The typed function references proposal defines br_on_null and br_on_non_null: https://github.com/WebAssembly/function-references/blob/main/proposals/function-references/Overview.md#optional-references These are currently unimplemented in JSC.
<rdar://problem/104836753>
Pull request: https://github.com/WebKit/WebKit/pull/21134
Committed 271399@main (26cb4d1f6cc3): <https://commits.webkit.org/271399@main> Reviewed commits have been landed. Closing PR #21134 and removing active labels.