Fast path for jsStringWithCache() when asked for the same string repeatedly.
[WebKit-https.git] / Source / JavaScriptCore / runtime / VM.h
1 /*
2  * Copyright (C) 2008, 2009, 2013, 2014 Apple Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1.  Redistributions of source code must retain the above copyright
9  *     notice, this list of conditions and the following disclaimer. 
10  * 2.  Redistributions in binary form must reproduce the above copyright
11  *     notice, this list of conditions and the following disclaimer in the
12  *     documentation and/or other materials provided with the distribution. 
13  * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
14  *     its contributors may be used to endorse or promote products derived
15  *     from this software without specific prior written permission. 
16  *
17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28
29 #ifndef VM_h
30 #define VM_h
31
32 #include "DateInstanceCache.h"
33 #include "ExecutableAllocator.h"
34 #include "Heap.h"
35 #include "Intrinsic.h"
36 #include "JITThunks.h"
37 #include "JSCJSValue.h"
38 #include "JSLock.h"
39 #include "LLIntData.h"
40 #include "MacroAssemblerCodeRef.h"
41 #include "NumericStrings.h"
42 #include "PrivateName.h"
43 #include "PrototypeMap.h"
44 #include "SmallStrings.h"
45 #include "SourceCode.h"
46 #include "Strong.h"
47 #include "ThunkGenerators.h"
48 #include "TypedArrayController.h"
49 #include "Watchdog.h"
50 #include "Watchpoint.h"
51 #include "WeakRandom.h"
52 #include <wtf/BumpPointerAllocator.h>
53 #include <wtf/DateMath.h>
54 #include <wtf/Forward.h>
55 #include <wtf/HashMap.h>
56 #include <wtf/HashSet.h>
57 #include <wtf/RefCountedArray.h>
58 #include <wtf/SimpleStats.h>
59 #include <wtf/StackBounds.h>
60 #include <wtf/ThreadSafeRefCounted.h>
61 #include <wtf/ThreadSpecific.h>
62 #include <wtf/WTFThreadData.h>
63 #include <wtf/text/WTFString.h>
64 #if ENABLE(REGEXP_TRACING)
65 #include <wtf/ListHashSet.h>
66 #endif
67
68 namespace JSC {
69
70     class ArityCheckFailReturnThunks;
71     class BuiltinExecutables;
72     class CodeBlock;
73     class CodeCache;
74     class CommonIdentifiers;
75     class ExecState;
76     class HandleStack;
77     class Identifier;
78     class Interpreter;
79     class JSGlobalObject;
80     class JSObject;
81     class Keywords;
82     class LLIntOffsetsExtractor;
83     class LegacyProfiler;
84     class NativeExecutable;
85     class ParserArena;
86     class RegExpCache;
87     class SourceProvider;
88     class SourceProviderCache;
89     struct StackFrame;
90     class Stringifier;
91     class Structure;
92 #if ENABLE(REGEXP_TRACING)
93     class RegExp;
94 #endif
95     class UnlinkedCodeBlock;
96     class UnlinkedEvalCodeBlock;
97     class UnlinkedFunctionExecutable;
98     class UnlinkedProgramCodeBlock;
99     class VMEntryScope;
100     class Watchpoint;
101     class WatchpointSet;
102
103 #if ENABLE(DFG_JIT)
104     namespace DFG {
105     class LongLivedState;
106     }
107 #endif // ENABLE(DFG_JIT)
108 #if ENABLE(FTL_JIT)
109     namespace FTL {
110     class Thunks;
111     }
112 #endif // ENABLE(FTL_JIT)
113     namespace CommonSlowPaths {
114     struct ArityCheckData;
115     }
116     namespace Profiler {
117     class Database;
118     }
119
120     struct HashTable;
121     struct Instruction;
122
123     struct LocalTimeOffsetCache {
124         LocalTimeOffsetCache()
125             : start(0.0)
126             , end(-1.0)
127             , increment(0.0)
128         {
129         }
130         
131         void reset()
132         {
