swift234

[sil-simplify-cfg] Improve the trampoline elimination code.

Replace cond branches to a trampoline BB without BBargs, by direct cond branches to the destination BB of the trampoline. Apply this transformation only if it does not introduce new critical edges as this may destroy the canonical form of the CFG which is required/assumed by some other optimizations (e.g. LoopRotate, ABCOpts, etc).

rdar://16450429

Swift SVN r24236