[ic] Avoid memory wasting when allocating names table of type feedback metadata.

BUG=chromium:625894

Review-Url: https://codereview.chromium.org/2181303002
Cr-Commit-Position: refs/heads/master@{#38047}

src/objects.cc

@@ -16425,20 +16425,23 @@ template class Dictionary<UnseededNumberDictionary,
                           uint32_t>;
 
 template Handle<SeededNumberDictionary>
-Dictionary<SeededNumberDictionary, SeededNumberDictionaryShape, uint32_t>::
-    New(Isolate*, int at_least_space_for, PretenureFlag pretenure);
+Dictionary<SeededNumberDictionary, SeededNumberDictionaryShape, uint32_t>::New(
+    Isolate*, int at_least_space_for, PretenureFlag pretenure,
+    MinimumCapacity capacity_option);
 
 template Handle<UnseededNumberDictionary>
-Dictionary<UnseededNumberDictionary, UnseededNumberDictionaryShape, uint32_t>::
-    New(Isolate*, int at_least_space_for, PretenureFlag pretenure);
+Dictionary<UnseededNumberDictionary, UnseededNumberDictionaryShape,
+           uint32_t>::New(Isolate*, int at_least_space_for,
+                          PretenureFlag pretenure,
+                          MinimumCapacity capacity_option);
 
 template Handle<NameDictionary>
-Dictionary<NameDictionary, NameDictionaryShape, Handle<Name> >::
-    New(Isolate*, int n, PretenureFlag pretenure);
+Dictionary<NameDictionary, NameDictionaryShape, Handle<Name>>::New(
+    Isolate*, int n, PretenureFlag pretenure, MinimumCapacity capacity_option);
 
 template Handle<GlobalDictionary>
-Dictionary<GlobalDictionary, GlobalDictionaryShape, Handle<Name> >::New(
-    Isolate*, int n, PretenureFlag pretenure);
+Dictionary<GlobalDictionary, GlobalDictionaryShape, Handle<Name>>::New(
+    Isolate*, int n, PretenureFlag pretenure, MinimumCapacity capacity_option);
 
 template Handle<SeededNumberDictionary>
 Dictionary<SeededNumberDictionary, SeededNumberDictionaryShape, uint32_t>::
@@ -17230,17 +17233,13 @@ void CompilationCacheTable::Remove(Object* value) {
   return;
 }
 
-
-template<typename Derived, typename Shape, typename Key>
+template <typename Derived, typename Shape, typename Key>
 Handle<Derived> Dictionary<Derived, Shape, Key>::New(
-    Isolate* isolate,
-    int at_least_space_for,
-    PretenureFlag pretenure) {
+    Isolate* isolate, int at_least_space_for, PretenureFlag pretenure,
+    MinimumCapacity capacity_option) {
   DCHECK(0 <= at_least_space_for);
-  Handle<Derived> dict = DerivedHashTable::New(isolate,
-                                               at_least_space_for,
-                                               USE_DEFAULT_MINIMUM_CAPACITY,
-                                               pretenure);
+  Handle<Derived> dict = DerivedHashTable::New(isolate, at_least_space_for,
+                                               capacity_option, pretenure);
 
   // Initialize the next enumeration index.
   dict->SetNextEnumerationIndex(PropertyDetails::kInitialIndex);

src/objects.h

@@ -3512,9 +3512,9 @@ class Dictionary: public HashTable<Derived, Shape, Key> {
 
   // Creates a new dictionary.
   MUST_USE_RESULT static Handle<Derived> New(
-      Isolate* isolate,
-      int at_least_space_for,
-      PretenureFlag pretenure = NOT_TENURED);
+      Isolate* isolate, int at_least_space_for,
+      PretenureFlag pretenure = NOT_TENURED,
+      MinimumCapacity capacity_option = USE_DEFAULT_MINIMUM_CAPACITY);
 
   // Ensures that a new dictionary is created when the capacity is checked.
   void SetRequiresCopyOnCapacityChange();

src/type-feedback-vector.cc

@@ -100,8 +100,12 @@ Handle<TypeFeedbackMetadata> TypeFeedbackMetadata::New(Isolate* isolate,
   // Add names to NamesTable.
   const int name_count = spec->name_count();
 
-  Handle<UnseededNumberDictionary> names =
-      UnseededNumberDictionary::New(isolate, name_count);
+  Handle<UnseededNumberDictionary> names;
+  if (name_count) {
+    names = UnseededNumberDictionary::New(
+        isolate, base::bits::RoundUpToPowerOfTwo32(name_count), TENURED,
+        USE_CUSTOM_MINIMUM_CAPACITY);
+  }
 
   int name_index = 0;
   for (int i = 0; i < slot_count; i++) {
@@ -115,7 +119,8 @@ Handle<TypeFeedbackMetadata> TypeFeedbackMetadata::New(Isolate* isolate,
     }
   }
   DCHECK_EQ(name_count, name_index);
-  metadata->set(kNamesTableIndex, *names);
+  metadata->set(kNamesTableIndex,
+                name_count ? static_cast<Object*>(*names) : Smi::FromInt(0));
 
   // It's important that the TypeFeedbackMetadata have a COW map, since it's
   // pointed to by both a SharedFunctionInfo and indirectly by closures through