133             offset = LocalTimeOffset();
134             start = 0.0;
135             end = -1.0;
136             increment = 0.0;
137         }
138
139         LocalTimeOffset offset;
140         double start;
141         double end;
142         double increment;
143     };
144
145     class ConservativeRoots;
146
147 #if COMPILER(MSVC)
148 #pragma warning(push)
149 #pragma warning(disable: 4200) // Disable "zero-sized array in struct/union" warning
150 #endif
151     struct ScratchBuffer {
152         ScratchBuffer()
153         {
154             u.m_activeLength = 0;
155         }
156
157         static ScratchBuffer* create(size_t size)
158         {
159             ScratchBuffer* result = new (fastMalloc(ScratchBuffer::allocationSize(size))) ScratchBuffer;
160
161             return result;
162         }
163
164         static size_t allocationSize(size_t bufferSize) { return sizeof(ScratchBuffer) + bufferSize; }
165         void setActiveLength(size_t activeLength) { u.m_activeLength = activeLength; }
166         size_t activeLength() const { return u.m_activeLength; };
167         size_t* activeLengthPtr() { return &u.m_activeLength; };
168         void* dataBuffer() { return m_buffer; }
169
170         union {
171             size_t m_activeLength;
172             double pad; // Make sure m_buffer is double aligned.
173         } u;
174 #if CPU(MIPS) && (defined WTF_MIPS_ARCH_REV && WTF_MIPS_ARCH_REV == 2)
175         void* m_buffer[0] __attribute__((aligned(8)));
176 #else
177         void* m_buffer[0];
178 #endif
179     };
180 #if COMPILER(MSVC)
181 #pragma warning(pop)
182 #endif
183
184     class VM : public ThreadSafeRefCounted<VM> {
185     public:
186         // WebCore has a one-to-one mapping of threads to VMs;
187         // either create() or createLeaked() should only be called once
188         // on a thread, this is the 'default' VM (it uses the
189         // thread's default string uniquing table from wtfThreadData).
190         // API contexts created using the new context group aware interface
191         // create APIContextGroup objects which require less locking of JSC
192         // than the old singleton APIShared VM created for use by
193         // the original API.
194         enum VMType { Default, APIContextGroup, APIShared };
195         
196         struct ClientData {
197             JS_EXPORT_PRIVATE virtual ~ClientData() = 0;
198         };
199
200         bool isSharedInstance() { return vmType == APIShared; }
201         bool usingAPI() { return vmType != Default; }
202         JS_EXPORT_PRIVATE static bool sharedInstanceExists();
203         JS_EXPORT_PRIVATE static VM& sharedInstance();
204
205         JS_EXPORT_PRIVATE static PassRefPtr<VM> create(HeapType = SmallHeap);
206         JS_EXPORT_PRIVATE static PassRefPtr<VM> createLeaked(HeapType = SmallHeap);
207         static PassRefPtr<VM> createContextGroup(HeapType = SmallHeap);
208         JS_EXPORT_PRIVATE ~VM();
209
210         void makeUsableFromMultipleThreads() { heap.machineThreads().makeUsableFromMultipleThreads(); }
211         
212     private:
213         RefPtr<JSLock> m_apiLock;
214
215     public:
216 #if ENABLE(ASSEMBLER)
217         // executableAllocator should be destructed after the heap, as the heap can call executableAllocator
218         // in its destructor.
219         ExecutableAllocator executableAllocator;
220 #endif
221
222         // The heap should be just after executableAllocator and before other members to ensure that it's
223         // destructed after all the objects that reference it.
