Free up 11 bits in fast-mode PropertyDetails by removing the enumeration-index.

The descriptors are nowadays ordered in order of addition, so that info was
duplicated.

Review URL: https://chromiumcodereview.appspot.com/14622005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14571 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/bootstrapper.cc

@@ -2409,7 +2409,7 @@ void Genesis::TransferNamedProperties(Handle<JSObject> from,
   if (from->HasFastProperties()) {
     Handle<DescriptorArray> descs =
         Handle<DescriptorArray>(from->map()->instance_descriptors());
-    for (int i = 0; i < descs->number_of_descriptors(); i++) {
+    for (int i = 0; i < from->map()->NumberOfOwnDescriptors(); i++) {
       PropertyDetails details = descs->GetDetails(i);
       switch (details.type()) {
         case FIELD: {
@@ -2443,10 +2443,8 @@ void Genesis::TransferNamedProperties(Handle<JSObject> from,
           // Add to dictionary.
           Handle<Name> key = Handle<Name>(descs->GetKey(i));
           Handle<Object> callbacks(descs->GetCallbacksObject(i), isolate());
-          PropertyDetails d = PropertyDetails(details.attributes(),
-                                              CALLBACKS,
-                                              Representation::Tagged(),
-                                              details.descriptor_index());
+          PropertyDetails d = PropertyDetails(
+              details.attributes(), CALLBACKS, i + 1);
           JSObject::SetNormalizedProperty(to, key, callbacks, d);
           break;
         }

src/heap-snapshot-generator.cc

@@ -1309,8 +1309,7 @@ void V8HeapExplorer::ExtractPropertyReferences(JSObject* js_obj, int entry) {
   if (js_obj->HasFastProperties()) {
     DescriptorArray* descs = js_obj->map()->instance_descriptors();
     int real_size = js_obj->map()->NumberOfOwnDescriptors();
-    for (int i = 0; i < descs->number_of_descriptors(); i++) {
-      if (descs->GetDetails(i).descriptor_index() > real_size) continue;
+    for (int i = 0; i < real_size; i++) {
       switch (descs->GetType(i)) {
         case FIELD: {
           int index = descs->GetFieldIndex(i);

src/heap.cc

@@ -4160,7 +4160,7 @@ MaybeObject* Heap::AllocateInitialMap(JSFunction* fun) {
         ASSERT(name->IsInternalizedString());
         // TODO(verwaest): Since we cannot update the boilerplate's map yet,
         // initialize to the worst case.
-        FieldDescriptor field(name, i, NONE, Representation::Tagged(), i + 1);
+        FieldDescriptor field(name, i, NONE, Representation::Tagged());
         descriptors->Set(i, &field, witness);
       }
       descriptors->Sort();
@@ -4589,13 +4589,10 @@ MaybeObject* Heap::AllocateGlobalObject(JSFunction* constructor) {
   // The global object might be created from an object template with accessors.
   // Fill these accessors into the dictionary.
   DescriptorArray* descs = map->instance_descriptors();
-  for (int i = 0; i < descs->number_of_descriptors(); i++) {
+  for (int i = 0; i < map->NumberOfOwnDescriptors(); i++) {
     PropertyDetails details = descs->GetDetails(i);
     ASSERT(details.type() == CALLBACKS);  // Only accessors are expected.
-    PropertyDetails d = PropertyDetails(details.attributes(),
-                                        CALLBACKS,
-                                        Representation::None(),
-                                        details.descriptor_index());
+    PropertyDetails d = PropertyDetails(details.attributes(), CALLBACKS, i + 1);
     Object* value = descs->GetCallbacksObject(i);
     MaybeObject* maybe_value = AllocateJSGlobalPropertyCell(value);
     if (!maybe_value->ToObject(&value)) return maybe_value;

