Add an implementation of thunks for varargs methods.  The implementation is a bit messy, but it is correct as long as the method in question doesn't use indirect gotos.  A couple of possible alternative implementations are outlined in FIXME's in this patch. rdar://problem/8077308 .

llvm-svn: 130993
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 4bf1e3a..96aa725 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -793,14 +793,19 @@
       return;
 
     if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
+      // Make sure to emit the definition(s) before we emit the thunks.
+      // This is necessary for the generation of certain thunks.
+      if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Method))
+        EmitCXXConstructor(CD, GD.getCtorType());
+      else if (const CXXDestructorDecl *DD =dyn_cast<CXXDestructorDecl>(Method))
+        EmitCXXDestructor(DD, GD.getDtorType());
+      else
+        EmitGlobalFunctionDefinition(GD);
+
       if (Method->isVirtual())
         getVTables().EmitThunks(GD);
 
-      if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Method))
-        return EmitCXXConstructor(CD, GD.getCtorType());
-  
-      if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Method))
-        return EmitCXXDestructor(DD, GD.getDtorType());
+      return;
     }
 
     return EmitGlobalFunctionDefinition(GD);