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[runtime] Drop unnecessary NameDictionaryBase

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This class contained a by-now unnecessary optimization of FindEntry. Since we always deal with internalized names by now anyway, there's no need to micro-optimize locally (it's a nop).

Bug: 
Change-Id: I5a0046bcd23e2cb77c5902e850bac6211bd5518f
Reviewed-on: https://chromium-review.googlesource.com/538581
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45983}
This commit is contained in:
Toon Verwaest 2017-06-16 17:39:19 +02:00 committed by Commit Bot
parent 18d05c8727
commit e94a97ffb8
4 changed files with 31 additions and 67 deletions
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11
src/objects-inl.h
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@ -2618,12 +2618,15 @@ int HashTable<Derived, Shape>::FindEntry(Isolate* isolate, Key key,
// EnsureCapacity will guarantee the hash table is never full.
Object* undefined = isolate->heap()->undefined_value();
Object* the_hole = isolate->heap()->the_hole_value();
USE(the_hole);
while (true) {
Object* element = KeyAt(entry);
// Empty entry. Uses raw unchecked accessors because it is called by the
// string table during bootstrapping.
if (element == undefined) break;
if (element != the_hole && Shape::IsMatch(key, element)) return entry;
if (!(Shape::kNeedsHoleCheck && the_hole == element)) {
if (Shape::IsMatch(key, element)) return entry;
}
entry = NextProbe(entry, count++, capacity);
}
return kNotFound;
@ -2650,7 +2653,8 @@ bool ObjectHashSet::Has(Isolate* isolate, Handle<Object> key) {
}
bool StringSetShape::IsMatch(String* key, Object* value) {
return value->IsString() && key->Equals(String::cast(value));
DCHECK(value->IsString());
return key->Equals(String::cast(value));
}
uint32_t StringSetShape::Hash(String* key) { return key->Hash(); }
@ -6086,7 +6090,8 @@ Handle<Object> NumberDictionaryShape::AsHandle(Isolate* isolate, uint32_t key) {
bool NameDictionaryShape::IsMatch(Handle<Name> key, Object* other) {
DCHECK(Name::cast(other)->IsUniqueName());
DCHECK(other->IsTheHole(key->GetIsolate()) ||
Name::cast(other)->IsUniqueName());
DCHECK(key->IsUniqueName());
return *key == other;
}

52
src/objects.cc
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@ -15813,7 +15813,7 @@ class StringSharedKey : public HashTableKey {
bool IsMatch(Object* other) override {
DisallowHeapAllocation no_allocation;
if (!other->IsFixedArray()) {
if (!other->IsNumber()) return false;
DCHECK(other->IsNumber());
uint32_t other_hash = static_cast<uint32_t>(other->Number());
return Hash() == other_hash;
}
@ -16181,48 +16181,15 @@ Handle<Derived> HashTable<Derived, Shape>::New(Isolate* isolate, int capacity,
return table;
}
// Find entry for key otherwise return kNotFound.
template <typename Derived, typename Shape>
int NameDictionaryBase<Derived, Shape>::FindEntry(Handle<Name> key) {
if (!key->IsUniqueName()) {
return DerivedDictionary::FindEntry(key);
}
// Optimized for unique names. Knowledge of the key type allows:
// 1. Move the check if the key is unique out of the loop.
// 2. Avoid comparing hash codes in unique-to-unique comparison.
// 3. Detect a case when a dictionary key is not unique but the key is.
// In case of positive result the dictionary key may be replaced by the
// internalized string with minimal performance penalty. It gives a chance
// to perform further lookups in code stubs (and significant performance
// boost a certain style of code).
// EnsureCapacity will guarantee the hash table is never full.
uint32_t capacity = this->Capacity();
uint32_t entry = Derived::FirstProbe(key->Hash(), capacity);
uint32_t count = 1;
Isolate* isolate = this->GetIsolate();
while (true) {
Object* element = this->KeyAt(entry);
if (element->IsUndefined(isolate)) break; // Empty entry.
if (*key == element) return entry;
DCHECK(element->IsTheHole(isolate) || element->IsUniqueName());
entry = Derived::NextProbe(entry, count++, capacity);
}
return Derived::kNotFound;
}
template <typename Derived, typename Shape>
void HashTable<Derived, Shape>::Rehash(Handle<Derived> new_table) {
DCHECK(NumberOfElements() < new_table->Capacity());
void HashTable<Derived, Shape>::Rehash(Derived* new_table) {
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = new_table->GetWriteBarrierMode(no_gc);
DCHECK_LT(NumberOfElements(), new_table->Capacity());
// Copy prefix to new array.
for (int i = kPrefixStartIndex;
i < kPrefixStartIndex + Shape::kPrefixSize;
i++) {
for (int i = kPrefixStartIndex; i < kElementsStartIndex; i++) {
new_table->set(i, get(i), mode);
}
@ -16313,7 +16280,7 @@ void HashTable<Derived, Shape>::Rehash() {
Object* undefined = isolate->heap()->undefined_value();
for (uint32_t current = 0; current < capacity; current++) {
if (KeyAt(current) == the_hole) {
set(EntryToIndex(current) + Derived::kEntryKeyIndex, undefined);
set(EntryToIndex(current) + kEntryKeyIndex, undefined);
}
}
SetNumberOfDeletedElements(0);
@ -16336,7 +16303,7 @@ Handle<Derived> HashTable<Derived, Shape>::EnsureCapacity(
HashTable::New(isolate, new_nof, USE_DEFAULT_MINIMUM_CAPACITY,
should_pretenure ? TENURED : NOT_TENURED);
table->Rehash(new_table);
table->Rehash(*new_table);
return new_table;
}
@ -16382,7 +16349,7 @@ Handle<Derived> HashTable<Derived, Shape>::Shrink(Handle<Derived> table) {
USE_DEFAULT_MINIMUM_CAPACITY,
pretenure ? TENURED : NOT_TENURED);
table->Rehash(new_table);
table->Rehash(*new_table);
return new_table;
}
@ -16536,9 +16503,6 @@ template Handle<NameDictionary>
Dictionary<NameDictionary, NameDictionaryShape>::EnsureCapacity(
Handle<NameDictionary>, int);
template int NameDictionaryBase<NameDictionary, NameDictionaryShape>::FindEntry(
Handle<Name>);
template int Dictionary<GlobalDictionary,
GlobalDictionaryShape>::NumberOfEnumerableProperties();

