Reland r22082 "Replace HeapNumber as doublebox with an explicit MutableHeapNumber."

src/objects.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/api.h"
 #include "src/arguments.h"
@@ skipping 1522 matching lines @@
         String::cast(symbol->name())->StringShortPrint(accumulator);
       }
       accumulator->Add(">");
       break;
     }
     case HEAP_NUMBER_TYPE:
       accumulator->Add("<Number: ");
       HeapNumber::cast(this)->HeapNumberPrint(accumulator);
       accumulator->Put('>');
       break;
+    case MUTABLE_HEAP_NUMBER_TYPE:
+      accumulator->Add("<MutableNumber: ");
+      HeapNumber::cast(this)->HeapNumberPrint(accumulator);
+      accumulator->Put('>');
+      break;
     case JS_PROXY_TYPE:
       accumulator->Add("<JSProxy>");
       break;
     case JS_FUNCTION_PROXY_TYPE:
       accumulator->Add("<JSFunctionProxy>");
       break;
     case FOREIGN_TYPE:
       accumulator->Add("<Foreign>");
       break;
     case CELL_TYPE:
@@ skipping 105 matching lines @@
       Cell::BodyDescriptor::IterateBody(this, v);
       break;
     case PROPERTY_CELL_TYPE:
       PropertyCell::BodyDescriptor::IterateBody(this, v);
       break;
     case SYMBOL_TYPE:
       Symbol::BodyDescriptor::IterateBody(this, v);
       break;
 
     case HEAP_NUMBER_TYPE:
+    case MUTABLE_HEAP_NUMBER_TYPE:
     case FILLER_TYPE:
     case BYTE_ARRAY_TYPE:
     case FREE_SPACE_TYPE:
       break;
 
 #define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size)                        \
     case EXTERNAL_##TYPE##_ARRAY_TYPE:                                         \
     case FIXED_##TYPE##_ARRAY_TYPE:                                            \
       break;
 
@@ skipping 21 matching lines @@
   }
 }
 
 
 bool HeapNumber::HeapNumberBooleanValue() {
   return DoubleToBoolean(value());
 }
 
 
 void HeapNumber::HeapNumberPrint(FILE* out) {
-  PrintF(out, "%.16g", Number());
+  PrintF(out, "%.16g", value());
 }
 
 
 void HeapNumber::HeapNumberPrint(StringStream* accumulator) {
   // The Windows version of vsnprintf can allocate when printing a %g string
   // into a buffer that may not be big enough.  We don't want random memory
   // allocation when producing post-crash stack traces, so we print into a
   // buffer that is plenty big enough for any floating point number, then
   // print that using vsnprintf (which may truncate but never allocate if
   // there is no more space in the buffer).
   EmbeddedVector<char, 100> buffer;
-  SNPrintF(buffer, "%.16g", Number());
+  SNPrintF(buffer, "%.16g", value());
   accumulator->Add("%s", buffer.start());
 }
 
 
 String* JSReceiver::class_name() {
   if (IsJSFunction() && IsJSFunctionProxy()) {
     return GetHeap()->function_class_string();
   }
   if (map()->constructor()->IsJSFunction()) {
     JSFunction* constructor = JSFunction::cast(map()->constructor());
@@ skipping 331 matching lines @@
   // If fields were added (or removed), rewrite the instance.
   int number_of_fields = NumberOfFields();
   ASSERT(target_number_of_fields >= number_of_fields);
   if (target_number_of_fields != number_of_fields) return true;
 
   // If smi descriptors were replaced by double descriptors, rewrite.
   DescriptorArray* old_desc = instance_descriptors();
   DescriptorArray* new_desc = target->instance_descriptors();
   int limit = NumberOfOwnDescriptors();
   for (int i = 0; i < limit; i++) {
-    if (new_desc->GetDetails(i).representation().IsDouble() &&
-        !old_desc->GetDetails(i).representation().IsDouble()) {
+    if (new_desc->GetDetails(i).representation().IsDouble() !=
+        old_desc->GetDetails(i).representation().IsDouble()) {
       return true;
     }
   }
 
   // If no fields were added, and no inobject properties were removed, setting
   // the map is sufficient.
   if (target_inobject == inobject_properties()) return false;
   // In-object slack tracking may have reduced the object size of the new map.
   // In that case, succeed if all existing fields were inobject, and they still
   // fit within the new inobject size.
@@ skipping 76 matching lines @@
     // This migration is a transition from a map that has run out out property
     // space. Therefore it could be done by extending the backing store.
     Handle<FixedArray> old_storage = handle(object->properties(), isolate);
     Handle<FixedArray> new_storage =
         FixedArray::CopySize(old_storage, external);
 
     // Properly initialize newly added property.
     PropertyDetails details = new_map->GetLastDescriptorDetails();
     Handle<Object> value;
     if (details.representation().IsDouble()) {
-      value = isolate->factory()->NewHeapNumber(0);
+      value = isolate->factory()->NewHeapNumber(0, MUTABLE);
     } else {
       value = isolate->factory()->uninitialized_value();
     }
     ASSERT(details.type() == FIELD);
     int target_index = details.field_index() - inobject;
     ASSERT(target_index >= 0);  // Must be a backing store index.
     new_storage->set(target_index, *value);
 
     // From here on we cannot fail and we shouldn't GC anymore.
     DisallowHeapAllocation no_allocation;
@@ skipping 27 matching lines @@
     Object* raw_value = old_details.type() == CONSTANT
         ? old_descriptors->GetValue(i)
         : object->RawFastPropertyAt(FieldIndex::ForDescriptor(*old_map, i));
     Handle<Object> value(raw_value, isolate);
     if (!old_details.representation().IsDouble() &&
         details.representation().IsDouble()) {
       if (old_details.representation().IsNone()) {
         value = handle(Smi::FromInt(0), isolate);
       }
       value = Object::NewStorageFor(isolate, value, details.representation());
+    } else if (old_details.representation().IsDouble() &&
+               !details.representation().IsDouble()) {
+      value = Object::WrapForRead(isolate, value, old_details.representation());
     }
     ASSERT(!(details.representation().IsDouble() && value->IsSmi()));
     int target_index = new_descriptors->GetFieldIndex(i) - inobject;
     if (target_index < 0) target_index += total_size;
     array->set(target_index, *value);
   }
 
   for (int i = old_nof; i < new_nof; i++) {
     PropertyDetails details = new_descriptors->GetDetails(i);
     if (details.type() != FIELD) continue;
     Handle<Object> value;
     if (details.representation().IsDouble()) {
-      value = isolate->factory()->NewHeapNumber(0);
+      value = isolate->factory()->NewHeapNumber(0, MUTABLE);
     } else {
       value = isolate->factory()->uninitialized_value();
     }
     int target_index = new_descriptors->GetFieldIndex(i) - inobject;
     if (target_index < 0) target_index += total_size;
     array->set(target_index, *value);
   }
 
   // From here on we cannot fail and we shouldn't GC anymore.
   DisallowHeapAllocation no_allocation;
@@ skipping 1726 matching lines @@
   DescriptorArray* desc = map()->instance_descriptors();
   PropertyDetails details = desc->GetDetails(descriptor);
 
   ASSERT(details.type() == FIELD);
 
   FieldIndex index = FieldIndex::ForDescriptor(map(), descriptor);
   if (details.representation().IsDouble()) {
     // Nothing more to be done.
     if (value->IsUninitialized()) return;
     HeapNumber* box = HeapNumber::cast(RawFastPropertyAt(index));
+    ASSERT(box->IsMutableHeapNumber());
     box->set_value(value->Number());
   } else {
     FastPropertyAtPut(index, value);
   }
 }
 
 
 void JSObject::SetPropertyToField(LookupResult* lookup, Handle<Object> value) {
   if (lookup->type() == CONSTANT || !lookup->CanHoldValue(value)) {
     Representation field_representation = value->OptimalRepresentation();
@@ skipping 627 matching lines @@
         PropertyDetails d = PropertyDetails(
             details.attributes(), NORMAL, i + 1);
         dictionary = NameDictionary::Add(dictionary, key, value, d);
         break;
       }
       case FIELD: {
         Handle<Name> key(descs->GetKey(i));
         FieldIndex index = FieldIndex::ForDescriptor(*map, i);
         Handle<Object> value(
             object->RawFastPropertyAt(index), isolate);
+        if (details.representation().IsDouble()) {
+          ASSERT(value->IsMutableHeapNumber());
+          Handle<HeapNumber> old = Handle<HeapNumber>::cast(value);
+          value = isolate->factory()->NewHeapNumber(old->value());
+        }
         PropertyDetails d =
             PropertyDetails(details.attributes(), NORMAL, i + 1);
         dictionary = NameDictionary::Add(dictionary, key, value, d);
         break;
       }
       case CALLBACKS: {
         Handle<Name> key(descs->GetKey(i));
         Handle<Object> value(descs->GetCallbacksObject(i), isolate);
         PropertyDetails d = PropertyDetails(
             details.attributes(), CALLBACKS, i + 1);
@@ skipping 1152 matching lines @@
   }
   JSObject::MigrateToMap(object, new_map);
 }
 
 
 Handle<Object> JSObject::FastPropertyAt(Handle<JSObject> object,
                                         Representation representation,
                                         FieldIndex index) {
   Isolate* isolate = object->GetIsolate();
   Handle<Object> raw_value(object->RawFastPropertyAt(index), isolate);
-  return Object::NewStorageFor(isolate, raw_value, representation);
+  return Object::WrapForRead(isolate, raw_value, representation);
 }
 
 
 template<class ContextObject>
 class JSObjectWalkVisitor {
  public:
   JSObjectWalkVisitor(ContextObject* site_context, bool copying,
                       JSObject::DeepCopyHints hints)
     : site_context_(site_context),
       copying_(copying),
@@ skipping 1170 matching lines @@
 
 Object* JSObject::SlowReverseLookup(Object* value) {
   if (HasFastProperties()) {
     int number_of_own_descriptors = map()->NumberOfOwnDescriptors();
     DescriptorArray* descs = map()->instance_descriptors();
     for (int i = 0; i < number_of_own_descriptors; i++) {
       if (descs->GetType(i) == FIELD) {
         Object* property =
             RawFastPropertyAt(FieldIndex::ForDescriptor(map(), i));
         if (descs->GetDetails(i).representation().IsDouble()) {
-          ASSERT(property->IsHeapNumber());
+          ASSERT(property->IsMutableHeapNumber());
           if (value->IsNumber() && property->Number() == value->Number()) {
             return descs->GetKey(i);
           }
         } else if (property == value) {
           return descs->GetKey(i);
         }
       } else if (descs->GetType(i) == CONSTANT) {
         if (descs->GetConstant(i) == value) {
           return descs->GetKey(i);
         }
@@ skipping 9941 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal