[Bug target/71460] Copying structs can trap (on x86-32) due to SNaN to QNaN

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71460

--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Richard Biener from comment #3)
> It looks like RTL expansion uses DFmode to copy the aggregate which is likely
> because the backend (or stor-layout.c) assigns DFmode to struct s.  A similar
> issue should exist on Itanium.
> 
> This means the x86 target, to fix this particular case, should implement
> targetm.member_type_forces_blk for x87 modes (and -fsignalling-nans?).

We already have this hook defined for XFmode. IMO, we just have to use
IS_STACK_MODE macro instead (and perhaps flag_signaling_nans).