Compiler/PoolAlloc.cpp

//
// Copyright (c) 2002-2010 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#include "PoolAlloc.h"
#include "Common.h"

#include "InitializeGlobals.h"
#include "osinclude.h"

OS_TLSIndex PoolIndex = TLS_OUT_OF_INDEXES;

void InitializeGlobalPools()
{
	TThreadGlobalPools* globalPools= static_cast<TThreadGlobalPools*>(OS_GetTLSValue(PoolIndex));    
	if (globalPools)
		return;

	TPoolAllocator *globalPoolAllocator = new TPoolAllocator(true);

	TThreadGlobalPools* threadData = new TThreadGlobalPools();
	
	threadData->globalPoolAllocator = globalPoolAllocator;
		
	OS_SetTLSValue(PoolIndex, threadData);     
	globalPoolAllocator->push();
}

void FreeGlobalPools()
{
	// Release the allocated memory for this thread.
	TThreadGlobalPools* globalPools= static_cast<TThreadGlobalPools*>(OS_GetTLSValue(PoolIndex));    
	if (!globalPools)
		return;
	
	GlobalPoolAllocator.popAll();
	delete &GlobalPoolAllocator;       
	delete globalPools;
}

bool InitializePoolIndex()
{
	// Allocate a TLS index.
	if ((PoolIndex = OS_AllocTLSIndex()) == OS_INVALID_TLS_INDEX)
		return false;

	return true;
}

void FreePoolIndex()
{
	// Release the TLS index.
	OS_FreeTLSIndex(PoolIndex);
}

TPoolAllocator& GetGlobalPoolAllocator()
{
	TThreadGlobalPools* threadData = static_cast<TThreadGlobalPools*>(OS_GetTLSValue(PoolIndex));

	return *threadData->globalPoolAllocator;
}

void SetGlobalPoolAllocatorPtr(TPoolAllocator* poolAllocator)
{
	TThreadGlobalPools* threadData = static_cast<TThreadGlobalPools*>(OS_GetTLSValue(PoolIndex));

	threadData->globalPoolAllocator = poolAllocator;
}

//
// Implement the functionality of the TPoolAllocator class, which
// is documented in PoolAlloc.h.
//
TPoolAllocator::TPoolAllocator(bool g, int growthIncrement, int allocationAlignment) : 
	global(g),
	pageSize(growthIncrement),
	alignment(allocationAlignment),
	freeList(0),
	inUseList(0),
	numCalls(0)
{
	//
	// Don't allow page sizes we know are smaller than all common
	// OS page sizes.
	//
	if (pageSize < 4*1024)
		pageSize = 4*1024;

	//
	// A large currentPageOffset indicates a new page needs to
	// be obtained to allocate memory.
	//
	currentPageOffset = pageSize;

	//
	// Adjust alignment to be at least pointer aligned and
	// power of 2.
	//
	size_t minAlign = sizeof(void*);
	alignment &= ~(minAlign - 1);
	if (alignment < minAlign)
		alignment = minAlign;
	size_t a = 1;
	while (a < alignment)
		a <<= 1;
	alignment = a;
	alignmentMask = a - 1;

	//
	// Align header skip
	//
	headerSkip = minAlign;
	if (headerSkip < sizeof(tHeader)) {
		headerSkip = (sizeof(tHeader) + alignmentMask) & ~alignmentMask;
	}
}

TPoolAllocator::~TPoolAllocator()
{
	if (!global) {
		//
		// Then we know that this object is not being 
		// allocated after other, globally scoped objects
		// that depend on it.  So we can delete the "in use" memory.
		//
		while (inUseList) {
			tHeader* next = inUseList->nextPage;
			inUseList->~tHeader();
			delete [] reinterpret_cast<char*>(inUseList);
			inUseList = next;
		}
	}

	//
	// Always delete the free list memory - it can't be being
	// (correctly) referenced, whether the pool allocator was
	// global or not.  We should not check the guard blocks
	// here, because we did it already when the block was
	// placed into the free list.
	//
	while (freeList) {
		tHeader* next = freeList->nextPage;
		delete [] reinterpret_cast<char*>(freeList);
		freeList = next;
	}
}

// Support MSVC++ 6.0
const unsigned char TAllocation::guardBlockBeginVal = 0xfb;
const unsigned char TAllocation::guardBlockEndVal   = 0xfe;
const unsigned char TAllocation::userDataFill       = 0xcd;

#   ifdef GUARD_BLOCKS
	const size_t TAllocation::guardBlockSize = 16;
#   else
	const size_t TAllocation::guardBlockSize = 0;
#   endif

