Introduce FeedbackNexus for vector-based ics.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index 98d86b5e39f41e97b45bc301e92e5768ba4a2616..ed567de434b962049a2069e955b608761ce12e10 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -89,8 +89,8 @@ const char* GetTransitionMarkModifier(KeyedAccessStoreMode mode) {
 
 void IC::TraceIC(const char* type, Handle<Object> name) {
   if (FLAG_trace_ic) {
-    Code* new_target = raw_target();
-    State new_state = new_target->ic_state();
+    State new_state =
+        UseVector() ? nexus()->StateFromFeedback() : raw_target()->ic_state();
     TraceIC(type, name, state(), new_state);
   }
 }
@@ -134,12 +134,16 @@ void IC::TraceIC(const char* type, Handle<Object> name, State old_state,
   }
 }
 
+
 #define TRACE_IC(type, name) TraceIC(type, name)
-#define TRACE_VECTOR_IC(type, name, old_state, new_state) \
-  TraceIC(type, name, old_state, new_state)
 
-IC::IC(FrameDepth depth, Isolate* isolate)
-    : isolate_(isolate), target_set_(false), target_maps_set_(false) {
+
+IC::IC(FrameDepth depth, Isolate* isolate, FeedbackNexus* nexus,
+       bool for_queries_only)
+    : isolate_(isolate),
+      target_set_(false),
+      target_maps_set_(false),
+      nexus_(nexus) {
   // To improve the performance of the (much used) IC code, we unfold a few
   // levels of the stack frame iteration code. This yields a ~35% speedup when
   // running DeltaBlue and a ~25% speedup of gbemu with the '--nouse-ic' flag.
@@ -178,8 +182,10 @@ IC::IC(FrameDepth depth, Isolate* isolate)
   }
   pc_address_ = StackFrame::ResolveReturnAddressLocation(pc_address);
   target_ = handle(raw_target(), isolate);
-  state_ = target_->ic_state();
   kind_ = target_->kind();
+  state_ = (!for_queries_only && UseVector()) ? nexus->StateFromFeedback()
+                                              : target_->ic_state();
+  old_state_ = state_;
   extra_ic_state_ = target_->extra_ic_state();
 }
 
@@ -419,6 +425,30 @@ void IC::OnTypeFeedbackChanged(Isolate* isolate, Address address,
 }
 
 
+// static
+void IC::OnTypeFeedbackChanged(Isolate* isolate, Code* host,
+                               TypeFeedbackVector* vector, State old_state,
+                               State new_state) {
+  if (host->kind() != Code::FUNCTION) return;
+
+  if (FLAG_type_info_threshold > 0) {
+    int polymorphic_delta = 0;  // "Polymorphic" here includes monomorphic.
+    int generic_delta = 0;      // "Generic" here includes megamorphic.
+    ComputeTypeInfoCountDelta(old_state, new_state, &polymorphic_delta,
+                              &generic_delta);
+    vector->change_ic_with_type_info_count(polymorphic_delta);
+    vector->change_ic_generic_count(generic_delta);
+  }
+  TypeFeedbackInfo* info = TypeFeedbackInfo::cast(host->type_feedback_info());
+  info->change_own_type_change_checksum();
+  host->set_profiler_ticks(0);
+  isolate->runtime_profiler()->NotifyICChanged();
+  // TODO(2029): When an optimized function is patched, it would
+  // be nice to propagate the corresponding type information to its
+  // unoptimized version for the benefit of later inlining.
+}
+
+
 void IC::PostPatching(Address address, Code* target, Code* old_target) {
   // Type vector based ICs update these statistics at a different time because
   // they don't always patch on state change.
@@ -508,10 +538,11 @@ void IC::Clear(Isolate* isolate, Address address,
 
 
 void IC::Clear(Isolate* isolate, Code::Kind kind, Code* host,
-               TypeFeedbackVector* vector, FeedbackVectorICSlot slot) {
+               FeedbackNexus* nexus) {
   switch (kind) {
     case Code::CALL_IC:
-      return CallIC::Clear(isolate, host, vector, slot);
+      return CallIC::Clear(isolate, host,
+                           reinterpret_cast<CallICNexus*>(nexus));

[Igor Sheludko, 2014/10/28 11:12:36]

static_cast?

[mvstanton, 2014/10/28 13:23:28]

I hated the cast anyway, so I've changed this to a template method where you
need to pass the appropriate kind of FeedbackNexus in order to compile. That
should be better, at least.

     default:
       UNREACHABLE();
   }
@@ -529,18 +560,15 @@ void KeyedLoadIC::Clear(Isolate* isolate, Address address, Code* target,
 }
 
 
-void CallIC::Clear(Isolate* isolate, Code* host, TypeFeedbackVector* vector,
-                   FeedbackVectorICSlot slot) {
-  DCHECK(vector != NULL && !slot.IsInvalid());
-  Object* feedback = vector->Get(slot);
+void CallIC::Clear(Isolate* isolate, Code* host, CallICNexus* nexus) {
   // Determine our state.
-  State state = FeedbackToState(isolate, vector, slot);
+  Object* feedback = nexus->vector()->Get(nexus->slot());
+  State state = nexus->StateFromFeedback();
 
   if (state != UNINITIALIZED && !feedback->IsAllocationSite()) {
-    vector->Set(slot, isolate->heap()->uninitialized_symbol(),
-                SKIP_WRITE_BARRIER);
+    nexus->ConfigureUninitialized();

[Igor Sheludko, 2014/10/28 11:12:36]

Does it make sense to proceed skipping write barriers for Uninitialized and
Generic sentinels?

[mvstanton, 2014/10/28 13:23:28]

It does indeed, I've make that fix in type-feedback-vector.cc, thanks!

     // The change in state must be processed.
-    OnTypeFeedbackChanged(isolate, host, vector, state, UNINITIALIZED);
+    OnTypeFeedbackChanged(isolate, host, nexus->vector(), state, UNINITIALIZED);
   }
 }
 
@@ -1940,34 +1968,8 @@ MaybeHandle<Object> KeyedStoreIC::Store(Handle<Object> object,
 }
 
 
-// static
-void CallIC::OnTypeFeedbackChanged(Isolate* isolate, Code* host,
-                                   TypeFeedbackVector* vector, State old_state,
-                                   State new_state) {
-  if (host->kind() != Code::FUNCTION) return;
-
-  if (FLAG_type_info_threshold > 0) {
-    int polymorphic_delta = 0;  // "Polymorphic" here includes monomorphic.
-    int generic_delta = 0;      // "Generic" here includes megamorphic.
-    ComputeTypeInfoCountDelta(old_state, new_state, &polymorphic_delta,
-                              &generic_delta);
-    vector->change_ic_with_type_info_count(polymorphic_delta);
-    vector->change_ic_generic_count(generic_delta);
-  }
-  TypeFeedbackInfo* info = TypeFeedbackInfo::cast(host->type_feedback_info());
-  info->change_own_type_change_checksum();
-  host->set_profiler_ticks(0);
-  isolate->runtime_profiler()->NotifyICChanged();
-  // TODO(2029): When an optimized function is patched, it would
-  // be nice to propagate the corresponding type information to its
-  // unoptimized version for the benefit of later inlining.
-}
-
-
 bool CallIC::DoCustomHandler(Handle<Object> receiver, Handle<Object> function,
-                             Handle<TypeFeedbackVector> vector,
-                             FeedbackVectorICSlot slot,
-                             const CallICState& state) {
+                             const CallICState& callic_state) {
   DCHECK(FLAG_use_ic && function->IsJSFunction());
 
   // Are we the array function?
@@ -1975,42 +1977,33 @@ bool CallIC::DoCustomHandler(Handle<Object> receiver, Handle<Object> function,
       Handle<JSFunction>(isolate()->native_context()->array_function());
   if (array_function.is_identical_to(Handle<JSFunction>::cast(function))) {
     // Alter the slot.
-    IC::State old_state = FeedbackToState(isolate(), *vector, slot);
-    Object* feedback = vector->Get(slot);
-    if (!feedback->IsAllocationSite()) {
-      Handle<AllocationSite> new_site =
-          isolate()->factory()->NewAllocationSite();
-      vector->Set(slot, *new_site);
-    }
+    CallICNexus* nexus = casted_nexus<CallICNexus>();
+    nexus->ConfigureMonomorphicArray();
 
-    CallIC_ArrayStub stub(isolate(), state);
+    CallIC_ArrayStub stub(isolate(), callic_state);
     set_target(*stub.GetCode());
     Handle<String> name;
     if (array_function->shared()->name()->IsString()) {
       name = Handle<String>(String::cast(array_function->shared()->name()),
                             isolate());
     }
-
-    IC::State new_state = FeedbackToState(isolate(), *vector, slot);
-    OnTypeFeedbackChanged(isolate(), get_host(), *vector, old_state, new_state);
-    TRACE_VECTOR_IC("CallIC (custom handler)", name, old_state, new_state);
+    TRACE_IC("CallIC", name);
+    OnTypeFeedbackChanged(isolate(), get_host(), nexus->vector(), state(),
+                          MONOMORPHIC);
     return true;
   }
   return false;
 }
 
 
-void CallIC::PatchMegamorphic(Handle<Object> function,
-                              Handle<TypeFeedbackVector> vector,
-                              FeedbackVectorICSlot slot) {
-  CallICState state(target()->extra_ic_state());
-  IC::State old_state = FeedbackToState(isolate(), *vector, slot);
+void CallIC::PatchMegamorphic(Handle<Object> function) {
+  CallICState callic_state(target()->extra_ic_state());
 
   // We are going generic.
-  vector->Set(slot, *TypeFeedbackVector::MegamorphicSentinel(isolate()),
-              SKIP_WRITE_BARRIER);
+  CallICNexus* nexus = casted_nexus<CallICNexus>();
+  nexus->ConfigureGeneric();
 
