Merged: [runtime] Set instance prototypes directly on maps

verwaest · V8 LUCI CQ · commit a1efa5343880 · 2023-06-23T14:18:45.000Z
Bug: chromium:1452137 (cherry picked from commit c7c4477) Change-Id: I611c41f942e2e51f3c4b4f1d119c18410617188e Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4637888 Commit-Queue: Igor Sheludko <ishell@chromium.org> Auto-Submit: Igor Sheludko <ishell@chromium.org> Commit-Queue: Toon Verwaest <verwaest@chromium.org> Reviewed-by: Toon Verwaest <verwaest@chromium.org> Cr-Commit-Position: refs/branch-heads/11.4@{#47} Cr-Branched-From: 8a8a1e7-refs/heads/11.4.183@{#1} Cr-Branched-From: 5483d8e-refs/heads/main@{#87241}
diff --git a/src/objects/js-function.cc b/src/objects/js-function.cc
@@ -676,6 +676,10 @@ 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");
@@ -801,8 +805,10 @@ 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());
 
