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Fixing bugs in promotion of elements transitions (r1175). - Fixed inv…

…alid memory access when reading enum-cache from descriptor array with elements transitions but 0 real descriptors. - Fixed infinite recursion in the intrusive map iterator when visiting elements transitions. - Properly cached non-fastmode elements transitions.

Review URL: https://chromiumcodereview.appspot.com/10565030

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@11841 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
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commit 8a6ef65c2c8b39a040c6566bc91841989803631d 1 parent 7282ce9
@verwaest verwaest authored piscisaureus committed
Showing with 68 additions and 45 deletions.
  1. +61 −37 deps/v8/src/objects.cc
  2. +7 −8 deps/v8/src/objects.h
View
98 deps/v8/src/objects.cc
@@ -2243,7 +2243,12 @@ Handle<Map> Map::FindTransitionedMap(MapHandleList* candidates) {
static Map* FindClosestElementsTransition(Map* map, ElementsKind to_kind) {
Map* current_map = map;
int index = GetSequenceIndexFromFastElementsKind(map->elements_kind());
- int to_index = GetSequenceIndexFromFastElementsKind(to_kind);
+ int to_index = IsFastElementsKind(to_kind)
+ ? GetSequenceIndexFromFastElementsKind(to_kind)
+ : GetSequenceIndexFromFastElementsKind(TERMINAL_FAST_ELEMENTS_KIND);
+
+ ASSERT(index <= to_index);
+
for (; index < to_index; ++index) {
Map* next_map = current_map->elements_transition_map();
if (next_map == NULL) {
@@ -2251,27 +2256,36 @@ static Map* FindClosestElementsTransition(Map* map, ElementsKind to_kind) {
}
current_map = next_map;
}
- ASSERT(current_map->elements_kind() == to_kind);
+ if (!IsFastElementsKind(to_kind)) {
+ Map* next_map = current_map->elements_transition_map();
+ if (next_map != NULL && next_map->elements_kind() == to_kind) {
+ return next_map;
+ }
+ ASSERT(current_map->elements_kind() == TERMINAL_FAST_ELEMENTS_KIND);
+ } else {
+ ASSERT(current_map->elements_kind() == to_kind);
+ }
return current_map;
}
Map* Map::LookupElementsTransitionMap(ElementsKind to_kind) {
- if (this->instance_descriptors()->MayContainTransitions() &&
- IsMoreGeneralElementsKindTransition(this->elements_kind(), to_kind)) {
- Map* to_map = FindClosestElementsTransition(this, to_kind);
- if (to_map->elements_kind() == to_kind) {
- return to_map;
- }
- }
+ Map* to_map = FindClosestElementsTransition(this, to_kind);
+ if (to_map->elements_kind() == to_kind) return to_map;
return NULL;
}
MaybeObject* Map::CreateNextElementsTransition(ElementsKind next_kind) {
- ASSERT(elements_transition_map() == NULL);
- ASSERT(GetSequenceIndexFromFastElementsKind(elements_kind()) ==
- (GetSequenceIndexFromFastElementsKind(next_kind) - 1));
+ ASSERT(elements_transition_map() == NULL ||
+ ((elements_transition_map()->elements_kind() == DICTIONARY_ELEMENTS ||
+ IsExternalArrayElementsKind(
+ elements_transition_map()->elements_kind())) &&
+ (next_kind == DICTIONARY_ELEMENTS ||
+ IsExternalArrayElementsKind(next_kind))));
+ ASSERT(!IsFastElementsKind(next_kind) ||
+ IsMoreGeneralElementsKindTransition(elements_kind(), next_kind));
+ ASSERT(next_kind != elements_kind());
Map* next_map;
MaybeObject* maybe_next_map =
@@ -2287,19 +2301,31 @@ MaybeObject* Map::CreateNextElementsTransition(ElementsKind next_kind) {
static MaybeObject* AddMissingElementsTransitions(Map* map,
ElementsKind to_kind) {
- int index = GetSequenceIndexFromFastElementsKind(map->elements_kind()) + 1;
- int to_index = GetSequenceIndexFromFastElementsKind(to_kind);
+ ASSERT(IsFastElementsKind(map->elements_kind()));
+ int index = GetSequenceIndexFromFastElementsKind(map->elements_kind());
+ int to_index = IsFastElementsKind(to_kind)
+ ? GetSequenceIndexFromFastElementsKind(to_kind)
+ : GetSequenceIndexFromFastElementsKind(TERMINAL_FAST_ELEMENTS_KIND);
+
ASSERT(index <= to_index);
Map* current_map = map;
- for (; index <= to_index; ++index) {
- ElementsKind next_kind = GetFastElementsKindFromSequenceIndex(index);
+ for (; index < to_index; ++index) {
+ ElementsKind next_kind = GetFastElementsKindFromSequenceIndex(index + 1);
MaybeObject* maybe_next_map =
current_map->CreateNextElementsTransition(next_kind);
if (!maybe_next_map->To(&current_map)) return maybe_next_map;
}
+ // In case we are exiting the fast elements kind system, just add the map in
