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/IfConversion.cpp b/llvm/lib/CodeGen/IfConversion.cpp
index 1bac568..a22ce0d 100644
--- a/llvm/lib/CodeGen/IfConversion.cpp
+++ b/llvm/lib/CodeGen/IfConversion.cpp
@@ -337,7 +337,7 @@
 INITIALIZE_PASS_END(IfConverter, DEBUG_TYPE, "If Converter", false, false)
 
 bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
-  if (skipFunction(*MF.getFunction()) || (PredicateFtor && !PredicateFtor(MF)))
+  if (skipFunction(MF.getFunction()) || (PredicateFtor && !PredicateFtor(MF)))
     return false;
 
   const TargetSubtargetInfo &ST = MF.getSubtarget();