224         Heap heap;
225         
226 #if ENABLE(DFG_JIT)
227         OwnPtr<DFG::LongLivedState> dfgState;
228 #endif // ENABLE(DFG_JIT)
229
230         VMType vmType;
231         ClientData* clientData;
232         ExecState* topCallFrame;
233         std::unique_ptr<Watchdog> watchdog;
234
235         const OwnPtr<const HashTable> arrayConstructorTable;
236         const OwnPtr<const HashTable> arrayPrototypeTable;
237         const OwnPtr<const HashTable> booleanPrototypeTable;
238         const OwnPtr<const HashTable> dataViewTable;
239         const OwnPtr<const HashTable> dateTable;
240         const OwnPtr<const HashTable> dateConstructorTable;
241         const OwnPtr<const HashTable> errorPrototypeTable;
242         const OwnPtr<const HashTable> globalObjectTable;
243         const OwnPtr<const HashTable> jsonTable;
244         const OwnPtr<const HashTable> numberConstructorTable;
245         const OwnPtr<const HashTable> numberPrototypeTable;
246         const OwnPtr<const HashTable> objectConstructorTable;
247         const OwnPtr<const HashTable> privateNamePrototypeTable;
248         const OwnPtr<const HashTable> regExpTable;
249         const OwnPtr<const HashTable> regExpConstructorTable;
250         const OwnPtr<const HashTable> regExpPrototypeTable;
251         const OwnPtr<const HashTable> stringConstructorTable;
252 #if ENABLE(PROMISES)
253         const OwnPtr<const HashTable> promisePrototypeTable;
254         const OwnPtr<const HashTable> promiseConstructorTable;
255 #endif
256
257         Strong<Structure> structureStructure;
258         Strong<Structure> structureRareDataStructure;
259         Strong<Structure> debuggerActivationStructure;
260         Strong<Structure> terminatedExecutionErrorStructure;
261         Strong<Structure> stringStructure;
262         Strong<Structure> notAnObjectStructure;
263         Strong<Structure> propertyNameIteratorStructure;
264         Strong<Structure> getterSetterStructure;
265         Strong<Structure> customGetterSetterStructure;
266         Strong<Structure> apiWrapperStructure;
267         Strong<Structure> JSScopeStructure;
268         Strong<Structure> executableStructure;
269         Strong<Structure> nativeExecutableStructure;
270         Strong<Structure> evalExecutableStructure;
271         Strong<Structure> programExecutableStructure;
272         Strong<Structure> functionExecutableStructure;
273         Strong<Structure> regExpStructure;
274         Strong<Structure> symbolTableStructure;
275         Strong<Structure> structureChainStructure;
276         Strong<Structure> sparseArrayValueMapStructure;
277         Strong<Structure> arrayBufferNeuteringWatchpointStructure;
278         Strong<Structure> withScopeStructure;
279         Strong<Structure> unlinkedFunctionExecutableStructure;
280         Strong<Structure> unlinkedProgramCodeBlockStructure;
281         Strong<Structure> unlinkedEvalCodeBlockStructure;
282         Strong<Structure> unlinkedFunctionCodeBlockStructure;
283         Strong<Structure> propertyTableStructure;
284         Strong<Structure> mapDataStructure;
285         Strong<Structure> weakMapDataStructure;
286 #if ENABLE(PROMISES)
287         Strong<Structure> promiseDeferredStructure;
288         Strong<Structure> promiseReactionStructure;
289 #endif
290         Strong<JSCell> iterationTerminator;
291
292         AtomicStringTable* m_atomicStringTable;
293         CommonIdentifiers* propertyNames;
294         const MarkedArgumentBuffer* emptyList; // Lists are supposed to be allocated on the stack to have their elements properly marked, which is not the case here - but this list has nothing to mark.
