/*
- * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
+ * Copyright (C) 2007, 2008, 2012-2014 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 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 Computer, Inc. ("Apple") nor the names of
+ * 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.
*
#ifndef SymbolTable_h
#define SymbolTable_h
+#include "ConcurrentJITLock.h"
#include "JSObject.h"
-#include "UString.h"
-#include <wtf/AlwaysInline.h>
+#include "VariableWatchpointSet.h"
+#include <memory>
+#include <wtf/HashTraits.h>
+#include <wtf/text/StringImpl.h>
namespace JSC {
- static ALWAYS_INLINE int missingSymbolMarker() { return std::numeric_limits<int>::max(); }
+struct SlowArgument {
+public:
+ enum Status {
+ Normal = 0,
+ Captured = 1,
+ Deleted = 2
+ };
- // The bit twiddling in this class assumes that every register index is a
- // reasonably small positive or negative number, and therefore has its high
- // four bits all set or all unset.
+ SlowArgument()
+ : status(Normal)
+ , index(0)
+ {
+ }
- struct SymbolTableEntry {
- SymbolTableEntry()
- : m_bits(0)
- {
- }
+ Status status;
+ int index; // If status is 'Deleted', index is bogus.
+};
- SymbolTableEntry(int index)
- {
- ASSERT(isValidIndex(index));
- pack(index, false, false);
- }
+static ALWAYS_INLINE int missingSymbolMarker() { return std::numeric_limits<int>::max(); }
+
+// The bit twiddling in this class assumes that every register index is a
+// reasonably small positive or negative number, and therefore has its high
+// four bits all set or all unset.
+
+// In addition to implementing semantics-mandated variable attributes and
+// implementation-mandated variable indexing, this class also implements
+// watchpoints to be used for JIT optimizations. Because watchpoints are
+// meant to be relatively rare, this class optimizes heavily for the case
+// that they are not being used. To that end, this class uses the thin-fat
+// idiom: either it is thin, in which case it contains an in-place encoded
+// word that consists of attributes, the index, and a bit saying that it is
+// thin; or it is fat, in which case it contains a pointer to a malloc'd
+// data structure and a bit saying that it is fat. The malloc'd data
+// structure will be malloced a second time upon copy, to preserve the
+// property that in-place edits to SymbolTableEntry do not manifest in any
+// copies. However, the malloc'd FatEntry data structure contains a ref-
+// counted pointer to a shared WatchpointSet. Thus, in-place edits of the
+// WatchpointSet will manifest in all copies. Here's a picture:
+//
+// SymbolTableEntry --> FatEntry --> VariableWatchpointSet
+//
+// If you make a copy of a SymbolTableEntry, you will have:
+//
+// original: SymbolTableEntry --> FatEntry --> VariableWatchpointSet
+// copy: SymbolTableEntry --> FatEntry -----^
- SymbolTableEntry(int index, unsigned attributes)
+struct SymbolTableEntry {
+ // Use the SymbolTableEntry::Fast class, either via implicit cast or by calling
+ // getFast(), when you (1) only care about isNull(), getIndex(), and isReadOnly(),
+ // and (2) you are in a hot path where you need to minimize the number of times
+ // that you branch on isFat() when getting the bits().
+ class Fast {
+ public:
+ Fast()
+ : m_bits(SlimFlag)
{
- ASSERT(isValidIndex(index));
- pack(index, attributes & ReadOnly, attributes & DontEnum);
}
+ ALWAYS_INLINE Fast(const SymbolTableEntry& entry)
+ : m_bits(entry.bits())
+ {
+ }
+
bool isNull() const
{
- return !m_bits;
+ return !(m_bits & ~SlimFlag);
}
int getIndex() const
{
- return m_bits >> FlagBits;
+ return static_cast<int>(m_bits >> FlagBits);
}
-
+
+ bool isReadOnly() const
+ {
+ return m_bits & ReadOnlyFlag;
+ }
+
unsigned getAttributes() const
{
unsigned attributes = 0;
return attributes;
}
- void setAttributes(unsigned attributes)
+ bool isFat() const
{
- pack(getIndex(), attributes & ReadOnly, attributes & DontEnum);
+ return !(m_bits & SlimFlag);
}
+
+ private:
+ friend struct SymbolTableEntry;
+ intptr_t m_bits;
+ };
- bool isReadOnly() const
- {
- return m_bits & ReadOnlyFlag;
- }
+ SymbolTableEntry()
+ : m_bits(SlimFlag)
+ {
+ }
- private:
- static const unsigned ReadOnlyFlag = 0x1;
- static const unsigned DontEnumFlag = 0x2;
- static const unsigned NotNullFlag = 0x4;
- static const unsigned FlagBits = 3;
+ SymbolTableEntry(int index)
+ : m_bits(SlimFlag)
+ {
+ ASSERT(isValidIndex(index));
+ pack(index, false, false);
+ }
- void pack(int index, bool readOnly, bool dontEnum)
+ SymbolTableEntry(int index, unsigned attributes)
+ : m_bits(SlimFlag)
+ {
+ ASSERT(isValidIndex(index));
+ pack(index, attributes & ReadOnly, attributes & DontEnum);
+ }
+
+ ~SymbolTableEntry()
+ {
+ freeFatEntry();
+ }
+
+ SymbolTableEntry(const SymbolTableEntry& other)
+ : m_bits(SlimFlag)
+ {
+ *this = other;
+ }
+
+ SymbolTableEntry& operator=(const SymbolTableEntry& other)
+ {
+ if (UNLIKELY(other.isFat()))
+ return copySlow(other);
+ freeFatEntry();
+ m_bits = other.m_bits;
+ return *this;
+ }
+
+ bool isNull() const
+ {
+ return !(bits() & ~SlimFlag);
+ }
+
+ int getIndex() const
+ {
+ return static_cast<int>(bits() >> FlagBits);
+ }
+
+ ALWAYS_INLINE Fast getFast() const
+ {
+ return Fast(*this);
+ }
+
+ ALWAYS_INLINE Fast getFast(bool& wasFat) const
+ {
+ Fast result;
+ wasFat = isFat();
+ if (wasFat)
+ result.m_bits = fatEntry()->m_bits | SlimFlag;
+ else
+ result.m_bits = m_bits;
+ return result;
+ }
+
+ unsigned getAttributes() const
+ {
+ return getFast().getAttributes();
+ }
+
+ void setAttributes(unsigned attributes)
+ {
+ pack(getIndex(), attributes & ReadOnly, attributes & DontEnum);
+ }
+
+ bool isReadOnly() const
+ {
+ return bits() & ReadOnlyFlag;
+ }
+
+ JSValue inferredValue();
+
+ void prepareToWatch(SymbolTable*);
+
+ void addWatchpoint(Watchpoint*);
+
+ VariableWatchpointSet* watchpointSet()
+ {
+ if (!isFat())
+ return 0;
+ return fatEntry()->m_watchpoints.get();
+ }
+
+ ALWAYS_INLINE void notifyWrite(VM& vm, JSValue value)
+ {
+ if (LIKELY(!isFat()))
+ return;
+ notifyWriteSlow(vm, value);
+ }
+
+private:
+ static const intptr_t SlimFlag = 0x1;
+ static const intptr_t ReadOnlyFlag = 0x2;
+ static const intptr_t DontEnumFlag = 0x4;
+ static const intptr_t NotNullFlag = 0x8;
+ static const intptr_t FlagBits = 4;
+
+ class FatEntry {
+ WTF_MAKE_FAST_ALLOCATED;
+ public:
+ FatEntry(intptr_t bits)
+ : m_bits(bits & ~SlimFlag)
{
- m_bits = (index << FlagBits) | NotNullFlag;
- if (readOnly)
- m_bits |= ReadOnlyFlag;
- if (dontEnum)
- m_bits |= DontEnumFlag;
}
- bool isValidIndex(int index)
- {
- return ((index << FlagBits) >> FlagBits) == index;
- }
-
- int m_bits;
+ intptr_t m_bits; // always has FatFlag set and exactly matches what the bits would have been if this wasn't fat.
+
+ RefPtr<VariableWatchpointSet> m_watchpoints;
};
+
+ SymbolTableEntry& copySlow(const SymbolTableEntry&);
+ JS_EXPORT_PRIVATE void notifyWriteSlow(VM&, JSValue);
+
+ bool isFat() const
+ {
+ return !(m_bits & SlimFlag);
+ }
+
+ const FatEntry* fatEntry() const
+ {
+ ASSERT(isFat());
+ return bitwise_cast<const FatEntry*>(m_bits);
+ }
+
+ FatEntry* fatEntry()
+ {
+ ASSERT(isFat());
+ return bitwise_cast<FatEntry*>(m_bits);
+ }
+
+ FatEntry* inflate()
+ {
+ if (LIKELY(isFat()))
+ return fatEntry();
+ return inflateSlow();
+ }
+
+ FatEntry* inflateSlow();
+
+ ALWAYS_INLINE intptr_t bits() const
+ {
+ if (isFat())
+ return fatEntry()->m_bits;
+ return m_bits;
+ }
+
+ ALWAYS_INLINE intptr_t& bits()
+ {
+ if (isFat())
+ return fatEntry()->m_bits;
+ return m_bits;
+ }
+
+ void freeFatEntry()
+ {
+ if (LIKELY(!isFat()))
+ return;
+ freeFatEntrySlow();
+ }
- struct SymbolTableIndexHashTraits {
- typedef SymbolTableEntry TraitType;
- static SymbolTableEntry emptyValue() { return SymbolTableEntry(); }
- static const bool emptyValueIsZero = true;
- static const bool needsDestruction = false;
- };
+ JS_EXPORT_PRIVATE void freeFatEntrySlow();
+
+ void pack(int index, bool readOnly, bool dontEnum)
+ {
+ ASSERT(!isFat());
+ intptr_t& bitsRef = bits();
+ bitsRef = (static_cast<intptr_t>(index) << FlagBits) | NotNullFlag | SlimFlag;
+ if (readOnly)
+ bitsRef |= ReadOnlyFlag;
+ if (dontEnum)
+ bitsRef |= DontEnumFlag;
+ }
+
+ bool isValidIndex(int index)
+ {
+ return ((static_cast<intptr_t>(index) << FlagBits) >> FlagBits) == static_cast<intptr_t>(index);
+ }
- typedef HashMap<RefPtr<UString::Rep>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, SymbolTableIndexHashTraits> SymbolTable;
+ intptr_t m_bits;
+};
- class SharedSymbolTable : public SymbolTable, public RefCounted<SharedSymbolTable>
+struct SymbolTableIndexHashTraits : HashTraits<SymbolTableEntry> {
+ static const bool needsDestruction = true;
+};
+
+class SymbolTable : public JSCell {
+public:
+ typedef JSCell Base;
+
+ typedef HashMap<RefPtr<StringImpl>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<StringImpl>>, SymbolTableIndexHashTraits> Map;
+
+ static SymbolTable* create(VM& vm)
+ {
+ SymbolTable* symbolTable = new (NotNull, allocateCell<SymbolTable>(vm.heap)) SymbolTable(vm);
+ symbolTable->finishCreation(vm);
+ return symbolTable;
+ }
+ static const bool needsDestruction = true;
+ static const bool hasImmortalStructure = true;
+ static void destroy(JSCell*);
+
+ static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
+ {
+ return Structure::create(vm, globalObject, prototype, TypeInfo(LeafType, StructureFlags), info());
+ }
+
+ // You must hold the lock until after you're done with the iterator.
