[llvm] r364515 - [DebugInfo] Avoid register coalesing unsoundly changing DBG_VALUE locations

[Jeremy Morse via llvm-commits]

Hi Jordan,

No problemo, I'm currently building/testing the revert, will have it
backed out in ~30 mins if no-one else does.

There are a couple of activities in the patch that might happen a lot
(RegUnit iteration, LiveInterval queries), but I don't have a feel for
their performance characteristics, so a reproducer would be highly
appreciated.

--
Thanks,
Jeremy