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JMockit is a Java toolkit for automated developer testing.
It contains APIs for the creation of the objects to be tested, for mocking dependencies, and for faking external
APIs; JUnit (4 & 5) and TestNG test runners are supported.
It also contains an advanced code coverage tool.
/*
* ASM: a very small and fast Java bytecode manipulation framework
* Copyright (c) 2000-2011 INRIA, France Telecom
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
package mockit.external.asm;
import javax.annotation.*;
import static mockit.external.asm.Opcodes.*;
/**
* A {@link MethodVisitor} that generates methods in bytecode form. Each visit method of this class appends the bytecode
* corresponding to the visited instruction to a byte vector, in the order these methods are called.
*/
public final class MethodWriter extends MethodVisitor
{
/**
* The class writer to which this method must be added.
*/
@Nonnull final ClassWriter cw;
/**
* The index of the constant pool item that contains the name of this method.
*/
private final int name;
/**
* The index of the constant pool item that contains the descriptor of this method.
*/
private final int desc;
/**
* The descriptor of this method.
*/
@Nonnull final String descriptor;
@Nullable private final SignatureWriter signatureWriter;
/**
* If not zero, indicates that the code of this method must be copied from the ClassReader associated to this writer
* in cw.cr. More precisely, this field gives the index of the first byte to copied from
* cw.cr.code.
*/
@Nonnegative int classReaderOffset;
/**
* If not zero, indicates that the code of this method must be copied from the ClassReader associated to this writer
* in cw.cr. More precisely, this field gives the number of bytes to copied from cw.cr.code.
*/
@Nonnegative int classReaderLength;
@Nullable private final ThrowsClause throwsClause;
/**
* The runtime visible parameter annotations of this method. May be null.
*/
@Nullable private AnnotationWriter[] parameterAnnotations;
/**
* The bytecode of this method.
*/
@Nonnull private final ByteVector code;
@Nonnull private final FrameAndStackComputation frameAndStack;
@Nonnull private final ExceptionHandling exceptionHandling;
@Nonnull private final LocalVariables localVariables;
@Nonnull private final LineNumbers lineNumbers;
@Nonnull private final CFGAnalysis cfgAnalysis;
private final boolean computeFrames;
/**
* Initializes the MethodWriter.
*
* @param cw the class writer in which the method must be added.
* @param access the method's access flags (see {@link Opcodes}).
* @param name the method's name.
* @param desc the method's descriptor (see {@link JavaType}).
* @param signature the method's signature. May be null.
* @param exceptions the internal names of the method's exceptions. May be null.
* @param computeFrames true if the stack map tables must be recomputed from scratch.
*/
MethodWriter(
@Nonnull ClassWriter cw, int access, @Nonnull String name, @Nonnull String desc, @Nullable String signature,
@Nullable String[] exceptions, boolean computeFrames
) {
this.cw = cw;
cp = cw.cp;
this.access = "".equals(name) ? (access | Access.CONSTRUCTOR) : access;
this.name = cp.newUTF8(name);
this.desc = cp.newUTF8(desc);
descriptor = desc;
signatureWriter = signature == null ? null : new SignatureWriter(cp, signature);
throwsClause = exceptions == null ? null : new ThrowsClause(cp, exceptions);
code = new ByteVector();
this.computeFrames = computeFrames;
frameAndStack = new FrameAndStackComputation(this, access, desc);
exceptionHandling = new ExceptionHandling(cp);
localVariables = new LocalVariables(cp);
lineNumbers = new LineNumbers(cp);
cfgAnalysis = new CFGAnalysis(cw, code, computeFrames);
createMarkerAttributes(cw.version);
}
@Nonnull @Override
public AnnotationVisitor visitAnnotation(@Nonnull String desc) {
return addAnnotation(desc);
}
@Nonnull @Override
public AnnotationVisitor visitParameterAnnotation(@Nonnegative int parameter, @Nonnull String desc) {
AnnotationWriter aw = new AnnotationWriter(cp, desc);
if (parameterAnnotations == null) {
int numParameters = JavaType.getArgumentTypes(descriptor).length;
parameterAnnotations = new AnnotationWriter[numParameters];
}
aw.next = parameterAnnotations[parameter];
parameterAnnotations[parameter] = aw;
return aw;
}
@Override
public void visitInsn(int opcode) {
// Adds the instruction to the bytecode of the method.
code.putByte(opcode);
cfgAnalysis.updateCurrentBlockForZeroOperandInstruction(opcode);
}
@Override
public void visitIntInsn(int opcode, int operand) {
cfgAnalysis.updateCurrentBlockForSingleIntOperandInstruction(opcode, operand);
// Adds the instruction to the bytecode of the method.
