handles.cc revision 756813857a4c2a4d8ad2e805969d5768d3cf43a0 
1// Copyright 2009 the V8 project authors. All rights reserved.
2// Redistribution and use in source and binary forms, with or without
3// modification, are permitted provided that the following conditions are
4// met:
5//
6//     * Redistributions of source code must retain the above copyright
7//       notice, this list of conditions and the following disclaimer.
8//     * Redistributions in binary form must reproduce the above
9//       copyright notice, this list of conditions and the following
10//       disclaimer in the documentation and/or other materials provided
11//       with the distribution.
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13//       contributors may be used to endorse or promote products derived
14//       from this software without specific prior written permission.
15//
16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28#include "v8.h"
29
30#include "accessors.h"
31#include "api.h"
32#include "arguments.h"
33#include "bootstrapper.h"
34#include "codegen.h"
35#include "compiler.h"
36#include "debug.h"
37#include "execution.h"
38#include "global-handles.h"
39#include "natives.h"
40#include "runtime.h"
41#include "stub-cache.h"
42
43namespace v8 {
44namespace internal {
45
46
47v8::ImplementationUtilities::HandleScopeData HandleScope::current_ =
48    { -1, NULL, NULL };
49
50
51int HandleScope::NumberOfHandles() {
52  int n = HandleScopeImplementer::instance()->blocks()->length();
53  if (n == 0) return 0;
54  return ((n - 1) * kHandleBlockSize) + static_cast<int>(
55      (current_.next - HandleScopeImplementer::instance()->blocks()->last()));
56}
57
58
59Object** HandleScope::Extend() {
60  Object** result = current_.next;
61
62  ASSERT(result == current_.limit);
63  // Make sure there's at least one scope on the stack and that the
64  // top of the scope stack isn't a barrier.
65  if (current_.extensions < 0) {
66    Utils::ReportApiFailure("v8::HandleScope::CreateHandle()",
67                            "Cannot create a handle without a HandleScope");
68    return NULL;
69  }
70  HandleScopeImplementer* impl = HandleScopeImplementer::instance();
71  // If there's more room in the last block, we use that. This is used
72  // for fast creation of scopes after scope barriers.
73  if (!impl->blocks()->is_empty()) {
74    Object** limit = &impl->blocks()->last()[kHandleBlockSize];
75    if (current_.limit != limit) {
76      current_.limit = limit;
77    }
78  }
79
80  // If we still haven't found a slot for the handle, we extend the
81  // current handle scope by allocating a new handle block.
82  if (result == current_.limit) {
83    // If there's a spare block, use it for growing the current scope.
84    result = impl->GetSpareOrNewBlock();
85    // Add the extension to the global list of blocks, but count the
86    // extension as part of the current scope.
87    impl->blocks()->Add(result);
88    current_.extensions++;
89    current_.limit = &result[kHandleBlockSize];
90  }
91
92  return result;
93}
94
95
96void HandleScope::DeleteExtensions() {
97  ASSERT(current_.extensions != 0);
98  HandleScopeImplementer::instance()->DeleteExtensions(current_.extensions);
99}
100
101
102void HandleScope::ZapRange(Object** start, Object** end) {
103  if (start == NULL) return;
104  for (Object** p = start; p < end; p++) {
105    *reinterpret_cast<Address*>(p) = v8::internal::kHandleZapValue;
106  }
107}
108
109
110Address HandleScope::current_extensions_address() {
111  return reinterpret_cast<Address>(&current_.extensions);
112}
113
114
115Address HandleScope::current_next_address() {
116  return reinterpret_cast<Address>(&current_.next);
117}
118
119
120Address HandleScope::current_limit_address() {
121  return reinterpret_cast<Address>(&current_.limit);
122}
123
124
125Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray> content,
126                                      Handle<JSArray> array) {
127  CALL_HEAP_FUNCTION(content->AddKeysFromJSArray(*array), FixedArray);
128}
129
130
131Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first,
132                               Handle<FixedArray> second) {
133  CALL_HEAP_FUNCTION(first->UnionOfKeys(*second), FixedArray);
134}
135
136
137Handle<JSGlobalProxy> ReinitializeJSGlobalProxy(
138    Handle<JSFunction> constructor,
139    Handle<JSGlobalProxy> global) {
140  CALL_HEAP_FUNCTION(Heap::ReinitializeJSGlobalProxy(*constructor, *global),
141                     JSGlobalProxy);
142}
143
144
145void SetExpectedNofProperties(Handle<JSFunction> func, int nof) {
146  func->shared()->set_expected_nof_properties(nof);
147  if (func->has_initial_map()) {
148    Handle<Map> new_initial_map =
149        Factory::CopyMapDropTransitions(Handle<Map>(func->initial_map()));
150    new_initial_map->set_unused_property_fields(nof);
151    func->set_initial_map(*new_initial_map);
152  }
153}
154
155
156void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value) {
157  CALL_HEAP_FUNCTION_VOID(func->SetPrototype(*value));
158}
159
160
161static int ExpectedNofPropertiesFromEstimate(int estimate) {
162  // TODO(1231235): We need dynamic feedback to estimate the number
163  // of expected properties in an object. The static hack below
164  // is barely a solution.
