// static
bool RedhawkGCInterface::InitializeSubsystems(GCType gcType)
{
g_pConfig->Construct();
#ifdef FEATURE_ETW
MICROSOFT_WINDOWS_REDHAWK_GC_PRIVATE_PROVIDER_Context.IsEnabled = FALSE;
MICROSOFT_WINDOWS_REDHAWK_GC_PUBLIC_PROVIDER_Context.IsEnabled = FALSE;
// Register the Redhawk event provider with the system.
RH_ETW_REGISTER_Microsoft_Windows_Redhawk_GC_Private();
RH_ETW_REGISTER_Microsoft_Windows_Redhawk_GC_Public();
MICROSOFT_WINDOWS_REDHAWK_GC_PRIVATE_PROVIDER_Context.RegistrationHandle = Microsoft_Windows_Redhawk_GC_PrivateHandle;
MICROSOFT_WINDOWS_REDHAWK_GC_PUBLIC_PROVIDER_Context.RegistrationHandle = Microsoft_Windows_Redhawk_GC_PublicHandle;
#endif // FEATURE_ETW
if (!InitializeSystemInfo())
{
return false;
}
// Initialize the special EEType used to mark free list entries in the GC heap.
g_FreeObjectEEType.InitializeAsGcFreeType();
// Place the pointer to this type in a global cell (typed as the structurally equivalent MethodTable
// that the GC understands).
g_pFreeObjectMethodTable = (MethodTable *)&g_FreeObjectEEType;
g_pFreeObjectEEType = &g_FreeObjectEEType;
if (!g_SuspendEELock.InitNoThrow(CrstSuspendEE))
return false;
// Set the GC heap type.
bool fUseServerGC = (gcType == GCType_Server);
GCHeap::InitializeHeapType(fUseServerGC);
// Create the GC heap itself.
GCHeap *pGCHeap = GCHeap::CreateGCHeap();
if (!pGCHeap)
return false;
// Initialize the GC subsystem.
HRESULT hr = pGCHeap->Initialize();
if (FAILED(hr))
return false;
if (!FinalizerThread::Initialize())
return false;
// Initialize HandleTable.
if (!Ref_Initialize())
return false;
return true;
}
void SystemDelete(void *p)
{
#ifdef MMGC_MEMORY_PROFILER
if (p) {
// heap can be NULL during OOM shutdown
GCHeap* heap = GCHeap::GetGCHeap();
if (heap)
heap->TrackSystemFree(p);
}
#endif
VMPI_free(p);
}
// Block the current thread until at least one object needs to be finalized (returns true) or memory is low
// (returns false and the finalizer thread should initiate a garbage collection).
EXTERN_C REDHAWK_API UInt32_BOOL __cdecl RhpWaitForFinalizerRequest()
{
// We can wait for two events; finalization queue has been populated and low memory resource notification.
// But if the latter is signalled we shouldn't wait on it again immediately -- if the garbage collection
// the finalizer thread initiates as a result is not sufficient to remove the low memory condition the
// event will still be signalled and we'll end up looping doing cpu intensive collections, which won't
// help the situation at all and could make it worse. So we remember whether the last event we reported
// was low memory and if so we'll wait at least two seconds (the CLR value) on just a finalization
// request.
static bool fLastEventWasLowMemory = false;
GCHeap * pHeap = GCHeap::GetGCHeap();
// Wait in a loop because we may have to retry if we decide to only wait for finalization events but the
// two second timeout expires.
do
{
HANDLE lowMemEvent = NULL;
#if 0 // TODO: hook up low memory notification
lowMemEvent = pHeap->GetLowMemoryNotificationEvent();
#endif // 0
HANDLE rgWaitHandles[] = { FinalizerThread::GetFinalizerEvent(), lowMemEvent };
UInt32 cWaitHandles = (fLastEventWasLowMemory || (lowMemEvent == NULL)) ? 1 : 2;
UInt32 uTimeout = fLastEventWasLowMemory ? 2000 : INFINITE;
UInt32 uResult = PalWaitForMultipleObjectsEx(cWaitHandles, rgWaitHandles, FALSE, uTimeout, FALSE);
switch (uResult)
{
case WAIT_OBJECT_0:
// At least one object is ready for finalization.
return TRUE;
case WAIT_OBJECT_0 + 1:
// Memory is low, tell the finalizer thread to garbage collect.