+ // the end.
+ if (!IsFastElementsKind(to_kind)) {
+ MaybeObject* maybe_next_map =
+ current_map->CreateNextElementsTransition(to_kind);
+ if (!maybe_next_map->To(&current_map)) return maybe_next_map;
+ }
+
ASSERT(current_map->elements_kind() == to_kind);
return current_map;
}
@@ -2345,10 +2371,14 @@ MaybeObject* JSObject::GetElementsTransitionMapSlow(ElementsKind to_kind) {
// non-matching element transition.
(global_context->object_function()->map() != map()) &&
!start_map->IsUndefined() && !start_map->is_shared() &&
- // Only store fast element maps in ascending generality.
- IsTransitionableFastElementsKind(from_kind) &&
- IsFastElementsKind(to_kind) &&
- IsMoreGeneralElementsKindTransition(from_kind, to_kind);
+ IsFastElementsKind(from_kind);
+
+ // Only store fast element maps in ascending generality.
+ if (IsFastElementsKind(to_kind)) {
+ allow_store_transition &=
+ IsTransitionableFastElementsKind(from_kind) &&
+ IsMoreGeneralElementsKindTransition(from_kind, to_kind);
+ }
if (!allow_store_transition) {
// Create a new free-floating map only if we are not allowed to store it.
@@ -5063,7 +5093,7 @@ class IntrusiveMapTransitionIterator {
if (index == descriptor_array_->number_of_descriptors()) {
Map* elements_transition = descriptor_array_->elements_transition_map();
if (elements_transition != NULL) {
- *DescriptorArrayHeader() = Smi::FromInt(index + 1);
+ *DescriptorArrayHeader() = Smi::FromInt(raw_index + 2);
return elements_transition;
}
}
@@ -5765,24 +5795,18 @@ MaybeObject* DescriptorArray::Allocate(int number_of_descriptors,
Heap* heap = Isolate::Current()->heap();
// Do not use DescriptorArray::cast on incomplete object.
FixedArray* result;
- if (number_of_descriptors == 0) {
- if (shared_mode == MAY_BE_SHARED) {
- return heap->empty_descriptor_array();
- }
- { MaybeObject* maybe_array =
- heap->AllocateFixedArray(kTransitionsIndex + 1);
- if (!maybe_array->To(&result)) return maybe_array;
- }
- } else {
- // Allocate the array of keys.
- { MaybeObject* maybe_array =
- heap->AllocateFixedArray(ToKeyIndex(number_of_descriptors));
- if (!maybe_array->To(&result)) return maybe_array;
- }
- result->set(kEnumerationIndexIndex,
- Smi::FromInt(PropertyDetails::kInitialIndex));
+ if (number_of_descriptors == 0 && shared_mode == MAY_BE_SHARED) {
+ return heap->empty_descriptor_array();
+ }
+ // Allocate the array of keys.
+ { MaybeObject* maybe_array =
+ heap->AllocateFixedArray(ToKeyIndex(number_of_descriptors));
+ if (!maybe_array->To(&result)) return maybe_array;
}
+
result->set(kBitField3StorageIndex, Smi::FromInt(0));
+ result->set(kEnumerationIndexIndex,
+ Smi::FromInt(PropertyDetails::kInitialIndex));
result->set(kTransitionsIndex, Smi::FromInt(0));
return result;
}
View
15 deps/v8/src/objects.h
@@ -2441,9 +2441,7 @@ class DescriptorArray: public FixedArray {
// Returns the number of descriptors in the array.
int number_of_descriptors() {
- ASSERT(length() > kFirstIndex ||
- length() == kTransitionsIndex ||
- IsEmpty());
+ ASSERT(length() >= kFirstIndex || IsEmpty());
int len = length();
return len <= kFirstIndex ? 0 : (len - kFirstIndex) / kDescriptorSize;
}
@@ -2615,8 +2613,8 @@ class DescriptorArray: public FixedArray {
static const int kNotFound = -1;
static const int kBitField3StorageIndex = 0;
- static const int kTransitionsIndex = 1;
- static const int kEnumerationIndexIndex = 2;
+ static const int kEnumerationIndexIndex = 1;
+ static const int kTransitionsIndex = 2;
static const int kFirstIndex = 3;
// The length of the "bridge" to the enum cache.
@@ -2627,9 +2625,10 @@ class DescriptorArray: public FixedArray {
// Layout description.
static const int kBitField3StorageOffset = FixedArray::kHeaderSize;
- static const int kTransitionsOffset = kBitField3StorageOffset + kPointerSize;
- static const int kEnumerationIndexOffset = kTransitionsOffset + kPointerSize;
- static const int kFirstOffset = kEnumerationIndexOffset + kPointerSize;
+ static const int kEnumerationIndexOffset =
+ kBitField3StorageOffset + kPointerSize;
+ static const int kTransitionsOffset = kEnumerationIndexOffset + kPointerSize;
+ static const int kFirstOffset = kTransitionsOffset + kPointerSize;
// Layout description for the bridge array.
static const int kEnumCacheBridgeEnumOffset = FixedArray::kHeaderSize;

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