C++ MM_GCExtensionsBase::getObjectAlignmentInBytes方法代码示例

void
MM_CollectorLanguageInterfaceImpl::scavenger_fixupDestroyedSlot(MM_EnvironmentBase *env, MM_ForwardedHeader *forwardedHeader, MM_MemorySubSpaceSemiSpace *subSpaceNew)
{
	/* This method must be implemented if (and only if) the object header is stored in a compressed slot. in that
	 * case the other half of the full (omrobjectptr_t sized) slot may hold a compressed object reference that
	 * must be restored by this method.
	 */
	/* This assumes that all slots are object slots, including the slot adjacent to the header slot */
	if ((0 != forwardedHeader->getPreservedOverlap()) && !_extensions->objectModel.isIndexable(forwardedHeader)) {
		MM_GCExtensionsBase *extensions = MM_GCExtensionsBase::getExtensions(_omrVM);
		/* Get the uncompressed reference from the slot */
		fomrobject_t preservedOverlap = (fomrobject_t)forwardedHeader->getPreservedOverlap();
		GC_SlotObject preservedSlotObject(_omrVM, &preservedOverlap);
		omrobjectptr_t survivingCopyAddress = preservedSlotObject.readReferenceFromSlot();
		/* Check if the address we want to read is aligned (since mis-aligned reads may still be less than a top address but extend beyond it) */
		if (0 == ((uintptr_t)survivingCopyAddress & (extensions->getObjectAlignmentInBytes() - 1))) {
			/* Ensure that the address we want to read is within part of the heap which could contain copied objects (tenure or survivor) */
			void *topOfObject = (void *)((uintptr_t *)survivingCopyAddress + 1);
			if (subSpaceNew->isObjectInNewSpace(survivingCopyAddress, topOfObject) || extensions->isOld(survivingCopyAddress, topOfObject)) {
				/* if the slot points to a reverse-forwarded object, restore the original location (in evacuate space) */
				MM_ForwardedHeader reverseForwardedHeader(survivingCopyAddress);
				if (reverseForwardedHeader.isReverseForwardedPointer()) {
					/* overlapped slot must be fixed up */
					fomrobject_t fixupSlot = 0;
					GC_SlotObject fixupSlotObject(_omrVM, &fixupSlot);
					fixupSlotObject.writeReferenceToSlot(reverseForwardedHeader.getReverseForwardedPointer());
					forwardedHeader->restoreDestroyedOverlap((uint32_t)fixupSlot);
				}
			}
		}
	}
}

	MMINLINE bool
	isValidObject(omrobjectptr_t objectPtr)
	{
		bool shouldCheck = isCommittedHeapObject(objectPtr) && OMR_ARE_NO_BITS_SET((uintptr_t)objectPtr, _extensions->getObjectAlignmentInBytes() - 1);
		if (shouldCheck) {
			return _objectMap->isBitSet(objectPtr);
		}
		/* Everything else is not a valid object. */
		return false;
	}