1// Copyright 2012 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.
12//     * Neither the name of Google Inc. nor the names of its
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
24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 "compiler.h"
35#include "debug.h"
36#include "execution.h"
37#include "global-handles.h"
38#include "natives.h"
39#include "runtime.h"
40#include "string-search.h"
41#include "stub-cache.h"
42#include "vm-state-inl.h"
43
44namespace v8 {
45namespace internal {
46
47
48int HandleScope::NumberOfHandles(Isolate* isolate) {
49  HandleScopeImplementer* impl = isolate->handle_scope_implementer();
50  int n = impl->blocks()->length();
51  if (n == 0) return 0;
52  return ((n - 1) * kHandleBlockSize) + static_cast<int>(
53      (isolate->handle_scope_data()->next - impl->blocks()->last()));
54}
55
56
57Object** HandleScope::Extend(Isolate* isolate) {
58  v8::ImplementationUtilities::HandleScopeData* current =
59      isolate->handle_scope_data();
60
61  Object** result = current->next;
62
63  ASSERT(result == current->limit);
64  // Make sure there's at least one scope on the stack and that the
65  // top of the scope stack isn't a barrier.
66  if (current->level == 0) {
67    Utils::ReportApiFailure("v8::HandleScope::CreateHandle()",
68                            "Cannot create a handle without a HandleScope");
69    return NULL;
70  }
71  HandleScopeImplementer* impl = isolate->handle_scope_implementer();
72  // If there's more room in the last block, we use that. This is used
73  // for fast creation of scopes after scope barriers.
74  if (!impl->blocks()->is_empty()) {
75    Object** limit = &impl->blocks()->last()[kHandleBlockSize];
76    if (current->limit != limit) {
77      current->limit = limit;
78      ASSERT(limit - current->next < kHandleBlockSize);
79    }
80  }
81
82  // If we still haven't found a slot for the handle, we extend the
83  // current handle scope by allocating a new handle block.
84  if (result == current->limit) {
85    // If there's a spare block, use it for growing the current scope.
86    result = impl->GetSpareOrNewBlock();
87    // Add the extension to the global list of blocks, but count the
88    // extension as part of the current scope.
89    impl->blocks()->Add(result);
90    current->limit = &result[kHandleBlockSize];
91  }
92
93  return result;
94}
95
96
97void HandleScope::DeleteExtensions(Isolate* isolate) {
98  v8::ImplementationUtilities::HandleScopeData* current =
99      isolate->handle_scope_data();
100  isolate->handle_scope_implementer()->DeleteExtensions(current->limit);
101}
102
103
104#ifdef ENABLE_HANDLE_ZAPPING
105void HandleScope::ZapRange(Object** start, Object** end) {
106  ASSERT(end - start <= kHandleBlockSize);
107  for (Object** p = start; p != end; p++) {
108    *reinterpret_cast<Address*>(p) = v8::internal::kHandleZapValue;
109  }
110}
111#endif
112
113
114Address HandleScope::current_level_address(Isolate* isolate) {
115  return reinterpret_cast<Address>(&isolate->handle_scope_data()->level);
116}
117
118
119Address HandleScope::current_next_address(Isolate* isolate) {
120  return reinterpret_cast<Address>(&isolate->handle_scope_data()->next);
121}
122
123
124Address HandleScope::current_limit_address(Isolate* isolate) {
125  return reinterpret_cast<Address>(&isolate->handle_scope_data()->limit);
126}
127
128
129Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray> content,
130                                      Handle<JSArray> array) {
131  CALL_HEAP_FUNCTION(content->GetIsolate(),
132                     content->AddKeysFromJSArray(*array), FixedArray);
133}
134
135
136Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first,
137                               Handle<FixedArray> second) {
138  CALL_HEAP_FUNCTION(first->GetIsolate(),
139                     first->UnionOfKeys(*second), FixedArray);
140}
141
142
143Handle<JSGlobalProxy> ReinitializeJSGlobalProxy(
144    Handle<JSFunction> constructor,
145    Handle<JSGlobalProxy> global) {
146  CALL_HEAP_FUNCTION(
147      constructor->GetIsolate(),
148      constructor->GetHeap()->ReinitializeJSGlobalProxy(*constructor, *global),
149      JSGlobalProxy);
150}
151
152
153void FlattenString(Handle<String> string) {
154  CALL_HEAP_FUNCTION_VOID(string->GetIsolate(), string->TryFlatten());
155}
156
157
158Handle<String> FlattenGetString(Handle<String> string) {
159  CALL_HEAP_FUNCTION(string->GetIsolate(), string->TryFlatten(), String);
160}
161
162
163Handle<Object> ForceSetProperty(Handle<JSObject> object,
164                                Handle<Object> key,
165                                Handle<Object> value,
166                                PropertyAttributes attributes) {
167  return Runtime::ForceSetObjectProperty(object->GetIsolate(), object, key,
168                                        value, attributes);
169}
170
171
172Handle<Object> DeleteProperty(Handle<JSObject> object, Handle<Object> key) {
173  Isolate* isolate = object->GetIsolate();
174  CALL_HEAP_FUNCTION(isolate,
175                     Runtime::DeleteObjectProperty(
176                         isolate, object, key, JSReceiver::NORMAL_DELETION),
177                     Object);
178}
179
180
181Handle<Object> ForceDeleteProperty(Handle<JSObject> object,
182                                   Handle<Object> key) {
183  Isolate* isolate = object->GetIsolate();
184  CALL_HEAP_FUNCTION(isolate,
185                     Runtime::DeleteObjectProperty(
186                         isolate, object, key, JSReceiver::FORCE_DELETION),
187                     Object);
188}
189
190
191Handle<Object> HasProperty(Handle<JSReceiver> obj, Handle<Object> key) {
192  Isolate* isolate = obj->GetIsolate();
193  CALL_HEAP_FUNCTION(isolate,
194                     Runtime::HasObjectProperty(isolate, obj, key), Object);
195}
196
197
198Handle<Object> GetProperty(Handle<JSReceiver> obj,
199                           const char* name) {
200  Isolate* isolate = obj->GetIsolate();
201  Handle<String> str = isolate->factory()->InternalizeUtf8String(name);
202  CALL_HEAP_FUNCTION(isolate, obj->GetProperty(*str), Object);
203}
204
205
206Handle<Object> GetProperty(Isolate* isolate,
207                           Handle<Object> obj,
208                           Handle<Object> key) {
209  CALL_HEAP_FUNCTION(isolate,
210                     Runtime::GetObjectProperty(isolate, obj, key), Object);
211}
212
213
214Handle<Object> LookupSingleCharacterStringFromCode(Isolate* isolate,
215                                                   uint32_t index) {
216  CALL_HEAP_FUNCTION(
217      isolate,
218      isolate->heap()->LookupSingleCharacterStringFromCode(index), Object);
219}
220
221
222// Wrappers for scripts are kept alive and cached in weak global
223// handles referred from foreign objects held by the scripts as long as
224// they are used. When they are not used anymore, the garbage
225// collector will call the weak callback on the global handle
226// associated with the wrapper and get rid of both the wrapper and the
227// handle.
228static void ClearWrapperCache(v8::Isolate* v8_isolate,
229                              Persistent<v8::Value>* handle,
230                              void*) {
231  Handle<Object> cache = Utils::OpenPersistent(handle);
232  JSValue* wrapper = JSValue::cast(*cache);
233  Foreign* foreign = Script::cast(wrapper->value())->wrapper();
234  ASSERT(foreign->foreign_address() ==
235         reinterpret_cast<Address>(cache.location()));
236  foreign->set_foreign_address(0);
237  Isolate* isolate = reinterpret_cast<Isolate*>(v8_isolate);
238  isolate->global_handles()->Destroy(cache.location());
239  isolate->counters()->script_wrappers()->Decrement();
240}
241
242
243Handle<JSValue> GetScriptWrapper(Handle<Script> script) {
244  if (script->wrapper()->foreign_address() != NULL) {
245    // Return a handle for the existing script wrapper from the cache.
246    return Handle<JSValue>(
247        *reinterpret_cast<JSValue**>(script->wrapper()->foreign_address()));
248  }
249  Isolate* isolate = script->GetIsolate();
250  // Construct a new script wrapper.
251  isolate->counters()->script_wrappers()->Increment();
252  Handle<JSFunction> constructor = isolate->script_function();
253  Handle<JSValue> result =
254      Handle<JSValue>::cast(isolate->factory()->NewJSObject(constructor));
255
256  // The allocation might have triggered a GC, which could have called this
257  // function recursively, and a wrapper has already been created and cached.
258  // In that case, simply return a handle for the cached wrapper.
259  if (script->wrapper()->foreign_address() != NULL) {
260    return Handle<JSValue>(
261        *reinterpret_cast<JSValue**>(script->wrapper()->foreign_address()));
262  }
263
264  result->set_value(*script);
265
266  // Create a new weak global handle and use it to cache the wrapper
267  // for future use. The cache will automatically be cleared by the
268  // garbage collector when it is not used anymore.
269  Handle<Object> handle = isolate->global_handles()->Create(*result);
270  isolate->global_handles()->MakeWeak(handle.location(),
271                                      NULL,
272                                      &ClearWrapperCache);
273  script->wrapper()->set_foreign_address(
274      reinterpret_cast<Address>(handle.location()));
275  return result;
276}
277
278
279// Init line_ends array with code positions of line ends inside script
280// source.
281void InitScriptLineEnds(Handle<Script> script) {
282  if (!script->line_ends()->IsUndefined()) return;
283
284  Isolate* isolate = script->GetIsolate();
285
286  if (!script->source()->IsString()) {
287    ASSERT(script->source()->IsUndefined());
288    Handle<FixedArray> empty = isolate->factory()->NewFixedArray(0);
289    script->set_line_ends(*empty);
290    ASSERT(script->line_ends()->IsFixedArray());
291    return;
292  }
293
294  Handle<String> src(String::cast(script->source()), isolate);
295
296  Handle<FixedArray> array = CalculateLineEnds(src, true);
297
298  if (*array != isolate->heap()->empty_fixed_array()) {
299    array->set_map(isolate->heap()->fixed_cow_array_map());
300  }
301
302  script->set_line_ends(*array);
303  ASSERT(script->line_ends()->IsFixedArray());
304}
305
306
307template <typename SourceChar>
308static void CalculateLineEnds(Isolate* isolate,
309                              List<int>* line_ends,
310                              Vector<const SourceChar> src,
311                              bool with_last_line) {
312  const int src_len = src.length();
313  StringSearch<uint8_t, SourceChar> search(isolate, STATIC_ASCII_VECTOR("\n"));
314
315  // Find and record line ends.
316  int position = 0;
317  while (position != -1 && position < src_len) {
318    position = search.Search(src, position);
319    if (position != -1) {
320      line_ends->Add(position);
321      position++;
322    } else if (with_last_line) {
323      // Even if the last line misses a line end, it is counted.
324      line_ends->Add(src_len);
325      return;
326    }
327  }
328}
329
330
331Handle<FixedArray> CalculateLineEnds(Handle<String> src,
332                                     bool with_last_line) {
333  src = FlattenGetString(src);
334  // Rough estimate of line count based on a roughly estimated average
335  // length of (unpacked) code.
336  int line_count_estimate = src->length() >> 4;
337  List<int> line_ends(line_count_estimate);
338  Isolate* isolate = src->GetIsolate();
339  {
340    DisallowHeapAllocation no_allocation;  // ensure vectors stay valid.
341    // Dispatch on type of strings.
342    String::FlatContent content = src->GetFlatContent();
343    ASSERT(content.IsFlat());
344    if (content.IsAscii()) {
345      CalculateLineEnds(isolate,
346                        &line_ends,
347                        content.ToOneByteVector(),
348                        with_last_line);
349    } else {
350      CalculateLineEnds(isolate,
351                        &line_ends,
352                        content.ToUC16Vector(),
353                        with_last_line);
354    }
355  }
356  int line_count = line_ends.length();
357  Handle<FixedArray> array = isolate->factory()->NewFixedArray(line_count);
358  for (int i = 0; i < line_count; i++) {
359    array->set(i, Smi::FromInt(line_ends[i]));
360  }
361  return array;
362}
363
364
365// Convert code position into line number.
366int GetScriptLineNumber(Handle<Script> script, int code_pos) {
367  InitScriptLineEnds(script);
368  DisallowHeapAllocation no_allocation;
369  FixedArray* line_ends_array = FixedArray::cast(script->line_ends());
370  const int line_ends_len = line_ends_array->length();
371
372  if (!line_ends_len) return -1;
373
374  if ((Smi::cast(line_ends_array->get(0)))->value() >= code_pos) {
375    return script->line_offset()->value();
376  }
377
378  int left = 0;
379  int right = line_ends_len;
380  while (int half = (right - left) / 2) {
381    if ((Smi::cast(line_ends_array->get(left + half)))->value() > code_pos) {
382      right -= half;
383    } else {
384      left += half;
385    }
386  }
387  return right + script->line_offset()->value();
388}
389
390
391// Convert code position into column number.
