methods which have strangely different semantics in different backends,
and noone knew what any did.
Getting rid of these ALSO allows the dependence of MachineInstr.h on
MRegisterInfo.h to be removed, which makes me much happier, and probably
alkis too. :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11287 91177308-0d34-0410-b5e6-96231b3b80d8