Introduce FeedbackNexus for vector-based ics.

src/ic/ic.h

Index: src/ic/ic.h
diff --git a/src/ic/ic.h b/src/ic/ic.h
index 5177ff8e22881aa53bd119419142a96a5894a830..c29b8316a56ac0fa66cbddef08d4278ee050c982 100644
--- a/src/ic/ic.h
+++ b/src/ic/ic.h
@@ -59,7 +59,8 @@ class IC {
 
   // Construct the IC structure with the given number of extra
   // JavaScript frames on the stack.
-  IC(FrameDepth depth, Isolate* isolate);
+  IC(FrameDepth depth, Isolate* isolate, FeedbackNexus* nexus = NULL,
+     bool for_queries_only = false);
   virtual ~IC() {}
 
   State state() const { return state_; }
@@ -71,6 +72,7 @@ class IC {
   bool IsNameCompatibleWithPrototypeFailure(Handle<Object> name);
   void MarkPrototypeFailure(Handle<Object> name) {
     DCHECK(IsNameCompatibleWithPrototypeFailure(name));
+    old_state_ = state_;
     state_ = PROTOTYPE_FAILURE;
   }
 
@@ -87,8 +89,9 @@ class IC {
                     ConstantPoolArray* constant_pool);
 
   // Clear the vector-based inline cache to initial state.
+  template <class Nexus>
   static void Clear(Isolate* isolate, Code::Kind kind, Code* host,
-                    TypeFeedbackVector* vector, FeedbackVectorICSlot slot);
+                    Nexus* nexus);
 
 #ifdef DEBUG
   bool IsLoadStub() const {
@@ -117,6 +120,11 @@ class IC {
     return state == UNINITIALIZED || state == PREMONOMORPHIC;
   }
 
+  static bool IsCleared(FeedbackNexus* nexus) {
+    InlineCacheState state = nexus->StateFromFeedback();
+    return state == UNINITIALIZED || state == PREMONOMORPHIC;
+  }
+
   // Utility functions to convert maps to types and back. There are two special
   // cases:
   // - The heap_number_map is used as a marker which includes heap numbers as
@@ -149,6 +157,15 @@ class IC {
   inline void set_target(Code* code);
   bool is_target_set() { return target_set_; }
 
+  bool UseVector() const {
+    bool use = (FLAG_vector_ics &&
+                (kind() == Code::LOAD_IC || kind() == Code::KEYED_LOAD_IC)) ||
+               kind() == Code::CALL_IC;
+    // If we are supposed to use the nexus, verify the nexus is non-null.
+    DCHECK(!use || nexus_ != NULL);
+    return use;
+  }
+
   char TransitionMarkFromState(IC::State state);
   void TraceIC(const char* type, Handle<Object> name);
   void TraceIC(const char* type, Handle<Object> name, State old_state,
@@ -166,6 +183,10 @@ class IC {
   static void OnTypeFeedbackChanged(Isolate* isolate, Address address,
                                     State old_state, State new_state,
                                     bool target_remains_ic_stub);
+  // As a vector-based IC, type feedback must be updated differently.
+  static void OnTypeFeedbackChanged(Isolate* isolate, Code* host,
+                                    TypeFeedbackVector* vector, State old_state,
+                                    State new_state);
   static void PostPatching(Address address, Code* target, Code* old_target);
 
   // Compute the handler either by compiling or by retrieving a cached version.
@@ -229,6 +250,20 @@ class IC {
 
   inline void UpdateTarget();
 
+  Handle<TypeFeedbackVector> vector() const { return nexus()->vector_handle(); }
+  FeedbackVectorICSlot slot() const { return nexus()->slot(); }
+  State saved_state() const {
+    return state() == PROTOTYPE_FAILURE ? old_state_ : state();
+  }
+
+  template <class NexusClass>
+  NexusClass* casted_nexus() {
+    return static_cast<NexusClass*>(nexus_);
+  }
+  FeedbackNexus* nexus() const { return nexus_; }
+
+  inline Code* get_host();
+
  private:
   inline Code* raw_target() const;
   inline ConstantPoolArray* constant_pool() const;
@@ -263,6 +298,7 @@ class IC {
   // The original code target that missed.
   Handle<Code> target_;
   bool target_set_;
+  State old_state_;  // For saving if we marked as prototype failure.
   State state_;
   Code::Kind kind_;
   Handle<HeapType> receiver_type_;
@@ -272,6 +308,8 @@ class IC {
   MapHandleList target_maps_;
   bool target_maps_set_;
 
+  FeedbackNexus* nexus_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(IC);
 };
 
@@ -295,38 +333,24 @@ class IC_Utility {
 
 class CallIC : public IC {
  public:
-  explicit CallIC(Isolate* isolate) : IC(EXTRA_CALL_FRAME, isolate) {}
+  CallIC(Isolate* isolate, CallICNexus* nexus)
+      : IC(EXTRA_CALL_FRAME, isolate, nexus) {
+    DCHECK(nexus != NULL);
+  }
 
-  void PatchMegamorphic(Handle<Object> function,
-                        Handle<TypeFeedbackVector> vector,
-                        FeedbackVectorICSlot slot);
+  void PatchMegamorphic(Handle<Object> function);
 
-  void HandleMiss(Handle<Object> receiver, Handle<Object> function,
-                  Handle<TypeFeedbackVector> vector, FeedbackVectorICSlot slot);
+  void HandleMiss(Handle<Object> receiver, Handle<Object> function);
 
   // Returns true if a custom handler was installed.
   bool DoCustomHandler(Handle<Object> receiver, Handle<Object> function,
-                       Handle<TypeFeedbackVector> vector,
-                       FeedbackVectorICSlot slot, const CallICState& state);
+                       const CallICState& callic_state);
 
   // Code generator routines.
   static Handle<Code> initialize_stub(Isolate* isolate, int argc,
                                       CallICState::CallType call_type);
 
-  static void Clear(Isolate* isolate, Code* host, TypeFeedbackVector* vector,
-                    FeedbackVectorICSlot slot);
-
- private:
-  static inline IC::State FeedbackToState(Isolate* isolate,
-                                          TypeFeedbackVector* vector,
-                                          FeedbackVectorICSlot slot);
-
-  inline Code* get_host();
-
-  // As a vector-based IC, type feedback must be updated differently.
-  static void OnTypeFeedbackChanged(Isolate* isolate, Code* host,
-                                    TypeFeedbackVector* vector, State old_state,
-                                    State new_state);
+  static void Clear(Isolate* isolate, Code* host, CallICNexus* nexus);
 };