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LibJS: Stop converting between Object <-> IteratorRecord all the time

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This patch makes IteratorRecord an Object. Although it's not exposed to
author code, this does allow us to store it in a VM register.

Now that we can store it in a VM register, we don't need to convert it
back and forth between IteratorRecord and Object when accessing it from
bytecode.

The big win here is avoiding 3 [[Get]] accesses on every iteration step
of for..of loops. There are also a bunch of smaller efficiencies gained.

20% speed-up on this microbenchmark:

    function go(a) {
        for (const p of a) {
        }
    }
    const a = [];
    a.length = 1_000_000;
    go(a);
This commit is contained in:
Andreas Kling 2023-12-07 10:44:41 +01:00
parent 4966c083df
commit 4699c81fc1
23 changed files with 226 additions and 144 deletions
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7
Userland/Libraries/LibJS/Runtime/AsyncFromSyncIterator.cpp
View file

@ -13,12 +13,12 @@ namespace JS {
JS_DEFINE_ALLOCATOR(AsyncFromSyncIterator);
NonnullGCPtr<AsyncFromSyncIterator> AsyncFromSyncIterator::create(Realm& realm, IteratorRecord sync_iterator_record)
NonnullGCPtr<AsyncFromSyncIterator> AsyncFromSyncIterator::create(Realm& realm, NonnullGCPtr<IteratorRecord> sync_iterator_record)
{
return realm.heap().allocate<AsyncFromSyncIterator>(realm, realm, sync_iterator_record);
}
AsyncFromSyncIterator::AsyncFromSyncIterator(Realm& realm, IteratorRecord sync_iterator_record)
AsyncFromSyncIterator::AsyncFromSyncIterator(Realm& realm, NonnullGCPtr<IteratorRecord> sync_iterator_record)
: Object(ConstructWithPrototypeTag::Tag, realm.intrinsics().async_from_sync_iterator_prototype())
, m_sync_iterator_record(sync_iterator_record)
{
@ -27,8 +27,7 @@ AsyncFromSyncIterator::AsyncFromSyncIterator(Realm& realm, IteratorRecord sync_i
void AsyncFromSyncIterator::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_sync_iterator_record.iterator);
visitor.visit(m_sync_iterator_record.next_method);
visitor.visit(m_sync_iterator_record);
}
}