Re: i386 and x86_64 fenv support

[Joel Sherrill <joel at rtems dot org>]

On Tue, Aug 27, 2019 at 10:39 AM Corinna Vinschen <vinschen@redhat.com> wrote:
>
> On Aug 27 08:31, Joel Sherrill wrote:
> > Hi
> >
> > Earlier we discussed moving the winsup fenv.h files to newlib. Splitting
> > winsup/cygwin/include/fenv.h to create a sys/fenv.h looks easy enough.
> > But I have some status and a question after tinkering with this code out
> > of tree and compiling with the RTEMS i386 and x86_64
> >
> > It includes winsup.h and wincap.h but it doesn't need them.
>
> Yeah, that's kind of a boilerplate include in Cygwin code.  Just scratch
> it, it can't be overly important for the fenv functionality.
>
> > [...]
> > There are prototypes for fegetprec() and fesetprec(). I think the
> > prototypes need to move to the shared fenv.h and commented
> > stubs for the constants needs to be in the shared dummy sys/fenv.h.
> > Does this sound right?
>
> As far as I can see, none of Linux or BSD have these functions.  It may
> be the right thing to do to keep them local to Cygwin since they never
> made it into a standard or one of the systems we're interested in here.
>
> Ideally they are never defined in a header, not even on Cygwin.  We only
> have to keep exporting these symbols in Cygwin for backward compat.

OK. They will disappear from the machine .h files then if that's OK.

>
> > My remaining issue is that it appears that i386 and x86_64 will need to
> > share the same files. Do I just copy the files to both machine directories?
> > I don't know if newlib's build infrastructure supports putting it in one
> > place and using it in another architecture.
>
> Shouldn't a symlink from x86_64/file to ../i386/file work?  git handles
> symlinks just fine.

Didn't think of that. Sounds good to me.

How does a patch to winsup get handled? Given the fact I can't build it,
should I just let you handle it after the patch is merged into newlib

I'll keep plugging at this slowly.

Thanks.

--joel

>
>
>
> Corinna
>
> --
> Corinna Vinschen
> Cygwin Maintainer
> Red Hat