corresponding MachineCodeForInstruction vectors.
I need to be able to get the register allocated for the thing which is
called PhiCpRes in this code; this should make that task easier, plus,
Phi nodes are no longer "special" in the sense that their
MachineCodeForInstruction is empty.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13904 91177308-0d34-0410-b5e6-96231b3b80d8