commit 5516e06237c9f0013121f47319e8c253c896d52d
author Olivier Flückiger <olivf@chromium.org> Mon Aug 14 07:05:22 2023
committer V8 LUCI CQ <v8-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Aug 16 16:24:16 2023
tree d7d4188372d84a2fe0885a2a87bacf08f083e560
parent 36d9025f7f0c83bd5e70d4a93773b99635bae4ce

[runtime] Don't try to create empty enum cache.

When copying maps and the new map has no enumerable properties we
should not try to initialize an enum cache.

This happens if the deprecation is due to making the only property in
a map non enumerable.

Bug: chromium:1472317, chromium:1470668
Change-Id: I7a6af63e50dc30592e2caacce0caccfb31f534cf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4775581
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Olivier Flückiger <olivf@chromium.org>
Cr-Commit-Position: refs/heads/main@{#89534}

src/objects/map-updater.cc

diff --git a/src/objects/map-updater.cc b/src/objects/map-updater.cc
index 7a864d9..9c20491 100644
--- a/src/objects/map-updater.cc
+++ b/src/objects/map-updater.cc
@@ -1040,7 +1040,8 @@
   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) {
+  if (old_descriptors_->enum_cache()->keys()->length() > 0 &&
+      new_map->NumberOfEnumerableProperties() > 0) {
     FastKeyAccumulator::InitializeFastPropertyEnumCache(
         isolate_, new_map, new_map->NumberOfEnumerableProperties());
   }