Adapt Danno's Track Allocation Info idea to fast literals. When allocating a literal array,

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 7b05bbe04a538084facb4f8e4008e5a4d57ff0b4..c9506595a6b1bff5c3dea54990bc372053c8dbc0 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -291,6 +291,7 @@ const int kStubMinorKeyBits = kBitsPerInt - kSmiTagSize - kStubMajorKeyBits;
   V(OBJECT_TEMPLATE_INFO_TYPE)                                                 \
   V(SIGNATURE_INFO_TYPE)                                                       \
   V(TYPE_SWITCH_INFO_TYPE)                                                     \
+  V(ALLOCATION_SITE_INFO_TYPE)                                                 \
   V(SCRIPT_TYPE)                                                               \
   V(CODE_CACHE_TYPE)                                                           \
   V(POLYMORPHIC_CODE_CACHE_TYPE)                                               \
@@ -444,6 +445,7 @@ 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_INFO, AllocationSiteInfo, allocation_site_info)            \
   V(CODE_CACHE, CodeCache, code_cache)                                         \
   V(POLYMORPHIC_CODE_CACHE, PolymorphicCodeCache, polymorphic_code_cache)      \
   V(TYPE_FEEDBACK_INFO, TypeFeedbackInfo, type_feedback_info)                  \
@@ -606,6 +608,7 @@ enum InstanceType {
   OBJECT_TEMPLATE_INFO_TYPE,
   SIGNATURE_INFO_TYPE,
   TYPE_SWITCH_INFO_TYPE,
+  ALLOCATION_SITE_INFO_TYPE,
   SCRIPT_TYPE,
   CODE_CACHE_TYPE,
   POLYMORPHIC_CODE_CACHE_TYPE,
@@ -2012,6 +2015,8 @@ class JSObject: public JSReceiver {
                                                ElementsKind to_kind);
 
   MUST_USE_RESULT MaybeObject* TransitionElementsKind(ElementsKind to_kind);
+  MUST_USE_RESULT MaybeObject* PossiblyTransitionBoilerplate(
+      ElementsKind to_kind);
 
   // Replaces an existing transition with a transition to a map with a FIELD.
   MUST_USE_RESULT MaybeObject* ConvertTransitionToMapTransition(
@@ -6897,6 +6902,33 @@ class TypeFeedbackInfo: public Struct {
 };
 
 
+class AllocationSiteInfo: public Struct {
+ public:
+  DECL_ACCESSORS(payload, Object)
+
+  static inline AllocationSiteInfo* cast(Object* obj);
+
+#ifdef OBJECT_PRINT
+  inline void AllocationSiteInfoPrint() {
+    AllocationSiteInfoPrint(stdout);
+  }
+  void AllocationSiteInfoPrint(FILE* out);

[danno, 2013/01/04 08:50:55]

Maybe use some variant of DECLARE_PRINTER?

[mvstanton, 2013/01/04 12:07:52]

Done.

+#endif
+#ifdef DEBUG
+  void AllocationSiteInfoVerify();

[danno, 2013/01/04 08:50:55]

Use DECLARE_VERIFIER instead of explicitly declaring the Verifier yourself.

[mvstanton, 2013/01/04 12:07:52]

Done.

+#endif
+
+  // Returns NULL if no AllocationSiteInfo is available for object.
+  static AllocationSiteInfo* FindAfterJSObject(JSObject* object);
+
+  static const int kPayloadOffset = HeapObject::kHeaderSize;
+  static const int kSize = kPayloadOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationSiteInfo);
+};
+
+
 // Representation of a slow alias as part of a non-strict arguments objects.
 // For fast aliases (if HasNonStrictArgumentsElements()):
 // - the parameter map contains an index into the context