392int GetScriptColumnNumber(Handle<Script> script, int code_pos) {
393  int line_number = GetScriptLineNumber(script, code_pos);
394  if (line_number == -1) return -1;
395
396  DisallowHeapAllocation no_allocation;
397  FixedArray* line_ends_array = FixedArray::cast(script->line_ends());
398  line_number = line_number - script->line_offset()->value();
399  if (line_number == 0) return code_pos + script->column_offset()->value();
400  int prev_line_end_pos =
401      Smi::cast(line_ends_array->get(line_number - 1))->value();
402  return code_pos - (prev_line_end_pos + 1);
403}
404
405
406int GetScriptLineNumberSafe(Handle<Script> script, int code_pos) {
407  DisallowHeapAllocation no_allocation;
408  if (!script->line_ends()->IsUndefined()) {
409    return GetScriptLineNumber(script, code_pos);
410  }
411  // Slow mode: we do not have line_ends. We have to iterate through source.
412  if (!script->source()->IsString()) {
413    return -1;
414  }
415  String* source = String::cast(script->source());
416  int line = 0;
417  int len = source->length();
418  for (int pos = 0; pos < len; pos++) {
419    if (pos == code_pos) {
420      break;
421    }
422    if (source->Get(pos) == '\n') {
423      line++;
424    }
425  }
426  return line;
427}
428
429
430// Compute the property keys from the interceptor.
431// TODO(rossberg): support symbols in API, and filter here if needed.
432v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSReceiver> receiver,
433                                                 Handle<JSObject> object) {
434  Isolate* isolate = receiver->GetIsolate();
435  Handle<InterceptorInfo> interceptor(object->GetNamedInterceptor());
436  PropertyCallbackArguments
437      args(isolate, interceptor->data(), *receiver, *object);
438  v8::Handle<v8::Array> result;
439  if (!interceptor->enumerator()->IsUndefined()) {
440    v8::NamedPropertyEnumeratorCallback enum_fun =
441        v8::ToCData<v8::NamedPropertyEnumeratorCallback>(
442            interceptor->enumerator());
443    LOG(isolate, ApiObjectAccess("interceptor-named-enum", *object));
444    result = args.Call(enum_fun);
445  }
446#if ENABLE_EXTRA_CHECKS
447  CHECK(result.IsEmpty() || v8::Utils::OpenHandle(*result)->IsJSObject());
448#endif
449  return v8::Local<v8::Array>::New(reinterpret_cast<v8::Isolate*>(isolate),
450                                   result);
451}
452
453
454// Compute the element keys from the interceptor.
455v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSReceiver> receiver,
456                                                   Handle<JSObject> object) {
457  Isolate* isolate = receiver->GetIsolate();
458  Handle<InterceptorInfo> interceptor(object->GetIndexedInterceptor());
459  PropertyCallbackArguments
460      args(isolate, interceptor->data(), *receiver, *object);
461  v8::Handle<v8::Array> result;
462  if (!interceptor->enumerator()->IsUndefined()) {
463    v8::IndexedPropertyEnumeratorCallback enum_fun =
464        v8::ToCData<v8::IndexedPropertyEnumeratorCallback>(
465            interceptor->enumerator());
466    LOG(isolate, ApiObjectAccess("interceptor-indexed-enum", *object));
467    result = args.Call(enum_fun);
468#if ENABLE_EXTRA_CHECKS
469    CHECK(result.IsEmpty() || v8::Utils::OpenHandle(*result)->IsJSObject());
470#endif
471  }
472  return v8::Local<v8::Array>::New(reinterpret_cast<v8::Isolate*>(isolate),
473                                   result);
474}
475
476
477Handle<Object> GetScriptNameOrSourceURL(Handle<Script> script) {
478  Isolate* isolate = script->GetIsolate();
479  Handle<String> name_or_source_url_key =
480      isolate->factory()->InternalizeOneByteString(
481          STATIC_ASCII_VECTOR("nameOrSourceURL"));
482  Handle<JSValue> script_wrapper = GetScriptWrapper(script);
483  Handle<Object> property = GetProperty(isolate,
484                                        script_wrapper,
485                                        name_or_source_url_key);
486  ASSERT(property->IsJSFunction());
487  Handle<JSFunction> method = Handle<JSFunction>::cast(property);
488  bool caught_exception;
489  Handle<Object> result = Execution::TryCall(method, script_wrapper, 0,
490                                             NULL, &caught_exception);
491  if (caught_exception) {
492    result = isolate->factory()->undefined_value();
493  }
494  return result;
495}
496
497
498static bool ContainsOnlyValidKeys(Handle<FixedArray> array) {
499  int len = array->length();
500  for (int i = 0; i < len; i++) {
501    Object* e = array->get(i);
502    if (!(e->IsString() || e->IsNumber())) return false;
503  }
504  return true;
505}
506
507
508Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSReceiver> object,
509                                          KeyCollectionType type,
510                                          bool* threw) {
511  USE(ContainsOnlyValidKeys);
512  Isolate* isolate = object->GetIsolate();
513  Handle<FixedArray> content = isolate->factory()->empty_fixed_array();
514  Handle<JSObject> arguments_boilerplate = Handle<JSObject>(
515      isolate->context()->native_context()->arguments_boilerplate(),
516      isolate);
517  Handle<JSFunction> arguments_function = Handle<JSFunction>(
518      JSFunction::cast(arguments_boilerplate->map()->constructor()),
519      isolate);
520
521  // Only collect keys if access is permitted.
522  for (Handle<Object> p = object;
523       *p != isolate->heap()->null_value();
524       p = Handle<Object>(p->GetPrototype(isolate), isolate)) {
525    if (p->IsJSProxy()) {
526      Handle<JSProxy> proxy(JSProxy::cast(*p), isolate);
527      Handle<Object> args[] = { proxy };
528      Handle<Object> names = Execution::Call(isolate,
529                                             isolate->proxy_enumerate(),
530                                             object,
531                                             ARRAY_SIZE(args),
532                                             args,
533                                             threw);
534      if (*threw) return content;
535      content = AddKeysFromJSArray(content, Handle<JSArray>::cast(names));
536      break;
537    }
538
539    Handle<JSObject> current(JSObject::cast(*p), isolate);
540
541    // Check access rights if required.
542    if (current->IsAccessCheckNeeded() &&
543        !isolate->MayNamedAccess(*current,
544                                 isolate->heap()->undefined_value(),
545                                 v8::ACCESS_KEYS)) {
546      isolate->ReportFailedAccessCheck(*current, v8::ACCESS_KEYS);
547      if (isolate->has_scheduled_exception()) {
548        isolate->PromoteScheduledException();
549        *threw = true;
550      }
551      break;
552    }
553
554    // Compute the element keys.
555    Handle<FixedArray> element_keys =
556        isolate->factory()->NewFixedArray(current->NumberOfEnumElements());
557    current->GetEnumElementKeys(*element_keys);
558    content = UnionOfKeys(content, element_keys);
559    ASSERT(ContainsOnlyValidKeys(content));
560
561    // Add the element keys from the interceptor.
562    if (current->HasIndexedInterceptor()) {
563      v8::Handle<v8::Array> result =
564          GetKeysForIndexedInterceptor(object, current);
565      if (!result.IsEmpty())
566        content = AddKeysFromJSArray(content, v8::Utils::OpenHandle(*result));
567      ASSERT(ContainsOnlyValidKeys(content));
568    }
569
570    // We can cache the computed property keys if access checks are
571    // not needed and no interceptors are involved.
572    //
573    // We do not use the cache if the object has elements and
574    // therefore it does not make sense to cache the property names
575    // for arguments objects.  Arguments objects will always have
576    // elements.
577    // Wrapped strings have elements, but don't have an elements
578    // array or dictionary.  So the fast inline test for whether to
579    // use the cache says yes, so we should not create a cache.
580    bool cache_enum_keys =
581        ((current->map()->constructor() != *arguments_function) &&
582         !current->IsJSValue() &&
583         !current->IsAccessCheckNeeded() &&
584         !current->HasNamedInterceptor() &&
585         !current->HasIndexedInterceptor());
586    // Compute the property keys and cache them if possible.
587    content =
588        UnionOfKeys(content, GetEnumPropertyKeys(current, cache_enum_keys));
589    ASSERT(ContainsOnlyValidKeys(content));
590
591    // Add the property keys from the interceptor.
