[ic] Data handlers for loads of non-existent properties.

src/ic/ic.h

 // Copyright 2012 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_IC_H_
 #define V8_IC_H_
 
 #include "src/ic/ic-state.h"
 #include "src/macro-assembler.h"
 #include "src/messages.h"
@@ skipping 293 matching lines @@
   // Update the inline cache and the global stub cache based on the
   // lookup result.
   void UpdateCaches(LookupIterator* lookup);
 
   Handle<Object> GetMapIndependentHandler(LookupIterator* lookup) override;
 
   Handle<Code> CompileHandler(LookupIterator* lookup, Handle<Object> unused,
                               CacheHolderFlag cache_holder) override;
 
  private:
+  // Creates a data handler that represents a load of a field by given index.
   Handle<Object> SimpleFieldLoad(FieldIndex index);
 
   // Returns 0 if the validity cell check is enough to ensure that the
   // prototype chain from |receiver_map| till |holder| did not change.
+  // If the |holder| is an empty handle then the full prototype chain is
+  // checked.
   // Returns -1 if the handler has to be compiled or the number of prototype
   // checks otherwise.
   int GetPrototypeCheckCount(Handle<Map> receiver_map, Handle<JSObject> holder);
 
   // Creates a data handler that represents a prototype chain check followed
   // by given Smi-handler that encoded a load from the holder.
-  // Can be used only if IsPrototypeValidityCellCheckEnough() predicate is true.
+  // Can be used only if GetPrototypeCheckCount() returns non negative value.
   Handle<Object> SimpleLoadFromPrototype(Handle<Map> receiver_map,
                                          Handle<JSObject> holder,
                                          Handle<Name> name,
                                          Handle<Object> smi_handler);
 
+  // Creates a data handler that represents a load of a non-existent property.
+  Handle<Object> SimpleLoadNonExistent(Handle<Map> receiver_map,
+                                       Handle<Name> name);
   friend class IC;
 };
 
 class LoadGlobalIC : public LoadIC {
  public:
   LoadGlobalIC(FrameDepth depth, Isolate* isolate, FeedbackNexus* nexus = NULL)
       : LoadIC(depth, isolate, nexus) {}
 
   MUST_USE_RESULT MaybeHandle<Object> Load(Handle<Name> name);
 
@@ skipping 176 matching lines @@
 
 // Helper for BinaryOpIC and CompareIC.
 enum InlinedSmiCheck { ENABLE_INLINED_SMI_CHECK, DISABLE_INLINED_SMI_CHECK };
 void PatchInlinedSmiCode(Isolate* isolate, Address address,
                          InlinedSmiCheck check);
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_IC_H_