From 01f7bd262fb1be893fe4bdc6b98a1b43c5a0bb7d Mon Sep 17 00:00:00 2001
From: Aaron Kennedy <aaron.kennedy@nokia.com>
Date: Mon, 23 May 2011 15:55:26 +1000
Subject: [PATCH 02/16] Add a bit field 3 to Map

Bit field 3 will be used to add QML specific map flags.
---
 src/heap.cc       |    2 ++
 src/objects-inl.h |   10 ++++++++++
 src/objects.cc    |    2 ++
 src/objects.h     |    9 ++++++++-
 4 files changed, 22 insertions(+), 1 deletions(-)

diff --git a/src/heap.cc b/src/heap.cc
index 930c97b..900f462 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -1573,6 +1573,7 @@ MaybeObject* Heap::AllocatePartialMap(InstanceType instance_type,
   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);
+  reinterpret_cast<Map*>(result)->set_bit_field3(0);
   return result;
 }
 
@@ -1599,6 +1600,7 @@ MaybeObject* Heap::AllocateMap(InstanceType instance_type, int instance_size) {
   map->set_unused_property_fields(0);
   map->set_bit_field(0);
   map->set_bit_field2((1 << Map::kIsExtensible) | (1 << Map::kHasFastElements));
+  map->set_bit_field3(0);
 
   // If the map object is aligned fill the padding area with Smi 0 objects.
   if (Map::kPadStart < Map::kSize) {
diff --git a/src/objects-inl.h b/src/objects-inl.h
index c82080d..cce3edd 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2430,6 +2430,16 @@ void Map::set_bit_field2(byte value) {
 }
 
 
+byte Map::bit_field3() {
+  return READ_BYTE_FIELD(this, kBitField3Offset);
+}
+
+
+void Map::set_bit_field3(byte value) {
+  WRITE_BYTE_FIELD(this, kBitField3Offset, value);
+}
+
+
 void Map::set_non_instance_prototype(bool value) {
   if (value) {
     set_bit_field(bit_field() | (1 << kHasNonInstancePrototype));
diff --git a/src/objects.cc b/src/objects.cc
index dc4b260..79d7240 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -3614,6 +3614,7 @@ MaybeObject* Map::CopyDropDescriptors() {
   }
   Map::cast(result)->set_bit_field(bit_field());
   Map::cast(result)->set_bit_field2(bit_field2());
+  Map::cast(result)->set_bit_field3(bit_field3());
   Map::cast(result)->set_is_shared(false);
   Map::cast(result)->ClearCodeCache(heap);
   return result;
@@ -3642,6 +3643,7 @@ MaybeObject* Map::CopyNormalized(PropertyNormalizationMode mode,
 
   Map::cast(result)->set_bit_field(bit_field());
   Map::cast(result)->set_bit_field2(bit_field2());
+  Map::cast(result)->set_bit_field3(bit_field3());
 
   Map::cast(result)->set_is_shared(sharing == SHARED_NORMALIZED_MAP);
 
diff --git a/src/objects.h b/src/objects.h
index 6e26f57..07e1089 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3597,6 +3597,10 @@ class Map: public HeapObject {
   inline byte bit_field2();
   inline void set_bit_field2(byte value);
 
+  // Bit field 3.
+  inline byte bit_field3();
+  inline void set_bit_field3(byte value);
+
   // Tells whether the object in the prototype property will be used
   // for instances created from this function.  If the prototype
   // property is set to a value that is not a JSObject, the prototype
@@ -3844,7 +3848,7 @@ class Map: public HeapObject {
   // Layout description.
   static const int kInstanceSizesOffset = HeapObject::kHeaderSize;
   static const int kInstanceAttributesOffset = kInstanceSizesOffset + kIntSize;
-  static const int kPrototypeOffset = kInstanceAttributesOffset + kIntSize;
+  static const int kPrototypeOffset = POINTER_SIZE_ALIGN(kInstanceAttributesOffset + 2 * kIntSize);
   static const int kConstructorOffset = kPrototypeOffset + kPointerSize;
   static const int kInstanceDescriptorsOffset =
       kConstructorOffset + kPointerSize;
@@ -3876,6 +3880,7 @@ class Map: public HeapObject {
   static const int kUnusedPropertyFieldsOffset = kInstanceAttributesOffset + 1;
   static const int kBitFieldOffset = kInstanceAttributesOffset + 2;
   static const int kBitField2Offset = kInstanceAttributesOffset + 3;
+  static const int kBitField3Offset = kInstanceAttributesOffset + 4;
 
   STATIC_CHECK(kInstanceTypeOffset == Internals::kMapInstanceTypeOffset);
 
@@ -3898,6 +3903,8 @@ class Map: public HeapObject {
   static const int kIsShared = 5;
   static const int kHasExternalArrayElements = 6;
 
+  // Bit positions for bit field 3
+
   // Layout of the default cache. It holds alternating name and code objects.
   static const int kCodeCacheEntrySize = 2;
   static const int kCodeCacheEntryNameOffset = 0;
-- 
1.7.4.4