init(final Frame frame) {
returnValue = frame.returnValue;
if (values.length < frame.values.length) {
values = frame.values.clone();
} else {
System.arraycopy(frame.values, 0, values, 0, frame.values.length);
}
numLocals = frame.numLocals;
numStack = frame.numStack;
maxStack = frame.maxStack;
return this;
}
/**
* Initializes a frame corresponding to the target or to the successor of a jump instruction. This
* method is called by {@link Analyzer#analyze(String, org.objectweb.asm.tree.MethodNode)} while
* interpreting jump instructions. It is called once for each possible target of the jump
* instruction, and once for its successor instruction (except for GOTO and JSR), before the frame
* is merged with the existing frame at this location. The default implementation of this method
* does nothing.
*
* Overriding this method and changing the frame values allows implementing branch-sensitive
* analyses.
*
* @param opcode the opcode of the jump instruction. Can be IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE,
* IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE,
* GOTO, JSR, IFNULL, IFNONNULL, TABLESWITCH or LOOKUPSWITCH.
* @param target a target of the jump instruction this frame corresponds to, or {@literal null} if
* this frame corresponds to the successor of the jump instruction (i.e. the next instruction
* in the instructions sequence).
*/
public void initJumpTarget(final int opcode, final LabelNode target) {
// Does nothing by default.
}
/**
* Sets the expected return type of the analyzed method.
*
* @param v the expected return type of the analyzed method, or {@literal null} if the method
* returns void.
*/
public void setReturn(final V v) {
returnValue = v;
}
/**
* Returns the maximum number of local variables of this frame. Long and double values are
* represented with two variables.
*
* @return the maximum number of local variables of this frame.
*/
public int getLocals() {
return numLocals;
}
/**
* Returns the maximum number of elements in the operand stack of this frame. Long and double
* values are represented with a single element.
*
* @return the maximum number of elements in the operand stack of this frame.
*/
public int getMaxStackSize() {
return maxStack;
}
/**
* Returns the value of the given local variable. Long and double values are represented with two
* variables.
*
* @param index a local variable index.
* @return the value of the given local variable.
* @throws IndexOutOfBoundsException if the variable does not exist.
*/
public V getLocal(final int index) {
if (index >= numLocals) {
throw new IndexOutOfBoundsException("Trying to get an inexistant local variable " + index);
}
return values[index];
}
/**
* Sets the value of the given local variable. Long and double values are represented with two
* variables.
*
* @param index a local variable index.
* @param value the new value of this local variable.
* @throws IndexOutOfBoundsException if the variable does not exist.
*/
public void setLocal(final int index, final V value) {
if (index >= numLocals) {
throw new IndexOutOfBoundsException("Trying to set an inexistant local variable " + index);
}
values[index] = value;
}
/**
* Returns the number of elements in the operand stack of this frame. Long and double values are
* represented with a single element.
*
* @return the number of elements in the operand stack of this frame.
*/
public int getStackSize() {
return numStack;
}
/**
* Returns the value of the given operand stack slot.
*
* @param index the index of an operand stack slot.
* @return the value of the given operand stack slot.
* @throws IndexOutOfBoundsException if the operand stack slot does not exist.
*/
public V getStack(final int index) {
return values[numLocals + index];
}
/**
* Sets the value of the given stack slot.
*
* @param index the index of an operand stack slot.
* @param value the new value of the stack slot.
* @throws IndexOutOfBoundsException if the stack slot does not exist.
*/
public void setStack(final int index, final V value) {
values[numLocals + index] = value;
}
/** Clears the operand stack of this frame. */
public void clearStack() {
numStack = 0;
}
/**
* Pops a value from the operand stack of this frame.
*
* @return the value that has been popped from the stack.
* @throws IndexOutOfBoundsException if the operand stack is empty.
