Reland "In-object double fields unboxing (for 64-bit only)."

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 2290 matching lines @@
 AllocationResult Heap::AllocatePartialMap(InstanceType instance_type,
                                           int instance_size) {
   Object* result;
   AllocationResult allocation = AllocateRaw(Map::kSize, MAP_SPACE, MAP_SPACE);
   if (!allocation.To(&result)) return allocation;
 
   // Map::cast cannot be used due to uninitialized map field.
   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));
+      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)->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);
   reinterpret_cast<Map*>(result)->set_bit_field3(bit_field3);
   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_visitor_id(
-      StaticVisitorBase::GetVisitorId(instance_type, instance_size));
   map->set_prototype(null_value(), SKIP_WRITE_BARRIER);
   map->set_constructor(null_value(), SKIP_WRITE_BARRIER);
   map->set_instance_size(instance_size);
   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->init_back_pointer(undefined_value());
   map->set_unused_property_fields(0);
   map->set_instance_descriptors(empty_descriptor_array());
+  if (FLAG_unbox_double_fields) {
+    map->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
+  }
+  // Must be called only after |instance_type|, |instance_size| and
+  // |layout_descriptor| are set.
+  map->set_visitor_id(StaticVisitorBase::GetVisitorId(map));
   map->set_bit_field(0);
   map->set_bit_field2(1 << Map::kIsExtensible);
   int bit_field3 = Map::EnumLengthBits::encode(kInvalidEnumCacheSentinel) |
                    Map::OwnsDescriptors::encode(true);
   map->set_bit_field3(bit_field3);
   map->set_elements_kind(elements_kind);
 
   return map;
 }
 
@@ skipping 106 matching lines @@
     AllocationResult allocation = AllocateEmptyConstantPoolArray();
     if (!allocation.To(&obj)) return false;
   }
   set_empty_constant_pool_array(ConstantPoolArray::cast(obj));
 
   // Fix the instance_descriptors for the existing maps.
   meta_map()->set_code_cache(empty_fixed_array());
   meta_map()->set_dependent_code(DependentCode::cast(empty_fixed_array()));
   meta_map()->init_back_pointer(undefined_value());
   meta_map()->set_instance_descriptors(empty_descriptor_array());
+  if (FLAG_unbox_double_fields) {
+    meta_map()->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
+  }
 
   fixed_array_map()->set_code_cache(empty_fixed_array());
   fixed_array_map()->set_dependent_code(
       DependentCode::cast(empty_fixed_array()));
   fixed_array_map()->init_back_pointer(undefined_value());
   fixed_array_map()->set_instance_descriptors(empty_descriptor_array());
+  if (FLAG_unbox_double_fields) {
+    fixed_array_map()->set_layout_descriptor(
+        LayoutDescriptor::FastPointerLayout());
+  }
 
   undefined_map()->set_code_cache(empty_fixed_array());
   undefined_map()->set_dependent_code(DependentCode::cast(empty_fixed_array()));
   undefined_map()->init_back_pointer(undefined_value());
   undefined_map()->set_instance_descriptors(empty_descriptor_array());
+  if (FLAG_unbox_double_fields) {
+    undefined_map()->set_layout_descriptor(
+        LayoutDescriptor::FastPointerLayout());
+  }
 
   null_map()->set_code_cache(empty_fixed_array());
   null_map()->set_dependent_code(DependentCode::cast(empty_fixed_array()));
   null_map()->init_back_pointer(undefined_value());
   null_map()->set_instance_descriptors(empty_descriptor_array());
+  if (FLAG_unbox_double_fields) {
+    null_map()->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
+  }
 
   constant_pool_array_map()->set_code_cache(empty_fixed_array());
   constant_pool_array_map()->set_dependent_code(
       DependentCode::cast(empty_fixed_array()));
   constant_pool_array_map()->init_back_pointer(undefined_value());
   constant_pool_array_map()->set_instance_descriptors(empty_descriptor_array());
+  if (FLAG_unbox_double_fields) {
+    constant_pool_array_map()->set_layout_descriptor(
+        LayoutDescriptor::FastPointerLayout());
+  }
 
   // Fix prototype object for existing maps.
   meta_map()->set_prototype(null_value());
   meta_map()->set_constructor(null_value());
 
   fixed_array_map()->set_prototype(null_value());
   fixed_array_map()->set_constructor(null_value());
 
   undefined_map()->set_prototype(null_value());
   undefined_map()->set_constructor(null_value());
@@ skipping 3760 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal