[X86FixupBWInsts] Fix miscompilation if sibling sub-register is live.

Summary: The issues was found during D40524.

Reviewers: andrew.w.kaylor, craig.topper, MatzeB

Reviewed By: andrew.w.kaylor

Subscribers: aivchenk, llvm-commits

Differential Revision: https://reviews.llvm.org/D42533

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323635 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed