.
* @param maximumCodeFragmentLength the maximum length of the code that will
* be added as part of this fragment (more
* precisely, the maximum old instruction
* offset or label that is specified, plus
* one).
*/
public void beginCodeFragment(int maximumCodeFragmentLength)
{
level++;
if (level >= MAXIMUM_LEVELS)
{
throw new IllegalArgumentException("Maximum number of code fragment levels exceeded ["+level+"]");
}
// Make sure there is sufficient space for adding the code fragment.
// It's only a rough initial estimate for the code length, not even
// necessarily a length expressed in bytes.
maximumCodeLength += maximumCodeFragmentLength;
ensureCodeLength(maximumCodeLength);
// Try to reuse the previous array for this code fragment.
if (instructionOffsetMap[level].length <= maximumCodeFragmentLength)
{
instructionOffsetMap[level] = new int[maximumCodeFragmentLength + 1];
}
// Initialize the offset map.
for (int index = 0; index <= maximumCodeFragmentLength; index++)
{
instructionOffsetMap[level][index] = INVALID;
}
// Remember the location of the code fragment.
codeFragmentOffsets[level] = codeLength;
codeFragmentLengths[level] = maximumCodeFragmentLength;
}
/**
* Appends the given instruction with the given old offset.
* Branch instructions must fit, for instance by enabling automatic
* shrinking of instructions.
* @param oldInstructionOffset the old offset of the instruction, to which
* branches and other references in the current
* code fragment are pointing.
* @param instruction the instruction to be appended.
*/
public void appendInstruction(int oldInstructionOffset,
Instruction instruction)
{
if (shrinkInstructions)
{
instruction = instruction.shrink();
}
if (DEBUG)
{
println("["+codeLength+"] <- ", instruction.toString(oldInstructionOffset));
}
// Make sure the code and offset arrays are large enough.
int newCodeLength = codeLength + instruction.length(codeLength);
ensureCodeLength(newCodeLength);
// Remember the old offset of the appended instruction.
oldInstructionOffsets[codeLength] = oldInstructionOffset;
// Fill out the new offset of the appended instruction.
instructionOffsetMap[level][oldInstructionOffset] = codeLength;
// Write the instruction. The instruction writer may widen it later on,
// if necessary.
instruction.accept(null,
null,
new CodeAttribute(0, 0, 0, 0, code, 0, null, 0, null),
codeLength,
instructionWriter);
//instruction.write(code, codeLength);
// Continue appending at the next instruction offset.
codeLength = newCodeLength;
}
/**
* Appends the given label with the given old offset.
* @param oldInstructionOffset the old offset of the label, to which
* branches and other references in the current
* code fragment are pointing.
*/
public void appendLabel(int oldInstructionOffset)
{
if (DEBUG)
{
println("["+codeLength+"] <- ", "[" + oldInstructionOffset + "] (label)");
}
// Make sure the code and offset arrays are large enough.
ensureCodeLength(codeLength + 1);
// Remember the old offset of the following instruction.
oldInstructionOffsets[codeLength] = oldInstructionOffset;
// Fill out the new offset of the following instruction.
instructionOffsetMap[level][oldInstructionOffset] = codeLength;
}
/**
* Appends the given instruction without defined offsets.
* @param instructions the instructions to be appended.
*/
public void appendInstructions(Instruction[] instructions)
{
for (int index = 0; index < instructions.length; index++)
{
appendInstruction(instructions[index]);
}
}
/**
* Appends the given instruction without a defined offset.
* Branch instructions should have a label, to allow computing the
* new relative offset.
* Branch instructions must fit, for instance by enabling automatic
* shrinking of instructions.
* @param instruction the instruction to be appended.
*/
public void appendInstruction(Instruction instruction)
{
if (shrinkInstructions)
{
instruction = instruction.shrink();
}
if (DEBUG)
{
println("["+codeLength+"] <- ", instruction.toString());
}
// Make sure the code array is large enough.
int newCodeLength = codeLength + instruction.length(codeLength);
ensureCodeLength(newCodeLength);
// Write the instruction. The instruction writer may widen it later on,
// if necessary.
instruction.accept(null,
null,
new CodeAttribute(0, 0, 0, 0, code, 0, null, 0, null),
codeLength,
instructionWriter);
//instruction.write(code, codeLength);
// Continue appending at the next instruction offset.
codeLength = newCodeLength;
}
/**
* Appends the given exception to the exception table.
