of protocol types to correctly handle self-assignment.
This ends up creating such a large amount of code that it's
worth extracting into its own helper function. Fortunately,
this can be the same helper function for every protocol type.
Swift SVN r1905
first, we weren't registering the cleanup for the temporary
if it needed materialization, and second, we were potentially
double-consuming cleanups associated with the l-value, e.g.
subscript indices.
Swift SVN r1631
heap allocations it makes, and switch swift_alloc over to pass
that pointer in as well as the alignment. Also, compute
whether a type is POD during its generation and cache that in
the object, and introduce a method on TypeInfo to destroy an
object in memory.
Swift SVN r1356
