[PATCH] D55604: [AggressiveInstCombine] convert rotate with guard branch into funnel shift (PR34924)

[Nikita Popov via Phabricator via llvm-commits]

nikic accepted this revision.
nikic added a comment.
This revision is now accepted and ready to land.

LGTM. As a future extension, it would be nice to also handle non-rotate funnel shifts.

One note: We're not guarding whether the RotBB is reachable *only* from GuardBB, so it may be that it can also be executed with a shift amount of zero. However, in this case the result will be undef due to the oversized shift and we can assume that it coincides with the value provided by this transformation, so there shouldn't be a problem.


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https://reviews.llvm.org/D55604