Refactor DebugHandlerBase a bit to common non-debug-having-function filtering

llvm-svn: 295354
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
index c00fa18..659a921 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
@@ -80,6 +80,10 @@
     LabelsAfterInsn.insert(std::make_pair(MI, nullptr));
   }
 
+  virtual void beginFunctionImpl(const MachineFunction *MF) = 0;
+  virtual void endFunctionImpl(const MachineFunction *MF) = 0;
+  virtual void skippedNonDebugFunction() {}
+
   // AsmPrinterHandler overrides.
 public:
   void beginInstruction(const MachineInstr *MI) override;