swift

5dc80f62 - LoopRotate: don't rotate loops where the header block branches to a dead-end block.

LoopRotate: don't rotate loops where the header block branches to a dead-end block. Incomplete liveranges in the dead-end exit block can cause a missing adjacent phi-argument for a re-borrow if there is a borrow-scope is in the loop. But even when we have complete lifetimes, it's probably not worth rotating a loop where the header block branches to a dead-end block. Fixes a SIL verifier crash