Change use of MI to MIRBuilder for getting the Machine Function.

Co-authored-by: Matt Arsenault <[email protected]>

Author: HolyMolyCowMan

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -708,7 +708,7 @@ LegalizerHelper::LegalizeResult
 LegalizerHelper::emitModfLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder,
                                  unsigned Size, Type *OpType,
                                  LostDebugLocObserver &LocObserver) {
-  MachineFunction &MF = *MI.getMF();
+  MachineFunction &MF = MIRBuilder.getMF();
   MachineRegisterInfo &MRI = MF.getRegInfo();
 
   Register DstFrac = MI.getOperand(0).getReg();