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Re: [10/12] Add femode_t functions: s390


On Sat, Sep 03, 2016 at 05:38:32PM +0300, Yury Norov wrote:
> On Fri, Sep 02, 2016 at 09:58:37PM +0000, Joseph Myers wrote:
> 
> [...]
> 
> > diff --git a/sysdeps/s390/fpu/fesetmode.c b/sysdeps/s390/fpu/fesetmode.c
> > new file mode 100644
> > index 0000000..8feb9b6
> > --- /dev/null
> > +++ b/sysdeps/s390/fpu/fesetmode.c
> > @@ -0,0 +1,38 @@
> > +/* Install given floating-point control modes.  S/390 version.
> > +   Copyright (C) 2016 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#include <fenv.h>
> > +#include <fpu_control.h>
> > +#include <fenv_libc.h>
> > +
> > +#define FPC_STATUS (FPC_FLAGS_MASK | FPC_DXC_MASK)
> > +
> > +int
> > +fesetmode (const femode_t *modep)
> > +{
> > +  fpu_control_t fpc;
> > +
> > +  _FPU_GETCW (fpc);
> > +  if (modep == FE_DFL_ENV)
> > +    fpc = (fpc & FPC_STATUS) | _FPU_DEFAULT;
> > +  else
> > +    fpc = (fpc & FPC_STATUS) | (*modep & ~FPC_STATUS);
> 
> You do fpc = (fpc & FPC_STATUS) in both branches of condition.
> So you can save few instruction if move this snippet upper,
> and also increase readability.
> 
> Not sure how much gcc-s390 is smart, maybe it can do it for you, but
> readability is still in case.

The same is true for sh, spark, mips and hppa.


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