AsmPrinter.
getSubtargetInfo now asserts that the MachineFunction exists.
Debug printing of register naming now uses the register info
from MCAsmInfo as that's unchanging.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229978 91177308-0d34-0410-b5e6-96231b3b80d8