Replace LoadNamedFieldPolymorphic with explicit branches.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 28511f714208f6fcc9eb84a4d1812723f09ba01b..df53ad75b7df447bcf6caa12ecb30767a45184a5 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -2817,119 +2817,6 @@ void HLoadNamedField::PrintDataTo(StringStream* stream) {
 }
 
 
-// Returns true if an instance of this map can never find a property with this
-// name in its prototype chain.  This means all prototypes up to the top are
-// fast and don't have the name in them.  It would be good if we could optimize
-// polymorphic loads where the property is sometimes found in the prototype
-// chain.
-static bool PrototypeChainCanNeverResolve(
-    Handle<Map> map, Handle<String> name) {
-  Isolate* isolate = map->GetIsolate();
-  Object* current = map->prototype();
-  while (current != isolate->heap()->null_value()) {
-    if (current->IsJSGlobalProxy() ||
-        current->IsGlobalObject() ||
-        !current->IsJSObject() ||
-        JSObject::cast(current)->map()->has_named_interceptor() ||
-        JSObject::cast(current)->IsAccessCheckNeeded() ||
-        !JSObject::cast(current)->HasFastProperties()) {
-      return false;
-    }
-
-    LookupResult lookup(isolate);
-    Map* map = JSObject::cast(current)->map();
-    map->LookupDescriptor(NULL, *name, &lookup);
-    if (lookup.IsFound()) return false;
-    if (!lookup.IsCacheable()) return false;
-    current = JSObject::cast(current)->GetPrototype();
-  }
-  return true;
-}
-
-
-HLoadNamedFieldPolymorphic::HLoadNamedFieldPolymorphic(HValue* context,
-                                                       HValue* object,
-                                                       SmallMapList* types,
-                                                       Handle<String> name,
-                                                       Zone* zone)
-    : types_(Min(types->length(), kMaxLoadPolymorphism), zone),
-      name_(name),
-      types_unique_ids_(0, zone),
-      name_unique_id_(),
-      need_generic_(false) {
-  SetOperandAt(0, context);
-  SetOperandAt(1, object);
-  set_representation(Representation::Tagged());
-  SetGVNFlag(kDependsOnMaps);
-  SmallMapList negative_lookups;
-  for (int i = 0;
-       i < types->length() && types_.length() < kMaxLoadPolymorphism;
-       ++i) {
-    Handle<Map> map = types->at(i);
-    // Deprecated maps are updated to the current map in the type oracle.
-    ASSERT(!map->is_deprecated());
-    LookupResult lookup(map->GetIsolate());
-    map->LookupDescriptor(NULL, *name, &lookup);
-    if (lookup.IsFound()) {
-      switch (lookup.type()) {
-        case FIELD: {
-          int index = lookup.GetLocalFieldIndexFromMap(*map);
-          if (index < 0) {
-            SetGVNFlag(kDependsOnInobjectFields);
-          } else {
-            SetGVNFlag(kDependsOnBackingStoreFields);
-          }
-          if (FLAG_track_double_fields &&
-              lookup.representation().IsDouble()) {
-            // Since the value needs to be boxed, use a generic handler for
-            // loading doubles.
-            continue;
-          }
-          types_.Add(types->at(i), zone);
-          break;
-        }
-        case CONSTANT:
-          types_.Add(types->at(i), zone);
-          break;
-        case CALLBACKS:
-          break;
-        case TRANSITION:
-        case INTERCEPTOR:
-        case NONEXISTENT:
-        case NORMAL:
-        case HANDLER:
-          UNREACHABLE();
-          break;
-      }
-    } else if (lookup.IsCacheable() &&
-               // For dicts the lookup on the map will fail, but the object may
-               // contain the property so we cannot generate a negative lookup
-               // (which would just be a map check and return undefined).
-               !map->is_dictionary_map() &&
-               !map->has_named_interceptor() &&
-               PrototypeChainCanNeverResolve(map, name)) {
-      negative_lookups.Add(types->at(i), zone);
-    }
-  }
-
-  bool need_generic =
-      (types->length() != negative_lookups.length() + types_.length());
-  if (!need_generic && FLAG_deoptimize_uncommon_cases) {
-    SetFlag(kUseGVN);
-    for (int i = 0; i < negative_lookups.length(); i++) {
-      types_.Add(negative_lookups.at(i), zone);
-    }
-  } else {
-    // We don't have an easy way to handle both a call (to the generic stub) and
-    // a deopt in the same hydrogen instruction, so in this case we don't add
-    // the negative lookups which can deopt - just let the generic stub handle
-    // them.
-    SetAllSideEffects();
-    need_generic_ = true;
-  }
-}
-
-
 HCheckMaps* HCheckMaps::New(Zone* zone,
                             HValue* context,
                             HValue* value,
@@ -2958,46 +2845,6 @@ void HCheckMaps::FinalizeUniqueValueId() {
 }
 
 
-void HLoadNamedFieldPolymorphic::FinalizeUniqueValueId() {
-  if (!types_unique_ids_.is_empty()) return;
-  Zone* zone = block()->zone();
-  types_unique_ids_.Initialize(types_.length(), zone);
-  for (int i = 0; i < types_.length(); i++) {
-    types_unique_ids_.Add(UniqueValueId(types_.at(i)), zone);
-  }
-  name_unique_id_ = UniqueValueId(name_);
-}
-
-
-bool HLoadNamedFieldPolymorphic::DataEquals(HValue* value) {
-  ASSERT_EQ(types_.length(), types_unique_ids_.length());
-  HLoadNamedFieldPolymorphic* other = HLoadNamedFieldPolymorphic::cast(value);
-  if (name_unique_id_ != other->name_unique_id_) return false;
-  if (types_unique_ids_.length() != other->types_unique_ids_.length()) {
-    return false;
-  }
-  if (need_generic_ != other->need_generic_) return false;
-  for (int i = 0; i < types_unique_ids_.length(); i++) {
-    bool found = false;
-    for (int j = 0; j < types_unique_ids_.length(); j++) {
-      if (types_unique_ids_.at(j) == other->types_unique_ids_.at(i)) {
-        found = true;
-        break;
-      }
-    }
-    if (!found) return false;
-  }
-  return true;
-}
-
-
-void HLoadNamedFieldPolymorphic::PrintDataTo(StringStream* stream) {
-  object()->PrintNameTo(stream);
-  stream->Add(".");
-  stream->Add(*String::cast(*name())->ToCString());
-}
-
-
 void HLoadNamedGeneric::PrintDataTo(StringStream* stream) {
   object()->PrintNameTo(stream);
   stream->Add(".");