MachineFunction: Return reference from getFunction(); NFC

The Function can never be nullptr so we can return a reference.

llvm-svn: 320884
diff --git a/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp b/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
index ac4468f..9249fa8 100644
--- a/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -114,7 +114,7 @@
     : ScheduleDAG(mf), MLI(mli), MFI(mf.getFrameInfo()),
       RemoveKillFlags(RemoveKillFlags),
       UnknownValue(UndefValue::get(
-                             Type::getVoidTy(mf.getFunction()->getContext()))) {
+                             Type::getVoidTy(mf.getFunction().getContext()))) {
   DbgValues.clear();
 
   const TargetSubtargetInfo &ST = mf.getSubtarget();