Add a very basic implemenation of global blocks. This needs to be cleaned up.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64387 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprConstant.cpp b/lib/CodeGen/CGExprConstant.cpp
index 1f6da8a..91153f7 100644
--- a/lib/CodeGen/CGExprConstant.cpp
+++ b/lib/CodeGen/CGExprConstant.cpp
@@ -371,6 +371,10 @@
     return Visit(E->getSubExpr());
   }
     
+  llvm::Constant *VisitBlockExpr(const BlockExpr *E) {
+    return CGM.GetAddrOfGlobalBlock(E);
+  }
+  
   // Utility methods
   const llvm::Type *ConvertType(QualType T) {
     return CGM.getTypes().ConvertType(T);