[PowerPC] Use rldicr instruction for AND with an immediate if possible

Emit clrrdi (extended mnemonic for rldicr) for AND-ing with masks that
clear bits from the right hand size.

Committing on behalf of Hiroshi Inoue.

Differential Revision: https://reviews.llvm.org/D29388


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296143 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed