[PATCH] D128159: [DAG] Enable scalable vectors handling in computeKnownBits

[Paul Walker via Phabricator via llvm-commits]

paulwalker-arm added a comment.

I don't like the path this patch is taking.  In it current form it is changing what the current interface means without documenting such, nor paying much heed to what all the code paths might do.  This is why during initial scalable vector bring up, we decided to go the safest route and essentially bail for scalable vectors.  Sure this means we implicitly changed the meaning of the "all known" value but there was little else we could do.

It was discussed during the SVE sync calls we ran a while back and whilst no firm decision was made it was pretty clear that `KnownBits` will need to undergo the same transition as `TypeSize` and `ElementCount`.  I don't think this is something we can nor should short cut.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D128159/new/

https://reviews.llvm.org/D128159