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[web snapshot] Perf fix: pre-reserve the space in the global object

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Exports are properties in the global object. Pre-reserve the space,
since we know the count upfront.

Bug: v8:11525
Change-Id: Ia8ea992234ed8cf71a1060254766b0ba31562436
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3416231
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78767}
This commit is contained in:
Marja Hölttä 2022-01-26 09:58:51 +01:00 committed by V8 LUCI CQ
parent 3f9f569cd6
commit 12c79495d7
1 changed files with 12 additions and 2 deletions
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14
src/web-snapshot/web-snapshot.cc
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@ -1754,6 +1754,16 @@ void WebSnapshotDeserializer::DeserializeExports() {
Throw("Malformed export table");
return;
}
// Pre-reserve the space for the properties we're going to add to the global
// object.
Handle<JSGlobalObject> global = isolate_->global_object();
Handle<GlobalDictionary> dictionary(
global->global_dictionary(isolate_, kAcquireLoad), isolate_);
dictionary = GlobalDictionary::EnsureCapacity(isolate_, dictionary, count,
AllocationType::kYoung);
global->set_global_dictionary(*dictionary, kReleaseStore);
for (uint32_t i = 0; i < count; ++i) {
Handle<String> export_name = ReadString(true);
Handle<Object> export_value;
@ -1770,8 +1780,8 @@ void WebSnapshotDeserializer::DeserializeExports() {
return;
}
auto result = Object::SetProperty(isolate_, isolate_->global_object(),
export_name, export_value);
auto result =
Object::SetProperty(isolate_, global, export_name, export_value);
if (result.is_null()) {
Throw("Setting global property failed");
return;