[InstCombine] try harder to form select from logic ops
This is part of solving PR37549:
https://bugs.llvm.org/show_bug.cgi?id=37549
The patterns shown here are a special case of something
that we already convert to select. Using ComputeNumSignBits()
catches that case (but not the more complicated motivating
patterns yet).
The backend has hooks/logic to convert back to logic ops
if that's better for the target.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344609 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed