Emit a more sensible error message if no subclasses of Target are defined.
Patch contributed by Vladimir Prus.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14010 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeGenTarget.cpp b/utils/TableGen/CodeGenTarget.cpp
index bf641fa..842294a 100644
--- a/utils/TableGen/CodeGenTarget.cpp
+++ b/utils/TableGen/CodeGenTarget.cpp
@@ -72,6 +72,8 @@
 ///
 CodeGenTarget::CodeGenTarget() : PointerType(MVT::Other) {
   std::vector<Record*> Targets = Records.getAllDerivedDefinitions("Target");
+  if (Targets.size() == 0)
+    throw std::string("ERROR: No 'Target' subclasses defined!");  
   if (Targets.size() != 1)
     throw std::string("ERROR: Multiple subclasses of Target defined!");
   TargetRec = Targets[0];