[Bug target/94743] IRQ handler doesn't save scratch VFP registers

[rearnsha at gcc dot gnu.org]

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.