Create AllocationSite objects, pointed to by AllocationSiteInfo.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 0c8ee7147c04c3dbc033c9101f223a958e450f10..9a9dfd392bd2176322f49b52a361fd999a59e939 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -381,6 +381,7 @@ const int kStubMinorKeyBits = kBitsPerInt - kSmiTagSize - kStubMajorKeyBits;
   V(SIGNATURE_INFO_TYPE)                                                       \
   V(TYPE_SWITCH_INFO_TYPE)                                                     \
   V(ALLOCATION_SITE_INFO_TYPE)                                                 \
+  V(ALLOCATION_SITE_TYPE)                                                      \
   V(SCRIPT_TYPE)                                                               \
   V(CODE_CACHE_TYPE)                                                           \
   V(POLYMORPHIC_CODE_CACHE_TYPE)                                               \
@@ -543,6 +544,7 @@ const int kStubMinorKeyBits = kBitsPerInt - kSmiTagSize - kStubMajorKeyBits;
   V(SIGNATURE_INFO, SignatureInfo, signature_info)                             \
   V(TYPE_SWITCH_INFO, TypeSwitchInfo, type_switch_info)                        \
   V(SCRIPT, Script, script)                                                    \
+  V(ALLOCATION_SITE, AllocationSite, allocation_site)                          \
   V(ALLOCATION_SITE_INFO, AllocationSiteInfo, allocation_site_info)            \
   V(CODE_CACHE, CodeCache, code_cache)                                         \
   V(POLYMORPHIC_CODE_CACHE, PolymorphicCodeCache, polymorphic_code_cache)      \
@@ -702,6 +704,7 @@ enum InstanceType {
   OBJECT_TEMPLATE_INFO_TYPE,
   SIGNATURE_INFO_TYPE,
   TYPE_SWITCH_INFO_TYPE,
+  ALLOCATION_SITE_TYPE,
   ALLOCATION_SITE_INFO_TYPE,
   SCRIPT_TYPE,
   CODE_CACHE_TYPE,
@@ -2206,8 +2209,7 @@ class JSObject: public JSReceiver {
                                                ElementsKind to_kind);
 
   MUST_USE_RESULT MaybeObject* TransitionElementsKind(ElementsKind to_kind);
-  MUST_USE_RESULT MaybeObject* UpdateAllocationSiteInfo(
-      ElementsKind to_kind);
+  MUST_USE_RESULT MaybeObject* UpdateAllocationSite(ElementsKind to_kind);
 
   // Replaces an existing transition with a transition to a map with a FIELD.
   MUST_USE_RESULT MaybeObject* ConvertTransitionToMapTransition(
@@ -7455,6 +7457,45 @@ enum AllocationSiteMode {
 };
 
 
+class AllocationSite: public Struct {
+ public:
+  DECL_ACCESSORS(payload, Object)

[Hannes Payer (out of office), 2013/06/25 16:35:07]

Can we rename payload to something more meaningful? Like transition_data...?

[mvstanton, 2013/07/02 13:55:11]

For this one I added a TODO because I'd have to touch a lot. I'd like to do it
in the follow up CL which renames AllocationSiteInfo to be called
AllocationMemento. That will be very simple, even though it touches a lot.

+
+  static inline AllocationSite* cast(Object* obj);
+
+  void Initialize() {
+    set_payload(Smi::FromInt(GetInitialFastElementsKind()));

[Hannes Payer (out of office), 2013/06/25 16:35:07]

You can call SetElementsKindPayload there.

[mvstanton, 2013/07/02 13:55:11]

Done.

+  }

[Hannes Payer (out of office), 2013/06/25 16:35:07]

declaration order: Typedefs and Enums, Constants (static const data members),
Constructors, Destructor, Methods including static methods,
Data Members (except static const data members)

Moreover can we keep the static methods together?

[mvstanton, 2013/07/02 13:55:11]

I think I've arranged it better now, have a look.

+
+  DECLARE_PRINTER(AllocationSite)
+  DECLARE_VERIFIER(AllocationSite)
+
+  static inline AllocationSiteMode GetMode(
+      ElementsKind boilerplate_elements_kind);
+  static inline AllocationSiteMode GetMode(ElementsKind from, ElementsKind to);
+
+  static const int kPayloadOffset = HeapObject::kHeaderSize;
+  static const int kSize = kPayloadOffset + kPointerSize;
+  static const uint32_t kMaximumArrayBytesToPretransition = 8 * 1024;
+
+  ElementsKind GetElementsKindPayload() {
+    ASSERT(!IsLiteralSite());
+    return static_cast<ElementsKind>(Smi::cast(payload())->value());
+  }
+
+  void SetElementsKindPayload(ElementsKind kind) {
+    set_payload(Smi::FromInt(static_cast<int>(kind)));
+  }
+
+  bool IsLiteralSite() {
+    return !payload()->IsSmi();  // payload is a boilerplate

[Hannes Payer (out of office), 2013/06/25 16:35:07]

remove comment or make it clear.

[mvstanton, 2013/07/02 13:55:11]

Clarified, and made the test stronger: return payload()->IsJSArray().

+  }
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationSite);
+};
+
+
 class AllocationSiteInfo: public Struct {

[Hannes Payer (out of office), 2013/06/25 16:35:07]

declaration order... I just saw that it is not consistent in our code base but
the google coding style guide suggest to do that. Let's be a good example.

[mvstanton, 2013/07/02 13:55:11]

Done.

  public:
   DECL_ACCESSORS(payload, Object)
@@ -7466,15 +7507,10 @@ class AllocationSiteInfo: public Struct {
 
   // Returns NULL if no AllocationSiteInfo is available for object.
   static AllocationSiteInfo* FindForJSObject(JSObject* object);
-  static inline AllocationSiteMode GetMode(
-      ElementsKind boilerplate_elements_kind);
-  static inline AllocationSiteMode GetMode(ElementsKind from, ElementsKind to);
 
   static const int kPayloadOffset = HeapObject::kHeaderSize;

[Hannes Payer (out of office), 2013/06/25 16:35:07]

Do you think it makes sense to rename kPayloadOffset to kAllocationSiteOffset? I
do not think that we are going to add more fields to AllocationSiteInfo.

[mvstanton, 2013/07/02 13:55:11]

Done.

   static const int kSize = kPayloadOffset + kPointerSize;
-  static const uint32_t kMaximumArrayBytesToPretransition = 8 * 1024;
 
-  bool GetElementsKindPayload(ElementsKind* kind);
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationSiteInfo);
 };