[PATCH] D89542: [InstCombine] narrowFunnelShift - fold trunc/zext or(shl(a,x),lshr(b,sub(bw,x))) -> fshl(a,b,x) (PR35155)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: spatel, lebedev.ri, nikic, kbelochapka.
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As discussed on PR35155, this extends narrowFunnelShift (recently renamed from narrowRotate) to support basic funnel shift patterns.

Unlike matchFunnelShift we don't include the computeKnownBits limitation as extracting the pattern from the zext/trunc layers should be a indicator of reasonable funnel shift codegen, in D89139 <https://reviews.llvm.org/D89139> we demonstrated how to efficiently promote funnel shifts to wider types.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89542

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
  llvm/test/Transforms/InstCombine/funnel.ll

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