Megamorphic KeyedLoadIC needs special handling for vector ics.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index cec871403a718d8f2a88b8666af713e48ba56f54..52bd70a7527afdd53eac21a8288d01e9966a56f2 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -3058,6 +3058,19 @@ void Heap::CreateInitialObjects() {
   // Number of queued microtasks stored in Isolate::pending_microtask_count().
   set_microtask_queue(empty_fixed_array());
 
+  if (FLAG_vector_ics) {
+    FeedbackVectorSpec spec(0, 1);
+    spec.SetKind(0, Code::KEYED_LOAD_IC);
+    Handle<TypeFeedbackVector> dummy_vector =
+        factory->NewTypeFeedbackVector(spec);
+    dummy_vector->Set(FeedbackVectorICSlot(0),
+                      *TypeFeedbackVector::MegamorphicSentinel(isolate()),
+                      SKIP_WRITE_BARRIER);
+    set_keyed_load_dummy_vector(*dummy_vector);
+  } else {
+    set_keyed_load_dummy_vector(empty_fixed_array());
+  }
+
   Handle<SeededNumberDictionary> slow_element_dictionary =
       SeededNumberDictionary::New(isolate(), 0, TENURED);
   slow_element_dictionary->set_requires_slow_elements();