This patch does the following:
- Moves the logic for handling special-case of converting to/from AnyObject.Protocol (and existential.Protocol in general) into DynamicCasts, where all other cases are handled already.
- Moves the peephole which was folding checked_cast_br into an unchecked cast and branch from sil-combine into sil-simplify-cfg, because it is a better place for it, since this peephole affects the CFG. The corresponding test is also moved from sil_combine.sil into simplify_cfg.sil.
- Adds a few checked_cast_br peepholes to sil-combine. They try to simplify checked_cond_br instructions using existential metatypes by propagating a concrete type whenever it can be determined statically.
- Adds a new test with a lot of test-cases that make sure we are really folding many type-checks at compile-time now.
Swift SVN r25504
The logic for different special cases of type casting is spread over multiple places currently. This patch simply re-factors some of that code (folding of of type casts using statically known protocol conformances) and moves it into one central place, which makes it easier to maintain. Plus, it allows other clients of DynamicCasts benefit from it as well, e.g. the inliner can use this now. NFC.
Swift SVN r25486
unconditional_dynamic_cast_addr instruction.
Also, fix some major semantic problems with the
existing specialization of unconditional dynamic
casts by handling optional types and being much
more conservative about deciding that a cast is
infeasible.
This commit regresses specialization slightly by
failing to turn indirect dynamic casts into scalar
ones when possible; we can fix that easily enough
in a follow-up.
Swift SVN r19044
