[PATCH] D34391: [RegisterCoalescer] Fix for SubRange join unreachable

[David Stuttard via Phabricator via llvm-commits]

dstuttard added a comment.

I've added this change specifically to address a problem seen in the associated PR (http://llvm.org/PR33524), however I'm not sure that this is necessarily the right way to go about fixing this issue.

I think that the remat results in an incorrect segment in the SubRange - which looks something like [128r, 128d) and is also an undef - and removing it does clear up the problem. (Prior to the remat the segment in the SubRange is correct, albeit for an undef).
However, I wondered if the part of the code that went wrong later (results in an unreachable) should in fact be able to deal with this itself.


https://reviews.llvm.org/D34391