//
// Check a single guard block for damage
//
void TAllocation::checkGuardBlock(unsigned char* blockMem, unsigned char val, const char* locText) const
{
	for (size_t x = 0; x < guardBlockSize; x++) {
		if (blockMem[x] != val) {
			char assertMsg[80];

			// We don't print the assert message.  It's here just to be helpful.
			sprintf(assertMsg, "PoolAlloc: Damage %s %lu byte allocation at 0x%p\n",
					locText, size, data());
			assert(0 && "PoolAlloc: Damage in guard block");
		}
	}
}


void TPoolAllocator::push()
{
	tAllocState state = { currentPageOffset, inUseList };

	stack.push_back(state);
		
	//
	// Indicate there is no current page to allocate from.
	//
	currentPageOffset = pageSize;
}

//
// Do a mass-deallocation of all the individual allocations
// that have occurred since the last push(), or since the
// last pop(), or since the object's creation.
//
// The deallocated pages are saved for future allocations.
//
void TPoolAllocator::pop()
{
	if (stack.size() < 1)
		return;

	tHeader* page = stack.back().page;
	currentPageOffset = stack.back().offset;

	while (inUseList != page) {
		// invoke destructor to free allocation list
		inUseList->~tHeader();
		
		tHeader* nextInUse = inUseList->nextPage;
		if (inUseList->pageCount > 1)
			delete [] reinterpret_cast<char*>(inUseList);
		else {
			inUseList->nextPage = freeList;
			freeList = inUseList;
		}
		inUseList = nextInUse;
	}

	stack.pop_back();
}

//
// Do a mass-deallocation of all the individual allocations
// that have occurred.
//
void TPoolAllocator::popAll()
{
	while (stack.size() > 0)
		pop();
}

void* TPoolAllocator::allocate(size_t numBytes)
{
	// If we are using guard blocks, all allocations are bracketed by
	// them: [guardblock][allocation][guardblock].  numBytes is how
	// much memory the caller asked for.  allocationSize is the total
	// size including guard blocks.  In release build,
	// guardBlockSize=0 and this all gets optimized away.
	size_t allocationSize = TAllocation::allocationSize(numBytes);
	
	//
	// Just keep some interesting statistics.
	//
	++numCalls;
	totalBytes += numBytes;

	//
	// Do the allocation, most likely case first, for efficiency.
	// This step could be moved to be inline sometime.
	//
	if (currentPageOffset + allocationSize <= pageSize) {
		//
		// Safe to allocate from currentPageOffset.
		//
		unsigned char* memory = reinterpret_cast<unsigned char *>(inUseList) + currentPageOffset;
		currentPageOffset += allocationSize;
		currentPageOffset = (currentPageOffset + alignmentMask) & ~alignmentMask;

		return initializeAllocation(inUseList, memory, numBytes);
	}

	if (allocationSize + headerSkip > pageSize) {
		//
		// Do a multi-page allocation.  Don't mix these with the others.
		// The OS is efficient and allocating and free-ing multiple pages.
		//
		size_t numBytesToAlloc = allocationSize + headerSkip;
		tHeader* memory = reinterpret_cast<tHeader*>(::new char[numBytesToAlloc]);
		if (memory == 0)
			return 0;

		// Use placement-new to initialize header
		new(memory) tHeader(inUseList, (numBytesToAlloc + pageSize - 1) / pageSize);
		inUseList = memory;

		currentPageOffset = pageSize;  // make next allocation come from a new page

		// No guard blocks for multi-page allocations (yet)
		return reinterpret_cast<void*>(reinterpret_cast<UINT_PTR>(memory) + headerSkip);
	}

	//
	// Need a simple page to allocate from.
	//
	tHeader* memory;
	if (freeList) {
		memory = freeList;
		freeList = freeList->nextPage;
	} else {
		memory = reinterpret_cast<tHeader*>(::new char[pageSize]);
		if (memory == 0)
			return 0;
	}

	// Use placement-new to initialize header
	new(memory) tHeader(inUseList, 1);
	inUseList = memory;
	
	unsigned char* ret = reinterpret_cast<unsigned char *>(inUseList) + headerSkip;
	currentPageOffset = (headerSkip + allocationSize + alignmentMask) & ~alignmentMask;

	return initializeAllocation(inUseList, ret, numBytes);
}


//
// Check all allocations in a list for damage by calling check on each.
//
void TAllocation::checkAllocList() const
{
	for (const TAllocation* alloc = this; alloc != 0; alloc = alloc->prevAlloc)
		alloc->check();
}