src/objects-debug.cc

@@ -323,10 +323,6 @@ void Map::MapVerify() {
           instance_size() < HEAP->Capacity()));
   VerifyHeapPointer(prototype());
   VerifyHeapPointer(instance_descriptors());
-  DescriptorArray* descriptors = instance_descriptors();
-  for (int i = 0; i < NumberOfOwnDescriptors(); ++i) {
-    CHECK_EQ(i, descriptors->GetDetails(i).descriptor_index() - 1);
-  }
   SLOW_ASSERT(instance_descriptors()->IsSortedNoDuplicates());
   if (HasTransitionArray()) {
     SLOW_ASSERT(transitions()->IsSortedNoDuplicates());

src/objects-inl.h

@@ -58,10 +58,7 @@ PropertyDetails::PropertyDetails(Smi* smi) {
 
 
 Smi* PropertyDetails::AsSmi() {
-  // Ensure the upper 2 bits have the same value by sign extending it. This is
-  // necessary to be able to use the 31st bit of the property details.
-  int value = value_ << 1;
-  return Smi::FromInt(value >> 1);
+  return Smi::FromInt(value_);
 }
 
 
@@ -2347,9 +2344,6 @@ void DescriptorArray::Set(int descriptor_number,
                           const WhitenessWitness&) {
   // Range check.
   ASSERT(descriptor_number < number_of_descriptors());
-  ASSERT(desc->GetDetails().descriptor_index() <=
-         number_of_descriptors());
-  ASSERT(desc->GetDetails().descriptor_index() > 0);
 
   ASSERT(!desc->GetDetails().representation().IsNone());
   NoIncrementalWriteBarrierSet(this,
@@ -2367,9 +2361,6 @@ void DescriptorArray::Set(int descriptor_number,
 void DescriptorArray::Set(int descriptor_number, Descriptor* desc) {
   // Range check.
   ASSERT(descriptor_number < number_of_descriptors());
-  ASSERT(desc->GetDetails().descriptor_index() <=
-         number_of_descriptors());
-  ASSERT(desc->GetDetails().descriptor_index() > 0);
   ASSERT(!desc->GetDetails().representation().IsNone());
 
   set(ToKeyIndex(descriptor_number), desc->GetKey());
@@ -2381,9 +2372,7 @@ void DescriptorArray::Set(int descriptor_number, Descriptor* desc) {
 void DescriptorArray::Append(Descriptor* desc,
                              const WhitenessWitness& witness) {
   int descriptor_number = number_of_descriptors();
-  int enumeration_index = descriptor_number + 1;
   SetNumberOfDescriptors(descriptor_number + 1);
-  desc->SetEnumerationIndex(enumeration_index);
   Set(descriptor_number, desc, witness);
 
   uint32_t hash = desc->GetKey()->Hash();
@@ -2402,9 +2391,7 @@ void DescriptorArray::Append(Descriptor* desc,
 
 void DescriptorArray::Append(Descriptor* desc) {
   int descriptor_number = number_of_descriptors();
-  int enumeration_index = descriptor_number + 1;
   SetNumberOfDescriptors(descriptor_number + 1);
-  desc->SetEnumerationIndex(enumeration_index);
   Set(descriptor_number, desc);
 
   uint32_t hash = desc->GetKey()->Hash();
@@ -4152,23 +4139,6 @@ static MaybeObject* EnsureHasTransitionArray(Map* map) {
 
 void Map::InitializeDescriptors(DescriptorArray* descriptors) {
   int len = descriptors->number_of_descriptors();
-#ifdef DEBUG
-  ASSERT(len <= DescriptorArray::kMaxNumberOfDescriptors);
-
-  bool used_indices[DescriptorArray::kMaxNumberOfDescriptors];
-  for (int i = 0; i < len; ++i) used_indices[i] = false;
-
-  // Ensure that all enumeration indexes between 1 and length occur uniquely in
-  // the descriptor array.
-  for (int i = 0; i < len; ++i) {
-    int enum_index = descriptors->GetDetails(i).descriptor_index() -
-                     PropertyDetails::kInitialIndex;
-    ASSERT(0 <= enum_index && enum_index < len);
-    ASSERT(!used_indices[enum_index]);
-    used_indices[enum_index] = true;
-  }
-#endif
-
   set_instance_descriptors(descriptors);
   SetNumberOfOwnDescriptors(len);
 }

