Code-transformation directives allow the programmer to specify which trans- formation the compiler should apply and in which order (e.g. tile the loop nest, then parallelize the outermost and vectorize the inner most loop) with- out impacting the source’s maintainability. Currently, Clang only supports the "#pragma clang loop directives" which do not reliably take a sequence of trans- formations into account. We present the "#pragma clang transform" directive that specifically supports chaining transformations. These directives must be parsed, represented in the AST, instantiated for templates, (de-)serialized, dumped, semantically verified, and its LLVM-IR generated.