ASSERT(!fLastEventWasLowMemory);
fLastEventWasLowMemory = true;
return FALSE;
case WAIT_TIMEOUT:
// We were waiting only for finalization events but didn't get one within the timeout period. Go
// back to waiting for any event.
ASSERT(fLastEventWasLowMemory);
fLastEventWasLowMemory = false;
break;
default:
ASSERT(!"Unexpected PalWaitForMultipleObjectsEx() result");
return FALSE;
}
} while (true);
}
void AttachSampler(avmplus::Sampler* sampler)
{
GCHeap* heap = GCHeap::GetGCHeap(); // May be NULL during OOM shutdown
if (heap)
{
EnterFrame* ef = heap->GetEnterFrame();
if (ef)
{
GC* gc = ef->GetActiveGC();
if (gc)
gc->SetAttachedSampler(sampler);
}
}
}
avmplus::Sampler* GetSampler()
{
GCHeap* heap = GCHeap::GetGCHeap(); // May be NULL during OOM shutdown
if (heap)
{
EnterFrame* ef = heap->GetEnterFrame();
if (ef)
{
GC* gc = ef->GetActiveGC();
if (gc)
return (avmplus::Sampler*)gc->GetAttachedSampler();
}
}
return NULL;
}
// Need to know the maximum segment size for both the normal GC heap and the
// large object heap, as well as the top user-accessible address within the
// address space (ie, theoretically 2^31 - 1 on a 32 bit machine, but a tad
// lower in practice). This will help out with 32 bit machines running in
// 3 GB mode.
FCIMPL2(void, COMMemoryFailPoint::GetMemorySettings, UINT64* pMaxGCSegmentSize, UINT64* pTopOfMemory)
{
FCALL_CONTRACT;
GCHeap * pGC = GCHeap::GetGCHeap();
size_t segment_size = pGC->GetValidSegmentSize(FALSE);
size_t large_segment_size = pGC->GetValidSegmentSize(TRUE);
_ASSERTE(segment_size < SIZE_T_MAX && large_segment_size < SIZE_T_MAX);
if (segment_size > large_segment_size)
*pMaxGCSegmentSize = (UINT64) segment_size;
else
*pMaxGCSegmentSize = (UINT64) large_segment_size;
// GetTopMemoryAddress returns a void*, which can't be cast
// directly to a UINT64 without causing an error from GCC.
void * topOfMem = GetTopMemoryAddress();
*pTopOfMemory = (UINT64) (size_t) topOfMem;
}
void GCLargeAlloc::Free(const void *item)
{
LargeBlock *b = GetLargeBlock(item);
#ifdef GCDEBUG
// RCObject have contract that they must clean themselves, since they
// have to scan themselves to decrement other RCObjects they might as well
// clean themselves too, better than suffering a memset later
if(b->rcobject)
m_gc->RCObjectZeroCheck((RCObject*)GetUserPointer(item));
#endif
// We can't allow free'ing something during Sweeping, otherwise alloc counters
// get decremented twice and destructors will be called twice.
GCAssert(m_gc->collecting == false || m_gc->marking == true);
if (m_gc->marking && (m_gc->collecting || IsProtectedAgainstFree(b))) {
m_gc->AbortFree(GetUserPointer(item));
return;
}
m_gc->policy.signalFreeWork(b->size);
#ifdef MMGC_HOOKS
GCHeap* heap = GCHeap::GetGCHeap();
if(heap->HooksEnabled())
{
const void* p = GetUserPointer(item);
size_t userSize = GC::Size(p);
#ifdef MMGC_MEMORY_PROFILER
if(heap->GetProfiler())
m_totalAskSize -= heap->GetProfiler()->GetAskSize(p);
#endif
heap->FinalizeHook(p, userSize);
heap->FreeHook(p, userSize, uint8_t(GCHeap::GCFreedPoison));
}
#endif
if(b->flags[0] & kHasWeakRef)
m_gc->ClearWeakRef(GetUserPointer(item));
LargeBlock **prev = &m_blocks;
while(*prev)
{
if(b == *prev)
{
*prev = Next(b);
size_t numBlocks = b->GetNumBlocks();
m_totalAllocatedBytes -= b->size;
VALGRIND_MEMPOOL_FREE(b, b);
VALGRIND_MEMPOOL_FREE(b, item);
VALGRIND_DESTROY_MEMPOOL(b);
m_gc->FreeBlock(b, (uint32_t)numBlocks, m_partitionIndex);
return;
}
prev = (LargeBlock**)(&(*prev)->next);
}
GCAssertMsg(false, "Bad free!");
}
void *SystemNew(size_t size, FixedMallocOpts opts)
{
void *space = VMPI_alloc(size);
if (space == NULL)
{
if (opts & MMgc::kCanFail)
return NULL;
int attempt = 0;
do {
GCHeap::GetGCHeap()->SystemOOMEvent(size, attempt++);
space = VMPI_alloc(size);
} while (space == NULL);
}
#ifdef MMGC_MEMORY_PROFILER
GCHeap* heap = GCHeap::GetGCHeap();
if (heap)
heap->TrackSystemAlloc(space, size);
#endif
if (opts & MMgc::kZero)
VMPI_memset(space, 0, size);
return space;
}
/* static */
void GCAlloc::Free(const void *item)
{
GCBlock *b = GetBlock(item);
GCAlloc *a = b->alloc;
#ifdef MMGC_HOOKS
GCHeap* heap = GCHeap::GetGCHeap();
if(heap->HooksEnabled())
{
const void* p = GetUserPointer(item);
size_t userSize = GC::Size(p);
#ifdef MMGC_MEMORY_PROFILER
if(heap->GetProfiler())
a->m_totalAskSize -= heap->GetProfiler()->GetAskSize(p);
#endif
heap->FinalizeHook(p, userSize);
heap->FreeHook(p, userSize, 0xca);
}
#endif
#ifdef _DEBUG
// check that its not already been freed
void *free = b->firstFree;
while(free) {
GCAssert(free != item);
free = *((void**) free);
}
#endif
int index = GetIndex(b, item);
if(GetBit(b, index, kHasWeakRef)) {
b->gc->ClearWeakRef(GetUserPointer(item));
}
bool wasFull = b->IsFull();
if(b->needsSweeping) {
#ifdef _DEBUG
bool gone =
#endif
a->Sweep(b);
GCAssertMsg(!gone, "How can a page I'm about to free an item on be empty?");
wasFull = false;
}
if(wasFull) {
a->AddToFreeList(b);
}
b->FreeItem(item, index);
if(b->numItems == 0) {
a->UnlinkChunk(b);
a->FreeChunk(b);
}
}
/*static*/
void FixedAlloc::Free(void *item)
{
FixedBlock *b = (FixedBlock*) ((uintptr_t)item & ~0xFFF);
GCAssertMsg(b->alloc->m_heap->IsAddressInHeap(item), "Bogus pointer passed to free");
#ifdef MMGC_HOOKS
GCHeap *heap = b->alloc->m_heap;
if(heap->HooksEnabled()) {
#ifdef MMGC_MEMORY_PROFILER
if(heap->GetProfiler())
b->alloc->m_totalAskSize -= heap->GetProfiler()->GetAskSize(item);
#endif
heap->FinalizeHook(item, b->size - DebugSize());
heap->FreeHook(item, b->size - DebugSize(), 0xed);
}
#endif
item = GetRealPointer(item);
// Add this item to the free list
*((void**)item) = b->firstFree;
b->firstFree = item;
// We were full but now we have a free spot, add us to the free block list.