src/property-details.h

@@ -154,20 +154,21 @@ class PropertyDetails BASE_EMBEDDED {
  public:
   PropertyDetails(PropertyAttributes attributes,
                   PropertyType type,
-                  Representation representation,
-                  int index = 0) {
+                  int index) {
     value_ = TypeField::encode(type)
         | AttributesField::encode(attributes)
-        | RepresentationField::encode(EncodeRepresentation(representation))
         | DictionaryStorageField::encode(index);
 
     ASSERT(type == this->type());
     ASSERT(attributes == this->attributes());
-    if (representation.IsNone()) {
-      ASSERT(index == this->dictionary_index());
-    } else {
-      ASSERT(index == this->descriptor_index());
-    }
+  }
+
+  PropertyDetails(PropertyAttributes attributes,
+                  PropertyType type,
+                  Representation representation) {
+    value_ = TypeField::encode(type)
+        | AttributesField::encode(attributes)
+        | RepresentationField::encode(EncodeRepresentation(representation));
   }
 
   int pointer() { return DescriptorPointer::decode(value_); }
@@ -183,17 +184,10 @@ class PropertyDetails BASE_EMBEDDED {
   inline Smi* AsSmi();
 
   static uint8_t EncodeRepresentation(Representation representation) {
-    ASSERT(representation.kind() <= Representation::kTagged);
-    if (representation.kind() < Representation::kInteger32) {
-      return representation.kind();
-    } else {
-      return representation.kind() - 1;
-    }
+    return representation.kind();
   }
 
   static Representation DecodeRepresentation(uint32_t bits) {
-    ASSERT(bits <= Representation::kTagged);
-    if (bits >= Representation::kInteger32) bits += 1;
     return Representation::FromKind(static_cast<Representation::Kind>(bits));
   }
 
@@ -207,10 +201,6 @@ class PropertyDetails BASE_EMBEDDED {
     return DictionaryStorageField::decode(value_);
   }
 
-  int descriptor_index() {
-    return DescriptorStorageField::decode(value_);
-  }
-
   Representation representation() {
     return DecodeRepresentation(RepresentationField::decode(value_));
   }
@@ -232,9 +222,8 @@ class PropertyDetails BASE_EMBEDDED {
   class AttributesField:          public BitField<PropertyAttributes, 3,  3> {};
   class DeletedField:             public BitField<uint32_t,           6,  1> {};
   class DictionaryStorageField:   public BitField<uint32_t,           7, 24> {};
-  class DescriptorStorageField:   public BitField<uint32_t,           7, 11> {};
-  class DescriptorPointer:        public BitField<uint32_t,          18, 11> {};
-  class RepresentationField:      public BitField<uint32_t,          29,  2> {};
+  class DescriptorPointer:        public BitField<uint32_t,           7, 11> {};
+  class RepresentationField:      public BitField<uint32_t,          18,  3> {};
 
   static const int kInitialIndex = 1;
 

src/property.cc

@@ -112,7 +112,6 @@ void Descriptor::Print(FILE* out) {
   GetKey()->ShortPrint(out);
   PrintF(out, " @ ");
   GetValue()->ShortPrint(out);
-  PrintF(out, " %d\n", GetDetails().descriptor_index());
 }
 
 

src/property.h

@@ -64,11 +64,6 @@ class Descriptor BASE_EMBEDDED {
   void Print(FILE* out);
 #endif
 
