[PATCH] D57748: AMDGPU: Add inverse ballot intrinsic

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D57748#1390251 <https://reviews.llvm.org/D57748#1390251>, @cwabbott wrote:

> Adding a pattern for this wouldn't work for what I wanted to do, which was a ballot/inverseballot pair to operate directly on the bitmask representation of a boolean, since there's a bug where SelectionDAG forgets that ballot removes divergence, and it needs to be non-divergent for the pattern to fire. That being said, inserting two readlanes isn't that much better, so maybe I should just fix that instead...


Fixing DAG bugs is good. This would be also be if you could use mbcnt here instead of hoping readfirstlane works out OK


Repository:
  rL LLVM

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  https://reviews.llvm.org/D57748/new/

https://reviews.llvm.org/D57748