Fix PR12821.

RAFast must add an <imp-def> operand when it is rewriting a sub-register
def that isn't a read-modify-write.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156777 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed