[SYCL][NFC] Fix potential null-pointer access (#2197)

Signed-off-by: Premanand M Rao <premanand.m.rao@intel.com>

Author: premanandrao

clang/lib/CodeGen/CodeGenModule.cpp

@@ -3887,13 +3887,13 @@ LangAS CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D) {
   }
 
   if (LangOpts.SYCLIsDevice) {
+    if (!D)
+      return LangAS::opencl_global;
     auto *Scope = D->getAttr<SYCLScopeAttr>();
-
     if (Scope && Scope->isWorkGroup())
       return LangAS::opencl_local;
-    if (!D || D->getType().getAddressSpace() == LangAS::Default) {
+    if (D->getType().getAddressSpace() == LangAS::Default)
       return LangAS::opencl_global;
-    }
   }
 
   if (LangOpts.CUDA && LangOpts.CUDAIsDevice) {