[ic] Track the IC state change in FeedbackNexus::ConfigureMegamorphic

- This precents us from logging two ICEvents for a megamorphic miss that adds
  a new property
- We don't have to reset the profiler ticks anymore for this miss

The particular case for missing to add a new property happens ~1700 times in
the Speedometer Angular benchmark where we get an already internalized key
as property name.

Change-Id: I2362c3b7a66d9def1bc4295f6f1e64c96b25fe8a
Reviewed-on: https://chromium-review.googlesource.com/777259
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49464}

src/feedback-vector.cc

@@ -524,12 +524,22 @@ void FeedbackNexus::ConfigurePremonomorphic() {
                    SKIP_WRITE_BARRIER);
 }
 
-void FeedbackNexus::ConfigureMegamorphic(IcCheckType property_type) {
+bool FeedbackNexus::ConfigureMegamorphic(IcCheckType property_type) {
+  DisallowHeapAllocation no_gc;
   Isolate* isolate = GetIsolate();
-  SetFeedback(*FeedbackVector::MegamorphicSentinel(isolate),
-              SKIP_WRITE_BARRIER);
-  SetFeedbackExtra(Smi::FromInt(static_cast<int>(property_type)),
-                   SKIP_WRITE_BARRIER);
+  bool changed = false;
+  Symbol* sentinel = *FeedbackVector::MegamorphicSentinel(isolate);
+  if (GetFeedback() != sentinel) {
+    SetFeedback(sentinel, SKIP_WRITE_BARRIER);
+    changed = true;
+  }
+
+  Smi* extra = Smi::FromInt(static_cast<int>(property_type));
+  if (changed || GetFeedbackExtra() != extra) {
+    SetFeedbackExtra(extra, SKIP_WRITE_BARRIER);
+    changed = true;
+  }
+  return changed;
 }
 
 InlineCacheState LoadICNexus::StateFromFeedback() const {

src/feedback-vector.h

@@ -586,7 +586,7 @@ class FeedbackNexus {
   virtual void Clear() { ConfigureUninitialized(); }
   virtual void ConfigureUninitialized();
   void ConfigurePremonomorphic();
-  void ConfigureMegamorphic(IcCheckType property_type);
+  bool ConfigureMegamorphic(IcCheckType property_type);
 
   inline Object* GetFeedback() const;
   inline Object* GetFeedbackExtra() const;

src/ic/ic.cc

@@ -369,12 +369,16 @@ static bool MigrateDeprecated(Handle<Object> object) {
   return true;
 }
 
-void IC::ConfigureVectorState(IC::State new_state, Handle<Object> key) {
+bool IC::ConfigureVectorState(IC::State new_state, Handle<Object> key) {
   if (new_state == PREMONOMORPHIC) {
     nexus()->ConfigurePremonomorphic();
   } else if (new_state == MEGAMORPHIC) {
     DCHECK_IMPLIES(!is_keyed(), key->IsName());
-    nexus()->ConfigureMegamorphic(key->IsName() ? PROPERTY : ELEMENT);
+    IcCheckType property_type = key->IsName() ? PROPERTY : ELEMENT;
+    if (!nexus()->ConfigureMegamorphic(property_type)) {
+      vector_set_ = true;
+      return false;
+    }
   } else {
     UNREACHABLE();
   }
@@ -383,6 +387,7 @@ void IC::ConfigureVectorState(IC::State new_state, Handle<Object> key) {
   OnFeedbackChanged(
       isolate(), *vector(), slot(), GetHostFunction(),
       new_state == PREMONOMORPHIC ? "Premonomorphic" : "Megamorphic");
+  return true;
 }
 
 void IC::ConfigureVectorState(Handle<Name> name, Handle<Map> map,
@@ -1392,6 +1397,7 @@ void StoreIC::UpdateCaches(LookupIterator* lookup, Handle<Object> value,
     if (created_new_transition_) {
       // The first time a transition is performed, there's a good chance that
       // it won't be taken again, so don't bother creating a handler.
+      TRACE_GENERIC_IC("new transition");
       TRACE_IC("StoreIC", lookup->name());
       return;
     }
@@ -1943,9 +1949,10 @@ MaybeHandle<Object> KeyedStoreIC::Store(Handle<Object> object,
                        JSReceiver::MAY_BE_STORE_FROM_KEYED),
         Object);
     if (vector_needs_update()) {
-      ConfigureVectorState(MEGAMORPHIC, key);
-      TRACE_GENERIC_IC("unhandled internalized string key");
-      TRACE_IC("StoreIC", key);
+      if (ConfigureVectorState(MEGAMORPHIC, key)) {
+        TRACE_GENERIC_IC("unhandled internalized string key");
+        TRACE_IC("StoreIC", key);
+      }
     }
     return store_handle;
   }

src/ic/ic.h

@@ -90,7 +90,7 @@ class IC {
   }
 
   // Configure for most states.
-  void ConfigureVectorState(IC::State new_state, Handle<Object> key);
+  bool ConfigureVectorState(IC::State new_state, Handle<Object> key);
   // Configure the vector for MONOMORPHIC.
   void ConfigureVectorState(Handle<Name> name, Handle<Map> map,
                             Handle<Object> handler);