commit 8c07aa51175f5df99defedf883117b429d751def
author Martin Kustermann <kustermann@google.com> Thu Aug 22 11:05:46 2024 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Aug 22 11:05:46 2024 +0000
tree bd72be7ff8eaf92a84fc78c685384f833a2ed45e
parent a645b6b4f791cc0eaf92d0494954fa97119b02d3

[dart2wasm] Handle is/as checks that only require nullability check in backend.

Up to Patchset 4 reverts commit 36fb02decad14ae79e6e410fa46340cd9502cada

Remaining Patchsets implement specialized support in is/as check
implementation to handle cases where only a null check is required. The
most common case in iterators:

  class <...>Iterator<T> {
    T? _current;

    T get current => _current as T;
  }

This ensures we're never emitting the general subtype checking code as
this only requres checking whether the object is non-`null` or whether
the destination type is declared nullable.

The asymmetry between `is` and `as` checks comes due to the fact that
the `as` checks have to (for the slow case) materialize a type object
for a nice error message.


Issue https://github.com/dart-lang/sdk/issues/55516

Change-Id: Ie4a845816ec4eda37a5a2e78cac0aeda0e411abd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/381482
Reviewed-by: Ömer Ağacan <omersa@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>