/**
* 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;
}
/**
* Verifies that the current state of the local variables array matches the state specified by a
* stack map entry.
*
* @param target the target encapsulating a stack map entry specifying what the current state of
* the local variables array should be
* @param replaceWithTarget if true, then the current state of the local variable array is updated
* to reflect the state recorded in the stack map entry
*/
public void mergeLocals(Target target, boolean replaceWithTarget) {
Klass[] recordedTypes = target.getLocals();
if (recordedTypes.length > localTypes.length) {
throw codeParser.verifyError("size of recorded and derived local variable array differs");
}
/*
* Check the locals
*/
for (int i = 0; i < recordedTypes.length; i++) {
Klass recordedType = recordedTypes[i];
Klass derivedType = localTypes[i];
if (!recordedType.isAssignableFrom(derivedType)) {
/*
* For some reason, the preverifier occasionally generates
* stack map entries for local variables even though the
* local variable is dead. What's more, in these cases,
* it determines that the type resulting from merging an
* object type and an interface type is the interface
* type. This makes no sense to me, but the case must be
* allowed.
*/
if (!recordedType.isInterface() || derivedType.isPrimitive()) {
throw codeParser.verifyError("invalid type in local variable");
}
}
if (replaceWithTarget) {
localTypes[i] = recordedType;
}
}
}
/**
* Emulates loading a value of a given type from a local variable.
*
* @param index the index of the local variable being loaded from
* @param localType the expected type of the variable from which the value is loaded
* @return the variable from which the value is loaded
*/
public Local load(int index, Klass localType) {
verifyLocalVariableIndex(localType, index);
Klass derivedType = localTypes[index];
if (!localType.isAssignableFrom(derivedType)) {
throw codeParser.verifyError("incompatible type in local variable");
}
if (localType.isDoubleWord()) {
Klass secondWordType = Klass.getSecondWordType(localType);
if (!secondWordType.isAssignableFrom(localTypes[index + 1])) {
throw codeParser.verifyError("incompatible type in local variable");
}
}
if (derivedType.isSquawkPrimitive()) {
localType = derivedType;
}
return allocateLocal(localType, index);
}
/**
* Emulates the storing of a value to a local variable.
*
* @param index the index of the local variable being stored to
* @param type the type of the value
* @param local the variable to which the value is stored
*/
public void store(int index, Klass type, Local local) {
Klass localType = local.getType();
Assert.that(localType.isAssignableFrom(type) || localType == getLocalTypeFor(type));
verifyLocalVariableIndex(localType, index);
localTypes[index] = type;
if (localType.isDoubleWord()) {
localTypes[index + 1] = Klass.getSecondWordType(localType);
} else {
verifyUseOfSquawkPrimitive(localType, type);
}
}
/**
* 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;
}
/**
* Merges the current state of the operand stack into the saved state at a control flow target.
* This method also verifies that the current state of the operand stack matches the expected
* state of the operand stack at the target as pecified by a stack map entry.
*
* @param target the target encapsulting the merged state of the operand stack at a distinct
* address
* @param replaceWithTarget if true, then the current state of the operand stack is updated to
* reflect the state recorded in the stack map entry
*/
public void mergeStack(Target target, boolean replaceWithTarget) {
Klass[] recordedTypes = target.getStack();
/*
* Fail if the map sp is different
*/
if (recordedTypes.length != getStackSize()) {
throw codeParser.verifyError("size of recorded and derived stack differs");
}
/*
* Check the stack items
*/
for (int r = 0, d = 0; r < recordedTypes.length; ++r, ++d) {
Klass recordedType = recordedTypes[r];
Klass derivedType = getStackTypeAt(d);
if (!recordedType.isAssignableFrom(derivedType)) {
// Interfaces are treated like java.lang.Object in the verifier according to the CLDC spec.
if (!recordedType.isInterface() || !Klass.OBJECT.isAssignableFrom(derivedType)) {
throw codeParser.verifyError(
"invalid type on operand stack @ "
+ d
+ ": expected "
+ recordedType
+ ", received "
+ derivedType);
}
}
}
/*
* Merge the instructions on the stack
*/
target.merge(this);
if (replaceWithTarget) {
resetStack(target, false);
}
}
