[KeyedLoadIC] Support Smi "handlers" for element loads

src/ic/handler-compiler.cc

Index: src/ic/handler-compiler.cc
diff --git a/src/ic/handler-compiler.cc b/src/ic/handler-compiler.cc
index a1d1467ab1f3600d1994d7d62c4380db4408ccf2..72d945d9865d8f57f3c4091a0e7b02620cb8bd5f 100644
--- a/src/ic/handler-compiler.cc
+++ b/src/ic/handler-compiler.cc
@@ -577,7 +577,7 @@ Handle<Code> NamedStoreHandlerCompiler::CompileStoreCallback(
 #undef __
 
 // static
-Handle<Code> ElementHandlerCompiler::GetKeyedLoadHandler(
+Handle<Object> ElementHandlerCompiler::GetKeyedLoadHandler(
     Handle<Map> receiver_map, Isolate* isolate) {
   if (receiver_map->has_indexed_interceptor() &&
       !receiver_map->GetIndexedInterceptor()->getter()->IsUndefined(isolate) &&
@@ -610,10 +610,18 @@ Handle<Code> ElementHandlerCompiler::GetKeyedLoadHandler(
   bool convert_hole_to_undefined =
       is_js_array && elements_kind == FAST_HOLEY_ELEMENTS &&
       *receiver_map == isolate->get_initial_js_array_map(elements_kind);
-  TRACE_HANDLER_STATS(isolate, KeyedLoadIC_LoadFastElementStub);
-  return LoadFastElementStub(isolate, is_js_array, elements_kind,
-                             convert_hole_to_undefined)
-      .GetCode();
+  if (FLAG_tf_load_ic_stub) {
+    int config = KeyedLoadElementsKind::encode(elements_kind) |
+                 KeyedLoadConvertHole::encode(convert_hole_to_undefined) |
+                 KeyedLoadIsJsarray::encode(is_js_array) |
+                 0;  // Element marker (as opposed to property).
+    return handle(Smi::FromInt(config), isolate);
+  } else {
+    TRACE_HANDLER_STATS(isolate, KeyedLoadIC_LoadFastElementStub);
+    return LoadFastElementStub(isolate, is_js_array, elements_kind,
+                               convert_hole_to_undefined)
+        .GetCode();
+  }
 }
 
 void ElementHandlerCompiler::CompileElementHandlers(