+ Map::iterator find(const ConcurrentJITLocker&, StringImpl* key)
+ {
+ return m_map.find(key);
+ }
+
+ Map::iterator find(const GCSafeConcurrentJITLocker&, StringImpl* key)
+ {
+ return m_map.find(key);
+ }
+
+ SymbolTableEntry get(const ConcurrentJITLocker&, StringImpl* key)
+ {
+ return m_map.get(key);
+ }
+
+ SymbolTableEntry get(StringImpl* key)
+ {
+ ConcurrentJITLocker locker(m_lock);
+ return get(locker, key);
+ }
+
+ SymbolTableEntry inlineGet(const ConcurrentJITLocker&, StringImpl* key)
+ {
+ return m_map.inlineGet(key);
+ }
+
+ SymbolTableEntry inlineGet(StringImpl* key)
+ {
+ ConcurrentJITLocker locker(m_lock);
+ return inlineGet(locker, key);
+ }
+
+ Map::iterator begin(const ConcurrentJITLocker&)
+ {
+ return m_map.begin();
+ }
+
+ Map::iterator end(const ConcurrentJITLocker&)
+ {
+ return m_map.end();
+ }
+
+ Map::iterator end(const GCSafeConcurrentJITLocker&)
+ {
+ return m_map.end();
+ }
+
+ size_t size(const ConcurrentJITLocker&) const
+ {
+ return m_map.size();
+ }
+
+ size_t size() const
{
+ ConcurrentJITLocker locker(m_lock);
+ return size(locker);
+ }
+
+ Map::AddResult add(const ConcurrentJITLocker&, StringImpl* key, const SymbolTableEntry& entry)
+ {
+ return m_map.add(key, entry);
+ }
+
+ void add(StringImpl* key, const SymbolTableEntry& entry)
+ {
+ ConcurrentJITLocker locker(m_lock);
+ add(locker, key, entry);
+ }
+
+ Map::AddResult set(const ConcurrentJITLocker&, StringImpl* key, const SymbolTableEntry& entry)
+ {
+ return m_map.set(key, entry);
+ }
+
+ void set(StringImpl* key, const SymbolTableEntry& entry)
+ {
+ ConcurrentJITLocker locker(m_lock);
+ set(locker, key, entry);
+ }
+
+ bool contains(const ConcurrentJITLocker&, StringImpl* key)
+ {
+ return m_map.contains(key);
+ }
+
+ bool contains(StringImpl* key)
+ {
+ ConcurrentJITLocker locker(m_lock);
+ return contains(locker, key);
+ }
+
+ bool usesNonStrictEval() { return m_usesNonStrictEval; }
+ void setUsesNonStrictEval(bool usesNonStrictEval) { m_usesNonStrictEval = usesNonStrictEval; }
+
+ int captureStart() const { return m_captureStart; }
+ void setCaptureStart(int captureStart) { m_captureStart = captureStart; }
+
+ int captureEnd() const { return m_captureEnd; }
+ void setCaptureEnd(int captureEnd) { m_captureEnd = captureEnd; }
+
+ int captureCount() const { return -(m_captureEnd - m_captureStart); }
+
+ bool isCaptured(int operand)
+ {
+ return operand <= captureStart() && operand > captureEnd();
+ }
+
+ int parameterCount() { return m_parameterCountIncludingThis - 1; }
+ int parameterCountIncludingThis() { return m_parameterCountIncludingThis; }
+ void setParameterCountIncludingThis(int parameterCountIncludingThis) { m_parameterCountIncludingThis = parameterCountIncludingThis; }
+
+ // 0 if we don't capture any arguments; parameterCount() in length if we do.
+ const SlowArgument* slowArguments() { return m_slowArguments.get(); }
+ void setSlowArguments(std::unique_ptr<SlowArgument[]> slowArguments) { m_slowArguments = WTF::move(slowArguments); }
+
+ SymbolTable* cloneCapturedNames(VM&);
+
+ static void visitChildren(JSCell*, SlotVisitor&);
+
+ DECLARE_EXPORT_INFO;
+
+protected:
+ static const unsigned StructureFlags = StructureIsImmortal | Base::StructureFlags;
+
+private:
+ class WatchpointCleanup : public UnconditionalFinalizer {
+ public:
+ WatchpointCleanup(SymbolTable*);
+ virtual ~WatchpointCleanup();
+
+ protected:
+ virtual void finalizeUnconditionally() override;
+
+ private:
+ SymbolTable* m_symbolTable;
};
+ JS_EXPORT_PRIVATE SymbolTable(VM&);
+ ~SymbolTable();
+
+ Map m_map;
+
+ int m_parameterCountIncludingThis;
+ bool m_usesNonStrictEval;
+
+ int m_captureStart;
+ int m_captureEnd;
+
+ std::unique_ptr<SlowArgument[]> m_slowArguments;
+
+ std::unique_ptr<WatchpointCleanup> m_watchpointCleanup;
+
+public:
+ InlineWatchpointSet m_functionEnteredOnce;
+
+ mutable ConcurrentJITLock m_lock;
+};
+
} // namespace JSC
#endif // SymbolTable_h
projects / apple / javascriptcore.git / blobdiff