if (opcode == SIPUSH) {
code.put12(opcode, operand);
}
else { // BIPUSH or NEWARRAY
code.put11(opcode, operand);
}
}
@Override
public void visitVarInsn(int opcode, @Nonnegative int var) {
cfgAnalysis.updateCurrentBlockForLocalVariableInstruction(opcode, var);
updateMaxLocals(opcode, var);
// Adds the instruction to the bytecode of the method.
if (var < 4) {
int opt;
if (opcode < ISTORE) { // ILOAD_0
opt = 26 + ((opcode - ILOAD) << 2) + var;
}
else { // ISTORE_0
opt = 59 + ((opcode - ISTORE) << 2) + var;
}
code.putByte(opt);
}
else if (var >= 256) {
code.putByte(WIDE).put12(opcode, var);
}
else {
code.put11(opcode, var);
}
if (opcode >= ISTORE && computeFrames && exceptionHandling.hasHandlers()) {
visitLabel(new Label());
}
}
private void updateMaxLocals(int opcode, @Nonnegative int var) {
int n = opcode == LLOAD || opcode == DLOAD || opcode == LSTORE || opcode == DSTORE ? var + 2 : var + 1;
frameAndStack.updateMaxLocals(n);
}
@Override
public void visitTypeInsn(int opcode, @Nonnull String type) {
StringItem typeItem = cp.newClassItem(type);
cfgAnalysis.updateCurrentBlockForTypeInstruction(opcode, typeItem);
// Adds the instruction to the bytecode of the method.
code.put12(opcode, typeItem.index);
}
@Override
public void visitFieldInsn(int opcode, @Nonnull String owner, @Nonnull String name, @Nonnull String desc) {
ClassMemberItem fieldItem = cp.newFieldItem(owner, name, desc);
cfgAnalysis.updateCurrentBlockForFieldInstruction(opcode, fieldItem, desc);
// Adds the instruction to the bytecode of the method.
code.put12(opcode, fieldItem.index);
}
@Override
public void visitMethodInsn(
int opcode, @Nonnull String owner, @Nonnull String name, @Nonnull String desc, boolean itf
) {
ClassMemberItem invokeItem = cp.newMethodItem(owner, name, desc, itf);
cfgAnalysis.updateCurrentBlockForInvokeInstruction(invokeItem, opcode, desc);
// Adds the instruction to the bytecode of the method.
code.put12(opcode, invokeItem.index);
if (opcode == INVOKEINTERFACE) {
int argSize = invokeItem.getArgSizeComputingIfNeeded(desc);
code.put11(argSize >> 2, 0);
}
}
@Override
public void visitInvokeDynamicInsn(
@Nonnull String name, @Nonnull String desc, @Nonnull MethodHandle bsm, @Nonnull Object... bsmArgs
) {
//noinspection ConstantConditions
InvokeDynamicItem invokeItem = cw.bootstrapMethods.addInvokeDynamicReference(name, desc, bsm, bsmArgs);
cfgAnalysis.updateCurrentBlockForInvokeInstruction(invokeItem, INVOKEDYNAMIC, desc);
// Adds the instruction to the bytecode of the method.
code.put12(INVOKEDYNAMIC, invokeItem.index);
code.putShort(0);
}
@Override
public void visitJumpInsn(int opcode, @Nonnull Label label) {
Label nextInsn = cfgAnalysis.updateCurrentBlockForJumpInstruction(opcode, label);
// Adds the instruction to the bytecode of the method.
if (label.isResolved() && label.position - code.length < Short.MIN_VALUE) {
// Case of a backward jump with an offset < -32768. In this case we automatically replace GOTO with GOTO_W and
// IFxxx with IFNOTxxx GOTO_W , where IFNOTxxx is the "opposite" opcode of IFxxx
// (i.e., IFNE for IFEQ) and where designates the instruction just after the GOTO_W.
if (opcode == GOTO) {
code.putByte(GOTO_W);
}
else {
// If the IF instruction is transformed into IFNOT GOTO_W the next instruction becomes the target of the
// IFNOT instruction.
if (nextInsn != null) {
nextInsn.markAsTarget();
}
code.putByte(opcode <= 166 ? ((opcode + 1) ^ 1) - 1 : opcode ^ 1);
code.putShort(8); // jump offset
code.putByte(GOTO_W);
}
label.put(code, code.length - 1, true);
}
else {
// Case of a backward jump with an offset >= -32768, or of a forward jump with, of course, an unknown offset.
