diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3280,6 +3280,10 @@
 
 llvm::DISubprogram *CGDebugInfo::getFunctionFwdDeclOrStub(GlobalDecl GD,
                                                           bool Stub) {
+  auto *FD = dyn_cast<FunctionDecl>(GD.getDecl());
+  if (!FD)
+    return nullptr;
+
   llvm::DINodeArray TParamsArray;
   StringRef Name, LinkageName;
   llvm::DINode::DIFlags Flags = llvm::DINode::FlagZero;
@@ -3290,13 +3294,10 @@
   unsigned Line = getLineNumber(Loc);
   collectFunctionDeclProps(GD, Unit, Name, LinkageName, DContext, TParamsArray,
                            Flags);
-  auto *FD = dyn_cast<FunctionDecl>(GD.getDecl());
-
   // Build function type.
   SmallVector<QualType, 16> ArgTypes;
-  if (FD)
-    for (const ParmVarDecl *Parm : FD->parameters())
-      ArgTypes.push_back(Parm->getType());
+  for (const ParmVarDecl *Parm : FD->parameters())
+    ArgTypes.push_back(Parm->getType());
   CallingConv CC = FD->getType()->castAs<FunctionType>()->getCallConv();
   QualType FnType = CGM.getContext().getFunctionType(
       FD->getReturnType(), ArgTypes, FunctionProtoType::ExtProtoInfo(CC));