165  if (estimate == 0) return 4;
166  return estimate + 2;
167}
168
169
170void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared,
171                                          int estimate) {
172  shared->set_expected_nof_properties(
173      ExpectedNofPropertiesFromEstimate(estimate));
174}
175
176
177void NormalizeProperties(Handle<JSObject> object,
178                         PropertyNormalizationMode mode,
179                         int expected_additional_properties) {
180  CALL_HEAP_FUNCTION_VOID(object->NormalizeProperties(
181      mode,
182      expected_additional_properties));
183}
184
185
186void NormalizeElements(Handle<JSObject> object) {
187  CALL_HEAP_FUNCTION_VOID(object->NormalizeElements());
188}
189
190
191void TransformToFastProperties(Handle<JSObject> object,
192                               int unused_property_fields) {
193  CALL_HEAP_FUNCTION_VOID(
194      object->TransformToFastProperties(unused_property_fields));
195}
196
197
198void FlattenString(Handle<String> string) {
199  CALL_HEAP_FUNCTION_VOID(string->TryFlatten());
200}
201
202
203Handle<String> FlattenGetString(Handle<String> string) {
204  Handle<String> result;
205  CALL_AND_RETRY(string->TryFlatten(),
206                 { result = Handle<String>(String::cast(__object__));
207                   break; },
208                 return Handle<String>());
209  ASSERT(string->IsFlat());
210  return result;
211}
212
213
214Handle<Object> SetPrototype(Handle<JSFunction> function,
215                            Handle<Object> prototype) {
216  ASSERT(function->should_have_prototype());
217  CALL_HEAP_FUNCTION(Accessors::FunctionSetPrototype(*function,
218                                                     *prototype,
219                                                     NULL),
220                     Object);
221}
222
223
224Handle<Object> SetProperty(Handle<JSObject> object,
225                           Handle<String> key,
226                           Handle<Object> value,
227                           PropertyAttributes attributes) {
228  CALL_HEAP_FUNCTION(object->SetProperty(*key, *value, attributes), Object);
229}
230
231
232Handle<Object> SetProperty(Handle<Object> object,
233                           Handle<Object> key,
234                           Handle<Object> value,
235                           PropertyAttributes attributes) {
236  CALL_HEAP_FUNCTION(
237      Runtime::SetObjectProperty(object, key, value, attributes), Object);
238}
239
240
241Handle<Object> ForceSetProperty(Handle<JSObject> object,
242                                Handle<Object> key,
243                                Handle<Object> value,
244                                PropertyAttributes attributes) {
245  CALL_HEAP_FUNCTION(
246      Runtime::ForceSetObjectProperty(object, key, value, attributes), Object);
247}
248
249
250Handle<Object> SetNormalizedProperty(Handle<JSObject> object,
251                                     Handle<String> key,
252                                     Handle<Object> value,
253                                     PropertyDetails details) {
254  CALL_HEAP_FUNCTION(object->SetNormalizedProperty(*key, *value, details),
255                     Object);
256}
257
258
259Handle<Object> ForceDeleteProperty(Handle<JSObject> object,
260                                   Handle<Object> key) {
261  CALL_HEAP_FUNCTION(Runtime::ForceDeleteObjectProperty(object, key), Object);
262}
263
264
265Handle<Object> IgnoreAttributesAndSetLocalProperty(
266    Handle<JSObject> object,
267    Handle<String> key,
268    Handle<Object> value,
269    PropertyAttributes attributes) {
270  CALL_HEAP_FUNCTION(object->
271      IgnoreAttributesAndSetLocalProperty(*key, *value, attributes), Object);
272}
273
274
275Handle<Object> SetPropertyWithInterceptor(Handle<JSObject> object,
276                                          Handle<String> key,
277                                          Handle<Object> value,
278                                          PropertyAttributes attributes) {
279  CALL_HEAP_FUNCTION(object->SetPropertyWithInterceptor(*key,
280                                                        *value,
281                                                        attributes),
282                     Object);
283}
284
285
286Handle<Object> GetProperty(Handle<JSObject> obj,
287                           const char* name) {
288  Handle<String> str = Factory::LookupAsciiSymbol(name);
289  CALL_HEAP_FUNCTION(obj->GetProperty(*str), Object);
290}
291
292
293Handle<Object> GetProperty(Handle<Object> obj,
294                           Handle<Object> key) {
295  CALL_HEAP_FUNCTION(Runtime::GetObjectProperty(obj, key), Object);
296}
297
298
299Handle<Object> GetElement(Handle<Object> obj,
300                          uint32_t index) {
301  CALL_HEAP_FUNCTION(Runtime::GetElement(obj, index), Object);
302}
303
304
305Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver,
306                                          Handle<JSObject> holder,
307                                          Handle<String> name,
308                                          PropertyAttributes* attributes) {
309  CALL_HEAP_FUNCTION(holder->GetPropertyWithInterceptor(*receiver,
310                                                        *name,
311                                                        attributes),
312                     Object);
313}
314
315
316Handle<Object> GetPrototype(Handle<Object> obj) {
317  Handle<Object> result(obj->GetPrototype());
318  return result;
319}
320
321
322Handle<Object> SetPrototype(Handle<JSObject> obj, Handle<Object> value) {
323  const bool skip_hidden_prototypes = false;
324  CALL_HEAP_FUNCTION(obj->SetPrototype(*value, skip_hidden_prototypes), Object);
325}
326
327
328Handle<Object> GetHiddenProperties(Handle<JSObject> obj,
329                                   bool create_if_needed) {
330  Object* holder = obj->BypassGlobalProxy();
331  if (holder->IsUndefined()) return Factory::undefined_value();
332  obj = Handle<JSObject>(JSObject::cast(holder));
333
334  if (obj->HasFastProperties()) {
335    // If the object has fast properties, check whether the first slot
336    // in the descriptor array matches the hidden symbol. Since the
337    // hidden symbols hash code is zero (and no other string has hash
338    // code zero) it will always occupy the first entry if present.
339    DescriptorArray* descriptors = obj->map()->instance_descriptors();
340    if ((descriptors->number_of_descriptors() > 0) &&
341        (descriptors->GetKey(0) == Heap::hidden_symbol()) &&
342        descriptors->IsProperty(0)) {
343      ASSERT(descriptors->GetType(0) == FIELD);
344      return Handle<Object>(obj->FastPropertyAt(descriptors->GetFieldIndex(0)));
345    }
346  }
347
348  // Only attempt to find the hidden properties in the local object and not
349  // in the prototype chain.  Note that HasLocalProperty() can cause a GC in
350  // the general case in the presence of interceptors.
351  if (!obj->HasHiddenPropertiesObject()) {
352    // Hidden properties object not found. Allocate a new hidden properties
353    // object if requested. Otherwise return the undefined value.
