/**
* Pops a value off the operand stack.
*
* @param type the type that the value popped off the operand stack must be assignable to
* @return the instruction that produced the popped value
*/
public StackProducer pop(Klass type) {
StackProducer producer;
if (type.isDoubleWord()) {
if (sp < 2) {
throw codeParser.verifyError("operand stack underflow");
}
if (!isTopDoubleWord()) {
throw codeParser.verifyError("incompatible type on operand stack " + tosKlassName());
}
sp -= 2;
producer = stack[sp];
} else {
if (sp < 1) {
throw codeParser.verifyError("operand stack underflow");
}
if (isTopDoubleWord()) {
throw codeParser.verifyError("incompatible type on operand stack " + tosKlassName());
}
producer = stack[--sp];
/*
* The primitive one-word, non-float types are all assignment compatible with each other
*/
if (type.isPrimitive() && type != Klass.FLOAT) {
type = Klass.INT;
}
}
Assert.that(producer != null);
/*
* Interfaces are treated as java.lang.Object in the verifier.
*/
if (type.isInterface()) {
type = Klass.OBJECT;
}
/*
* Verify that the instruction is producing the correct type.
*/
if (!type.isAssignableFrom(producer.getType())) {
throw codeParser.verifyError(
"incompatible type: '" + type + "' is not assignable from '" + producer.getType() + "'");
}
return producer;
}
/**
* Returns the internal name of the top type on the stack.
*
* @return the name
*/
private String tosKlassName() {
StackProducer top = stack[sp - (isTopDoubleWord() ? 2 : 1)];
if (top == null) {
return "null";
}
return top.getType().getInternalName();
}
/**
* Changes the type of any object in a local variable or on the operand stack whose current type
* is matches <code>fromType</code> to be <code>toType</code>.
*/
public void replaceTypeWithType(Klass fromType, Klass toType) {
for (int i = 0; i < localTypes.length; i++) {
if (localTypes[i] == fromType) {
localTypes[i] = toType;
}
}
for (int i = 0; i < sp; i++) {
StackProducer producer = stack[i];
if (producer != null && producer.getType() == fromType) {
producer.updateType(toType);
}
}
}
/**
* Determines if the operand stack or local variable array currently contains an entry whose type
* is equal to or a subtype of a given type.
*
* @param type the type to search for
* @return true if an entry was found
*/
public boolean containsType(Klass type) {
for (int i = 0; i < localTypes.length; i++) {
if (type.isAssignableFrom(localTypes[i])) {
return true;
}
}
for (int i = 0; i < sp; i++) {
StackProducer producer = stack[i];
if (producer != null && type.isAssignableFrom(producer.getType())) {
return true;
}
}
return false;
}
/**
* Pushes a value to the operand stack.
*
* @param producer the instruction producing the value being pushed
*/
public void push(StackProducer producer) {
Klass type = producer.getType();
Assert.that(type != Klass.VOID);
/*
* Check for overflow and push the producer.
*/
if (sp == maxStack) {
throw codeParser.verifyError("operand stack overflow");
}
stack[sp++] = producer;
/*
* For long and double check for overflow and then add a null word to the stack.
*/
if (type.isDoubleWord()) {
if (sp == maxStack) {
throw codeParser.verifyError("operand stack overflow");
}
stack[sp++] = null;
}
}
/**
* Allocate local that is used for spilling.
*
* @param producer the instruction producing the value that needs to be spilled
* @return a unique local to be used to hold the value
*/
public Local allocateLocalForSpill(StackProducer producer) {
Klass type = getLocalTypeFor(producer.getType());
return new Local(type, --nextSpillLocalId, false);
}