23
src/objects/dictionary.h
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@ -29,12 +29,12 @@ class Dictionary : public HashTable<Derived, Shape> {
typedef typename Shape::Key Key;
// Returns the value at entry.
Object* ValueAt(int entry) {
return this->get(Derived::EntryToIndex(entry) + 1);
return this->get(DerivedHashTable::EntryToIndex(entry) + 1);
}
// Set the value for entry.
void ValueAtPut(int entry, Object* value) {
this->set(Derived::EntryToIndex(entry) + 1, value);
this->set(DerivedHashTable::EntryToIndex(entry) + 1, value);
}
// Returns the property details for the property at entry.
@ -138,16 +138,6 @@ class Dictionary : public HashTable<Derived, Shape> {
PropertyDetails details, uint32_t hash);
};
template <typename Derived, typename Shape>
class NameDictionaryBase : public Dictionary<Derived, Shape> {
typedef Dictionary<Derived, Shape> DerivedDictionary;
public:
// Find entry for key, otherwise return kNotFound. Optimized version of
// HashTable::FindEntry.
int FindEntry(Handle<Name> key);
};
template <typename Key>
class BaseDictionaryShape : public BaseShape<Key> {
public:
@ -188,12 +178,11 @@ class NameDictionaryShape : public BaseDictionaryShape<Handle<Name>> {
static const int kEntryValueIndex = 1;
static const int kEntryDetailsIndex = 2;
static const bool kIsEnumerable = true;
static const bool kNeedsHoleCheck = false;
};
class NameDictionary
: public NameDictionaryBase<NameDictionary, NameDictionaryShape> {
typedef NameDictionaryBase<NameDictionary, NameDictionaryShape>
DerivedDictionary;
class NameDictionary : public Dictionary<NameDictionary, NameDictionaryShape> {
typedef Dictionary<NameDictionary, NameDictionaryShape> DerivedDictionary;
public:
DECLARE_CAST(NameDictionary)
@ -223,7 +212,7 @@ class GlobalDictionaryShape : public NameDictionaryShape {
};
class GlobalDictionary
: public NameDictionaryBase<GlobalDictionary, GlobalDictionaryShape> {
: public Dictionary<GlobalDictionary, GlobalDictionaryShape> {
public:
DECLARE_CAST(GlobalDictionary)

10
src/objects/hash-table.h
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@ -32,7 +32,7 @@ namespace internal {
// class ExampleShape {
// public:
// // Tells whether key matches other.
// static bool IsMatch(Object* other);
// static bool IsMatch(Key key, Object* other);
// // Returns the hash value for key.
// static uint32_t Hash(Key key);
// // Returns the hash value for object.
@ -44,6 +44,9 @@ namespace internal {
// static const int kPrefixSize = ..;
// // The Element size indicates number of elements per entry.
// static const int kEntrySize = ..;
// // Indicates whether IsMatch can deal with other being the_hole (a
// // deleted entry).
// static const bool kNeedsHoleCheck = ..;
// };
// The prefix size indicates an amount of memory in the
// beginning of the backing storage that can be used for non-element
@ -65,6 +68,7 @@ class BaseShape {
return HashForObject(object);
}
static inline Map* GetMap(Isolate* isolate);
static const bool kNeedsHoleCheck = true;
};
class V8_EXPORT_PRIVATE HashTableBase : public NON_EXPORTED_BASE(FixedArray) {
@ -249,7 +253,7 @@ class HashTable : public HashTableBase {
void Swap(uint32_t entry1, uint32_t entry2, WriteBarrierMode mode);
// Rehashes this hash-table into the new table.
void Rehash(Handle<Derived> new_table);
void Rehash(Derived* new_table);
};
// HashTableKey is an abstract superclass for virtual key behavior.
@ -283,6 +287,7 @@ class ObjectHashTableShape : public BaseShape<Handle<Object>> {
static inline Handle<Object> AsHandle(Isolate* isolate, Handle<Object> key);
static const int kPrefixSize = 0;
static const int kEntrySize = 2;
static const bool kNeedsHoleCheck = false;
};
// ObjectHashTable maps keys that are arbitrary objects to object values by
@ -566,6 +571,7 @@ class WeakHashTableShape : public BaseShape<Handle<Object>> {
static inline Handle<Object> AsHandle(Isolate* isolate, Handle<Object> key);
static const int kPrefixSize = 0;
static const int kEntrySize = entrysize;
static const bool kNeedsHoleCheck = false;
};
// WeakHashTable maps keys that are arbitrary heap objects to heap object