* @param exceptionInfo the exception to be appended.
*/
public void appendException(ExceptionInfo exceptionInfo)
{
if (DEBUG)
{
print(" ", "Exception ["+exceptionInfo.u2startPC+" -> "+exceptionInfo.u2endPC+": "+exceptionInfo.u2handlerPC+"]");
}
// Remap the exception right away.
visitExceptionInfo(null, null, null, exceptionInfo);
if (DEBUG)
{
System.out.println(" -> ["+exceptionInfo.u2startPC+" -> "+exceptionInfo.u2endPC+": "+exceptionInfo.u2handlerPC+"]");
}
// Don't add the exception if its instruction range is empty.
if (exceptionInfo.u2startPC == exceptionInfo.u2endPC)
{
if (DEBUG)
{
println(" ", " (not added because of empty instruction range)");
}
return;
}
// Add the exception.
exceptionTable =
(ExceptionInfo[])ArrayUtil.add(exceptionTable,
exceptionTableLength++,
exceptionInfo);
}
/**
* Inserts the given line number at the appropriate position in the line
* number table.
* @param lineNumberInfo the line number to be inserted.
* @return the index where the line number was actually inserted.
*/
public int insertLineNumber(LineNumberInfo lineNumberInfo)
{
return insertLineNumber(0, lineNumberInfo);
}
/**
* Inserts the given line number at the appropriate position in the line
* number table.
* @param minimumIndex the minimum index where the line number may be
* inserted.
* @param lineNumberInfo the line number to be inserted.
* @return the index where the line number was inserted.
*/
public int insertLineNumber(int minimumIndex, LineNumberInfo lineNumberInfo)
{
if (DEBUG)
{
print(" ", "Line number ["+lineNumberInfo.u2startPC+"]");
}
// Remap the line number right away.
visitLineNumberInfo(null, null, null, lineNumberInfo);
if (DEBUG)
{
System.out.println(" -> ["+lineNumberInfo.u2startPC+"] line "+lineNumberInfo.u2lineNumber+(lineNumberInfo.getSource()==null ? "":" ["+lineNumberInfo.getSource()+"]"));
}
lineNumberTable =
(LineNumberInfo[])ArrayUtil.extendArray(lineNumberTable,
lineNumberTableLength + 1);
// Find the insertion index, starting from the end.
// Don't insert before a negative line number, in case of a tie.
int index = lineNumberTableLength++;
while (index > minimumIndex &&
(lineNumberTable[index - 1].u2startPC > lineNumberInfo.u2startPC ||
lineNumberTable[index - 1].u2startPC >= lineNumberInfo.u2startPC &&
lineNumberTable[index - 1].u2lineNumber >= 0))
{
lineNumberTable[index] = lineNumberTable[--index];
}
lineNumberTable[index] = lineNumberInfo;
return index;
}
/**
* Appends the given line number to the line number table.
* @param lineNumberInfo the line number to be appended.
*/
public void appendLineNumber(LineNumberInfo lineNumberInfo)
{
if (DEBUG)
{
print(" ", "Line number ["+lineNumberInfo.u2startPC+"]");
}
// Remap the line number right away.
visitLineNumberInfo(null, null, null, lineNumberInfo);
if (DEBUG)
{
System.out.println(" -> ["+lineNumberInfo.u2startPC+"] line "+lineNumberInfo.u2lineNumber+(lineNumberInfo.getSource()==null ? "":" ["+lineNumberInfo.getSource()+"]"));
}
// Add the line number.
lineNumberTable =
(LineNumberInfo[])ArrayUtil.add(lineNumberTable,
lineNumberTableLength++,
lineNumberInfo);
}
/**
* Wraps up the current code fragment, continuing with the previous one on
* the stack.
*/
public void endCodeFragment()
{
if (level < 0)
{
throw new IllegalArgumentException("Code fragment not begun ["+level+"]");
}
// Remap the instructions of the code fragment.
int instructionOffset = codeFragmentOffsets[level];
while (instructionOffset < codeLength)
{
// Get the next instruction.