-  void SetEnumerationIndex(int index) {
-    details_ = PropertyDetails(details_.attributes(), details_.type(),
-                               details_.representation(), index);
-  }
-
   void SetSortedKeyIndex(int index) { details_ = details_.set_pointer(index); }
 
  private:
@@ -94,11 +89,10 @@ class Descriptor BASE_EMBEDDED {
              Object* value,
              PropertyAttributes attributes,
              PropertyType type,
-             Representation representation,
-             int index)
+             Representation representation)
       : key_(key),
         value_(value),
-        details_(attributes, type, representation, index) { }
+        details_(attributes, type, representation) { }
 
   friend class DescriptorArray;
 };
@@ -109,10 +103,9 @@ class FieldDescriptor: public Descriptor {
   FieldDescriptor(Name* key,
                   int field_index,
                   PropertyAttributes attributes,
-                  Representation representation,
-                  int index = 0)
+                  Representation representation)
       : Descriptor(key, Smi::FromInt(field_index), attributes,
-                   FIELD, representation, index) {}
+                   FIELD, representation) {}
 };
 
 
@@ -120,10 +113,9 @@ class ConstantFunctionDescriptor: public Descriptor {
  public:
   ConstantFunctionDescriptor(Name* key,
                              JSFunction* function,
-                             PropertyAttributes attributes,
-                             int index)
-      : Descriptor(key, function, attributes,
-                   CONSTANT_FUNCTION, Representation::Tagged(), index) {}
+                             PropertyAttributes attributes)
+      : Descriptor(key, function, attributes, CONSTANT_FUNCTION,
+                   Representation::Tagged()) {}
 };
 
 
@@ -131,10 +123,9 @@ class CallbacksDescriptor:  public Descriptor {
  public:
   CallbacksDescriptor(Name* key,
                       Object* foreign,
-                      PropertyAttributes attributes,
-                      int index = 0)
+                      PropertyAttributes attributes)
       : Descriptor(key, foreign, attributes, CALLBACKS,
-                   Representation::Tagged(), index) {}
+                   Representation::Tagged()) {}
 };
 
 

src/runtime.cc

@@ -2316,8 +2316,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionSetReadOnlyPrototype) {
 
     CallbacksDescriptor new_desc(name,
         instance_desc->GetValue(index),
-        static_cast<PropertyAttributes>(details.attributes() | READ_ONLY),
-        details.descriptor_index());
+        static_cast<PropertyAttributes>(details.attributes() | READ_ONLY));
 
     // Create a new map featuring the new field descriptors array.
     Map* new_map;
@@ -2335,7 +2334,6 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionSetReadOnlyPrototype) {
     PropertyDetails new_details(
         static_cast<PropertyAttributes>(details.attributes() | READ_ONLY),
         details.type(),
-        Representation::None(),
         details.dictionary_index());
     function->property_dictionary()->DetailsAtPut(entry, new_details);
   }

src/string-stream.cc

@@ -350,9 +350,8 @@ void StringStream::PrintUsingMap(JSObject* js_object) {
   }
   int real_size = map->NumberOfOwnDescriptors();
   DescriptorArray* descs = map->instance_descriptors();
-  for (int i = 0; i < descs->number_of_descriptors(); i++) {
+  for (int i = 0; i < real_size; i++) {
     PropertyDetails details = descs->GetDetails(i);
-    if (details.descriptor_index() > real_size) continue;
     if (details.type() == FIELD) {
       Object* key = descs->GetKey(i);
       if (key->IsString() || key->IsNumber()) {

test/cctest/test-alloc.cc

@@ -142,8 +142,7 @@ TEST(StressJS) {
 
   CallbacksDescriptor d(*name,
                         *foreign,
-                        static_cast<PropertyAttributes>(0),
-                        v8::internal::PropertyDetails::kInitialIndex);
+                        static_cast<PropertyAttributes>(0));
   map->AppendDescriptor(&d, witness);
 
   // Add the Foo constructor the global object.