[Hexagon] Don't kill live registers when creating mux out of tfr

The second part of r305300: when placing the mux at the later location,
make sure that it won't use any register that was killed between the
two original instructions. Remove any such kills and transfer them to
the mux.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305553 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed