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michael@0:  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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michael@0:  * ***** END LICENSE BLOCK ***** */
michael@0: 
michael@0: #ifndef yarr_OSAllocator_h
michael@0: #define yarr_OSAllocator_h
michael@0: 
michael@0: #include <stdlib.h>
michael@0: #include "yarr/wtfbridge.h"
michael@0: #include "assembler/wtf/VMTags.h"
michael@0: #include "assembler/wtf/Assertions.h"
michael@0: 
michael@0: namespace WTF {
michael@0: 
michael@0: class OSAllocator {
michael@0: public:
michael@0:     enum Usage {
michael@0:         UnknownUsage = -1,
michael@0:         FastMallocPages = VM_TAG_FOR_TCMALLOC_MEMORY,
michael@0:         JSGCHeapPages = VM_TAG_FOR_COLLECTOR_MEMORY,
michael@0:         JSVMStackPages = VM_TAG_FOR_REGISTERFILE_MEMORY,
michael@0:         JSJITCodePages = VM_TAG_FOR_EXECUTABLEALLOCATOR_MEMORY
michael@0:     };
michael@0: 
michael@0:     // These methods are symmetric; reserveUncommitted allocates VM in an uncommitted state,
michael@0:     // releaseDecommitted should be called on a region of VM allocated by a single reservation,
michael@0:     // the memory must all currently be in a decommitted state.
michael@0:     static void* reserveUncommitted(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false);
michael@0:     static void releaseDecommitted(void*, size_t);
michael@0: 
michael@0:     // These methods are symmetric; they commit or decommit a region of VM (uncommitted VM should
michael@0:     // never be accessed, since the OS may not have attached physical memory for these regions).
michael@0:     // Clients should only call commit on uncommitted regions and decommit on committed regions.
michael@0:     static void commit(void*, size_t, bool writable, bool executable);
michael@0:     static void decommit(void*, size_t);
michael@0: 
michael@0:     // These methods are symmetric; reserveAndCommit allocates VM in an committed state,
michael@0:     // decommitAndRelease should be called on a region of VM allocated by a single reservation,
michael@0:     // the memory must all currently be in a committed state.
michael@0:     static void* reserveAndCommit(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false);
michael@0:     static void decommitAndRelease(void* base, size_t size);
michael@0: 
michael@0:     // These methods are akin to reserveAndCommit/decommitAndRelease, above - however rather than
michael@0:     // committing/decommitting the entire region additional parameters allow a subregion to be
michael@0:     // specified.
michael@0:     static void* reserveAndCommit(size_t reserveSize, size_t commitSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
michael@0:     static void decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize);
michael@0: };
michael@0: 
michael@0: inline void* OSAllocator::reserveAndCommit(size_t reserveSize, size_t commitSize, Usage usage, bool writable, bool executable)
michael@0: {
michael@0:     void* base = reserveUncommitted(reserveSize, usage, writable, executable);
michael@0:     commit(base, commitSize, writable, executable);
michael@0:     return base;
michael@0: }
michael@0: 
michael@0: inline void OSAllocator::decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize)
michael@0: {
michael@0:     ASSERT(decommitBase >= releaseBase && (static_cast<char*>(decommitBase) + decommitSize) <= (static_cast<char*>(releaseBase) + releaseSize));
michael@0: #if WTF_OS_WINCE || WTF_OS_SYMBIAN
michael@0:     // On most platforms we can actually skip this final decommit; releasing the VM will
michael@0:     // implicitly decommit any physical memory in the region. This is not true on WINCE.
michael@0:     // On Symbian, this makes implementation simpler and better aligned with the RChunk API
michael@0:     decommit(decommitBase, decommitSize);
michael@0: #endif
michael@0:     releaseDecommitted(releaseBase, releaseSize);
michael@0: }
michael@0: 
michael@0: inline void OSAllocator::decommitAndRelease(void* base, size_t size)
michael@0: {
michael@0:     decommitAndRelease(base, size, base, size);
michael@0: }
michael@0: 
michael@0: } // namespace WTF
michael@0: 
michael@0: using WTF::OSAllocator;
michael@0: 
michael@0: #endif /* yarr_OSAllocator_h */