-  CallICStub stub(isolate(), state);
+  CallICStub stub(isolate(), callic_state);
   Handle<Code> code = stub.GetCode();
   set_target(*code);
 
@@ -2020,27 +2013,24 @@ void CallIC::PatchMegamorphic(Handle<Object> function,
     name = handle(js_function->shared()->name(), isolate());
   }
 
-  IC::State new_state = FeedbackToState(isolate(), *vector, slot);
-  OnTypeFeedbackChanged(isolate(), get_host(), *vector, old_state, new_state);
-  TRACE_VECTOR_IC("CallIC", name, old_state, new_state);
+  TRACE_IC("CallIC", name);
+  OnTypeFeedbackChanged(isolate(), get_host(), nexus->vector(), state(),
+                        GENERIC);
 }
 
 
-void CallIC::HandleMiss(Handle<Object> receiver, Handle<Object> function,
-                        Handle<TypeFeedbackVector> vector,
-                        FeedbackVectorICSlot slot) {
-  CallICState state(target()->extra_ic_state());
-  IC::State old_state = FeedbackToState(isolate(), *vector, slot);
+void CallIC::HandleMiss(Handle<Object> receiver, Handle<Object> function) {
+  CallICState callic_state(target()->extra_ic_state());
   Handle<Object> name = isolate()->factory()->empty_string();
-  Object* feedback = vector->Get(slot);
+  CallICNexus* nexus = casted_nexus<CallICNexus>();
+  Object* feedback = nexus->GetFeedback();
 
   // Hand-coded MISS handling is easier if CallIC slots don't contain smis.
   DCHECK(!feedback->IsSmi());
 
   if (feedback->IsJSFunction() || !function->IsJSFunction()) {
     // We are going generic.
-    vector->Set(slot, *TypeFeedbackVector::MegamorphicSentinel(isolate()),
-                SKIP_WRITE_BARRIER);
+    nexus->ConfigureGeneric();
   } else {
     // The feedback is either uninitialized or an allocation site.
     // It might be an allocation site because if we re-compile the full code
@@ -2052,12 +2042,11 @@ void CallIC::HandleMiss(Handle<Object> receiver, Handle<Object> function,
            feedback->IsAllocationSite());
 
     // Do we want to install a custom handler?
-    if (FLAG_use_ic &&
-        DoCustomHandler(receiver, function, vector, slot, state)) {
+    if (FLAG_use_ic && DoCustomHandler(receiver, function, callic_state)) {
       return;
     }
 
-    vector->Set(slot, *function);
+    nexus->ConfigureMonomorphic(Handle<JSFunction>::cast(function));
   }
 
   if (function->IsJSFunction()) {
@@ -2065,9 +2054,9 @@ void CallIC::HandleMiss(Handle<Object> receiver, Handle<Object> function,
     name = handle(js_function->shared()->name(), isolate());
   }
 
-  IC::State new_state = FeedbackToState(isolate(), *vector, slot);
-  OnTypeFeedbackChanged(isolate(), get_host(), *vector, old_state, new_state);
-  TRACE_VECTOR_IC("CallIC", name, old_state, new_state);
+  IC::State new_state = nexus->StateFromFeedback();
+  OnTypeFeedbackChanged(isolate(), get_host(), *vector(), state(), new_state);
+  TRACE_IC("CallIC", name);
 }
 
 
@@ -2083,13 +2072,14 @@ RUNTIME_FUNCTION(CallIC_Miss) {
   TimerEventScope<TimerEventIcMiss> timer(isolate);
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
-  CallIC ic(isolate);
   Handle<Object> receiver = args.at<Object>(0);
   Handle<Object> function = args.at<Object>(1);
   Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(2);
   Handle<Smi> slot = args.at<Smi>(3);
   FeedbackVectorICSlot vector_slot = vector->ToICSlot(slot->value());
-  ic.HandleMiss(receiver, function, vector, vector_slot);
+  CallICNexus nexus(vector, vector_slot);
+  CallIC ic(isolate, &nexus);
+  ic.HandleMiss(receiver, function);
   return *function;
 }
 
@@ -2099,12 +2089,14 @@ RUNTIME_FUNCTION(CallIC_Customization_Miss) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
   // A miss on a custom call ic always results in going megamorphic.

[Igor Sheludko, 2014/10/28 11:12:36]

This comment can be removed from here.

[mvstanton, 2014/10/28 13:23:28]

Done.

-  CallIC ic(isolate);
   Handle<Object> function = args.at<Object>(1);
   Handle<TypeFeedbackVector> vector = args.at<TypeFeedbackVector>(2);
   Handle<Smi> slot = args.at<Smi>(3);
   FeedbackVectorICSlot vector_slot = vector->ToICSlot(slot->value());
-  ic.PatchMegamorphic(function, vector, vector_slot);
+  CallICNexus nexus(vector, vector_slot);
+  // A miss on a custom call ic always results in going megamorphic.
+  CallIC ic(isolate, &nexus);
+  ic.PatchMegamorphic(function);
   return *function;
 }