if (b->numAlloc == b->alloc->m_itemsPerBlock)
{
GCAssert(!b->nextFree && !b->prevFree);
b->nextFree = b->alloc->m_firstFree;
if (b->alloc->m_firstFree)
b->alloc->m_firstFree->prevFree = b;
b->alloc->m_firstFree = b;
}
#ifdef _DEBUG
else // we should already be on the free list
{
GCAssert ((b == b->alloc->m_firstFree) || b->prevFree);
}
#endif
b->numAlloc--;
if(b->numAlloc == 0) {
b->alloc->FreeChunk(b);
}
}
int main(int argc, char* argv[])
{
//
// Initialize system info
//
InitializeSystemInfo();
//
// Initialize free object methodtable. The GC uses a special array-like methodtable as placeholder
// for collected free space.
//
static MethodTable freeObjectMT;
freeObjectMT.InitializeFreeObject();
g_pFreeObjectMethodTable = &freeObjectMT;
//
// Initialize handle table
//
if (!Ref_Initialize())
return -1;
//
// Initialize GC heap
//
GCHeap *pGCHeap = GCHeap::CreateGCHeap();
if (!pGCHeap)
return -1;
if (FAILED(pGCHeap->Initialize()))
return -1;
//
// Initialize current thread
//
ThreadStore::AttachCurrentThread(false);
//
// Create a Methodtable with GCDesc
//
class My : Object {
public:
Object * m_pOther1;
int dummy_inbetween;
Object * m_pOther2;
};
static struct My_MethodTable
{
// GCDesc
CGCDescSeries m_series[2];
size_t m_numSeries;
// The actual methodtable
MethodTable m_MT;
}
My_MethodTable;
// 'My' contains the MethodTable*
size_t baseSize = sizeof(My);
// GC expects the size of ObjHeader (extra void*) to be included in the size.
baseSize = baseSize + sizeof(ObjHeader);
// Add padding as necessary. GC requires the object size to be at least MIN_OBJECT_SIZE.
My_MethodTable.m_MT.m_baseSize = max(baseSize, MIN_OBJECT_SIZE);
My_MethodTable.m_MT.m_componentSize = 0; // Array component size
My_MethodTable.m_MT.m_flags = MTFlag_ContainsPointers;
My_MethodTable.m_numSeries = 2;
// The GC walks the series backwards. It expects the offsets to be sorted in descending order.
My_MethodTable.m_series[0].SetSeriesOffset(offsetof(My, m_pOther2));
My_MethodTable.m_series[0].SetSeriesCount(1);
My_MethodTable.m_series[0].seriessize -= My_MethodTable.m_MT.m_baseSize;
My_MethodTable.m_series[1].SetSeriesOffset(offsetof(My, m_pOther1));
My_MethodTable.m_series[1].SetSeriesCount(1);
My_MethodTable.m_series[1].seriessize -= My_MethodTable.m_MT.m_baseSize;
MethodTable * pMyMethodTable = &My_MethodTable.m_MT;
// Allocate instance of MyObject
Object * pObj = AllocateObject(pMyMethodTable);
if (pObj == NULL)
return -1;
// Create strong handle and store the object into it
OBJECTHANDLE oh = CreateGlobalHandle(pObj);
if (oh == NULL)
return -1;
for (int i = 0; i < 1000000; i++)
{
Object * pBefore = ((My *)ObjectFromHandle(oh))->m_pOther1;
// Allocate more instances of the same object
Object * p = AllocateObject(pMyMethodTable);
if (p == NULL)
return -1;
Object * pAfter = ((My *)ObjectFromHandle(oh))->m_pOther1;
// Uncomment this assert to see how GC triggered inside AllocateObject moved objects around
// assert(pBefore == pAfter);
// Store the newly allocated object into a field using WriteBarrier
WriteBarrier(&(((My *)ObjectFromHandle(oh))->m_pOther1), p);
}
// Create weak handle that points to our object
OBJECTHANDLE ohWeak = CreateGlobalWeakHandle(ObjectFromHandle(oh));
if (ohWeak == NULL)
return -1;
// Destroy the strong handle so that nothing will be keeping out object alive
DestroyGlobalHandle(oh);
// Explicitly trigger full GC
pGCHeap->GarbageCollect();
// Verify that the weak handle got cleared by the GC
assert(ObjectFromHandle(ohWeak) == NULL);
printf("Done\n");
return 0;
}
GCAlloc::GCBlock* GCAlloc::CreateChunk(int flags)
{
// Too many definitions of kBlockSize, make sure they're at least in sync.
GCAssert(uint32_t(kBlockSize) == GCHeap::kBlockSize);
// Get bitmap space; this may trigger OOM handling.
gcbits_t* bits = m_bitsInPage ? NULL : (gcbits_t*)m_gc->AllocBits(m_numBitmapBytes, m_sizeClassIndex);
// Allocate a new block; this may trigger OOM handling (though that
// won't affect the bitmap space, which is not GC'd individually).
GCBlock* b = (GCBlock*) m_gc->AllocBlock(1, PageMap::kGCAllocPage, /*zero*/true, (flags&GC::kCanFail) != 0);
if (b)
{
VALGRIND_CREATE_MEMPOOL(b, 0/*redZoneSize*/, 1/*zeroed*/);
// treat block header as a separate allocation
VALGRIND_MEMPOOL_ALLOC(b, b, sizeof(GCBlock));
b->gc = m_gc;
b->alloc = this;
b->size = m_itemSize;
b->slowFlags = 0;
if(m_gc->collecting && m_finalized)
b->finalizeState = m_gc->finalizedValue;
else
b->finalizeState = !m_gc->finalizedValue;
b->bibopTag = m_bibopTag;
#ifdef MMGC_FASTBITS
b->bitsShift = (uint8_t) m_bitsShift;
#endif
b->containsPointers = ContainsPointers();
b->rcobject = ContainsRCObjects();
if (m_bitsInPage)
b->bits = (gcbits_t*)b + sizeof(GCBlock);
else
b->bits = bits;
// ditto for in page bits
if (m_bitsInPage) {
VALGRIND_MEMPOOL_ALLOC(b, b->bits, m_numBitmapBytes);
}
// Link the block at the end of the list
b->prev = m_lastBlock;
b->next = 0;
if (m_lastBlock) {
m_lastBlock->next = b;
}
if (!m_firstBlock) {
m_firstBlock = b;
}
m_lastBlock = b;
// Add our new ChunkBlock to the firstFree list (which should be empty)
if (m_firstFree)
{
GCAssert(m_firstFree->prevFree == 0);
m_firstFree->prevFree = b;
}
b->nextFree = m_firstFree;
b->prevFree = 0;
m_firstFree = b;
// calculate back from end (better alignment, no dead space at end)
b->items = (char*)b+GCHeap::kBlockSize - m_itemsPerBlock * m_itemSize;
b->numFree = (short)m_itemsPerBlock;
// explode the new block onto its free list
//
// We must make the object look free, which means poisoning it properly and setting
// the mark bits correctly.
b->firstFree = b->items;
void** p = (void**)(void*)b->items;
int limit = m_itemsPerBlock-1;
#ifdef MMGC_HOOKS
GCHeap* heap = GCHeap::GetGCHeap();
#endif
for ( int i=0 ; i < limit ; i++ ) {
#ifdef MMGC_HOOKS
#ifdef MMGC_MEMORY_INFO // DebugSize is 0 if MEMORY_INFO is off, so we get an "obviously true" warning from GCC.