295         SmallStrings smallStrings;
296         NumericStrings numericStrings;
297         DateInstanceCache dateInstanceCache;
298         WTF::SimpleStats machineCodeBytesPerBytecodeWordForBaselineJIT;
299         WeakGCMap<StringImpl*, JSString, PtrHash<StringImpl*>> stringCache;
300         Weak<JSString> lastCachedString;
301
302         AtomicStringTable* atomicStringTable() const { return m_atomicStringTable; }
303
304         void setInDefineOwnProperty(bool inDefineOwnProperty)
305         {
306             m_inDefineOwnProperty = inDefineOwnProperty;
307         }
308
309         bool isInDefineOwnProperty()
310         {
311             return m_inDefineOwnProperty;
312         }
313
314         LegacyProfiler* enabledProfiler() { return m_enabledProfiler; }
315         void setEnabledProfiler(LegacyProfiler*);
316
317         void* enabledProfilerAddress() { return &m_enabledProfiler; }
318
319 #if ENABLE(JIT)
320         bool canUseJIT() { return m_canUseJIT; }
321 #else
322         bool canUseJIT() { return false; } // interpreter only
323 #endif
324
325 #if ENABLE(YARR_JIT)
326         bool canUseRegExpJIT() { return m_canUseRegExpJIT; }
327 #else
328         bool canUseRegExpJIT() { return false; } // interpreter only
329 #endif
330
331         SourceProviderCache* addSourceProviderCache(SourceProvider*);
332         void clearSourceProviderCaches();
333
334         PrototypeMap prototypeMap;
335
336         OwnPtr<ParserArena> parserArena;
337         typedef HashMap<RefPtr<SourceProvider>, RefPtr<SourceProviderCache>> SourceProviderCacheMap;
338         SourceProviderCacheMap sourceProviderCacheMap;
339         OwnPtr<Keywords> keywords;
340         Interpreter* interpreter;
341 #if ENABLE(JIT)
342         OwnPtr<JITThunks> jitStubs;
343         MacroAssemblerCodeRef getCTIStub(ThunkGenerator generator)
344         {
345             return jitStubs->ctiStub(this, generator);
346         }
347         NativeExecutable* getHostFunction(NativeFunction, Intrinsic);
348         
349         std::unique_ptr<ArityCheckFailReturnThunks> arityCheckFailReturnThunks;
350 #endif // ENABLE(JIT)
351         std::unique_ptr<CommonSlowPaths::ArityCheckData> arityCheckData;
352 #if ENABLE(FTL_JIT)
353         std::unique_ptr<FTL::Thunks> ftlThunks;
354 #endif
355         NativeExecutable* getHostFunction(NativeFunction, NativeFunction constructor);
356
357         static ptrdiff_t exceptionOffset()
358         {
359             return OBJECT_OFFSETOF(VM, m_exception);
360         }
361
362         static ptrdiff_t callFrameForThrowOffset()
363         {
364             return OBJECT_OFFSETOF(VM, callFrameForThrow);
365         }
366
367         static ptrdiff_t targetMachinePCForThrowOffset()
368         {
369             return OBJECT_OFFSETOF(VM, targetMachinePCForThrow);
370         }
371
372         JS_EXPORT_PRIVATE void clearException();
373         JS_EXPORT_PRIVATE void clearExceptionStack();
374         void getExceptionInfo(JSValue& exception, RefCountedArray<StackFrame>& exceptionStack);
375         void setExceptionInfo(JSValue& exception, RefCountedArray<StackFrame>& exceptionStack);
376         JSValue exception() const { return m_exception; }
377         JSValue* addressOfException() { return &m_exception; }
378         const RefCountedArray<StackFrame>& exceptionStack() const { return m_exceptionStack; }
379
380         JS_EXPORT_PRIVATE JSValue throwException(ExecState*, JSValue);
381         JS_EXPORT_PRIVATE JSObject* throwException(ExecState*, JSObject*);
382         
383         void* stackPointerAtVMEntry() const { return m_stackPointerAtVMEntry; }
384         void setStackPointerAtVMEntry(void*);
385
386         size_t reservedZoneSize() const { return m_reservedZoneSize; }
387         size_t updateReservedZoneSize(size_t reservedZoneSize);
388
389 #if ENABLE(FTL_JIT)
390         void updateFTLLargestStackSize(size_t);
391         void** addressOfFTLStackLimit() { return &m_ftlStackLimit; }
392 #endif
393
394 #if !ENABLE(JIT)
395         void* jsStackLimit() { return m_jsStackLimit; }
396         void setJSStackLimit(void* limit) { m_jsStackLimit = limit; }
397 #endif
398         void* stackLimit() { return m_stackLimit; }
399         void** addressOfStackLimit() { return &m_stackLimit; }
400
401         bool isSafeToRecurse(size_t neededStackInBytes = 0) const
402         {
403             ASSERT(wtfThreadData().stack().isGrowingDownward());
404             int8_t* curr = reinterpret_cast<int8_t*>(&curr);
405             int8_t* limit = reinterpret_cast<int8_t*>(m_stackLimit);
406             return curr >= limit && static_cast<size_t>(curr - limit) >= neededStackInBytes;
407         }
408
409         void* lastStackTop() { return m_lastStackTop; }
410         void setLastStackTop(void* lastStackTop) { m_lastStackTop = lastStackTop; }
411
412         const ClassInfo* const jsArrayClassInfo;
413         const ClassInfo* const jsFinalObjectClassInfo;
414
415         JSValue hostCallReturnValue;
416         ExecState* newCallFrameReturnValue;
417         ExecState* callFrameForThrow;
418         void* targetMachinePCForThrow;
419         Instruction* targetInterpreterPCForThrow;
420         uint32_t osrExitIndex;
421         void* osrExitJumpDestination;
422         Vector<ScratchBuffer*> scratchBuffers;
423         size_t sizeOfLastScratchBuffer;
424         
425         ScratchBuffer* scratchBufferForSize(size_t size)
426         {
427             if (!size)
428                 return 0;
429             
430             if (size > sizeOfLastScratchBuffer) {
431                 // Protect against a N^2 memory usage pathology by ensuring
432                 // that at worst, we get a geometric series, meaning that the
433                 // total memory usage is somewhere around
434                 // max(scratch buffer size) * 4.
435                 sizeOfLastScratchBuffer = size * 2;
436
437                 ScratchBuffer* newBuffer = ScratchBuffer::create(sizeOfLastScratchBuffer);
438                 RELEASE_ASSERT(newBuffer);
439                 scratchBuffers.append(newBuffer);
440             }
441
442             ScratchBuffer* result = scratchBuffers.last();
443             result->setActiveLength(0);
444             return result;
445         }
446
447         void gatherConservativeRoots(ConservativeRoots&);
448
449         VMEntryScope* entryScope;
450
451         HashSet<JSObject*> stringRecursionCheckVisitedObjects;
452
453         LocalTimeOffsetCache localTimeOffsetCache;
454         
455         String cachedDateString;
456         double cachedDateStringValue;
457
458         OwnPtr<Profiler::Database> m_perBytecodeProfiler;
459         RefPtr<TypedArrayController> m_typedArrayController;
460         RegExpCache* m_regExpCache;
461         BumpPointerAllocator m_regExpAllocator;
462
463 #if ENABLE(REGEXP_TRACING)
464         typedef ListHashSet<RegExp*> RTTraceList;
465         RTTraceList* m_rtTraceList;
466 #endif
467
468         bool hasExclusiveThread() const { return m_apiLock->hasExclusiveThread(); }
469         std::thread::id exclusiveThread() const { return m_apiLock->exclusiveThread(); }
470         void setExclusiveThread(std::thread::id threadId) { m_apiLock->setExclusiveThread(threadId); }
471
472         JS_EXPORT_PRIVATE void resetDateCache();
473
474         JS_EXPORT_PRIVATE void startSampling();
475         JS_EXPORT_PRIVATE void stopSampling();
476         JS_EXPORT_PRIVATE void dumpSampleData(ExecState* exec);
