[runtime] Set instance prototypes directly on maps

verwaest · V8 LUCI CQ · commit c7c447735f76 · 2023-06-16T15:51:52.000Z
Bug: chromium:1452137 Change-Id: If1de44950711c99da4ace2e988f188421e849330 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4618153 Commit-Queue: Toon Verwaest <verwaest@chromium.org> Reviewed-by: Igor Sheludko <ishell@chromium.org> Auto-Submit: Toon Verwaest <verwaest@chromium.org> Commit-Queue: Igor Sheludko <ishell@chromium.org> Cr-Commit-Position: refs/heads/main@{#88326}
diff --git a/src/objects/js-function.cc b/src/objects/js-function.cc
@@ -678,6 +678,10 @@ void SetInstancePrototype(Isolate* isolate, Handle<JSFunction> function,
       // At that point, a new initial map is created and the prototype is put
       // into the initial map where it belongs.
       function->set_prototype_or_initial_map(*value, kReleaseStore);
+      if (value->IsJSObjectThatCanBeTrackedAsPrototype()) {
+        // Optimize as prototype to detach it from its transition tree.
+        JSObject::OptimizeAsPrototype(Handle<JSObject>::cast(value));
+      }
     } else {
       Handle<Map> new_map =
           Map::Copy(isolate, initial_map, "SetInstancePrototype");
@@ -809,8 +813,10 @@ void JSFunction::EnsureHasInitialMap(Handle<JSFunction> function) {
   Handle<HeapObject> prototype;
   if (function->has_instance_prototype()) {
     prototype = handle(function->instance_prototype(), isolate);
+    map->set_prototype(*prototype);
   } else {
     prototype = isolate->factory()->NewFunctionPrototype(function);
+    Map::SetPrototype(isolate, map, prototype);
   }
   DCHECK(map->has_fast_object_elements());
 
