glslang-zig/glslang/MachineIndependent/PoolAlloc.cpp

//
// Copyright (C) 2002-2005  3Dlabs Inc. Ltd.
// All rights reserved.
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//    Redistributions in binary form must reproduce the above
//    copyright notice, this list of conditions and the following
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//    with the distribution.
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//    from this software without specific prior written permission.
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#include "../Include/Common.h"
#include "../Include/PoolAlloc.h"

#include "../Include/InitializeGlobals.h"
#include "../OSDependent/osinclude.h"

namespace glslang {

// Process-wide TLS index
OS_TLSIndex PoolIndex;

// Per-thread structure holding pool pointers.
struct TThreadMemoryPools
{
    TPoolAllocator* threadPoolAllocator; // the current pool
    TPoolAllocator* initialMemoryPool;   // the original pool owned by this thread (this file), to be freed here as well
};

// Return the thread-specific pool pointers.
TThreadMemoryPools* GetThreadMemoryPools()
{
    return static_cast<TThreadMemoryPools*>(OS_GetTLSValue(PoolIndex));
}

// Set the thread-specific pool pointers.
void SetThreadMemoryPools(TThreadMemoryPools* pools)
{
    OS_SetTLSValue(PoolIndex, pools);
}

// Return the thread-specific current pool.
TPoolAllocator& GetThreadPoolAllocator()
{
    return *GetThreadMemoryPools()->threadPoolAllocator;
}

// Set the thread-specific current pool.
void SetThreadPoolAllocator(TPoolAllocator* poolAllocator)
{
    GetThreadMemoryPools()->threadPoolAllocator = poolAllocator;
}

// Process-wide set up of the TLS pool storage.
bool InitializePoolIndex()
{
    // Allocate a TLS index.
    if ((PoolIndex = OS_AllocTLSIndex()) == OS_INVALID_TLS_INDEX)
        return false;

    SetThreadMemoryPools(nullptr);

    return true;
}

// Process-wide tear down of the TLS pool storage.
void FreePoolIndex()
{
    // Release the TLS index.
    OS_FreeTLSIndex(PoolIndex);
}

// Per-thread set up of the memory pools.
void InitializeMemoryPools()
{
    if (GetThreadMemoryPools() == nullptr) {
        SetThreadMemoryPools(new TThreadMemoryPools());
        GetThreadMemoryPools()->initialMemoryPool = new TPoolAllocator();
        SetThreadPoolAllocator(GetThreadMemoryPools()->initialMemoryPool);
    }
}

// Per-thread tear down of the memory pools.
void FreeMemoryPools()
{
    if (GetThreadMemoryPools() != nullptr) {
        if (GetThreadMemoryPools()->initialMemoryPool != nullptr)
            delete GetThreadMemoryPools()->initialMemoryPool;
        delete GetThreadMemoryPools();
        SetThreadMemoryPools(nullptr);
    }
}

//
// Implement the functionality of the TPoolAllocator class, which
// is documented in PoolAlloc.h.
//
TPoolAllocator::TPoolAllocator(int growthIncrement, int allocationAlignment) :
    pageSize(growthIncrement),
    alignment(allocationAlignment),
    freeList(nullptr),
    inUseList(nullptr),
    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;
    }

    push();
}

TPoolAllocator::~TPoolAllocator()
{
    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;
    }
}

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
//
#ifdef GUARD_BLOCKS
void TAllocation::checkGuardBlock(unsigned char* blockMem, unsigned char val, const char* locText) const
#else
void TAllocation::checkGuardBlock(unsigned char*, unsigned char, const char*) const
#endif
{
#ifdef GUARD_BLOCKS
    for (size_t x = 0; x < guardBlockSize; x++) {
        if (blockMem[x] != val) {
            const int maxSize = 80;
            char assertMsg[maxSize];

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

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();
}

} // end namespace glslang