*/
public V pop() {
if (numStack == 0) {
throw new IndexOutOfBoundsException("Cannot pop operand off an empty stack.");
}
return values[numLocals + (--numStack)];
}
/**
* Pushes a value into the operand stack of this frame.
*
* @param value the value that must be pushed into the stack.
* @throws IndexOutOfBoundsException if the operand stack is full.
*/
@SuppressWarnings("unchecked")
public void push(final V value) {
if (numLocals + numStack >= values.length) {
if (numLocals + numStack >= maxStack) {
throw new IndexOutOfBoundsException("Insufficient maximum stack size.");
}
V[] oldValues = values;
values = (V[]) new Value[2 * values.length];
System.arraycopy(oldValues, 0, values, 0, oldValues.length);
}
values[numLocals + (numStack++)] = value;
}
/**
* Simulates the execution of the given instruction on this execution stack frame.
*
* @param insn the instruction to execute.
* @param interpreter the interpreter to use to compute values from other values.
* @throws AnalyzerException if the instruction cannot be executed on this execution frame (e.g. a
* POP on an empty operand stack).
*/
public void execute(final AbstractInsnNode insn, final Interpreter interpreter)
throws AnalyzerException {
V value1;
V value2;
V value3;
V value4;
int varIndex;
switch (insn.getOpcode()) {
case Opcodes.NOP:
break;
case Opcodes.ACONST_NULL:
case Opcodes.ICONST_M1:
case Opcodes.ICONST_0:
case Opcodes.ICONST_1:
case Opcodes.ICONST_2:
case Opcodes.ICONST_3:
case Opcodes.ICONST_4:
case Opcodes.ICONST_5:
case Opcodes.LCONST_0:
case Opcodes.LCONST_1:
case Opcodes.FCONST_0:
case Opcodes.FCONST_1:
case Opcodes.FCONST_2:
case Opcodes.DCONST_0:
case Opcodes.DCONST_1:
case Opcodes.BIPUSH:
case Opcodes.SIPUSH:
case Opcodes.LDC:
push(interpreter.newOperation(insn));
break;
case Opcodes.ILOAD:
case Opcodes.LLOAD:
case Opcodes.FLOAD:
case Opcodes.DLOAD:
case Opcodes.ALOAD:
push(interpreter.copyOperation(insn, getLocal(((VarInsnNode) insn).var)));
break;
case Opcodes.ISTORE:
case Opcodes.LSTORE:
case Opcodes.FSTORE:
case Opcodes.DSTORE:
case Opcodes.ASTORE:
value1 = interpreter.copyOperation(insn, pop());
varIndex = ((VarInsnNode) insn).var;
setLocal(varIndex, value1);
if (value1.getSize() == 2) {
setLocal(varIndex + 1, interpreter.newEmptyValue(varIndex + 1));
}
if (varIndex > 0) {
Value local = getLocal(varIndex - 1);
if (local != null && local.getSize() == 2) {
setLocal(varIndex - 1, interpreter.newEmptyValue(varIndex - 1));
}
}
break;
case Opcodes.IASTORE:
case Opcodes.LASTORE:
case Opcodes.FASTORE:
case Opcodes.DASTORE:
case Opcodes.AASTORE:
case Opcodes.BASTORE:
case Opcodes.CASTORE:
case Opcodes.SASTORE:
value3 = pop();
value2 = pop();
value1 = pop();
interpreter.ternaryOperation(insn, value1, value2, value3);
break;
case Opcodes.POP:
if (pop().getSize() == 2) {
throw new AnalyzerException(insn, "Illegal use of POP");
}
break;
case Opcodes.POP2:
if (pop().getSize() == 1 && pop().getSize() != 1) {
throw new AnalyzerException(insn, "Illegal use of POP2");
}
break;
case Opcodes.DUP:
value1 = pop();
if (value1.getSize() != 1) {
throw new AnalyzerException(insn, "Illegal use of DUP");
