/// successfully traverse a PHI instruction and find suitable sources coming
/// from its edges. By inserting a new PHI, we provide a rewritten PHI def
/// suitable to be used in a new COPY instruction.
-MachineInstr *
+static MachineInstr *
insertPHI(MachineRegisterInfo *MRI, const TargetInstrInfo *TII,
const SmallVectorImpl<TargetInstrInfo::RegSubRegPair> &SrcRegs,
MachineInstr *OrigPHI) {