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/*
* Copyright (C) 2010 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. AND ITS CONTRIBUTORS ``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 ITS 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 OSAllocator_h
#define OSAllocator_h
#include <algorithm>
#include <wtf/UnusedParam.h>
#include <wtf/VMTags.h>
namespace WTF {
class OSAllocator {
public:
enum Usage {
UnknownUsage = -1,
FastMallocPages = VM_TAG_FOR_TCMALLOC_MEMORY,
JSGCHeapPages = VM_TAG_FOR_COLLECTOR_MEMORY,
JSVMStackPages = VM_TAG_FOR_REGISTERFILE_MEMORY,
JSJITCodePages = VM_TAG_FOR_EXECUTABLEALLOCATOR_MEMORY,
};
// These methods are symmetric; reserveUncommitted allocates VM in an uncommitted state,
// releaseDecommitted should be called on a region of VM allocated by a single reservation,
// the memory must all currently be in a decommitted state.
static void* reserveUncommitted(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false);
WTF_EXPORT_PRIVATE static void releaseDecommitted(void*, size_t);
// These methods are symmetric; they commit or decommit a region of VM (uncommitted VM should
// never be accessed, since the OS may not have attached physical memory for these regions).
// Clients should only call commit on uncommitted regions and decommit on committed regions.
static void commit(void*, size_t, bool writable, bool executable);
static void decommit(void*, size_t);
// These methods are symmetric; reserveAndCommit allocates VM in an committed state,
// decommitAndRelease should be called on a region of VM allocated by a single reservation,
// the memory must all currently be in a committed state.
WTF_EXPORT_PRIVATE static void* reserveAndCommit(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false, bool includesGuardPages = false);
static void decommitAndRelease(void* base, size_t size);
// These methods are akin to reserveAndCommit/decommitAndRelease, above - however rather than
// committing/decommitting the entire region additional parameters allow a subregion to be
// specified.
static void* reserveAndCommit(size_t reserveSize, size_t commitSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
static void decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize);
// Reallocate an existing, committed allocation.
// The prior allocation must be fully comitted, and the new size will also be fully committed.
// This interface is provided since it may be possible to optimize this operation on some platforms.
template<typename T>
static T* reallocateCommitted(T*, size_t oldSize, size_t newSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
};
inline void* OSAllocator::reserveAndCommit(size_t reserveSize, size_t commitSize, Usage usage, bool writable, bool executable)
{
void* base = reserveUncommitted(reserveSize, usage, writable, executable);
commit(base, commitSize, writable, executable);
return base;
}
inline void OSAllocator::decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize)
{
ASSERT(decommitBase >= releaseBase && (static_cast<char*>(decommitBase) + decommitSize) <= (static_cast<char*>(releaseBase) + releaseSize));
#if OS(WINCE)
// On most platforms we can actually skip this final decommit; releasing the VM will
// implicitly decommit any physical memory in the region. This is not true on WINCE.
decommit(decommitBase, decommitSize);
#else
UNUSED_PARAM(decommitBase);
UNUSED_PARAM(decommitSize);
#endif
releaseDecommitted(releaseBase, releaseSize);
}
inline void OSAllocator::decommitAndRelease(void* base, size_t size)
{
decommitAndRelease(base, size, base, size);
}
template<typename T>
inline T* OSAllocator::reallocateCommitted(T* oldBase, size_t oldSize, size_t newSize, Usage usage, bool writable, bool executable)
{
void* newBase = reserveAndCommit(newSize, usage, writable, executable);
memcpy(newBase, oldBase, std::min(oldSize, newSize));
decommitAndRelease(oldBase, oldSize);
return static_cast<T*>(newBase);
}
} // namespace WTF
using WTF::OSAllocator;
#endif // OSAllocator_h
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