}
push(value1);
push(interpreter.copyOperation(insn, value1));
break;
case Opcodes.DUP_X1:
value1 = pop();
value2 = pop();
if (value1.getSize() != 1 || value2.getSize() != 1) {
throw new AnalyzerException(insn, "Illegal use of DUP_X1");
}
push(interpreter.copyOperation(insn, value1));
push(value2);
push(value1);
break;
case Opcodes.DUP_X2:
value1 = pop();
if (value1.getSize() == 1 && executeDupX2(insn, value1, interpreter)) {
break;
}
throw new AnalyzerException(insn, "Illegal use of DUP_X2");
case Opcodes.DUP2:
value1 = pop();
if (value1.getSize() == 1) {
value2 = pop();
if (value2.getSize() == 1) {
push(value2);
push(value1);
push(interpreter.copyOperation(insn, value2));
push(interpreter.copyOperation(insn, value1));
break;
}
} else {
push(value1);
push(interpreter.copyOperation(insn, value1));
break;
}
throw new AnalyzerException(insn, "Illegal use of DUP2");
case Opcodes.DUP2_X1:
value1 = pop();
if (value1.getSize() == 1) {
value2 = pop();
if (value2.getSize() == 1) {
value3 = pop();
if (value3.getSize() == 1) {
push(interpreter.copyOperation(insn, value2));
push(interpreter.copyOperation(insn, value1));
push(value3);
push(value2);
push(value1);
break;
}
}
} else {
value2 = pop();
if (value2.getSize() == 1) {
push(interpreter.copyOperation(insn, value1));
push(value2);
push(value1);
break;
}
}
throw new AnalyzerException(insn, "Illegal use of DUP2_X1");
case Opcodes.DUP2_X2:
value1 = pop();
if (value1.getSize() == 1) {
value2 = pop();
if (value2.getSize() == 1) {
value3 = pop();
if (value3.getSize() == 1) {
value4 = pop();
if (value4.getSize() == 1) {
push(interpreter.copyOperation(insn, value2));
push(interpreter.copyOperation(insn, value1));
push(value4);
push(value3);
push(value2);
push(value1);
break;
}
} else {
push(interpreter.copyOperation(insn, value2));
push(interpreter.copyOperation(insn, value1));
push(value3);
push(value2);
push(value1);
break;
}
}
} else if (executeDupX2(insn, value1, interpreter)) {
break;
}
throw new AnalyzerException(insn, "Illegal use of DUP2_X2");
case Opcodes.SWAP:
value2 = pop();
value1 = pop();
if (value1.getSize() != 1 || value2.getSize() != 1) {
throw new AnalyzerException(insn, "Illegal use of SWAP");
}
push(interpreter.copyOperation(insn, value2));
push(interpreter.copyOperation(insn, value1));
break;
case Opcodes.IALOAD:
case Opcodes.LALOAD:
case Opcodes.FALOAD:
case Opcodes.DALOAD:
case Opcodes.AALOAD:
case Opcodes.BALOAD:
case Opcodes.CALOAD:
case Opcodes.SALOAD:
case Opcodes.IADD:
case Opcodes.LADD:
case Opcodes.FADD:
case Opcodes.DADD:
case Opcodes.ISUB:
case Opcodes.LSUB:
case Opcodes.FSUB:
case Opcodes.DSUB:
case Opcodes.IMUL:
case Opcodes.LMUL:
case Opcodes.FMUL:
case Opcodes.DMUL:
case Opcodes.IDIV:
case Opcodes.LDIV:
case Opcodes.FDIV:
case Opcodes.DDIV:
case Opcodes.IREM:
case Opcodes.LREM:
case Opcodes.FREM:
case Opcodes.DREM:
case Opcodes.ISHL:
case Opcodes.LSHL:
case Opcodes.ISHR:
case Opcodes.LSHR:
case Opcodes.IUSHR:
case Opcodes.LUSHR:
case Opcodes.IAND:
case Opcodes.LAND:
case Opcodes.IOR:
case Opcodes.LOR:
case Opcodes.IXOR:
case Opcodes.LXOR:
case Opcodes.LCMP:
case Opcodes.FCMPL:
