Restore the descriptor lookup cache outside of Turbofan.

This partially reverts commit bffe040e,
which bypassed the cache globally. Now we bypass it only in Turbofan.

R=jarin@chromium.org

Bug: v8:7790, chromium:854976
Change-Id: I62a9904c06915f6f6e4a6b628dc3dcba5151bb87
Reviewed-on: https://chromium-review.googlesource.com/1109969Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53955}

src/compiler/access-info.cc

@@ -349,7 +349,7 @@ bool AccessInfoFactory::ComputePropertyAccessInfo(
   do {
     // Lookup the named property on the {map}.
     Handle<DescriptorArray> descriptors(map->instance_descriptors(), isolate());
-    int const number = descriptors->SearchWithCache(isolate(), *name, *map);
+    int const number = descriptors->Search(*name, *map);
     if (number != DescriptorArray::kNotFound) {
       PropertyDetails const details = descriptors->GetDetails(number);
       if (access_mode == AccessMode::kStore ||

src/compiler/js-call-reducer.cc

@@ -4235,8 +4235,7 @@ bool IsReadOnlyLengthDescriptor(Isolate* isolate, Handle<Map> jsarray_map) {
   DCHECK(!jsarray_map->is_dictionary_map());
   Handle<Name> length_string = isolate->factory()->length_string();
   DescriptorArray* descriptors = jsarray_map->instance_descriptors();
-  int number =
-      descriptors->SearchWithCache(isolate, *length_string, *jsarray_map);
+  int number = descriptors->Search(*length_string, *jsarray_map);
   DCHECK_NE(DescriptorArray::kNotFound, number);
   return descriptors->GetDetails(number).IsReadOnly();
 }

src/objects-inl.h

@@ -1994,13 +1994,27 @@ int DescriptorArray::Search(Name* name, int valid_descriptors) {
                                          valid_descriptors, nullptr);
 }
 
+int DescriptorArray::Search(Name* name, Map* map) {
+  DCHECK(name->IsUniqueName());
+  int number_of_own_descriptors = map->NumberOfOwnDescriptors();
+  if (number_of_own_descriptors == 0) return kNotFound;
+  return Search(name, number_of_own_descriptors);
+}
+
 int DescriptorArray::SearchWithCache(Isolate* isolate, Name* name, Map* map) {
   DCHECK(name->IsUniqueName());
   int number_of_own_descriptors = map->NumberOfOwnDescriptors();
   if (number_of_own_descriptors == 0) return kNotFound;
 
-  // TODO(neis): As an experiment, don't actually use the cache.
-  return Search(name, number_of_own_descriptors);
+  DescriptorLookupCache* cache = isolate->descriptor_lookup_cache();
+  int number = cache->Lookup(map, name);
+
+  if (number == DescriptorLookupCache::kAbsent) {
+    number = Search(name, number_of_own_descriptors);
+    cache->Update(map, name, number);
+  }
+
+  return number;
 }
 
 

src/objects/descriptor-array.h

@@ -113,6 +113,7 @@ class DescriptorArray : public WeakFixedArray {
 
   // Search the instance descriptors for given name.
   INLINE(int Search(Name* name, int number_of_own_descriptors));
+  INLINE(int Search(Name* name, Map* map));
 
   // As the above, but uses DescriptorLookupCache and updates it when
   // necessary.