Hi Elouan,
Polly does not generate source code (C/C++) but only LLVM-IR.
You can ask for the "Polly AST" and dump it but other than that
there is no place for "pragmas". That said, you can look at the
LLVM-IR if you want, and one could place markers there too, I
don't think Polly does right now.
~ JOhannes