Debug Info: Implement DwarfUnit::addRegisterOffset using DwarfExpression.
No functional change.

llvm-svn: 225707
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
index ce4aae3..329737c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
@@ -42,6 +42,9 @@
   void EmitOp(uint8_t Op, const char* Comment) override;
   void EmitSigned(int Value) override;
   void EmitUnsigned(unsigned Value) override;
+  unsigned getFrameRegister() override {
+    llvm_unreachable("not available");
+  };
 };
 
 void DebugLocDwarfExpression::EmitOp(uint8_t Op, const char* Comment) {