[PATCH] D57748: AMDGPU: Add inverse ballot intrinsic
Matt Arsenault via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Feb 8 06:18:51 PST 2019
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
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https://reviews.llvm.org/D57748/new/
https://reviews.llvm.org/D57748
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