Specifically, when we optimize conversions such as:
Optional<@escaping () -> ()>
->
Optional<@noescape () -> ()>
->
Optional<@noescape @convention(block) () -> ()>
previously we were lifetime extending over the @noescape lifetime barrier by
making a copy and then putting a mark_dependence from the copy onto the original
value. This was just a quick way to tell the ownership verifier that the copy
was tied to the other value and thus should not be eliminated. The correctness
of the actual lifetime extension comes from the optimizer being conservative
around rr insts.
This commit instead changes our optimization to borrow the copied optional
value, extract the payload, and use that instead.
This just eliminates -enable-sil-ownership from all target-swift-frontend and
target-swift-emit-silgen RUN lines. Both of those now include
enable-sil-ownership in their expansion.
This beyond being slightly cleaner ensures that we do not try to promote in
PredictableMemOpts any loads from the alloc_stack. Doing this would force us to
insert a copy in ossa which then would break is_escaping_closure even when we
don't escape.
rdar://problem/46188001