592    if (current->HasNamedInterceptor()) {
593      v8::Handle<v8::Array> result =
594          GetKeysForNamedInterceptor(object, current);
595      if (!result.IsEmpty())
596        content = AddKeysFromJSArray(content, v8::Utils::OpenHandle(*result));
597      ASSERT(ContainsOnlyValidKeys(content));
598    }
599
600    // If we only want local properties we bail out after the first
601    // iteration.
602    if (type == LOCAL_ONLY)
603      break;
604  }
605  return content;
606}
607
608
609Handle<JSArray> GetKeysFor(Handle<JSReceiver> object, bool* threw) {
610  Isolate* isolate = object->GetIsolate();
611  isolate->counters()->for_in()->Increment();
612  Handle<FixedArray> elements =
613      GetKeysInFixedArrayFor(object, INCLUDE_PROTOS, threw);
614  return isolate->factory()->NewJSArrayWithElements(elements);
615}
616
617
618Handle<FixedArray> ReduceFixedArrayTo(Handle<FixedArray> array, int length) {
619  ASSERT(array->length() >= length);
620  if (array->length() == length) return array;
621
622  Handle<FixedArray> new_array =
623      array->GetIsolate()->factory()->NewFixedArray(length);
624  for (int i = 0; i < length; ++i) new_array->set(i, array->get(i));
625  return new_array;
626}
627
628
629Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
630                                       bool cache_result) {
631  Isolate* isolate = object->GetIsolate();
632  if (object->HasFastProperties()) {
633    if (object->map()->instance_descriptors()->HasEnumCache()) {
634      int own_property_count = object->map()->EnumLength();
635      // If we have an enum cache, but the enum length of the given map is set
636      // to kInvalidEnumCache, this means that the map itself has never used the
637      // present enum cache. The first step to using the cache is to set the
638      // enum length of the map by counting the number of own descriptors that
639      // are not DONT_ENUM or SYMBOLIC.
640      if (own_property_count == kInvalidEnumCacheSentinel) {
641        own_property_count = object->map()->NumberOfDescribedProperties(
642            OWN_DESCRIPTORS, DONT_SHOW);
643
644        if (cache_result) object->map()->SetEnumLength(own_property_count);
645      }
646
647      DescriptorArray* desc = object->map()->instance_descriptors();
648      Handle<FixedArray> keys(desc->GetEnumCache(), isolate);
649
650      // In case the number of properties required in the enum are actually
651      // present, we can reuse the enum cache. Otherwise, this means that the
652      // enum cache was generated for a previous (smaller) version of the
653      // Descriptor Array. In that case we regenerate the enum cache.
654      if (own_property_count <= keys->length()) {
655        isolate->counters()->enum_cache_hits()->Increment();
656        return ReduceFixedArrayTo(keys, own_property_count);
657      }
658    }
659
660    Handle<Map> map(object->map());
661
662    if (map->instance_descriptors()->IsEmpty()) {
663      isolate->counters()->enum_cache_hits()->Increment();
664      if (cache_result) map->SetEnumLength(0);
665      return isolate->factory()->empty_fixed_array();
666    }
667
668    isolate->counters()->enum_cache_misses()->Increment();
669    int num_enum = map->NumberOfDescribedProperties(ALL_DESCRIPTORS, DONT_SHOW);
670
671    Handle<FixedArray> storage = isolate->factory()->NewFixedArray(num_enum);
672    Handle<FixedArray> indices = isolate->factory()->NewFixedArray(num_enum);
673
674    Handle<DescriptorArray> descs =
675        Handle<DescriptorArray>(object->map()->instance_descriptors(), isolate);
676
677    int real_size = map->NumberOfOwnDescriptors();
678    int enum_size = 0;
679    int index = 0;
680
681    for (int i = 0; i < descs->number_of_descriptors(); i++) {
682      PropertyDetails details = descs->GetDetails(i);
683      Object* key = descs->GetKey(i);
684      if (!(details.IsDontEnum() || key->IsSymbol())) {
685        if (i < real_size) ++enum_size;
686        storage->set(index, key);
687        if (!indices.is_null()) {
688          if (details.type() != FIELD) {
689            indices = Handle<FixedArray>();
690          } else {
691            int field_index = descs->GetFieldIndex(i);
692            if (field_index >= map->inobject_properties()) {
693              field_index = -(field_index - map->inobject_properties() + 1);
