/**
* Pop an address from the address stack, return zero if the stack is empty.
*
* @return The next address in the address stack, or zero if the stack is empty
*/
@Inline
public final ObjectReference pop() {
if (checkDequeue(1)) {
return uncheckedDequeue().toObjectReference();
} else {
return ObjectReference.nullReference();
}
}
/**
* This method is the core method during the trace of the object graph. The role of this method is
* to:
*
* <p>1. Ensure the traced object is not collected. 2. If this is the first visit to the object
* enqueue it to be scanned. 3. Return the forwarded reference to the object.
*
* @param object The object to be traced.
* @return The new reference to the same object instance.
*/
@Inline
public ObjectReference traceObject(ObjectReference object) {
if (Space.isInSpace(Plan.VM_SPACE, object))
return (Plan.SCAN_BOOT_IMAGE) ? object : Plan.vmSpace.traceObject(this, object);
if (Space.isInSpace(Plan.IMMORTAL, object)) return Plan.immortalSpace.traceObject(this, object);
if (Space.isInSpace(Plan.LOS, object)) return Plan.loSpace.traceObject(this, object);
if (Space.isInSpace(Plan.PLOS, object)) return Plan.ploSpace.traceObject(this, object);
if (Plan.USE_CODE_SPACE && Space.isInSpace(Plan.SMALL_CODE, object))
return Plan.smallCodeSpace.traceObject(this, object);
if (Plan.USE_CODE_SPACE && Space.isInSpace(Plan.LARGE_CODE, object))
return Plan.largeCodeSpace.traceObject(this, object);
if (VM.VERIFY_ASSERTIONS)
VM.assertions._assert(false, "No special case for space in traceObject");
return ObjectReference.nullReference();
}