[PATCH] D103788: [InstCombine] Eliminate casts to optimize ctlz operation

[Datta Nagraj via Phabricator via llvm-commits]

datta.nagraj added a comment.

@lebedev.ri Sir, but if we don't take trunc into consideration, then how are we optimizing this?
Earlier it was 2 insts (zext - ctlz), and now its 3 insts(ctlz - add - zext). I agree that the ctlz , add are done on a lower datatype.
If we consider trunc as well, then we can convert 3 insts (zext - ctlz - trunc) to 2 insts (ctlz - add).
Shouldn't we do this opt only when the trunc is present?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103788/new/

https://reviews.llvm.org/D103788