https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94743
--- Comment #14 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- (In reply to Christophe Lyon from comment #13) > But, in general (non-interrupt) code, what is supposed to happen if you > compile for a d32 VFP and run on d16 one ? (and the code uses the extra > registers) Well obviously that won't work. But if you build the interrupt routine with a d16 system and then call a function from it that requires d32 then that should still work if running on a d32 CPU. I think we can probably make that work, but it's probably a bit of a dance to get it all right. Hence the suggestion that this be done in a library function.