Propagate __attribute__((returns_twice)) from C to IL.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141002 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index eb0dcf3..f52abef 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -740,6 +740,9 @@
     if (TargetDecl->hasAttr<NoReturnAttr>())
       FuncAttrs |= llvm::Attribute::NoReturn;
 
+    if (TargetDecl->hasAttr<ReturnsTwiceAttr>())
+      FuncAttrs |= llvm::Attribute::ReturnsTwice;
+
     // 'const' and 'pure' attribute functions are also nounwind.
     if (TargetDecl->hasAttr<ConstAttr>()) {
       FuncAttrs |= llvm::Attribute::ReadNone;