354    if (create_if_needed) {
355      Handle<Object> hidden_obj = Factory::NewJSObject(Top::object_function());
356      CALL_HEAP_FUNCTION(obj->SetHiddenPropertiesObject(*hidden_obj), Object);
357    } else {
358      return Factory::undefined_value();
359    }
360  }
361  return Handle<Object>(obj->GetHiddenPropertiesObject());
362}
363
364
365Handle<Object> DeleteElement(Handle<JSObject> obj,
366                             uint32_t index) {
367  CALL_HEAP_FUNCTION(obj->DeleteElement(index, JSObject::NORMAL_DELETION),
368                     Object);
369}
370
371
372Handle<Object> DeleteProperty(Handle<JSObject> obj,
373                              Handle<String> prop) {
374  CALL_HEAP_FUNCTION(obj->DeleteProperty(*prop, JSObject::NORMAL_DELETION),
375                     Object);
376}
377
378
379Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index) {
380  CALL_HEAP_FUNCTION(Heap::LookupSingleCharacterStringFromCode(index), Object);
381}
382
383
384Handle<String> SubString(Handle<String> str,
385                         int start,
386                         int end,
387                         PretenureFlag pretenure) {
388  CALL_HEAP_FUNCTION(str->SubString(start, end, pretenure), String);
389}
390
391
392Handle<Object> SetElement(Handle<JSObject> object,
393                          uint32_t index,
394                          Handle<Object> value) {
395  if (object->HasPixelElements() || object->HasExternalArrayElements()) {
396    if (!value->IsSmi() && !value->IsHeapNumber() && !value->IsUndefined()) {
397      bool has_exception;
398      Handle<Object> number = Execution::ToNumber(value, &has_exception);
399      if (has_exception) return Handle<Object>();
400      value = number;
401    }
402  }
403  CALL_HEAP_FUNCTION(object->SetElement(index, *value), Object);
404}
405
406
407Handle<JSObject> Copy(Handle<JSObject> obj) {
408  CALL_HEAP_FUNCTION(Heap::CopyJSObject(*obj), JSObject);
409}
410
411
412Handle<Object> SetAccessor(Handle<JSObject> obj, Handle<AccessorInfo> info) {
413  CALL_HEAP_FUNCTION(obj->DefineAccessor(*info), Object);
414}
415
416
417// Wrappers for scripts are kept alive and cached in weak global
418// handles referred from proxy objects held by the scripts as long as
419// they are used. When they are not used anymore, the garbage
420// collector will call the weak callback on the global handle
421// associated with the wrapper and get rid of both the wrapper and the
422// handle.
423static void ClearWrapperCache(Persistent<v8::Value> handle, void*) {
424#ifdef ENABLE_HEAP_PROTECTION
425  // Weak reference callbacks are called as if from outside V8.  We
426  // need to reeenter to unprotect the heap.
427  VMState state(OTHER);
428#endif
429  Handle<Object> cache = Utils::OpenHandle(*handle);
430  JSValue* wrapper = JSValue::cast(*cache);
431  Proxy* proxy = Script::cast(wrapper->value())->wrapper();
432  ASSERT(proxy->proxy() == reinterpret_cast<Address>(cache.location()));
433  proxy->set_proxy(0);
434  GlobalHandles::Destroy(cache.location());
435  Counters::script_wrappers.Decrement();
436}
437
438
439Handle<JSValue> GetScriptWrapper(Handle<Script> script) {
440  if (script->wrapper()->proxy() != NULL) {
441    // Return the script wrapper directly from the cache.
442    return Handle<JSValue>(
443        reinterpret_cast<JSValue**>(script->wrapper()->proxy()));
444  }
445
446  // Construct a new script wrapper.
447  Counters::script_wrappers.Increment();
448  Handle<JSFunction> constructor = Top::script_function();
449  Handle<JSValue> result =
450      Handle<JSValue>::cast(Factory::NewJSObject(constructor));
451  result->set_value(*script);
452
453  // Create a new weak global handle and use it to cache the wrapper
454  // for future use. The cache will automatically be cleared by the
455  // garbage collector when it is not used anymore.
456  Handle<Object> handle = GlobalHandles::Create(*result);
457  GlobalHandles::MakeWeak(handle.location(), NULL, &ClearWrapperCache);
458  script->wrapper()->set_proxy(reinterpret_cast<Address>(handle.location()));
459  return result;
460}
461
462
463// Init line_ends array with code positions of line ends inside script
464// source.
465void InitScriptLineEnds(Handle<Script> script) {
466  if (!script->line_ends()->IsUndefined()) return;
467
468  if (!script->source()->IsString()) {
469    ASSERT(script->source()->IsUndefined());
470    script->set_line_ends(*(Factory::NewFixedArray(0)));
471    ASSERT(script->line_ends()->IsFixedArray());
472    return;
473  }
474
475  Handle<String> src(String::cast(script->source()));
476
477  Handle<FixedArray> array = CalculateLineEnds(src, true);
478
479  script->set_line_ends(*array);
480  ASSERT(script->line_ends()->IsFixedArray());
481}
482
483
484Handle<FixedArray> CalculateLineEnds(Handle<String> src,
485                                     bool with_imaginary_last_new_line) {
486  const int src_len = src->length();
487  Handle<String> new_line = Factory::NewStringFromAscii(CStrVector("\n"));
488
489  // Pass 1: Identify line count.
