Merged: Squashed multiple commits.

Merged: [runtime] Recreate enum cache on map update
Revision: 1c623f9

Merged: [runtime] Don't try to create empty enum cache.
Revision: 5516e06

BUG=chromium:1470668,chromium:1472317
R=tebbi@chromium.org

Change-Id: I31d5491aba663661ba68bb55631747a195ed084e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4788990
Commit-Queue: Samuel Groß <saelo@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/branch-heads/11.6@{v8#32}
Cr-Branched-From: e29c028-refs/heads/11.6.189@{v8#3}
Cr-Branched-From: 95cbef2-refs/heads/main@{#88340}

src/objects/map-updater.cc

@@ -12,6 +12,7 @@
 #include "src/handles/handles.h"
 #include "src/heap/parked-scope-inl.h"
 #include "src/objects/field-type.h"
+#include "src/objects/keys.h"
 #include "src/objects/objects-inl.h"
 #include "src/objects/objects.h"
 #include "src/objects/property-details.h"
@@ -1037,6 +1038,13 @@ MapUpdater::State MapUpdater::ConstructNewMap() {
   // the new descriptors to maintain descriptors sharing invariant.
   split_map->ReplaceDescriptors(isolate_, *new_descriptors);
 
+  // If the old descriptors had an enum cache, make sure the new ones do too.
+  if (old_descriptors_->enum_cache().keys().length() > 0 &&
+      new_map->NumberOfEnumerableProperties() > 0) {
+    FastKeyAccumulator::InitializeFastPropertyEnumCache(
+        isolate_, new_map, new_map->NumberOfEnumerableProperties());
+  }
+
   if (has_integrity_level_transition_) {
     target_map_ = new_map;
     state_ = kAtIntegrityLevelSource;