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Butterfly.h
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175 lines (146 loc) · 8.39 KB
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/*
* Copyright (C) 2012 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 Butterfly_h
#define Butterfly_h
#include "IndexingHeader.h"
#include "PropertyOffset.h"
#include "PropertyStorage.h"
#include <wtf/Noncopyable.h>
#include <wtf/Platform.h>
namespace JSC {
class VM;
class CopyVisitor;
struct ArrayStorage;
template <typename T> struct ContiguousData {
ContiguousData()
: m_data(0)
#if !ASSERT_DISABLED
, m_length(0)
#endif
{
}
ContiguousData(T* data, size_t length)
: m_data(data)
#if !ASSERT_DISABLED
, m_length(length)
#endif
{
UNUSED_PARAM(length);
}
const T& operator[](size_t index) const { ASSERT(index < m_length); return m_data[index]; }
T& operator[](size_t index) { ASSERT(index < m_length); return m_data[index]; }
T* data() const { return m_data; }
#if !ASSERT_DISABLED
size_t length() const { return m_length; }
#endif
private:
T* m_data;
#if !ASSERT_DISABLED
size_t m_length;
#endif
};
typedef ContiguousData<double> ContiguousDoubles;
typedef ContiguousData<WriteBarrier<Unknown>> ContiguousJSValues;
class Butterfly {
WTF_MAKE_NONCOPYABLE(Butterfly);
private:
Butterfly() { } // Not instantiable.
public:
static size_t totalSize(size_t preCapacity, size_t propertyCapacity, bool hasIndexingHeader, size_t indexingPayloadSizeInBytes)
{
ASSERT(indexingPayloadSizeInBytes ? hasIndexingHeader : true);
ASSERT(sizeof(EncodedJSValue) == sizeof(IndexingHeader));
return (preCapacity + propertyCapacity) * sizeof(EncodedJSValue) + (hasIndexingHeader ? sizeof(IndexingHeader) : 0) + indexingPayloadSizeInBytes;
}
static Butterfly* fromBase(void* base, size_t preCapacity, size_t propertyCapacity)
{
return reinterpret_cast<Butterfly*>(static_cast<EncodedJSValue*>(base) + preCapacity + propertyCapacity + 1);
}
// This method is here not just because it's handy, but to remind you that
// the whole point of butterflies is to do evil pointer arithmetic.
static Butterfly* fromPointer(char* ptr)
{
return reinterpret_cast<Butterfly*>(ptr);
}
char* pointer() { return reinterpret_cast<char*>(this); }
static ptrdiff_t offsetOfIndexingHeader() { return IndexingHeader::offsetOfIndexingHeader(); }
static ptrdiff_t offsetOfArrayBuffer() { return offsetOfIndexingHeader() + IndexingHeader::offsetOfArrayBuffer(); }
static ptrdiff_t offsetOfPublicLength() { return offsetOfIndexingHeader() + IndexingHeader::offsetOfPublicLength(); }
static ptrdiff_t offsetOfVectorLength() { return offsetOfIndexingHeader() + IndexingHeader::offsetOfVectorLength(); }
static Butterfly* createUninitialized(VM&, JSCell* intendedOwner, size_t preCapacity, size_t propertyCapacity, bool hasIndexingHeader, size_t indexingPayloadSizeInBytes);
static Butterfly* create(VM&, JSCell* intendedOwner, size_t preCapacity, size_t propertyCapacity, bool hasIndexingHeader, const IndexingHeader&, size_t indexingPayloadSizeInBytes);
static Butterfly* create(VM&, JSCell* intendedOwner, Structure*);
static Butterfly* createUninitializedDuringCollection(CopyVisitor&, size_t preCapacity, size_t propertyCapacity, bool hasIndexingHeader, size_t indexingPayloadSizeInBytes);
IndexingHeader* indexingHeader() { return IndexingHeader::from(this); }
const IndexingHeader* indexingHeader() const { return IndexingHeader::from(this); }
PropertyStorage propertyStorage() { return indexingHeader()->propertyStorage(); }