// In these cases we store the offset in 2 bytes (which will be increased in resizeInstructions, if needed).
code.putByte(opcode);
label.put(code, code.length - 1, false);
}
cfgAnalysis.updateCurrentBlockForJumpTarget(opcode, nextInsn);
}
@Override
public void visitLabel(@Nonnull Label label) {
cfgAnalysis.updateCurrentBlockForLabelBeforeNextInstruction(label);
}
@Override
public void visitLdcInsn(@Nonnull Object cst) {
Item constItem = cp.newConstItem(cst);
cfgAnalysis.updateCurrentBlockForLDCInstruction(constItem);
// Adds the instruction to the bytecode of the method.
int index = constItem.index;
if (constItem instanceof LongValueItem) {
code.put12(LDC2_W, index);
}
else if (index >= 256) {
code.put12(LDC_W, index);
}
else {
code.put11(LDC, index);
}
}
@Override
public void visitIincInsn(int var, int increment) {
cfgAnalysis.updateCurrentBlockForIINCInstruction(var);
// Updates max locals.
int n = var + 1;
frameAndStack.updateMaxLocals(n);
// Adds the instruction to the bytecode of the method.
if (var > 255 || increment > 127 || increment < -128) {
code.putByte(WIDE).put12(IINC, var).putShort(increment);
}
else {
code.putByte(IINC).put11(var, increment);
}
}
@Override
public void visitTableSwitchInsn(int min, int max, @Nonnull Label dflt, @Nonnull Label... labels) {
// Adds the instruction to the bytecode of the method.
int source = code.length;
code.putByte(TABLESWITCH);
code.increaseLengthBy((4 - code.length % 4) % 4);
dflt.put(code, source, true);
code.putInt(min).putInt(max);
for (Label label : labels) {
label.put(code, source, true);
}
cfgAnalysis.updateCurrentBlockForSwitchInstruction(dflt, labels);
}
@Override
public void visitLookupSwitchInsn(@Nonnull Label dflt, @Nonnull int[] keys, @Nonnull Label[] labels) {
// Adds the instruction to the bytecode of the method.
int source = code.length;
code.putByte(LOOKUPSWITCH);
code.increaseLengthBy((4 - code.length % 4) % 4);
dflt.put(code, source, true);
code.putInt(labels.length);
for (int i = 0; i < labels.length; i++) {
code.putInt(keys[i]);
labels[i].put(code, source, true);
}
cfgAnalysis.updateCurrentBlockForSwitchInstruction(dflt, labels);
}
@Override
public void visitMultiANewArrayInsn(@Nonnull String desc, @Nonnegative int dims) {
StringItem arrayTypeItem = cp.newClassItem(desc);
cfgAnalysis.updateCurrentBlockForMULTIANEWARRAYInstruction(arrayTypeItem, dims);
// Adds the instruction to the bytecode of the method.
code.put12(MULTIANEWARRAY, arrayTypeItem.index).putByte(dims);
}
@Override
public void visitTryCatchBlock(
@Nonnull Label start, @Nonnull Label end, @Nonnull Label handler, @Nullable String type
) {
exceptionHandling.addHandler(start, end, handler, type);
}
@Override
public void visitLocalVariable(
@Nonnull String name, @Nonnull String desc, @Nullable String signature, @Nonnull Label start, @Nonnull Label end,
@Nonnegative int index
) {
int localsCount = localVariables.addLocalVariable(name, desc, signature, start, end, index);
frameAndStack.updateMaxLocals(localsCount);
}
@Override
public void visitLineNumber(@Nonnegative int line, @Nonnull Label start) {
lineNumbers.addLineNumber(line, start);
}
@Override
public void visitMaxStack(@Nonnegative int maxStack) {
int computedMaxStack;
if (computeFrames) {
exceptionHandling.completeControlFlowGraphWithExceptionHandlerBlocksFromComputedFrames();
Frame firstFrame = cfgAnalysis.getFirstFrame();
frameAndStack.createAndVisitFirstFrame(firstFrame);
computedMaxStack = cfgAnalysis.computeMaxStackSizeFromComputedFrames();
computedMaxStack = visitAllFramesToBeStoredInStackMap(computedMaxStack);
exceptionHandling.countNumberOfHandlers();
}
else {
// TODO: figure out if/when the next call is needed, since no tests fail if commented out
exceptionHandling.completeControlFlowGraphWithExceptionHandlerBlocks();
computedMaxStack = cfgAnalysis.computeMaxStackSize();
computedMaxStack = Math.max(maxStack, computedMaxStack);
}
frameAndStack.setMaxStack(computedMaxStack);
}
@Nonnegative
private int visitAllFramesToBeStoredInStackMap(@Nonnegative int max) {
Label label = cfgAnalysis.getLabelForFirstBasicBlock();
Frame frame;
while (label != null) {
frame = label.frame;
if (label.isStoringFrame()) {
frameAndStack.visitFrame(frame);
}
if (!label.isReachable()) {
// Finds start and end of dead basic block.
