swift234

[sil-combine] Propagate information about a concrete type from init_existential or init_existential_ref into witness_method conformances and into apply instructions.

This helps the devirtualizer to replace witness_method by class_method instructions and then devirtualize.

Note: Invocation of protocol methods from generic classes and structs is not supported by this patch yet.

rdar://18857054 and rdar://18506660

Swift SVN r23596