694            }
695            indices->set(index, Smi::FromInt(field_index));
696          }
697        }
698        index++;
699      }
700    }
701    ASSERT(index == storage->length());
702
703    Handle<FixedArray> bridge_storage =
704        isolate->factory()->NewFixedArray(
705            DescriptorArray::kEnumCacheBridgeLength);
706    DescriptorArray* desc = object->map()->instance_descriptors();
707    desc->SetEnumCache(*bridge_storage,
708                       *storage,
709                       indices.is_null() ? Object::cast(Smi::FromInt(0))
710                                         : Object::cast(*indices));
711    if (cache_result) {
712      object->map()->SetEnumLength(enum_size);
713    }
714
715    return ReduceFixedArrayTo(storage, enum_size);
716  } else {
717    Handle<NameDictionary> dictionary(object->property_dictionary());
718
719    int length = dictionary->NumberOfElements();
720    if (length == 0) {
721      return Handle<FixedArray>(isolate->heap()->empty_fixed_array());
722    }
723
724    // The enumeration array is generated by allocating an array big enough to
725    // hold all properties that have been seen, whether they are are deleted or
726    // not. Subsequently all visible properties are added to the array. If some
727    // properties were not visible, the array is trimmed so it only contains
728    // visible properties. This improves over adding elements and sorting by
729    // index by having linear complexity rather than n*log(n).
730
731    // By comparing the monotonous NextEnumerationIndex to the NumberOfElements,
732    // we can predict the number of holes in the final array. If there will be
733    // more than 50% holes, regenerate the enumeration indices to reduce the
734    // number of holes to a minimum. This avoids allocating a large array if
735    // many properties were added but subsequently deleted.
736    int next_enumeration = dictionary->NextEnumerationIndex();
737    if (!object->IsGlobalObject() && next_enumeration > (length * 3) / 2) {
738      NameDictionary::DoGenerateNewEnumerationIndices(dictionary);
739      next_enumeration = dictionary->NextEnumerationIndex();
740    }
741
742    Handle<FixedArray> storage =
743        isolate->factory()->NewFixedArray(next_enumeration);
744
745    storage = Handle<FixedArray>(dictionary->CopyEnumKeysTo(*storage));
746    ASSERT(storage->length() == object->NumberOfLocalProperties(DONT_SHOW));
747    return storage;
748  }
749}
750
751
752DeferredHandleScope::DeferredHandleScope(Isolate* isolate)
753    : impl_(isolate->handle_scope_implementer()) {
754  impl_->BeginDeferredScope();
755  v8::ImplementationUtilities::HandleScopeData* data =
756      impl_->isolate()->handle_scope_data();
757  Object** new_next = impl_->GetSpareOrNewBlock();
758  Object** new_limit = &new_next[kHandleBlockSize];
759  ASSERT(data->limit == &impl_->blocks()->last()[kHandleBlockSize]);
760  impl_->blocks()->Add(new_next);
761
762#ifdef DEBUG
763  prev_level_ = data->level;
764#endif
765  data->level++;
766  prev_limit_ = data->limit;
767  prev_next_ = data->next;
768  data->next = new_next;
769  data->limit = new_limit;
770}
771
772
773DeferredHandleScope::~DeferredHandleScope() {
774  impl_->isolate()->handle_scope_data()->level--;
775  ASSERT(handles_detached_);
776  ASSERT(impl_->isolate()->handle_scope_data()->level == prev_level_);
777}
778
779
780DeferredHandles* DeferredHandleScope::Detach() {
781  DeferredHandles* deferred = impl_->Detach(prev_limit_);
782  v8::ImplementationUtilities::HandleScopeData* data =
783      impl_->isolate()->handle_scope_data();
784  data->next = prev_next_;
785  data->limit = prev_limit_;
786#ifdef DEBUG
787  handles_detached_ = true;
788#endif
789  return deferred;
790}
791
792
793void AddWeakObjectToCodeDependency(Heap* heap,
794                                   Handle<Object> object,
795                                   Handle<Code> code) {
796  heap->EnsureWeakObjectToCodeTable();
797  Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(*object));
798  dep = DependentCode::Insert(dep, DependentCode::kWeaklyEmbeddedGroup, code);
799  CALL_HEAP_FUNCTION_VOID(heap->isolate(),
800                          heap->AddWeakObjectToCodeDependency(*object, *dep));
801}
802
803
804} }  // namespace v8::internal
805