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/*
* Copyright (C) 2008, 2009 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.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE 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 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 EvalCodeCache_h
#define EvalCodeCache_h
#include "Executable.h"
#include "JSGlobalObject.h"
#include "JSScope.h"
#include "Options.h"
#include "SourceCode.h"
#include <wtf/HashMap.h>
#include <wtf/RefPtr.h>
#include <wtf/text/StringHash.h>
namespace JSC {
class SlotVisitor;
class EvalCodeCache {
public:
class CacheKey {
public:
CacheKey(const String& source, bool isArrowFunctionContext)
: m_source(source.impl())
, m_isArrowFunctionContext(isArrowFunctionContext)
{
}
CacheKey(WTF::HashTableDeletedValueType)
: m_source(WTF::HashTableDeletedValue)
{
}
CacheKey() = default;
unsigned hash() const { return m_source->hash(); }
bool isEmptyValue() const { return !m_source; }
bool operator==(const CacheKey& other) const
{
return m_source == other.m_source && m_isArrowFunctionContext == other.m_isArrowFunctionContext;
}
bool isHashTableDeletedValue() const { return m_source.isHashTableDeletedValue(); }
struct Hash {
static unsigned hash(const CacheKey& key)
{
return key.hash();
}
static bool equal(const CacheKey& lhs, const CacheKey& rhs)
{
return StringHash::equal(lhs.m_source, rhs.m_source) && lhs.m_isArrowFunctionContext == rhs.m_isArrowFunctionContext;
}
static const bool safeToCompareToEmptyOrDeleted = false;
};
typedef SimpleClassHashTraits<CacheKey> HashTraits;
private:
RefPtr<StringImpl> m_source;
bool m_isArrowFunctionContext { false };
};
EvalExecutable* tryGet(bool inStrictContext, const String& evalSource, bool isArrowFunctionContext, JSScope* scope)
{
if (isCacheable(inStrictContext, evalSource, scope)) {
ASSERT(!inStrictContext);
return m_cacheMap.fastGet(CacheKey(evalSource, isArrowFunctionContext)).get();
}
return nullptr;
}
EvalExecutable* getSlow(ExecState* exec, JSCell* owner, bool inStrictContext, ThisTDZMode thisTDZMode, DerivedContextType derivedContextType, bool isArrowFunctionContext, const String& evalSource, JSScope* scope)
{
VariableEnvironment variablesUnderTDZ;
JSScope::collectVariablesUnderTDZ(scope, variablesUnderTDZ);
EvalExecutable* evalExecutable = EvalExecutable::create(exec, makeSource(evalSource), inStrictContext, thisTDZMode, derivedContextType, isArrowFunctionContext, &variablesUnderTDZ);
if (!evalExecutable)
return nullptr;
if (isCacheable(inStrictContext, evalSource, scope) && m_cacheMap.size() < maxCacheEntries) {
ASSERT(!inStrictContext);
ASSERT_WITH_MESSAGE(thisTDZMode == ThisTDZMode::CheckIfNeeded, "Always CheckIfNeeded because the caching is enabled only in the sloppy mode.");
ASSERT_WITH_MESSAGE(derivedContextType == DerivedContextType::None, "derivedContextType is always None because class methods and class constructors are always evaluated as the strict code.");
m_cacheMap.set(CacheKey(evalSource, isArrowFunctionContext), WriteBarrier<EvalExecutable>(exec->vm(), owner, evalExecutable));
}
return evalExecutable;
}
bool isEmpty() const { return m_cacheMap.isEmpty(); }
void visitAggregate(SlotVisitor&);
void clear()
{
m_cacheMap.clear();
}
private:
ALWAYS_INLINE bool isCacheableScope(JSScope* scope)
{
return scope->isGlobalLexicalEnvironment() || scope->isFunctionNameScopeObject() || scope->isVarScope();
}
ALWAYS_INLINE bool isCacheable(bool inStrictContext, const String& evalSource, JSScope* scope)
{
// If eval() is called and it has access to a lexical scope, we can't soundly cache it.
// If the eval() only has access to the "var" scope, then we can cache it.
return !inStrictContext
&& static_cast<size_t>(evalSource.length()) < Options::maximumEvalCacheableSourceLength()
&& isCacheableScope(scope);
}
static const int maxCacheEntries = 64;
typedef HashMap<CacheKey, WriteBarrier<EvalExecutable>, CacheKey::Hash, CacheKey::HashTraits> EvalCacheMap;
EvalCacheMap m_cacheMap;
};
} // namespace JSC
#endif // EvalCodeCache_h
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