I don't understand the motivation for this feature. Can you give more info, or point me at the use-case you ran into for this?
Looking at the checklist in https://gcc.gnu.org/onlinedocs/jit/internals/index.html#submitting-patches it's missing documentation (which is another reason why I don't understand it - sorry!) -- https://forge.sourceware.org/gcc/gcc/pulls/190#issuecomment-7213
