Refactor platform-specific code for determining shared stub for keyed load/stores.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index 45d610bc4c018c7c420989834fb4a49c9a23a060..f63a92521952766ae9657874a67332d0e034bbda 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -2530,24 +2530,15 @@ MaybeObject* KeyedStoreStubCompiler::CompileStoreField(JSObject* object,
 }
 
 
-MaybeObject* KeyedStoreStubCompiler::CompileStoreElement(
-    Map* receiver_map) {
+MaybeObject* KeyedStoreStubCompiler::CompileStoreElement(Map* receiver_map) {
   // ----------- S t a t e -------------
   //  -- rax    : value
   //  -- rcx    : key
   //  -- rdx    : receiver
   //  -- rsp[0] : return address
   // -----------------------------------
-  MaybeObject* maybe_stub;
-  if (receiver_map->has_fast_elements()) {
-    bool is_js_array = receiver_map->instance_type() == JS_ARRAY_TYPE;
-    maybe_stub = KeyedStoreFastElementStub(is_js_array).TryGetCode();
-  } else {
-    ASSERT(receiver_map->has_external_array_elements());
-    JSObject::ElementsKind elements_kind = receiver_map->elements_kind();
-    maybe_stub = KeyedStoreExternalArrayStub(elements_kind).TryGetCode();
-  }
   Code* stub;
+  MaybeObject* maybe_stub = ComputeSharedKeyedStoreElementStub(receiver_map);
   if (!maybe_stub->To(&stub)) return maybe_stub;
   __ DispatchMap(rdx,
                  Handle<Map>(receiver_map),
@@ -3002,15 +2993,8 @@ MaybeObject* KeyedLoadStubCompiler::CompileLoadElement(Map* receiver_map) {
   //  -- rdx    : receiver
   //  -- rsp[0] : return address
   // -----------------------------------
-  MaybeObject* maybe_stub;
-  if (receiver_map->has_fast_elements()) {
-    maybe_stub = KeyedLoadFastElementStub().TryGetCode();
-  } else {
-    ASSERT(receiver_map->has_external_array_elements());
-    JSObject::ElementsKind elements_kind = receiver_map->elements_kind();
-    maybe_stub = KeyedLoadExternalArrayStub(elements_kind).TryGetCode();
-  }
   Code* stub;
+  MaybeObject* maybe_stub = ComputeSharedKeyedLoadElementStub(receiver_map);
   if (!maybe_stub->To(&stub)) return maybe_stub;
   __ DispatchMap(rdx,
                  Handle<Map>(receiver_map),