[PATCH v2] Add i386 and x86_64 fenv support from Cygwin.

[Corinna Vinschen]

On Sep  4 07:43, Joel Sherrill wrote:
> On Wed, Sep 4, 2019 at 3:19 AM Corinna Vinschen <vinschen@redhat.com> wrote:
> > On Sep  3 11:02, joel@rtems.org wrote:
> > > index 0000000..83f5995
> > > --- /dev/null
> > > +++ b/newlib/libc/machine/x86_64/sys/fenv.h
> > > @@ -0,0 +1,170 @@
> > > +/*
> > > + * SPDX-License-Identifier: BSD-2-Clause
> > > + *
> > > + * Copyright (c) 2010-2019 Red Hat, Inc.
> > > + * All rights reserved.
> > > + *
> > > + * Redistribution and use in source and binary forms, with or without
> > > + * modification, are permitted provided that the following conditions
> > > + * are met:
> > > + * 1. Redistributions of source code must retain the above copyright
> > > + *    notice, this list of conditions and the following disclaimer.
> > > + * 2. Redistributions in binary form must reproduce the above copyright
> > > + *    notice, this list of conditions and the following disclaimer in the
> > > + *    documentation and/or other materials provided with the distribution.
> > > + *
> > > + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
> > > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> > > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> > > + * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
> > > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> > > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> > > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> > > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> > > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> > > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> > > + * SUCH DAMAGE.
> > > + */
> >
> > The SPDX-License-Identifier usually replaces the license text...
> 
> Maybe in principle but I couldn't find a single file in newlib which had only
> an SPDX indicator. All 63 had SPDX and license text.

I didn't actually check newlib files, but SPDX + written out license
only makes marginal sense.  So, let's start with *these* files to do it
right, please.

> > Didn't we talk about defining those in their own file?
> 
> I had a patch which added them to the stub support but they aren't
> generic C/POSIX methods and there was a comment that they
> should be target specific.

Hmm, yeah, right.  I missed that, sorry.

> > I'm still not happy that all targets have to call _feinitialise() at
> > some arbitrary point in their init code to set up FE_DFL_ENV and
> > FE_NOMASK_ENV.  That may work for Cygwin with the Cygwin DLL being an
> > integral part of all processes, but for other targets that only makes
> > marginal sense, especially if no fenv functions are used.
> >
> > So, here's an idea:
> >
> > int
> > fesetenv (const fenv_t *envp)
> > {
> >   if ((envp == FE_DFL_ENV || envp == FE_NOMASK_ENV)
> >       && envp->_fpu._fpu_cw == 0)
> >     _feinitialise ();
> >   [...]
> > }
> >
> > In theory, this single test should cover all bases.  Even Cygwin
> > can drop the _feinitialise() call from its init code then.
> >
> > Am I missing something?
> 
> I think _feinitialize can now be static. I moved it to the top of the file
> 
> Doing that lets the prototype and a CYGWIN specific comment in the sys/fenv.h
> disappear.
> 
> Does that sound ok?

That sounds right to me.  Let's do that for now.

With the above changes I can push the patch, but I won't probably be
able to test this on Cygwin until after my vacation.  It might be
better to go ahead with the current code in Cygwin for the Cygwin 3.1
release and only afterr that I'll start switching, ok?


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat
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