[turbofan] Infer some receiver maps when lowering loads/stores.

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

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_JS_NATIVE_CONTEXT_SPECIALIZATION_H_
 #define V8_COMPILER_JS_NATIVE_CONTEXT_SPECIALIZATION_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/graph-reducer.h"
 
@@ skipping 67 matching lines @@
                               Node* index = nullptr);
 
   Reduction ReduceSoftDeoptimize(Node* node);
 
   // Adds stability dependencies on all prototypes of every class in
   // {receiver_type} up to (and including) the {holder}.
   void AssumePrototypesStable(Type* receiver_type,
                               Handle<Context> native_context,
                               Handle<JSObject> holder);
 
+  // Extract receiver maps from {nexus} and filter based on {receiver} if
+  // possible.
+  bool ExtractReceiverMaps(Node* receiver, Node* effect,
+                           FeedbackNexus const& nexus,
+                           MapHandleList* receiver_maps);
+
+  // Try to infer a map for the given {receiver} at the current {effect}.
+  // If a map is returned then you can be sure that the {receiver} definitely
+  // has the returned map at this point in the program (identified by {effect}).
+  MaybeHandle<Map> InferReceiverMap(Node* receiver, Node* effect);
+  // Try to infer a root map for the {receiver} independent of the current
+  // program location.
+  MaybeHandle<Map> InferReceiverRootMap(Node* receiver);
+
   // Retrieve the native context from the given {node} if known.
   MaybeHandle<Context> GetNativeContext(Node* node);
 
   Graph* graph() const;
   JSGraph* jsgraph() const { return jsgraph_; }
   Isolate* isolate() const;
   Factory* factory() const;
   CommonOperatorBuilder* common() const;
   JSOperatorBuilder* javascript() const;
   SimplifiedOperatorBuilder* simplified() const;
@@ skipping 13 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(JSNativeContextSpecialization);
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(JSNativeContextSpecialization::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_NATIVE_CONTEXT_SPECIALIZATION_H_