[PATCH] D54478: [InstCombine] fold funnel shift amount based on demanded bits

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
spatel added reviewers: RKSimon, craig.topper, fabiang.
Herald added a subscriber: mcrosier.

The shift amount of a funnel shift is modulo the scalar bitwidth:
http://llvm.org/docs/LangRef.html#llvm-fshl-intrinsic
...so we can use demanded bits analysis on that operand to simplify it.

This is another step towards canonicalizing {shift/shift/or} to the intrinsic in IR.


https://reviews.llvm.org/D54478

Files:
  lib/Transforms/InstCombine/InstCombineCalls.cpp
  test/Transforms/InstCombine/fsh.ll

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