// There are some fixups that we can only apply after all the objects are loaded, because
// they involve reference from one object to other objects which may not be available
// during the normal load process. These fixes are applied here
void ObjectMemory::PostLoadFix()
{
// Special case handling for Contexts because we store
// the sp's as integers in the image file, but at
// run-time they are expected to be direct pointers
const OTE* pEnd = m_pOT + m_nOTSize; // Loop invariant
for (OTE* ote = m_pOT; ote < pEnd; ote++)
{
if (!ote->isFree())
{
if (ote->isBytes())
{
#ifdef _DEBUG
{
// Its a byte object, and may be null terminated
const Behavior* behavior = ote->m_oteClass->m_location;
const BytesOTE* oteBytes = reinterpret_cast<const BytesOTE*>(ote);
const VariantByteObject* object = oteBytes->m_location;
ASSERT(behavior->m_instanceSpec.m_nullTerminated == ote->isNullTerminated());
}
#endif
}
else if (ote->m_oteClass == _Pointers.ClassProcess)
{
ASSERT(ote->heapSpace() == OTEFlags::VirtualSpace);
ProcessOTE* oteProcess = reinterpret_cast<ProcessOTE*>(ote);
Process* process = oteProcess->m_location;
process->PostLoadFix(oteProcess);
}
}
}
ProtectConstSpace(PAGE_READONLY);
#if defined(_DEBUG) && 0
{
// Dump out the pointers
TRACESTREAM << NumPointers<< L" VM Pointers..." << std::endl;
for (int i = 0; i < NumPointers; i++)
{
VariantObject* obj = static_cast<VariantObject*>(m_pConstObjs);
POTE pote = POTE(obj->m_fields[i]);
TRACESTREAM << i<< L": " << pote << std::endl;
}
}
#endif
}
void ObjectMemory::EmptyZct()
{
if (m_bIsReconcilingZct)
__debugbreak();
#ifdef _DEBUG
nDeleted = 0;
if (!alwaysReconcileOnAdd || Interpreter::executionTrace)
CHECKREFSNOFIX
else
checkStackRefs();
#endif
// Bump the refs from the stack. Any objects remaining in the ZCT with zero counts
// are truly garbage.
Interpreter::IncStackRefs();
OTE** pZct = m_pZct;
// This tells us that we are in the process of reconcilation
m_bIsReconcilingZct = true;
const int nOldZctEntries = m_nZctEntries;
m_nZctEntries = -1;
for (int i=0;i<nOldZctEntries;i++)
{
OTE* ote = pZct[i];
if (!ote->isFree() && ote->m_flags.m_count == 0)
{
// Note that deallocate cannot make new Zct entries
// Because we have bumped the ref. counts of all stack ref'd objects, only true
// garbage objects can ever have a ref. count of zero. Therefore if recursively
// counting down throws up new zero ref. counts, these should not be added to
// the Zct, but deallocated. To achieve this we set a global flag to indicate
// that we are reconciling, see AddToZct() above.
#ifdef _DEBUG
nDeleted++;
#endif
recursiveFree(ote);
}
}
// CHECKREFSNOFIX
}
// Compact an object by updating all the Oops it contains using the
// forwarding pointers in the old OT.
void ObjectMemory::compactObject(OTE* ote)
{
// We shouldn't come in here unless OTE already fixed for this object
HARDASSERT(ote >= m_pOT && ote < m_pFreePointerList);
// First fix up the class (remember that the new object pointer is stored in the
// old one's object location slot
compactOop(ote->m_oteClass);
if (ote->isPointers())
{
VariantObject* varObj = static_cast<VariantObject*>(ote->m_location);
const MWORD lastPointer = ote->pointersSize();
for (MWORD i = 0; i < lastPointer; i++)
{
// This will get nicely optimised by the Compiler
Oop fieldPointer = varObj->m_fields[i];
// We don't need to visit SmallIntegers and objects we've already visited
if (!isIntegerObject(fieldPointer))
{
OTE* fieldOTE = reinterpret_cast<OTE*>(fieldPointer);
// If pointing at a free'd object ,then it has been moved
if (fieldOTE->isFree())
{
// Should be one of the old OT entries, pointing outside the o
Oop movedTo = reinterpret_cast<Oop>(fieldOTE->m_location);
HARDASSERT(movedTo >= (Oop)m_pOT && movedTo < (Oop)m_pFreePointerList);
// Get the new OTE from the old ...
varObj->m_fields[i] = movedTo;
}
}
}
}
// else, we don't even need to look at the body of byte objects any more
}
template <MWORD ImageNullTerms> HRESULT ObjectMemory::LoadObjects(ibinstream & imageFile, const ImageHeader * pHeader, size_t & cbRead)
{
// Other free OTEs will be threaded in front of the first OTE off the end
// of the currently committed table space. We set the free list pointer
// to that OTE rather than NULL to distinguish attemps to access off the
// end of the current table, which then allows us to dynamically grow it
// on demand
OTE* pEnd = m_pOT + pHeader->nTableSize;
m_pFreePointerList = reinterpret_cast<OTE*>(pEnd);
#ifdef _DEBUG
unsigned numObjects = NumPermanent; // Allow for VM registry, etc!
m_nFreeOTEs = m_nOTSize - pHeader->nTableSize;
#endif
size_t nDataSize = 0;
for (OTE* ote = m_pOT + NumPermanent; ote < pEnd; ote++)
{
if (!ote->isFree())
{
MWORD byteSize = ote->getSize();
MWORD* oldLocation = reinterpret_cast<MWORD*>(ote->m_location);
Object* pBody;
// Allocate space for the object, and copy into that space
if (ote->heapSpace() == OTEFlags::VirtualSpace)
{
MWORD dwMaxAlloc;
if (!imageFile.read(&dwMaxAlloc, sizeof(MWORD)))
return ImageReadError(imageFile);
cbRead += sizeof(MWORD);
pBody = reinterpret_cast<Object*>(AllocateVirtualSpace(dwMaxAlloc, byteSize));
ote->m_location = pBody;
}
else
{
if (ote->isNullTerminated())
{
ASSERT(!ote->isPointers());
pBody = AllocObj(ote, byteSize + NULLTERMSIZE);
if (NULLTERMSIZE > ImageNullTerms)
{
// Ensure we have a full null-terminator
*reinterpret_cast<NULLTERMTYPE*>(static_cast<VariantByteObject*>(pBody)->m_fields+byteSize) = 0;
}
byteSize += ImageNullTerms;
}
else
{
pBody = AllocObj(ote, byteSize);
}
}
markObject(ote);
if (!imageFile.read(pBody, byteSize))
return ImageReadError(imageFile);
cbRead += byteSize;
FixupObject(ote, oldLocation, pHeader);
#ifdef _DEBUG
numObjects++;
#endif
}
else
{
// Thread onto the free list
ote->m_location = (reinterpret_cast<POBJECT>(m_pFreePointerList));
m_pFreePointerList = ote;
#ifdef _DEBUG
m_nFreeOTEs++;
#endif
}
}
// Note that we don't terminate the free list with a null, because
// it must point off into space in order to get a GPF when it
// needs to be expanded (at which point we commit more pages)
#ifdef _DEBUG
ASSERT(numObjects + m_nFreeOTEs == m_nOTSize);
ASSERT(m_nFreeOTEs = CountFreeOTEs());
TRACESTREAM << std::dec << numObjects<< L", " << m_nFreeOTEs<< L" free" << std::endl;
#endif
cbRead += nDataSize;
return S_OK;
}
// Perform a compacting GC
size_t ObjectMemory::compact(Oop* const sp)
{
TRACE("Compacting OT, size %d, free %d, ...\n", m_nOTSize, m_pOT + m_nOTSize - m_pFreePointerList);
EmptyZct(sp);
// First perform a normal GC
reclaimInaccessibleObjects(GCNormal);
Interpreter::freePools();
// Walk the OT from the bottom to locate free entries, and from the top to locate candidates to move
//
size_t moved = 0;
OTE* last = m_pOT + m_nOTSize - 1;
OTE* first = m_pOT;
#pragma warning(push)
#pragma warning(disable : 4127)
while(true)
#pragma warning(pop)
{
// Look for a tail ender
while (last > first && last->isFree())
last--;
// Look for a free slot
while (first < last && !first->isFree())
first++;
if (first == last)
break; // Met in the middle, we're done
HARDASSERT(first->isFree());
HARDASSERT(!last->isFree());
// Copy the tail ender over the free slot
*first = *last;
moved++;
// Leave forwarding pointer in the old slot
last->m_location = reinterpret_cast<POBJECT>(first);
last->beFree();
last->m_count = 0;
// Advance last as we've moved this slot
last--;
}
HARDASSERT(last == first);
// At this point, last == first, and the first free slot will be that after last
TRACE("%d OTEs compacted\n", moved);
// Now we can update the objects using the forwarding pointers in the old slots
// We must remove the const. spaces memory protect for the duration of the pointer update
ProtectConstSpace(PAGE_READWRITE);
// New head of free list is first OTE after the single contiguous block of used OTEs
// Need to set this before compacting as
m_pFreePointerList = last+1;
// Now run through the new OT and update the Oops in the objects
OTE* pOTE = m_pOT;
while (pOTE <= last)
{
compactObject(pOTE);
pOTE++;
}
// Note that this copies VMPointers to cache area
ProtectConstSpace(PAGE_READONLY);
// We must inform the interpreter that it needs to update any cached Oops from the forward pointers
// before we rebuild the free list (which will destroy those pointers to the new OTEs)
Interpreter::OnCompact();
// The last used slot will be the slot before the first entry in the free list
// Using this, round up from the last used slot to the to commit granularity, then uncommit any later slots
//
OTE* end = (OTE*)_ROUND2(reinterpret_cast<ULONG_PTR>(m_pFreePointerList + 1), dwAllocationGranularity);
#ifdef _DEBUG
m_nFreeOTEs = end - m_pFreePointerList;
#endif
SIZE_T bytesToDecommit = reinterpret_cast<ULONG_PTR>(m_pOT + m_nOTSize) - reinterpret_cast<ULONG_PTR>(end);
::VirtualFree(end, bytesToDecommit, MEM_DECOMMIT);
m_nOTSize = end - m_pOT;
// Now fix up the free list
OTE* cur = m_pFreePointerList;
while (cur < end)
{
HARDASSERT(cur->isFree());
cur->m_location = reinterpret_cast<POBJECT>(cur + 1);
cur++;
}
// Could do this before or after check refs, since that can account for Zct state
PopulateZct(sp);
CHECKREFERENCES
HeapCompact();
TRACE("... OT compacted, size %d, free %d.\n", m_nOTSize, end - m_pFreePointerList);
Interpreter::scheduleFinalization();
return m_pFreePointerList - m_pOT;
}