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/*
* Copyright (C) 2008, 2012-2015 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 StructureStubInfo_h
#define StructureStubInfo_h
#include "CodeOrigin.h"
#include "Instruction.h"
#include "JITStubRoutine.h"
#include "MacroAssembler.h"
#include "ObjectPropertyConditionSet.h"
#include "Opcode.h"
#include "Options.h"
#include "PolymorphicAccess.h"
#include "RegisterSet.h"
#include "Structure.h"
#include "StructureStubClearingWatchpoint.h"
namespace JSC {
#if ENABLE(JIT)
class PolymorphicAccess;
enum class AccessType : int8_t {
Get,
Put,
In
};
enum class CacheType : int8_t {
Unset,
GetByIdSelf,
PutByIdReplace,
Stub
};
class StructureStubInfo {
WTF_MAKE_NONCOPYABLE(StructureStubInfo);
WTF_MAKE_FAST_ALLOCATED;
public:
StructureStubInfo(AccessType);
~StructureStubInfo();
void initGetByIdSelf(CodeBlock*, Structure* baseObjectStructure, PropertyOffset);
void initPutByIdReplace(CodeBlock*, Structure* baseObjectStructure, PropertyOffset);
void initStub(CodeBlock*, std::unique_ptr<PolymorphicAccess>);
MacroAssemblerCodePtr addAccessCase(
CodeBlock*, const Identifier&, std::unique_ptr<AccessCase>);
void reset(CodeBlock*);
void deref();
void aboutToDie();
// Check if the stub has weak references that are dead. If it does, then it resets itself,
// either entirely or just enough to ensure that those dead pointers don't get used anymore.
void visitWeakReferences(CodeBlock*);
ALWAYS_INLINE bool considerCaching()
{
everConsidered = true;
if (!countdown) {
// Check if we have been doing repatching too frequently. If so, then we should cool off
// for a while.
willRepatch();
if (repatchCount > Options::repatchCountForCoolDown()) {
// We've been repatching too much, so don't do it now.
repatchCount = 0;
// The amount of time we require for cool-down depends on the number of times we've
// had to cool down in the past. The relationship is exponential. The max value we
// allow here is 2^256 - 2, since the slow paths may increment the count to indicate
// that they'd like to temporarily skip patching just this once.
countdown = WTF::leftShiftWithSaturation(
static_cast<uint8_t>(Options::initialCoolDownCount()),
numberOfCoolDowns,
static_cast<uint8_t>(std::numeric_limits<uint8_t>::max() - 1));
willCoolDown();
return false;
}
return true;
}
countdown--;
return false;
}
ALWAYS_INLINE void willRepatch()
{
WTF::incrementWithSaturation(repatchCount);
}
ALWAYS_INLINE void willCoolDown()
{
WTF::incrementWithSaturation(numberOfCoolDowns);
}
CodeLocationCall callReturnLocation;
CodeOrigin codeOrigin;
CallSiteIndex callSiteIndex;
bool containsPC(void* pc) const;
union {
struct {
WriteBarrierBase<Structure> baseObjectStructure;
PropertyOffset offset;
} byIdSelf;
PolymorphicAccess* stub;
} u;
struct {
int8_t baseGPR;
#if USE(JSVALUE32_64)
int8_t valueTagGPR;
int8_t baseTagGPR;
#endif
int8_t valueGPR;
RegisterSet usedRegisters;
int32_t deltaCallToDone;
int32_t deltaCallToJump;
int32_t deltaCallToSlowCase;
int32_t deltaCheckImmToCall;
#if USE(JSVALUE64)
int32_t deltaCallToLoadOrStore;
#else
int32_t deltaCallToTagLoadOrStore;
int32_t deltaCallToPayloadLoadOrStore;
#endif
} patch;
AccessType accessType;
CacheType cacheType;
uint8_t countdown; // We repatch only when this is zero. If not zero, we decrement.
uint8_t repatchCount;
uint8_t numberOfCoolDowns;
bool resetByGC : 1;
bool tookSlowPath : 1;
bool everConsidered : 1;
};
inline CodeOrigin getStructureStubInfoCodeOrigin(StructureStubInfo& structureStubInfo)
{
return structureStubInfo.codeOrigin;
}
typedef HashMap<CodeOrigin, StructureStubInfo*, CodeOriginApproximateHash> StubInfoMap;
#else
typedef HashMap<int, void*> StubInfoMap;
#endif // ENABLE(JIT)
} // namespace JSC
#endif // StructureStubInfo_h
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