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/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index 8f8013a..8c45ce2 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -757,9 +757,8 @@
   }
   regsLiveInButUnused = regsLive;
 
-  const MachineFrameInfo *MFI = MF->getFrameInfo();
-  assert(MFI && "Function has no frame info");
-  BitVector PR = MFI->getPristineRegs(*MF);
+  const MachineFrameInfo &MFI = MF->getFrameInfo();
+  BitVector PR = MFI.getPristineRegs(*MF);
   for (int I = PR.find_first(); I>0; I = PR.find_next(I)) {
     for (MCSubRegIterator SubRegs(I, TRI, /*IncludeSelf=*/true);
          SubRegs.isValid(); ++SubRegs)