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/AsmPrinter/AsmPrinterInlineAsm.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
index 580830d..04a72ba 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
@@ -514,7 +514,7 @@
   // Reset SanitizeAddress based on the function's attribute.
   MCTargetOptions MCOptions = TM.Options.MCOptions;
   MCOptions.SanitizeAddress =
-      MF->getFunction()->hasFnAttribute(Attribute::SanitizeAddress);
+      MF->getFunction().hasFnAttribute(Attribute::SanitizeAddress);
 
   EmitInlineAsm(OS.str(), getSubtargetInfo(), MCOptions, LocMD,
                 MI->getInlineAsmDialect());