[PATCH] D13250: Extend known bits to understand @llvm.bswap

[Philip Reames via llvm-commits]

reames created this revision.
reames added reviewers: majnemer, spatel, hfinkel, regehr.
reames added a subscriber: llvm-commits.

This is a cleaned up patch from the one written by John Regehr based on the findings of the Souper superoptimizer.

When writing tests, I was surprised to find that instsimplify apparently doesn't know how to collapse bit test sequences based purely on known bits.  This required me to split my tests across both instsimplify and instcombine.  

http://reviews.llvm.org/D13250

Files:
  lib/Analysis/ValueTracking.cpp
  test/Transforms/InstCombine/bswap-known-bits.ll
  test/Transforms/InstSimplify/bswap.ll

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