[turbofan] Move a special case out of ReduceElementAccess

...to make things easier to read.

R=jarin@chromium.org

Change-Id: I0e53ef67e34f696b5977d4e091c7bc7bdf0ec145
Reviewed-on: https://chromium-review.googlesource.com/c/1477739Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59706}

src/compiler/js-native-context-specialization.cc

@@ -1473,20 +1473,13 @@ Reduction JSNativeContextSpecialization::ReduceJSStoreNamedOwn(Node* node) {
                                     AccessMode::kStoreInLiteral);
 }
 
-Reduction JSNativeContextSpecialization::ReduceElementAccess(
-    Node* node, Node* index, Node* value, MapHandles const& receiver_maps,
-    AccessMode access_mode, KeyedAccessLoadMode load_mode,
-    KeyedAccessStoreMode store_mode) {
-  DCHECK(node->opcode() == IrOpcode::kJSLoadProperty ||
-         node->opcode() == IrOpcode::kJSStoreProperty ||
-         node->opcode() == IrOpcode::kJSStoreInArrayLiteral);
+Reduction JSNativeContextSpecialization::ReduceElementAccessOnString(
+    Node* node, Node* index, Node* value, AccessMode access_mode,
+    KeyedAccessLoadMode load_mode) {
   Node* receiver = NodeProperties::GetValueInput(node, 0);
   Node* effect = NodeProperties::GetEffectInput(node);
   Node* control = NodeProperties::GetControlInput(node);
-  Node* frame_state = NodeProperties::FindFrameStateBefore(node);
 
-  // Check for keyed access to strings.
-  if (HasOnlyStringMaps(receiver_maps)) {
   // Strings are immutable in JavaScript.
   if (access_mode == AccessMode::kStore) return NoChange();
 
@@ -1501,21 +1494,41 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
   // if the {index} is out of bounds (depending on the {load_mode}).
   value = BuildIndexedStringLoad(receiver, index, length, &effect, &control,
                                  load_mode);
-  } else {
+
+  ReplaceWithValue(node, value, effect, control);
+  return Replace(value);
+}
+
+Reduction JSNativeContextSpecialization::ReduceElementAccess(
+    Node* node, Node* index, Node* value, MapHandles const& receiver_maps,
+    AccessMode access_mode, KeyedAccessLoadMode load_mode,
+    KeyedAccessStoreMode store_mode) {
+  DCHECK(node->opcode() == IrOpcode::kJSLoadProperty ||
+         node->opcode() == IrOpcode::kJSStoreProperty ||
+         node->opcode() == IrOpcode::kJSStoreInArrayLiteral);
+  Node* receiver = NodeProperties::GetValueInput(node, 0);
+  Node* effect = NodeProperties::GetEffectInput(node);
+  Node* control = NodeProperties::GetControlInput(node);
+  Node* frame_state = NodeProperties::FindFrameStateBefore(node);
+
+  if (HasOnlyStringMaps(receiver_maps)) {
+    return ReduceElementAccessOnString(node, index, value, access_mode,
+                                       load_mode);
+  }
+
   // Compute element access infos for the receiver maps.
   AccessInfoFactory access_info_factory(
       broker(), dependencies(), native_context().object(), graph()->zone());
   ZoneVector<ElementAccessInfo> access_infos(zone());
-    if (!access_info_factory.ComputeElementAccessInfos(
-            receiver_maps, access_mode, &access_infos)) {
+  if (!access_info_factory.ComputeElementAccessInfos(receiver_maps, access_mode,
+                                                     &access_infos)) {
     return NoChange();
   }
 
   // Nothing to do if we have no non-deprecated maps.
   if (access_infos.empty()) {
     return ReduceSoftDeoptimize(
-          node,
-          DeoptimizeReason::kInsufficientTypeFeedbackForGenericKeyedAccess);
+        node, DeoptimizeReason::kInsufficientTypeFeedbackForGenericKeyedAccess);
   }
 
   // For holey stores or growing stores, we need to check that the prototype
@@ -1539,8 +1552,8 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
             Handle<Object> map_prototype(map->prototype(), isolate());
             if (map_prototype->IsNull(isolate())) break;
             if (!map_prototype->IsJSObject()) return NoChange();
-              map = handle(Handle<JSObject>::cast(map_prototype)->map(),
-                           isolate());
+            map =
+                handle(Handle<JSObject>::cast(map_prototype)->map(), isolate());
             if (!map->is_stable()) return NoChange();
             if (!IsFastElementsKind(map->elements_kind())) return NoChange();
             prototype_maps.push_back(map);
@@ -1582,8 +1595,8 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
     // elements kind transition above. This is because those operators
     // don't have the kNoWrite flag on it, even though they are not
     // observable by JavaScript.
-      effect = graph()->NewNode(common()->Checkpoint(), frame_state, effect,
-                                control);
+    effect =
+        graph()->NewNode(common()->Checkpoint(), frame_state, effect, control);
 
     // Perform map check on the {receiver}.
     access_builder.BuildCheckMaps(receiver, &effect, control,
@@ -1591,8 +1604,8 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
 
     // Access the actual element.
     ValueEffectControl continuation =
-          BuildElementAccess(receiver, index, value, effect, control,
-                             access_info, access_mode, load_mode, store_mode);
+        BuildElementAccess(receiver, index, value, effect, control, access_info,
+                           access_mode, load_mode, store_mode);
     value = continuation.value();
     effect = continuation.effect();
     control = continuation.control();
@@ -1614,14 +1627,12 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
       Node* this_control = fallthrough_control;
 
       // Perform possible elements kind transitions.
-        Handle<Map> const transition_target =
-            access_info.receiver_maps().front();
+      Handle<Map> const transition_target = access_info.receiver_maps().front();
       for (auto transition_source : access_info.transition_sources()) {
         DCHECK_EQ(access_info.receiver_maps().size(), 1);
         this_effect = graph()->NewNode(
-              simplified()->TransitionElementsKind(
-                  ElementsTransition(IsSimpleMapChangeTransition(
-                                         transition_source->elements_kind(),
+            simplified()->TransitionElementsKind(ElementsTransition(
+                IsSimpleMapChangeTransition(transition_source->elements_kind(),
                                             transition_target->elements_kind())
                     ? ElementsTransition::kFastTransition
                     : ElementsTransition::kSlowTransition,
@@ -1676,8 +1687,8 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
       effect = effects.front();
       control = controls.front();
     } else {
-        control = graph()->NewNode(common()->Merge(control_count),
-                                   control_count, &controls.front());
+      control = graph()->NewNode(common()->Merge(control_count), control_count,
+                                 &controls.front());
       values.push_back(control);
       value = graph()->NewNode(
           common()->Phi(MachineRepresentation::kTagged, control_count),
@@ -1687,7 +1698,6 @@ Reduction JSNativeContextSpecialization::ReduceElementAccess(
                                 control_count + 1, &effects.front());
     }
   }
-  }
 
   ReplaceWithValue(node, value, effect, control);
   return Replace(value);

src/compiler/js-native-context-specialization.h

@@ -118,6 +118,9 @@ class V8_EXPORT_PRIVATE JSNativeContextSpecialization final
   Reduction ReduceKeyedLoadFromHeapConstant(Node* node, Node* index,
                                             FeedbackNexus const& nexus,
                                             KeyedAccessLoadMode load_mode);
+  Reduction ReduceElementAccessOnString(Node* node, Node* index, Node* value,
+                                        AccessMode access_mode,
+                                        KeyedAccessLoadMode load_mode);
 
   Reduction ReduceSoftDeoptimize(Node* node, DeoptimizeReason reason);
   Reduction ReduceJSToString(Node* node);