Remove unused byte from Map::instance_sizes field.

src/heap/heap.cc

 // Copyright 2012 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/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 2704 matching lines @@
   reinterpret_cast<Map*>(result)->set_map(raw_unchecked_meta_map());
   reinterpret_cast<Map*>(result)->set_instance_type(instance_type);
   reinterpret_cast<Map*>(result)->set_instance_size(instance_size);
   // Initialize to only containing tagged fields.
   reinterpret_cast<Map*>(result)->set_visitor_id(
       StaticVisitorBase::GetVisitorId(instance_type, instance_size, false));
   if (FLAG_unbox_double_fields) {
     reinterpret_cast<Map*>(result)
         ->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
   }
+  reinterpret_cast<Map*>(result)->clear_unused();
   reinterpret_cast<Map*>(result)->set_inobject_properties(0);
-  reinterpret_cast<Map*>(result)->set_pre_allocated_property_fields(0);
   reinterpret_cast<Map*>(result)->set_unused_property_fields(0);
   reinterpret_cast<Map*>(result)->set_bit_field(0);
   reinterpret_cast<Map*>(result)->set_bit_field2(0);
   int bit_field3 = Map::EnumLengthBits::encode(kInvalidEnumCacheSentinel) |
                    Map::OwnsDescriptors::encode(true) |
                    Map::Counter::encode(Map::kRetainingCounterStart);
   reinterpret_cast<Map*>(result)->set_bit_field3(bit_field3);
   reinterpret_cast<Map*>(result)->set_weak_cell_cache(Smi::FromInt(0));
   return result;
 }
 
 
 AllocationResult Heap::AllocateMap(InstanceType instance_type,
                                    int instance_size,
                                    ElementsKind elements_kind) {
   HeapObject* result;
   AllocationResult allocation = AllocateRaw(Map::kSize, MAP_SPACE, MAP_SPACE);
   if (!allocation.To(&result)) return allocation;
 
   result->set_map_no_write_barrier(meta_map());
   Map* map = Map::cast(result);
   map->set_instance_type(instance_type);
   map->set_prototype(null_value(), SKIP_WRITE_BARRIER);
   map->set_constructor_or_backpointer(null_value(), SKIP_WRITE_BARRIER);
   map->set_instance_size(instance_size);
+  map->clear_unused();
   map->set_inobject_properties(0);
-  map->set_pre_allocated_property_fields(0);
   map->set_code_cache(empty_fixed_array(), SKIP_WRITE_BARRIER);
   map->set_dependent_code(DependentCode::cast(empty_fixed_array()),
                           SKIP_WRITE_BARRIER);
   map->set_weak_cell_cache(Smi::FromInt(0));
   map->set_raw_transitions(Smi::FromInt(0));
   map->set_unused_property_fields(0);
   map->set_instance_descriptors(empty_descriptor_array());
   if (FLAG_unbox_double_fields) {
     map->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
   }
@@ skipping 1419 matching lines @@
     DCHECK(obj->GetInternalFieldCount() == 0);
     filler = Heap::one_pointer_filler_map();
   } else {
     filler = Heap::undefined_value();
   }
   obj->InitializeBody(map, Heap::undefined_value(), filler);
 }
 
 
 AllocationResult Heap::AllocateJSObjectFromMap(
-    Map* map, PretenureFlag pretenure, bool allocate_properties,
-    AllocationSite* allocation_site) {
+    Map* map, PretenureFlag pretenure, AllocationSite* allocation_site) {
   // JSFunctions should be allocated using AllocateFunction to be
   // properly initialized.
   DCHECK(map->instance_type() != JS_FUNCTION_TYPE);
 
   // Both types of global objects should be allocated using
   // AllocateGlobalObject to be properly initialized.
   DCHECK(map->instance_type() != JS_GLOBAL_OBJECT_TYPE);
   DCHECK(map->instance_type() != JS_BUILTINS_OBJECT_TYPE);
 
   // Allocate the backing storage for the properties.
-  FixedArray* properties;
-  if (allocate_properties) {
-    int prop_size = map->InitialPropertiesLength();
-    DCHECK(prop_size >= 0);
-    {
-      AllocationResult allocation = AllocateFixedArray(prop_size, pretenure);
-      if (!allocation.To(&properties)) return allocation;
-    }
-  } else {
-    properties = empty_fixed_array();
-  }
+  FixedArray* properties = empty_fixed_array();
 
   // Allocate the JSObject.
   int size = map->instance_size();
   AllocationSpace space = SelectSpace(size, pretenure);
   JSObject* js_obj;
   AllocationResult allocation = Allocate(map, space, allocation_site);
   if (!allocation.To(&js_obj)) return allocation;
 
   // Initialize the JSObject.
   InitializeJSObjectFromMap(js_obj, properties, map);
   DCHECK(js_obj->HasFastElements() || js_obj->HasExternalArrayElements() ||
          js_obj->HasFixedTypedArrayElements());
   return js_obj;
 }
 
 
 AllocationResult Heap::AllocateJSObject(JSFunction* constructor,
                                         PretenureFlag pretenure,
                                         AllocationSite* allocation_site) {
   DCHECK(constructor->has_initial_map());
 
   // Allocate the object based on the constructors initial map.
   AllocationResult allocation = AllocateJSObjectFromMap(
-      constructor->initial_map(), pretenure, true, allocation_site);
+      constructor->initial_map(), pretenure, allocation_site);
 #ifdef DEBUG
   // Make sure result is NOT a global object if valid.
   HeapObject* obj;
   DCHECK(!allocation.To(&obj) || !obj->IsGlobalObject());
 #endif
   return allocation;
 }
 
 
 AllocationResult Heap::CopyJSObject(JSObject* source, AllocationSite* site) {
@@ skipping 2644 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }  // namespace internal
 }  // namespace v8