490  int line_count = 0;
491  int position = 0;
492  while (position != -1 && position < src_len) {
493    position = Runtime::StringMatch(src, new_line, position);
494    if (position != -1) {
495      position++;
496    }
497    if (position != -1) {
498      line_count++;
499    } else if (with_imaginary_last_new_line) {
500      // Even if the last line misses a line end, it is counted.
501      line_count++;
502    }
503  }
504
505  // Pass 2: Fill in line ends positions
506  Handle<FixedArray> array = Factory::NewFixedArray(line_count);
507  int array_index = 0;
508  position = 0;
509  while (position != -1 && position < src_len) {
510    position = Runtime::StringMatch(src, new_line, position);
511    if (position != -1) {
512      array->set(array_index++, Smi::FromInt(position++));
513    } else if (with_imaginary_last_new_line) {
514      // If the script does not end with a line ending add the final end
515      // position as just past the last line ending.
516      array->set(array_index++, Smi::FromInt(src_len));
517    }
518  }
519  ASSERT(array_index == line_count);
520
521  return array;
522}
523
524
525// Convert code position into line number.
526int GetScriptLineNumber(Handle<Script> script, int code_pos) {
527  InitScriptLineEnds(script);
528  AssertNoAllocation no_allocation;
529  FixedArray* line_ends_array = FixedArray::cast(script->line_ends());
530  const int line_ends_len = line_ends_array->length();
531
532  if (!line_ends_len)
533    return -1;
534
535  if ((Smi::cast(line_ends_array->get(0)))->value() >= code_pos)
536    return script->line_offset()->value();
537
538  int left = 0;
539  int right = line_ends_len;
540  while (int half = (right - left) / 2) {
541    if ((Smi::cast(line_ends_array->get(left + half)))->value() > code_pos) {
542      right -= half;
543    } else {
544      left += half;
545    }
546  }
547  return right + script->line_offset()->value();
548}
549
550
551int GetScriptLineNumberSafe(Handle<Script> script, int code_pos) {
552  AssertNoAllocation no_allocation;
553  if (!script->line_ends()->IsUndefined()) {
554    return GetScriptLineNumber(script, code_pos);
555  }
556  // Slow mode: we do not have line_ends. We have to iterate through source.
557  if (!script->source()->IsString()) {
558    return -1;
559  }
560  String* source = String::cast(script->source());
561  int line = 0;
562  int len = source->length();
563  for (int pos = 0; pos < len; pos++) {
564    if (pos == code_pos) {
565      break;
566    }
567    if (source->Get(pos) == '\n') {
568      line++;
569    }
570  }
571  return line;
572}
573
574
575void CustomArguments::IterateInstance(ObjectVisitor* v) {
576  v->VisitPointers(values_, values_ + ARRAY_SIZE(values_));
577}
578
579
580// Compute the property keys from the interceptor.
581v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSObject> receiver,
582                                                 Handle<JSObject> object) {
583  Handle<InterceptorInfo> interceptor(object->GetNamedInterceptor());
584  CustomArguments args(interceptor->data(), *receiver, *object);
585  v8::AccessorInfo info(args.end());
586  v8::Handle<v8::Array> result;
587  if (!interceptor->enumerator()->IsUndefined()) {
588    v8::NamedPropertyEnumerator enum_fun =
589        v8::ToCData<v8::NamedPropertyEnumerator>(interceptor->enumerator());
590    LOG(ApiObjectAccess("interceptor-named-enum", *object));
591    {
592      // Leaving JavaScript.
593      VMState state(EXTERNAL);
594      result = enum_fun(info);
595    }
596  }
597  return result;
598}
599
600
601// Compute the element keys from the interceptor.
602v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSObject> receiver,
603                                                   Handle<JSObject> object) {
604  Handle<InterceptorInfo> interceptor(object->GetIndexedInterceptor());
605  CustomArguments args(interceptor->data(), *receiver, *object);
606  v8::AccessorInfo info(args.end());
607  v8::Handle<v8::Array> result;
608  if (!interceptor->enumerator()->IsUndefined()) {
609    v8::IndexedPropertyEnumerator enum_fun =
610        v8::ToCData<v8::IndexedPropertyEnumerator>(interceptor->enumerator());
611    LOG(ApiObjectAccess("interceptor-indexed-enum", *object));
612    {
613      // Leaving JavaScript.
614      VMState state(EXTERNAL);
615      result = enum_fun(info);
616    }
617  }
618  return result;
619}
620
621
622Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSObject> object,
623                                          KeyCollectionType type) {
624  Handle<FixedArray> content = Factory::empty_fixed_array();
625  Handle<JSObject> arguments_boilerplate =
626      Handle<JSObject>(
627          Top::context()->global_context()->arguments_boilerplate());
628  Handle<JSFunction> arguments_function =
629      Handle<JSFunction>(
630          JSFunction::cast(arguments_boilerplate->map()->constructor()));
631
632  // Only collect keys if access is permitted.
633  for (Handle<Object> p = object;
634       *p != Heap::null_value();
635       p = Handle<Object>(p->GetPrototype())) {
636    Handle<JSObject> current(JSObject::cast(*p));
637
638    // Check access rights if required.
639    if (current->IsAccessCheckNeeded() &&
640        !Top::MayNamedAccess(*current, Heap::undefined_value(),
641                             v8::ACCESS_KEYS)) {
642      Top::ReportFailedAccessCheck(*current, v8::ACCESS_KEYS);
643      break;
644    }
645
646    // Compute the element keys.
647    Handle<FixedArray> element_keys =
648        Factory::NewFixedArray(current->NumberOfEnumElements());
649    current->GetEnumElementKeys(*element_keys);
650    content = UnionOfKeys(content, element_keys);
651
652    // Add the element keys from the interceptor.
653    if (current->HasIndexedInterceptor()) {
654      v8::Handle<v8::Array> result =
655          GetKeysForIndexedInterceptor(object, current);
656      if (!result.IsEmpty())
657        content = AddKeysFromJSArray(content, v8::Utils::OpenHandle(*result));
658    }
659
660    // We can cache the computed property keys if access checks are
661    // not needed and no interceptors are involved.
662    //
663    // We do not use the cache if the object has elements and
664    // therefore it does not make sense to cache the property names
665    // for arguments objects.  Arguments objects will always have
666    // elements.
667    // Wrapped strings have elements, but don't have an elements
668    // array or dictionary.  So the fast inline test for whether to
669    // use the cache says yes, so we should not create a cache.
670    bool cache_enum_keys =
671        ((current->map()->constructor() != *arguments_function) &&
672         !current->IsJSValue() &&
673         !current->IsAccessCheckNeeded() &&
674         !current->HasNamedInterceptor() &&
675         !current->HasIndexedInterceptor());
676    // Compute the property keys and cache them if possible.
677    content =
678        UnionOfKeys(content, GetEnumPropertyKeys(current, cache_enum_keys));
679
680    // Add the property keys from the interceptor.
681    if (current->HasNamedInterceptor()) {
682      v8::Handle<v8::Array> result =
683          GetKeysForNamedInterceptor(object, current);
684      if (!result.IsEmpty())
685        content = AddKeysFromJSArray(content, v8::Utils::OpenHandle(*result));
686    }
687
688    // If we only want local properties we bail out after the first
689    // iteration.
690    if (type == LOCAL_ONLY)
691      break;
692  }
693  return content;
694}
695
696
697Handle<JSArray> GetKeysFor(Handle<JSObject> object) {
698  Counters::for_in.Increment();
699  Handle<FixedArray> elements = GetKeysInFixedArrayFor(object,
700                                                       INCLUDE_PROTOS);
701  return Factory::NewJSArrayWithElements(elements);
702}
703
704
705Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
706                                       bool cache_result) {
707  int index = 0;
708  if (object->HasFastProperties()) {
709    if (object->map()->instance_descriptors()->HasEnumCache()) {
710      Counters::enum_cache_hits.Increment();
711      DescriptorArray* desc = object->map()->instance_descriptors();
712      return Handle<FixedArray>(FixedArray::cast(desc->GetEnumCache()));
713    }
714    Counters::enum_cache_misses.Increment();
715    int num_enum = object->NumberOfEnumProperties();
716    Handle<FixedArray> storage = Factory::NewFixedArray(num_enum);
717    Handle<FixedArray> sort_array = Factory::NewFixedArray(num_enum);
718    Handle<DescriptorArray> descs =
719        Handle<DescriptorArray>(object->map()->instance_descriptors());
720    for (int i = 0; i < descs->number_of_descriptors(); i++) {
721      if (descs->IsProperty(i) && !descs->IsDontEnum(i)) {
722        (*storage)->set(index, descs->GetKey(i));
723        PropertyDetails details(descs->GetDetails(i));
724        (*sort_array)->set(index, Smi::FromInt(details.index()));
725        index++;
726      }
727    }
728    (*storage)->SortPairs(*sort_array, sort_array->length());
729    if (cache_result) {
730      Handle<FixedArray> bridge_storage =
731          Factory::NewFixedArray(DescriptorArray::kEnumCacheBridgeLength);
732      DescriptorArray* desc = object->map()->instance_descriptors();
733      desc->SetEnumCache(*bridge_storage, *storage);
734    }
735    ASSERT(storage->length() == index);
736    return storage;
737  } else {
738    int num_enum = object->NumberOfEnumProperties();
739    Handle<FixedArray> storage = Factory::NewFixedArray(num_enum);
740    Handle<FixedArray> sort_array = Factory::NewFixedArray(num_enum);
741    object->property_dictionary()->CopyEnumKeysTo(*storage, *sort_array);
742    return storage;
743  }
744}
745
746
747bool EnsureCompiled(Handle<SharedFunctionInfo> shared,
748                    ClearExceptionFlag flag) {
749  return shared->is_compiled() || CompileLazyShared(shared, flag);
750}
751
752
753static bool CompileLazyHelper(CompilationInfo* info,
754                              ClearExceptionFlag flag) {
755  // Compile the source information to a code object.
756  ASSERT(!info->shared_info()->is_compiled());
757  bool result = Compiler::CompileLazy(info);
758  ASSERT(result != Top::has_pending_exception());
759  if (!result && flag == CLEAR_EXCEPTION) Top::clear_pending_exception();
760  return result;
761}
762
763
764bool CompileLazyShared(Handle<SharedFunctionInfo> shared,
765                       ClearExceptionFlag flag) {
766  CompilationInfo info(shared);
767  return CompileLazyHelper(&info, flag);
768}
769
770
771bool CompileLazy(Handle<JSFunction> function,
772                 Handle<Object> receiver,
773                 ClearExceptionFlag flag) {
774  if (function->shared()->is_compiled()) {
775    function->set_code(function->shared()->code());
776    function->shared()->set_code_age(0);
777    return true;
778  } else {
779    CompilationInfo info(function, 0, receiver);
780    bool result = CompileLazyHelper(&info, flag);
781    PROFILE(FunctionCreateEvent(*function));
782    return result;
783  }
784}
785
786
787bool CompileLazyInLoop(Handle<JSFunction> function,
788                       Handle<Object> receiver,
789                       ClearExceptionFlag flag) {
790  if (function->shared()->is_compiled()) {
791    function->set_code(function->shared()->code());
792    function->shared()->set_code_age(0);
793    return true;
794  } else {
795    CompilationInfo info(function, 1, receiver);
796    bool result = CompileLazyHelper(&info, flag);
797    PROFILE(FunctionCreateEvent(*function));
798    return result;
799  }
800}
801
802
803OptimizedObjectForAddingMultipleProperties::
804OptimizedObjectForAddingMultipleProperties(Handle<JSObject> object,
805                                           int expected_additional_properties,
806                                           bool condition) {
807  object_ = object;
808  if (condition && object_->HasFastProperties()) {
809    // Normalize the properties of object to avoid n^2 behavior
810    // when extending the object multiple properties. Indicate the number of
811    // properties to be added.
812    unused_property_fields_ = object->map()->unused_property_fields();
813    NormalizeProperties(object_,
814                        KEEP_INOBJECT_PROPERTIES,
815                        expected_additional_properties);
816    has_been_transformed_ = true;
817
818  } else {
819    has_been_transformed_ = false;
820  }
821}
822
823
824OptimizedObjectForAddingMultipleProperties::
825~OptimizedObjectForAddingMultipleProperties() {
826  // Reoptimize the object to allow fast property access.
827  if (has_been_transformed_) {
828    TransformToFastProperties(object_, unused_property_fields_);
829  }
830}
831
832} }  // namespace v8::internal
833