477         RegExpCache* regExpCache() { return m_regExpCache; }
478 #if ENABLE(REGEXP_TRACING)
479         void addRegExpToTrace(RegExp*);
480 #endif
481         JS_EXPORT_PRIVATE void dumpRegExpTrace();
482
483         bool isCollectorBusy() { return heap.isBusy(); }
484         JS_EXPORT_PRIVATE void releaseExecutableMemory();
485
486 #if ENABLE(GC_VALIDATION)
487         bool isInitializingObject() const; 
488         void setInitializingObjectClass(const ClassInfo*);
489 #endif
490
491         unsigned m_newStringsSinceLastHashCons;
492
493         static const unsigned s_minNumberOfNewStringsToHashCons = 100;
494
495         bool haveEnoughNewStringsToHashCons() { return m_newStringsSinceLastHashCons > s_minNumberOfNewStringsToHashCons; }
496         void resetNewStringsSinceLastHashCons() { m_newStringsSinceLastHashCons = 0; }
497
498         bool currentThreadIsHoldingAPILock() const { return m_apiLock->currentThreadIsHoldingLock(); }
499
500         JSLock& apiLock() { return *m_apiLock; }
501         CodeCache* codeCache() { return m_codeCache.get(); }
502
503         void waitForCompilationsToComplete();
504         
505         JS_EXPORT_PRIVATE void discardAllCode();
506
507         void registerWatchpointForImpureProperty(const Identifier&, Watchpoint*);
508         // FIXME: Use AtomicString once it got merged with Identifier.
509         JS_EXPORT_PRIVATE void addImpureProperty(const String&);
510         
511         BuiltinExecutables* builtinExecutables() { return m_builtinExecutables.get(); }
512
513     private:
514         friend class LLIntOffsetsExtractor;
515         friend class ClearExceptionScope;
516         friend class RecursiveAllocationScope;
517         
518         VM(VMType, HeapType);
519         static VM*& sharedInstanceInternal();
520         void createNativeThunk();
521
522         void updateStackLimit();
523
524 #if ENABLE(ASSEMBLER)
525         bool m_canUseAssembler;
526 #endif
527 #if ENABLE(JIT)
528         bool m_canUseJIT;
529 #endif
530 #if ENABLE(YARR_JIT)
531         bool m_canUseRegExpJIT;
532 #endif
533 #if ENABLE(GC_VALIDATION)
534         const ClassInfo* m_initializingObjectClass;
535 #endif
536         void* m_stackPointerAtVMEntry;
537         size_t m_reservedZoneSize;
538 #if !ENABLE(JIT)
539         struct {
540             void* m_stackLimit;
541             void* m_jsStackLimit;
542         };
543 #else
544         union {
545             void* m_stackLimit;
546             void* m_jsStackLimit;
547         };
548 #if ENABLE(FTL_JIT)
549         void* m_ftlStackLimit;
550         size_t m_largestFTLStackSize;
551 #endif
552 #endif
553         void* m_lastStackTop;
554         JSValue m_exception;
555         bool m_inDefineOwnProperty;
556         OwnPtr<CodeCache> m_codeCache;
557         LegacyProfiler* m_enabledProfiler;
558         OwnPtr<BuiltinExecutables> m_builtinExecutables;
559         RefCountedArray<StackFrame> m_exceptionStack;
560         HashMap<String, RefPtr<WatchpointSet>> m_impurePropertyWatchpointSets;
561     };
562
563 #if ENABLE(GC_VALIDATION)
564     inline bool VM::isInitializingObject() const
565     {
566         return !!m_initializingObjectClass;
567     }
568
569     inline void VM::setInitializingObjectClass(const ClassInfo* initializingObjectClass)
570     {
571         m_initializingObjectClass = initializingObjectClass;
572     }
573 #endif
574
575     inline Heap* WeakSet::heap() const
576     {
577         return &m_vm->heap;
578     }
579
580 #if ENABLE(JIT)
581     extern "C" void sanitizeStackForVMImpl(VM*);
582 #endif
583
584     void sanitizeStackForVM(VM*);
585     void logSanitizeStack(VM*);
586
587 } // namespace JSC
588
589 #endif // VM_h