case Opcodes.FCMPG:
case Opcodes.DCMPL:
case Opcodes.DCMPG:
value2 = pop();
value1 = pop();
push(interpreter.binaryOperation(insn, value1, value2));
break;
case Opcodes.INEG:
case Opcodes.LNEG:
case Opcodes.FNEG:
case Opcodes.DNEG:
push(interpreter.unaryOperation(insn, pop()));
break;
case Opcodes.IINC:
varIndex = ((IincInsnNode) insn).var;
setLocal(varIndex, interpreter.unaryOperation(insn, getLocal(varIndex)));
break;
case Opcodes.I2L:
case Opcodes.I2F:
case Opcodes.I2D:
case Opcodes.L2I:
case Opcodes.L2F:
case Opcodes.L2D:
case Opcodes.F2I:
case Opcodes.F2L:
case Opcodes.F2D:
case Opcodes.D2I:
case Opcodes.D2L:
case Opcodes.D2F:
case Opcodes.I2B:
case Opcodes.I2C:
case Opcodes.I2S:
push(interpreter.unaryOperation(insn, pop()));
break;
case Opcodes.IFEQ:
case Opcodes.IFNE:
case Opcodes.IFLT:
case Opcodes.IFGE:
case Opcodes.IFGT:
case Opcodes.IFLE:
interpreter.unaryOperation(insn, pop());
break;
case Opcodes.IF_ICMPEQ:
case Opcodes.IF_ICMPNE:
case Opcodes.IF_ICMPLT:
case Opcodes.IF_ICMPGE:
case Opcodes.IF_ICMPGT:
case Opcodes.IF_ICMPLE:
case Opcodes.IF_ACMPEQ:
case Opcodes.IF_ACMPNE:
case Opcodes.PUTFIELD:
value2 = pop();
value1 = pop();
interpreter.binaryOperation(insn, value1, value2);
break;
case Opcodes.GOTO:
break;
case Opcodes.JSR:
push(interpreter.newOperation(insn));
break;
case Opcodes.RET:
break;
case Opcodes.TABLESWITCH:
case Opcodes.LOOKUPSWITCH:
interpreter.unaryOperation(insn, pop());
break;
case Opcodes.IRETURN:
case Opcodes.LRETURN:
case Opcodes.FRETURN:
case Opcodes.DRETURN:
case Opcodes.ARETURN:
value1 = pop();
interpreter.unaryOperation(insn, value1);
interpreter.returnOperation(insn, value1, returnValue);
break;
case Opcodes.RETURN:
if (returnValue != null) {
throw new AnalyzerException(insn, "Incompatible return type");
}
break;
case Opcodes.GETSTATIC:
push(interpreter.newOperation(insn));
break;
case Opcodes.PUTSTATIC:
interpreter.unaryOperation(insn, pop());
break;
case Opcodes.GETFIELD:
push(interpreter.unaryOperation(insn, pop()));
break;
case Opcodes.INVOKEVIRTUAL:
case Opcodes.INVOKESPECIAL:
case Opcodes.INVOKESTATIC:
case Opcodes.INVOKEINTERFACE:
executeInvokeInsn(insn, ((MethodInsnNode) insn).desc, interpreter);
break;
case Opcodes.INVOKEDYNAMIC:
executeInvokeInsn(insn, ((InvokeDynamicInsnNode) insn).desc, interpreter);
break;
case Opcodes.NEW:
push(interpreter.newOperation(insn));
break;
case Opcodes.NEWARRAY:
case Opcodes.ANEWARRAY:
case Opcodes.ARRAYLENGTH:
push(interpreter.unaryOperation(insn, pop()));
break;
case Opcodes.ATHROW:
interpreter.unaryOperation(insn, pop());
break;
case Opcodes.CHECKCAST:
case Opcodes.INSTANCEOF:
push(interpreter.unaryOperation(insn, pop()));
break;
case Opcodes.MONITORENTER:
case Opcodes.MONITOREXIT:
interpreter.unaryOperation(insn, pop());
break;
case Opcodes.MULTIANEWARRAY:
List valueList = new ArrayList<>();
for (int i = ((MultiANewArrayInsnNode) insn).dims; i > 0; --i) {
valueList.add(0, pop());
}
push(interpreter.naryOperation(insn, valueList));
break;
case Opcodes.IFNULL:
case Opcodes.IFNONNULL:
interpreter.unaryOperation(insn, pop());
break;
default:
throw new AnalyzerException(insn, "Illegal opcode " + insn.getOpcode());
}
}
private boolean executeDupX2(
final AbstractInsnNode insn, final V value1, final Interpreter interpreter)
throws AnalyzerException {
V value2 = pop();
if (value2.getSize() == 1) {
V value3 = pop();
if (value3.getSize() == 1) {
push(interpreter.copyOperation(insn, value1));
push(value3);
push(value2);
push(value1);
return true;
}
} else {
push(interpreter.copyOperation(insn, value1));
push(value2);
push(value1);
return true;
}
return false;
}
private void executeInvokeInsn(
final AbstractInsnNode insn, final String methodDescriptor, final Interpreter interpreter)
throws AnalyzerException {
ArrayList valueList = new ArrayList<>();
for (int i = Type.getArgumentCount(methodDescriptor); i > 0; --i) {
valueList.add(0, pop());
}
if (insn.getOpcode() != Opcodes.INVOKESTATIC && insn.getOpcode() != Opcodes.INVOKEDYNAMIC) {
valueList.add(0, pop());
}
if (Type.getReturnType(methodDescriptor) == Type.VOID_TYPE) {
interpreter.naryOperation(insn, valueList);
} else {
push(interpreter.naryOperation(insn, valueList));
}
}
/**
* Merges the given frame into this frame.
*
* @param frame a frame. This frame is left unchanged by this method.
* @param interpreter the interpreter used to merge values.
* @return {@literal true} if this frame has been changed as a result of the merge operation, or
* {@literal false} otherwise.
* @throws AnalyzerException if the frames have incompatible sizes.
*/
public boolean merge(final Frame frame, final Interpreter interpreter)
throws AnalyzerException {
if (numStack != frame.numStack) {
throw new AnalyzerException(null, "Incompatible stack heights");
}
boolean changed = false;
for (int i = 0; i < numLocals + numStack; ++i) {
V v = interpreter.merge(values[i], frame.values[i]);
if (!v.equals(values[i])) {
values[i] = v;
changed = true;
}
}
return changed;
}
/**
* Merges the given frame into this frame (case of a subroutine). The operand stacks are not
* merged, and only the local variables that have not been used by the subroutine are merged.
*
* @param frame a frame. This frame is left unchanged by this method.
* @param localsUsed the local variables that are read or written by the subroutine. The i-th
* element is true if and only if the local variable at index i is read or written by the
* subroutine.
* @return {@literal true} if this frame has been changed as a result of the merge operation, or
* {@literal false} otherwise.
*/
public boolean merge(final Frame frame, final boolean[] localsUsed) {
boolean changed = false;
for (int i = 0; i < numLocals; ++i) {
if (!localsUsed[i] && !values[i].equals(frame.values[i])) {
values[i] = frame.values[i];
changed = true;
}
}
return changed;
}
/**
* Returns a string representation of this frame.
*
* @return a string representation of this frame.
*/
@Override
public String toString() {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < getLocals(); ++i) {
stringBuilder.append(getLocal(i));
}
stringBuilder.append(' ');
for (int i = 0; i < getStackSize(); ++i) {
stringBuilder.append(getStack(i).toString());
}
return stringBuilder.toString();
}
}