GCAssert(m_itemSize >= DebugSize());
#endif
if(heap->HooksEnabled())
heap->PseudoFreeHook(GetUserPointer(p), m_itemSize - DebugSize(), uint8_t(GCHeap::GCSweptPoison));
#endif
p = FLSeed(p, (char*)p + m_itemSize);
}
#ifdef MMGC_HOOKS
if(heap->HooksEnabled())
heap->PseudoFreeHook(GetUserPointer(p), m_itemSize - DebugSize(), uint8_t(GCHeap::GCSweptPoison));
#endif
p[0] = NULL;
// Set all the mark bits to 'free'
GCAssert(sizeof(gcbits_t) == 1);
GCAssert(kFreelist == 3);
GCAssert(m_numBitmapBytes % 4 == 0);
uint32_t *pbits = (uint32_t*)(void *)b->bits;
for(int i=0, n=m_numBitmapBytes>>2; i < n; i++)
pbits[i] = 0x03030303;
#ifdef MMGC_MEMORY_INFO
VerifyFreeBlockIntegrity(b->firstFree, m_itemSize);
#endif
}
else {
if (bits)
void* GCLargeAlloc::Alloc(size_t requestSize, int flags)
#endif
{
#ifdef DEBUG
m_gc->heap->CheckForOOMAbortAllocation();
#endif
GCHeap::CheckForAllocSizeOverflow(requestSize, sizeof(LargeBlock)+GCHeap::kBlockSize);
int blocks = (int)((requestSize+sizeof(LargeBlock)+GCHeap::kBlockSize-1) / GCHeap::kBlockSize);
uint32_t computedSize = blocks*GCHeap::kBlockSize - sizeof(LargeBlock);
// Allocation must be signalled before we allocate because no GC work must be allowed to
// come between an allocation and an initialization - if it does, we may crash, as
// GCFinalizedObject subclasses may not have a valid vtable, but the GC depends on them
// having it. In principle we could signal allocation late but only set the object
// flags after signaling, but we might still cause trouble for the profiler, which also
// depends on non-interruptibility.
m_gc->SignalAllocWork(computedSize);
// Pointer containing memory is always zeroed (see bug 594533).
if((flags&GC::kContainsPointers) != 0)
flags |= GC::kZero;
LargeBlock *block = (LargeBlock*) m_gc->AllocBlock(blocks, PageMap::kGCLargeAllocPageFirst,
(flags&GC::kZero) != 0, (flags&GC::kCanFail) != 0);
void *item = NULL;
if (block)
{
// Code below uses these optimizations
GCAssert((unsigned long)GC::kFinalize == (unsigned long)kFinalizable);
GCAssert((unsigned long)GC::kInternalExact == (unsigned long)kVirtualGCTrace);
gcbits_t flagbits0 = 0;
gcbits_t flagbits1 = 0;
#if defined VMCFG_EXACT_TRACING
flagbits0 = (flags & (GC::kFinalize|GC::kInternalExact));
#elif defined VMCFG_SELECTABLE_EXACT_TRACING
flagbits0 = (flags & (GC::kFinalize|m_gc->runtimeSelectableExactnessFlag)); // 0 or GC::kInternalExact
#else
flagbits0 = (flags & GC::kFinalize);
#endif
VALGRIND_CREATE_MEMPOOL(block, /*rdzone*/0, (flags&GC::kZero) != 0);
VALGRIND_MEMPOOL_ALLOC(block, block, sizeof(LargeBlock));
block->gc = this->m_gc;
block->alloc= this;
block->next = m_blocks;
block->size = computedSize;
block->bibopTag = 0;
#ifdef MMGC_FASTBITS
block->bitsShift = 12; // Always use bits[0]
#endif
block->containsPointers = ((flags&GC::kContainsPointers) != 0) ? 1 : 0;
block->rcobject = ((flags&GC::kRCObject) != 0) ? 1 : 0;
block->bits = block->flags;
m_blocks = block;
item = block->GetObject();
if(m_gc->collecting && !m_startedFinalize)
flagbits0 |= kMark;
block->flags[0] = flagbits0;
block->flags[1] = flagbits1;
#ifdef _DEBUG
(void)originalSize;
if (flags & GC::kZero)
{
if (!RUNNING_ON_VALGRIND)
{
// AllocBlock should take care of this
for(int i=0, n=(int)(requestSize/sizeof(int)); i<n; i++) {
if(((int*)item)[i] != 0)
GCAssert(false);
}
}
}
#endif
// see comments in GCAlloc about using full size instead of ask size
VALGRIND_MEMPOOL_ALLOC(block, item, computedSize);
#ifdef MMGC_HOOKS
GCHeap* heap = GCHeap::GetGCHeap();
if(heap->HooksEnabled()) {
size_t userSize = block->size - DebugSize();
#ifdef MMGC_MEMORY_PROFILER
m_totalAskSize += originalSize;
heap->AllocHook(GetUserPointer(item), originalSize, userSize, /*managed=*/true);
#else
heap->AllocHook(GetUserPointer(item), 0, userSize, /*managed=*/true);
#endif
}
#endif
}
return item;
}
void* GCAlloc::Alloc(int flags)
#endif
{
GCAssertMsg(((size_t)m_itemSize >= size), "allocator itemsize too small");
// Allocation must be signalled before we allocate because no GC work must be allowed to
// come between an allocation and an initialization - if it does, we may crash, as
// GCFinalizedObject subclasses may not have a valid vtable, but the GC depends on them
// having it. In principle we could signal allocation late but only set the object
// flags after signaling, but we might still cause trouble for the profiler, which also
// depends on non-interruptibility.
m_gc->SignalAllocWork(m_itemSize);
GCBlock* b = m_firstFree;
start:
if (b == NULL) {
if (m_needsSweeping && !m_gc->collecting) {
Sweep(m_needsSweeping);
b = m_firstFree;
goto start;
}
bool canFail = (flags & GC::kCanFail) != 0;
CreateChunk(canFail);
b = m_firstFree;
if (b == NULL) {
GCAssert(canFail);
return NULL;
}
}
GCAssert(!b->needsSweeping);
GCAssert(b == m_firstFree);
GCAssert(b && !b->IsFull());
void *item;
if(b->firstFree) {
item = b->firstFree;
b->firstFree = *((void**)item);
// clear free list pointer, the rest was zero'd in free
*(intptr_t*) item = 0;
#ifdef MMGC_MEMORY_INFO
//check for writes on deleted memory
VerifyFreeBlockIntegrity(item, b->size);
#endif
} else {
item = b->nextItem;
if(((uintptr_t)((char*)item + b->size) & 0xfff) != 0) {
b->nextItem = (char*)item + b->size;
} else {
b->nextItem = NULL;
}
}
// set up bits, items start out white and whether they need finalization
// is determined by the caller
// make sure we ended up in the right place
GCAssert(((flags&GC::kContainsPointers) != 0) == ContainsPointers());
// this assumes what we assert
GCAssert((unsigned long)GC::kFinalize == (unsigned long)GCAlloc::kFinalize);
int index = GetIndex(b, item);
GCAssert(index >= 0);
Clear4BitsAndSet(b, index, flags & kFinalize);
b->numItems++;
#ifdef MMGC_MEMORY_INFO
m_numAlloc++;
#endif
// If we're out of free items, be sure to remove ourselves from the
// list of blocks with free items. TODO Minor optimization: when we
// carve an item off the end of the block, we don't need to check here
// unless we just set b->nextItem to NULL.
if (b->IsFull()) {
m_firstFree = b->nextFree;
b->nextFree = NULL;
GCAssert(b->prevFree == NULL);
if (m_firstFree)
m_firstFree->prevFree = 0;
}
// prevent mid-collection (ie destructor) allocations on un-swept pages from
// getting swept. If the page is finalized and doesn't need sweeping we don't want
// to set the mark otherwise it will be marked when we start the next marking phase
// and write barriers won't fire (since its black)
if(m_gc->collecting)
{
if((b->finalizeState != m_gc->finalizedValue) || b->needsSweeping)
SetBit(b, index, kMark);
}
GCAssert((uintptr_t(item) & ~0xfff) == (uintptr_t) b);
GCAssert((uintptr_t(item) & 7) == 0);
#ifdef MMGC_HOOKS
GCHeap* heap = GCHeap::GetGCHeap();
if(heap->HooksEnabled())
{
size_t userSize = m_itemSize - DebugSize();
#ifdef MMGC_MEMORY_PROFILER
m_totalAskSize += size;
heap->AllocHook(GetUserPointer(item), size, userSize);
#else
heap->AllocHook(GetUserPointer(item), 0, userSize);
#endif
}
#endif
return item;
}
