https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93202
--- Comment #9 from Luís Marques <luismarques at lowrisc dot org> --- Thank you all participating in this discussion for your prompt replies and fixes! As usual, Jim spoils us with a comprehensive and clear description of the subject matter. I agree that those constraint modifiers only make sense to be used internally. I was looking into them only because I had been addressing modifier issues in LLVM and I wanted to take the opportunity to bring its implementation up to par with GCC (for compatibility). I believe that's the case now, since all of the remaining modifiers are intended for internal use only. Jim: it would indeed be a good idea to document the modifiers. AFAIK the GCC docs only document the X86 modifiers. If not adding to the HTML documentation, at least a quick tweak to the source comments to indicate which ones are internal only would be nice.