Label k = label.successor;
int start = label.position;
int end = (k == null ? code.length : k.position) - 1;
// If non empty basic block.
if (end >= start) {
max = Math.max(max, 1);
replaceInstructionsWithNOPAndATHROW(start, end);
frameAndStack.emitFrameForUnreachableBlock(start);
exceptionHandling.removeStartEndRange(label, k);
}
}
label = label.successor;
}
return max;
}
// Replaces instructions with NOP ... NOP ATHROW.
private void replaceInstructionsWithNOPAndATHROW(@Nonnegative int start, @Nonnegative int end) {
byte[] data = code.data;
for (int i = start; i < end; i++) {
data[i] = NOP;
}
data[end] = (byte) ATHROW;
}
/**
* Returns the size of the bytecode of this method.
*/
@Nonnegative
int getSize() {
if (classReaderOffset > 0) {
return 6 + classReaderLength;
}
int size = 8 + getMarkerAttributesSize() + getAnnotationsSize() + getParameterAnnotationsSize();
int codeLength = code.length;
if (codeLength > 0) {
if (codeLength > 65536) {
throw new RuntimeException("Method code too large!");
}
cp.newUTF8("Code");
size += 18 + codeLength + exceptionHandling.getSize();
size += localVariables.getSizeWhileAddingConstantPoolItems();
size += lineNumbers.getSizeWhileAddingConstantPoolItem();
size += frameAndStack.getSizeWhileAddingConstantPoolItem();
}
if (throwsClause != null) {
size += throwsClause.getSize();
}
if (signatureWriter != null) {
size += signatureWriter.getSize();
}
return size;
}
@Nonnegative
private int getParameterAnnotationsSize() {
int size = 0;
if (parameterAnnotations != null) {
cp.newUTF8("RuntimeVisibleParameterAnnotations");
int n = parameterAnnotations.length;
size += 7 + 2 * n;
for (int i = n - 1; i >= 0; i--) {
AnnotationWriter parameterAnnotation = parameterAnnotations[i];
size += parameterAnnotation == null ? 0 : parameterAnnotation.getSize();
}
}
return size;
}
/**
* Puts the bytecode of this method in the given byte vector.
*/
@Override
void put(@Nonnull ByteVector out) {
putAccess(out, Access.CONSTRUCTOR);
out.putShort(name);
out.putShort(desc);
if (classReaderOffset > 0) {
out.putByteArray(cw.cr.code, classReaderOffset, classReaderLength);
return;
}
putMethodAttributeCount(out);
putMethodCode(out);
if (throwsClause != null) {
throwsClause.put(out);
}
putMarkerAttributes(out);
if (signatureWriter != null) {
signatureWriter.put(out);
}
putAnnotationAttributes(out);
}
private void putMethodAttributeCount(@Nonnull ByteVector out) {
int attributeCount = getMarkerAttributeCount();
if (code.length > 0) {
attributeCount++;
}
if (throwsClause != null) {
attributeCount++;
}
if (signatureWriter != null) {
attributeCount++;
}
if (annotations != null) {
attributeCount++;
}
if (parameterAnnotations != null) {
attributeCount++;
}
out.putShort(attributeCount);
}
private void putMethodCode(@Nonnull ByteVector out) {
if (code.length > 0) {
putCodeSize(out);
frameAndStack.putMaxStackAndLocals(out);
out.putInt(code.length).putByteVector(code);
exceptionHandling.put(out);
int codeAttributeCount = localVariables.getAttributeCount();
if (lineNumbers.hasLineNumbers()) {
codeAttributeCount++;
}
if (frameAndStack.hasStackMap()) {
codeAttributeCount++;
}
out.putShort(codeAttributeCount);
localVariables.put(out);
lineNumbers.put(out);
frameAndStack.put(out);
}
}
private void putCodeSize(@Nonnull ByteVector out) {
int size =
12 + code.length +
exceptionHandling.getSize() + localVariables.getSize() + lineNumbers.getSize() + frameAndStack.getSize();
out.putShort(cp.newUTF8("Code")).putInt(size);
}
private void putAnnotationAttributes(@Nonnull ByteVector out) {
putAnnotations(out);
if (parameterAnnotations != null) {
out.putShort(cp.newUTF8("RuntimeVisibleParameterAnnotations"));
AnnotationWriter.put(out, parameterAnnotations);
}
}
@Nullable
public Label getCurrentBlock() { return cfgAnalysis.getLabelForCurrentBasicBlock(); }
}
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