Instruction instruction = InstructionFactory.create(code, instructionOffset);
// Does this instruction still have to be remapped?
if (oldInstructionOffsets[instructionOffset] >= 0)
{
// Adapt the instruction for its new offset.
instruction.accept(null, null, null, instructionOffset, this);
// Write the instruction back. The instruction writer may still
// widen it later on, if necessary.
instruction.accept(null,
null,
new CodeAttribute(0, 0, 0, 0, code, 0, null, 0, null),
instructionOffset,
instructionWriter);
//instruction.write(code, codeLength);
}
// Continue remapping at the next instruction offset.
instructionOffset += instruction.length(instructionOffset);
}
// Correct the estimated maximum code length, now that we know the
// actual length of this code fragment.
maximumCodeLength += codeLength - codeFragmentOffsets[level] -
codeFragmentLengths[level];
// Try to remap the exception handlers that couldn't be remapped before.
if (allowExternalExceptionHandlers)
{
for (int index = 0; index < exceptionTableLength; index++)
{
ExceptionInfo exceptionInfo = exceptionTable[index];
// Unmapped exception handlers are still negated.
int handlerPC = -exceptionInfo.u2handlerPC;
if (handlerPC > 0)
{
if (remappableExceptionHandler(handlerPC))
{
exceptionInfo.u2handlerPC = newInstructionOffset(handlerPC);
}
else if (level == 0)
{
throw new IllegalStateException("Couldn't remap exception handler offset ["+handlerPC+"]");
}
}
}
}
level--;
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
if (DEBUG)
{
System.out.println("CodeAttributeComposer: putting results in ["+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz)+"]");
}
if (level != -1)
{
throw new IllegalArgumentException("Code fragment not ended ["+level+"]");
}
level++;
// Make sure the code attribute has sufficient space for the composed
// code.
if (codeAttribute.u4codeLength < codeLength)
{
codeAttribute.code = new byte[codeLength];
}
// Copy the composed code over into the code attribute.
codeAttribute.u4codeLength = codeLength;
System.arraycopy(code, 0, codeAttribute.code, 0, codeLength);
// Remove exceptions with empty code blocks (done before).
//exceptionTableLength =
// removeEmptyExceptions(exceptionTable, exceptionTableLength);
// Make sure the exception table has sufficient space for the composed
// exceptions.
if (codeAttribute.exceptionTable.length < exceptionTableLength)
{
codeAttribute.exceptionTable = new ExceptionInfo[exceptionTableLength];
}
// Copy the exception table.
codeAttribute.u2exceptionTableLength = exceptionTableLength;
System.arraycopy(exceptionTable, 0, codeAttribute.exceptionTable, 0, exceptionTableLength);
// Update the maximum stack size and local variable frame size.
stackSizeUpdater.visitCodeAttribute(clazz, method, codeAttribute);
variableSizeUpdater.visitCodeAttribute(clazz, method, codeAttribute);
// Add a new line number table for the line numbers, if necessary.
if (lineNumberTableLength > 0 &&
codeAttribute.getAttribute(clazz, ClassConstants.ATTR_LineNumberTable) == null)
{
int attributeNameIndex =
new ConstantPoolEditor((ProgramClass)clazz)
.addUtf8Constant(ClassConstants.ATTR_LineNumberTable);
new AttributesEditor((ProgramClass)clazz, (ProgramMember)method, codeAttribute, false)
.addAttribute(new LineNumberTableAttribute(attributeNameIndex, 0, null));
}
// Copy the line number table and the local variable table.
codeAttribute.attributesAccept(clazz, method, this);
// Remap the exception table (done before).
//codeAttribute.exceptionsAccept(clazz, method, this);
// Remove exceptions with empty code blocks (done before).
//codeAttribute.u2exceptionTableLength =
// removeEmptyExceptions(codeAttribute.exceptionTable,
// codeAttribute.u2exceptionTableLength);
// Make sure instructions are widened if necessary.
instructionWriter.visitCodeAttribute(clazz, method, codeAttribute);
level--;
if (DEBUG)
{
codeAttribute.accept(clazz, method, new ClassPrinter());
}
}
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)
{
// Didn't we get line number new definitions?
if (lineNumberTableLength == 0)
{
// Remap all line number table entries of the existing table.
lineNumberTableAttribute.lineNumbersAccept(clazz, method, codeAttribute, this);
}
else
{
// Remove line numbers with empty code blocks.
// Actually, we'll do this elsewhere, to allow processing the
// line numbers of inlined methods.
//lineNumberTableLength =
// removeEmptyLineNumbers(lineNumberTable,
// lineNumberTableLength,
// codeAttribute.u4codeLength);
// Copy the line number table.
lineNumberTableAttribute.lineNumberTable = new LineNumberInfo[lineNumberTableLength];
lineNumberTableAttribute.u2lineNumberTableLength = lineNumberTableLength;
System.arraycopy(lineNumberTable, 0, lineNumberTableAttribute.lineNumberTable, 0, lineNumberTableLength);
}
}
public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute)
{
// Remap all local variable table entries.
localVariableTableAttribute.localVariablesAccept(clazz, method, codeAttribute, this);
// Remove local variables with empty code blocks.
localVariableTableAttribute.u2localVariableTableLength =
removeEmptyLocalVariables(localVariableTableAttribute.localVariableTable,
localVariableTableAttribute.u2localVariableTableLength,
codeAttribute.u2maxLocals);
}
public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute)
{
// Remap all local variable table entries.
localVariableTypeTableAttribute.localVariablesAccept(clazz, method, codeAttribute, this);
// Remove local variables with empty code blocks.
localVariableTypeTableAttribute.u2localVariableTypeTableLength =
removeEmptyLocalVariableTypes(localVariableTypeTableAttribute.localVariableTypeTable,
localVariableTypeTableAttribute.u2localVariableTypeTableLength,
codeAttribute.u2maxLocals);
}
public void visitAnyTypeAnnotationsAttribute(Clazz clazz, TypeAnnotationsAttribute typeAnnotationsAttribute)
{
typeAnnotationsAttribute.typeAnnotationsAccept(clazz, this);
}
// Implementations for InstructionVisitor.
public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}
public void visitBranchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, BranchInstruction branchInstruction)
{
try
{
// Adjust the branch offset.
branchInstruction.branchOffset =
newBranchOffset(offset, branchInstruction.branchOffset);
// Don't remap this instruction again.
oldInstructionOffsets[offset] = -1;
}
catch (IllegalArgumentException e)
{
if (level == 0 || !allowExternalBranchTargets)
{
throw e;
}
}
}
public void visitAnySwitchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SwitchInstruction switchInstruction)
{
try
{
// TODO: We're assuming we can adjust no offsets or all offsets at once.
// Adjust the default jump offset.
switchInstruction.defaultOffset =
newBranchOffset(offset, switchInstruction.defaultOffset);
// Adjust the jump offsets.
updateJumpOffsets(offset,
switchInstruction.jumpOffsets);
// Don't remap this instruction again.
oldInstructionOffsets[offset] = -1;
}
catch (IllegalArgumentException e)
{
if (level == 0 || !allowExternalBranchTargets)
{
throw e;
}
}
}
// 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 = newInstructionOffset(exceptionInfo.u2startPC);
exceptionInfo.u2endPC = newInstructionOffset(exceptionInfo.u2endPC);
// See if we can remap the handler right away. Unmapped exception
// handlers are negated, in order to mark them as external.
int handlerPC = exceptionInfo.u2handlerPC;
exceptionInfo.u2handlerPC =
!allowExternalExceptionHandlers ||
remappableExceptionHandler(handlerPC) ?
newInstructionOffset(handlerPC) :
-handlerPC;
}
// Implementations for StackMapFrameVisitor.
public void visitAnyStackMapFrame(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, StackMapFrame stackMapFrame)
{
// Remap the stack map frame offset.
int stackMapFrameOffset = newInstructionOffset(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 = newInstructionOffset(uninitializedType.u2newInstructionOffset);
}
// Implementations for LineNumberInfoVisitor.
public void visitLineNumberInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LineNumberInfo lineNumberInfo)
{
// Remap the code offset.
lineNumberInfo.u2startPC = newInstructionOffset(lineNumberInfo.u2startPC);
}
// Implementations for LocalVariableInfoVisitor.
public void visitLocalVariableInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableInfo localVariableInfo)
{
// Remap the code offset and length.
// TODO: The local variable frame might not be strictly preserved.
int startPC = newInstructionOffset(localVariableInfo.u2startPC);
int endPC = newInstructionOffset(localVariableInfo.u2startPC +
localVariableInfo.u2length);
localVariableInfo.u2startPC = startPC;
localVariableInfo.u2length = endPC - startPC;
}
// Implementations for LocalVariableTypeInfoVisitor.
public void visitLocalVariableTypeInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeInfo localVariableTypeInfo)
{
// Remap the code offset and length.
// TODO: The local variable frame might not be strictly preserved.
int startPC = newInstructionOffset(localVariableTypeInfo.u2startPC);
int endPC = newInstructionOffset(localVariableTypeInfo.u2startPC +
localVariableTypeInfo.u2length);
localVariableTypeInfo.u2startPC = startPC;
localVariableTypeInfo.u2length = endPC - startPC;
}
// Implementations for TypeAnnotationVisitor.
public void visitTypeAnnotation(Clazz clazz, TypeAnnotation typeAnnotation)
{
// Update all local variable targets.
typeAnnotation.targetInfoAccept(clazz, this);
}
// Implementations for TargetInfoVisitor.
public void visitAnyTargetInfo(Clazz clazz, TypeAnnotation typeAnnotation, TargetInfo targetInfo) {}
public void visitLocalVariableTargetInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, TypeAnnotation typeAnnotation, LocalVariableTargetInfo localVariableTargetInfo)
{
// Update the offsets of the variables.
localVariableTargetInfo.targetElementsAccept(clazz, method, codeAttribute, typeAnnotation, this);
}
public void visitOffsetTargetInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, TypeAnnotation typeAnnotation, OffsetTargetInfo offsetTargetInfo)
{
// Update the offset.
offsetTargetInfo.u2offset = newInstructionOffset(offsetTargetInfo.u2offset);
}
// Implementations for LocalVariableTargetElementVisitor.
public void visitLocalVariableTargetElement(Clazz clazz, Method method, CodeAttribute codeAttribute, TypeAnnotation typeAnnotation, LocalVariableTargetInfo localVariableTargetInfo, LocalVariableTargetElement localVariableTargetElement)
{
// Remap the code offset and length.
int startPC = newInstructionOffset(localVariableTargetElement.u2startPC);
int endPC = newInstructionOffset(localVariableTargetElement.u2startPC +
localVariableTargetElement.u2length);
localVariableTargetElement.u2startPC = startPC;
localVariableTargetElement.u2length = endPC - startPC;
}
// Small utility methods.
/**
* Make sure the code arrays have at least the given size.
*/
private void ensureCodeLength(int newCodeLength)
{
if (code.length < newCodeLength)
{
// Add 20% to avoid extending the arrays too often.
newCodeLength = newCodeLength * 6 / 5;
code = ArrayUtil.extendArray(code, newCodeLength);
oldInstructionOffsets = ArrayUtil.extendArray(oldInstructionOffsets, newCodeLength);
instructionWriter.extend(newCodeLength);
}
}
/**
* Adjusts the given jump offsets for the instruction at the given offset.
*/
private void updateJumpOffsets(int offset, int[] jumpOffsets)
{
for (int index = 0; index < jumpOffsets.length; index++)
{
jumpOffsets[index] = newBranchOffset(offset, jumpOffsets[index]);
}
}
/**
* Computes the new branch offset for the instruction at the given new offset
* with the given old branch offset.
*/
private int newBranchOffset(int newInstructionOffset, int oldBranchOffset)
{
if (newInstructionOffset < 0 ||
newInstructionOffset > codeLength)
{
throw new IllegalArgumentException("Invalid instruction offset ["+newInstructionOffset +"] in code with length ["+codeLength+"]");
}
int oldInstructionOffset = oldInstructionOffsets[newInstructionOffset];
// For ordinary branch instructions, we can compute the offset
// relative to the instruction itself.
return newInstructionOffset(oldInstructionOffset + oldBranchOffset) -
newInstructionOffset;
}
/**
* Computes the new instruction offset for the instruction at the given old
* offset.
