MachineFunction: Return reference for getFrameInfo(); NFC

getFrameInfo() never returns nullptr so we should use a reference
instead of a pointer.

llvm-svn: 277017
diff --git a/llvm/lib/CodeGen/ShrinkWrap.cpp b/llvm/lib/CodeGen/ShrinkWrap.cpp
index d361a6c..d8e9df1 100644
--- a/llvm/lib/CodeGen/ShrinkWrap.cpp
+++ b/llvm/lib/CodeGen/ShrinkWrap.cpp
@@ -521,9 +521,9 @@
                << ' ' << Save->getName() << "\nRestore: "
                << Restore->getNumber() << ' ' << Restore->getName() << '\n');
 
-  MachineFrameInfo *MFI = MF.getFrameInfo();
-  MFI->setSavePoint(Save);
-  MFI->setRestorePoint(Restore);
+  MachineFrameInfo &MFI = MF.getFrameInfo();
+  MFI.setSavePoint(Save);
+  MFI.setRestorePoint(Restore);
   ++NumCandidates;
   return false;
 }