[ic] Properly initialize dummy feedback vector.

Review-Url: https://codereview.chromium.org/2372173002
Cr-Commit-Position: refs/heads/master@{#39759}

src/heap/heap.cc

@@ -2779,18 +2779,18 @@ void Heap::CreateInitialObjects() {
 
   {
     StaticFeedbackVectorSpec spec;
-    FeedbackVectorSlot load_ic_slot = spec.AddLoadICSlot();
-    FeedbackVectorSlot keyed_load_ic_slot = spec.AddKeyedLoadICSlot();
-    FeedbackVectorSlot store_ic_slot = spec.AddStoreICSlot();
-    FeedbackVectorSlot keyed_store_ic_slot = spec.AddKeyedStoreICSlot();
-
-    DCHECK_EQ(load_ic_slot,
-              FeedbackVectorSlot(TypeFeedbackVector::kDummyLoadICSlot));
-    DCHECK_EQ(keyed_load_ic_slot,
+    FeedbackVectorSlot slot = spec.AddLoadICSlot();
+    DCHECK_EQ(slot, FeedbackVectorSlot(TypeFeedbackVector::kDummyLoadICSlot));
+
+    slot = spec.AddKeyedLoadICSlot();
+    DCHECK_EQ(slot,
               FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedLoadICSlot));
-    DCHECK_EQ(store_ic_slot,
-              FeedbackVectorSlot(TypeFeedbackVector::kDummyStoreICSlot));
-    DCHECK_EQ(keyed_store_ic_slot,
+
+    slot = spec.AddStoreICSlot();
+    DCHECK_EQ(slot, FeedbackVectorSlot(TypeFeedbackVector::kDummyStoreICSlot));
+
+    slot = spec.AddKeyedStoreICSlot();
+    DCHECK_EQ(slot,
               FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedStoreICSlot));
 
     Handle<TypeFeedbackMetadata> dummy_metadata =
@@ -2798,13 +2798,13 @@ void Heap::CreateInitialObjects() {
     Handle<TypeFeedbackVector> dummy_vector =
         TypeFeedbackVector::New(isolate(), dummy_metadata);
 
-    Object* megamorphic = *TypeFeedbackVector::MegamorphicSentinel(isolate());
-    dummy_vector->Set(load_ic_slot, megamorphic, SKIP_WRITE_BARRIER);
-    dummy_vector->Set(keyed_load_ic_slot, megamorphic, SKIP_WRITE_BARRIER);
-    dummy_vector->Set(store_ic_slot, megamorphic, SKIP_WRITE_BARRIER);
-    dummy_vector->Set(keyed_store_ic_slot, megamorphic, SKIP_WRITE_BARRIER);
-
     set_dummy_vector(*dummy_vector);
+
+    // Now initialize dummy vector's entries.
+    LoadICNexus(isolate()).ConfigureMegamorphic();
+    StoreICNexus(isolate()).ConfigureMegamorphic();
+    KeyedLoadICNexus(isolate()).ConfigureMegamorphicKeyed(PROPERTY);
+    KeyedStoreICNexus(isolate()).ConfigureMegamorphicKeyed(PROPERTY);
   }
 
   {

src/type-feedback-vector.h

@@ -566,6 +566,10 @@ class KeyedLoadICNexus : public FeedbackNexus {
       : FeedbackNexus(vector, slot) {
     DCHECK_EQ(FeedbackVectorSlotKind::KEYED_LOAD_IC, vector->GetKind(slot));
   }
+  explicit KeyedLoadICNexus(Isolate* isolate)
+      : FeedbackNexus(
+            TypeFeedbackVector::DummyVector(isolate),
+            FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedLoadICSlot)) {}
   KeyedLoadICNexus(TypeFeedbackVector* vector, FeedbackVectorSlot slot)
       : FeedbackNexus(vector, slot) {
     DCHECK_EQ(FeedbackVectorSlotKind::KEYED_LOAD_IC, vector->GetKind(slot));