*/
private int newInstructionOffset(int oldInstructionOffset)
{
if (oldInstructionOffset < 0 ||
oldInstructionOffset > codeFragmentLengths[level])
{
throw new IllegalArgumentException("Instruction offset ["+oldInstructionOffset +"] out of range in code fragment with length ["+codeFragmentLengths[level]+"] at level "+level);
}
int newInstructionOffset = instructionOffsetMap[level][oldInstructionOffset];
if (newInstructionOffset == INVALID)
{
throw new IllegalArgumentException("Invalid instruction offset ["+oldInstructionOffset +"] in code fragment at level "+level);
}
return newInstructionOffset;
}
/**
* Returns whether the given old exception handler can be remapped in the
* current code fragment.
*/
private boolean remappableExceptionHandler(int oldInstructionOffset)
{
// Can we index in the array?
if (oldInstructionOffset > codeFragmentLengths[level])
{
return false;
}
// Do we have a valid new instruction offset, but not yet right after
// the code? That offset is only labeled for mapping try blocks, not
// for mapping handlers.
int newInstructionOffset =
instructionOffsetMap[level][oldInstructionOffset];
return newInstructionOffset > INVALID &&
newInstructionOffset < codeLength;
}
/**
* 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;
}
}
// Clear the unused array entries.
Arrays.fill(exceptionInfos, newIndex, exceptionInfoCount, null);
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;
}
}
// Clear the unused array entries.
Arrays.fill(lineNumberInfos, newIndex, lineNumberInfoCount, null);
return newIndex;
}
/**
* Returns the given list of local variables, without the ones that have empty
* code blocks or that exceed the actual number of local variables.
*/
private int removeEmptyLocalVariables(LocalVariableInfo[] localVariableInfos,
int localVariableInfoCount,
int maxLocals)
{
// Overwrite all empty local variable entries.
int newIndex = 0;
for (int index = 0; index < localVariableInfoCount; index++)
{
LocalVariableInfo localVariableInfo = localVariableInfos[index];
if (localVariableInfo.u2length > 0 &&
localVariableInfo.u2index < maxLocals)
{
localVariableInfos[newIndex++] = localVariableInfo;
}
}
// Clear the unused array entries.
Arrays.fill(localVariableInfos, newIndex, localVariableInfoCount, null);
return newIndex;
}
/**
* Returns the given list of local variable types, without the ones that
* have empty code blocks or that exceed the actual number of local variables.
*/
private int removeEmptyLocalVariableTypes(LocalVariableTypeInfo[] localVariableTypeInfos,
int localVariableTypeInfoCount,
int maxLocals)
{
// Overwrite all empty local variable type entries.
int newIndex = 0;
for (int index = 0; index < localVariableTypeInfoCount; index++)
{
LocalVariableTypeInfo localVariableTypeInfo = localVariableTypeInfos[index];
if (localVariableTypeInfo.u2length > 0 &&
localVariableTypeInfo.u2index < maxLocals)
{
localVariableTypeInfos[newIndex++] = localVariableTypeInfo;
}
}
// Clear the unused array entries.
Arrays.fill(localVariableTypeInfos, newIndex, localVariableTypeInfoCount, null);
return newIndex;
}
private void println(String string1, String string2)
{
print(string1, string2);
System.out.println();
}
private void print(String string1, String string2)
{
System.out.print(string1);
for (int index = 0; index < level; index++)
{
System.out.print(" ");
}
System.out.print(string2);
}
public static void main(String[] args)
{
CodeAttributeComposer composer = new CodeAttributeComposer();
composer.beginCodeFragment(4);
composer.appendInstruction(0, new SimpleInstruction(InstructionConstants.OP_ICONST_0));
composer.appendInstruction(1, new VariableInstruction(InstructionConstants.OP_ISTORE, 0));
composer.appendInstruction(2, new BranchInstruction(InstructionConstants.OP_GOTO, 1));
composer.beginCodeFragment(4);
composer.appendInstruction(0, new VariableInstruction(InstructionConstants.OP_IINC, 0, 1));
composer.appendInstruction(1, new VariableInstruction(InstructionConstants.OP_ILOAD, 0));
composer.appendInstruction(2, new SimpleInstruction(InstructionConstants.OP_ICONST_5));
composer.appendInstruction(3, new BranchInstruction(InstructionConstants.OP_IFICMPLT, -3));
composer.endCodeFragment();
composer.appendInstruction(3, new SimpleInstruction(InstructionConstants.OP_RETURN));
composer.endCodeFragment();
}
}