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/*
* Copyright (C) 2008 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ExecutableAllocator_h
#define ExecutableAllocator_h
#if ENABLE(ASSEMBLER)
#include <wtf/Assertions.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefCounted.h>
#include <wtf/Vector.h>
#include <limits>
#define JIT_ALLOCATOR_PAGE_SIZE (ExecutableAllocator::pageSize)
#define JIT_ALLOCATOR_LARGE_ALLOC_SIZE (ExecutableAllocator::pageSize * 4)
namespace JSC {
class ExecutablePool : public RefCounted<ExecutablePool> {
private:
struct Allocation {
char* pages;
size_t size;
};
typedef Vector<Allocation, 2> AllocationList;
public:
static PassRefPtr<ExecutablePool> create(size_t n)
{
return adoptRef(new ExecutablePool(n));
}
void* alloc(size_t n)
{
ASSERT(m_freePtr <= m_end);
// Round 'n' up to a multiple of word size; if all allocations are of
// word sized quantities, then all subsequent allocations will be aligned.
n = roundUpAllocationSize(n, sizeof(void*));
if (static_cast<ptrdiff_t>(n) < (m_end - m_freePtr)) {
void* result = m_freePtr;
m_freePtr += n;
return result;
}
// Insufficient space to allocate in the existing pool
// so we need allocate into a new pool
return poolAllocate(n);
}
~ExecutablePool()
{
AllocationList::const_iterator end = m_pools.end();
for (AllocationList::const_iterator ptr = m_pools.begin(); ptr != end; ++ptr)
ExecutablePool::systemRelease(*ptr);
}
size_t available() const { return (m_pools.size() > 1) ? 0 : m_end - m_freePtr; }
private:
static Allocation systemAlloc(size_t n);
static void systemRelease(const Allocation& alloc);
inline size_t roundUpAllocationSize(size_t request, size_t granularity)
{
if ((std::numeric_limits<size_t>::max() - granularity) <= request)
CRASH(); // Allocation is too large
// Round up to next page boundary
size_t size = request + (granularity - 1);
size = size & ~(granularity - 1);
ASSERT(size >= request);
return size;
}
ExecutablePool(size_t n);
void* poolAllocate(size_t n);
char* m_freePtr;
char* m_end;
AllocationList m_pools;
};
class ExecutableAllocator {
public:
static size_t pageSize;
ExecutableAllocator()
{
if (!pageSize)
intializePageSize();
m_smallAllocationPool = ExecutablePool::create(JIT_ALLOCATOR_LARGE_ALLOC_SIZE);
}
PassRefPtr<ExecutablePool> poolForSize(size_t n)
{
// Try to fit in the existing small allocator
if (n < m_smallAllocationPool->available())
return m_smallAllocationPool;
// If the request is large, we just provide a unshared allocator
if (n > JIT_ALLOCATOR_LARGE_ALLOC_SIZE)
return ExecutablePool::create(n);
// Create a new allocator
RefPtr<ExecutablePool> pool = ExecutablePool::create(JIT_ALLOCATOR_LARGE_ALLOC_SIZE);
// If the new allocator will result in more free space than in
// the current small allocator, then we will use it instead
if ((pool->available() - n) > m_smallAllocationPool->available())
m_smallAllocationPool = pool;
return pool.release();
}
private:
RefPtr<ExecutablePool> m_smallAllocationPool;
static void intializePageSize();
};
inline ExecutablePool::ExecutablePool(size_t n)
{
size_t allocSize = roundUpAllocationSize(n, JIT_ALLOCATOR_PAGE_SIZE);
Allocation mem = systemAlloc(allocSize);
m_pools.append(mem);
m_freePtr = mem.pages;
if (!m_freePtr)
CRASH(); // Failed to allocate
m_end = m_freePtr + allocSize;
}
inline void* ExecutablePool::poolAllocate(size_t n)
{
size_t allocSize = roundUpAllocationSize(n, JIT_ALLOCATOR_PAGE_SIZE);
Allocation result = systemAlloc(allocSize);
if (!result.pages)
CRASH(); // Failed to allocate
ASSERT(m_end >= m_freePtr);
if ((allocSize - n) > static_cast<size_t>(m_end - m_freePtr)) {
// Replace allocation pool
m_freePtr = result.pages + n;
m_end = result.pages + allocSize;
}
m_pools.append(result);
return result.pages;
}
}
#endif // ENABLE(ASSEMBLER)
#endif // !defined(ExecutableAllocator)
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