[ARM] Remove redundant computeKnownBits helper.

Move the BFI logic to computeKnownBitsForTargetNode, and delete
the redundant CMOV logic.

This is intended as a cleanup, but it's probably possible to construct
a case where moving the BFI logic allows more combines.

Differential Revision: https://reviews.llvm.org/D31795



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300752 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed