This entry point is used in conditional downcasts (as?) to attempt to
bridge from an Objective-C class down to a specific native type (e.g.,
array, dictionary), bridging all elements eagerly so that it can
produce nil if the bridging would fail.
This is the scaffolding for <rdar://problem/17319154>, and makes the
example there work, but there is much more cleanup and optimization to
do.
Swift SVN r18999
This is the most general dynamic cast operation, permitting
arbitary source and destination types and handling arbitrary
changes in representation. A value of the destination type
is constructed in an address provided by the caller; flags
control the behavior w.r.t. the source value.
Not yet used; probably buggy in various particulars.
Swift SVN r18815
put the result in a different place.
WIP: no IRGen support yet.
This will eventually be the required form when casting
to an address-only type; the existing instructions will
have only scalar outputs.
Swift SVN r18780
dynamicCastClass assumes that the destination type is a
Swift class type.
dynamicCastObjCClass assumes that the destination type is
an ObjC class type (represented as ObjC metadata, not type
metadata).
dynamicCastUnknownClass assumes only that the destination
type is some kind of class.
Swift SVN r18776