ConstPropertyStorage propertyStorage() const { return indexingHeader()->propertyStorage(); }
uint32_t publicLength() { return indexingHeader()->publicLength(); }
uint32_t vectorLength() { return indexingHeader()->vectorLength(); }
void setPublicLength(uint32_t value) { indexingHeader()->setPublicLength(value); }
void setVectorLength(uint32_t value) { indexingHeader()->setVectorLength(value); }
template<typename T>
T* indexingPayload() { return reinterpret_cast_ptr<T*>(this); }
ArrayStorage* arrayStorage() { return indexingPayload<ArrayStorage>(); }
ContiguousJSValues contiguousInt32() { return ContiguousJSValues(indexingPayload<WriteBarrier<Unknown>>(), vectorLength()); }
ContiguousDoubles contiguousDouble() { return ContiguousDoubles(indexingPayload<double>(), vectorLength()); }
ContiguousJSValues contiguous() { return ContiguousJSValues(indexingPayload<WriteBarrier<Unknown>>(), vectorLength()); }
static Butterfly* fromContiguous(WriteBarrier<Unknown>* contiguous)
{
return reinterpret_cast<Butterfly*>(contiguous);
}
static Butterfly* fromContiguous(double* contiguous)
{
return reinterpret_cast<Butterfly*>(contiguous);
}
static ptrdiff_t offsetOfPropertyStorage() { return -static_cast<ptrdiff_t>(sizeof(IndexingHeader)); }
static int indexOfPropertyStorage()
{
ASSERT(sizeof(IndexingHeader) == sizeof(EncodedJSValue));
return -1;
}
void* base(size_t preCapacity, size_t propertyCapacity) { return propertyStorage() - propertyCapacity - preCapacity; }
void* base(Structure*);
static Butterfly* createOrGrowArrayRight(
Butterfly*, VM&, JSCell* intendedOwner, Structure* oldStructure,
size_t propertyCapacity, bool hadIndexingHeader,
size_t oldIndexingPayloadSizeInBytes, size_t newIndexingPayloadSizeInBytes);
// The butterfly reallocation methods perform the reallocation itself but do not change any
// of the meta-data to reflect that the reallocation occurred. Note that this set of
// methods is not exhaustive and is not intended to encapsulate all possible allocation
// modes of butterflies - there are code paths that allocate butterflies by calling
// directly into Heap::tryAllocateStorage.
Butterfly* growPropertyStorage(VM&, JSCell* intendedOwner, size_t preCapacity, size_t oldPropertyCapacity, bool hasIndexingHeader, size_t indexingPayloadSizeInBytes, size_t newPropertyCapacity);
Butterfly* growPropertyStorage(VM&, JSCell* intendedOwner, Structure* oldStructure, size_t oldPropertyCapacity, size_t newPropertyCapacity);
Butterfly* growPropertyStorage(VM&, JSCell* intendedOwner, Structure* oldStructure, size_t newPropertyCapacity);
Butterfly* growArrayRight(VM&, JSCell* intendedOwner, Structure* oldStructure, size_t propertyCapacity, bool hadIndexingHeader, size_t oldIndexingPayloadSizeInBytes, size_t newIndexingPayloadSizeInBytes); // Assumes that preCapacity is zero, and asserts as much.
Butterfly* growArrayRight(VM&, JSCell* intendedOwner, Structure*, size_t newIndexingPayloadSizeInBytes);
Butterfly* resizeArray(VM&, JSCell* intendedOwner, size_t propertyCapacity, bool oldHasIndexingHeader, size_t oldIndexingPayloadSizeInBytes, size_t newPreCapacity, bool newHasIndexingHeader, size_t newIndexingPayloadSizeInBytes);
Butterfly* resizeArray(VM&, JSCell* intendedOwner, Structure*, size_t newPreCapacity, size_t newIndexingPayloadSizeInBytes); // Assumes that you're not changing whether or not the object has an indexing header.
Butterfly* unshift(Structure*, size_t numberOfSlots);
Butterfly* shift(Structure*, size_t numberOfSlots);
};
} // namespace JSC
#endif // Butterfly_h