Re: [PATCH] PowerPC: modf optimization

[Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>]

Ping.

On 03/31/2013 06:56 PM, Adhemerval Zanella wrote:
> On 03/27/2013 11:11 AM, Andreas Jaeger wrote:
>> I'm fine with the benchtests addition (see one comment below).
>>
>> I'm not sure about the __ceil, __floor issue and would like feedback from others on how to handle this,
> I have added the copyright header and I changed to patch to use the new modf
> implementation for POWER5 or higher only, making the s_floor and s_ceil addition
> not required anymore.
>
> I also increased the iterations to 5e8 and I got the following results in a POWER7
> machine with 64 bits:
>
> MASTER: modf: ITERS:5e+08: TOTAL:5.96664s, MAX:42.302ns, MIN:9.104ns, 8.37993e+07 iter/s
> PATCH:  modf: ITERS:5e+08: TOTAL:3.00147s, MAX:40.334ns, MIN:5.63ns,  1.66585e+08 iter/s
>
> And clock_gettime is an vDSO for PowerPC, however afaik CLOCK_PROCESS_CPUTIME_ID
> fall-back to a syscall even for x86_64. Maybe we should increase the default
> iterations for all benchtests.
>
> Any tips, comments, advices?
>
> ---
>
> 2013-03-31  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
>
>     * sysdeps/powerpc/fpu/s_modf.c: New file: modf optimization for POWER.
>     * sysdeps/powerpc/fpu/s_modff.c: New file: modff optimization for POWER.
>     * sysdeps/powerpc/powerpc64/power5/Implies: Add powerpc/power5 and
>     powerpc/power5/fpu folders.
>     * sysdeps/powerpc/powerpc32/power5/Implies: Likewise.
>     * benchtests/Makefile: Add modf testcase.
>     * benchtests/bench-modf.c: New file: Benchmark test for modf.
>
> --
>
> diff --git a/benchtests/Makefile b/benchtests/Makefile
> index 74938b9..dbbc44c 100644
> --- a/benchtests/Makefile
> +++ b/benchtests/Makefile
> @@ -43,7 +43,7 @@
>  #   See pow-inputs for an example.
>
>  subdir := benchtests
> -bench := exp pow
> +bench := exp pow modf
>
>  exp-ITER = 100000
>  exp-ARGLIST = double
> diff --git a/benchtests/bench-modf.c b/benchtests/bench-modf.c
> new file mode 100644
> index 0000000..1f91556
> --- /dev/null
> +++ b/benchtests/bench-modf.c
> @@ -0,0 +1,27 @@
> +/* Copyright (C) 2013 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/>.  */
> +
> +extern double modf ( double, double*);
> +#define CALL_BENCH_FUNC(j, i) modf ( in[j].arg0, &i);
> +struct args { double arg0; } in[] = {{42.42}, {-42.42}
> +};
> +#define NUM_SAMPLES (sizeof (in) / sizeof (struct args))
> +static volatile double ret = 0.0;
> +#define BENCH_FUNC(j) ({double iptr; ret =  CALL_BENCH_FUNC (j, iptr);})
> +#define ITER 250000000
> +#define FUNCNAME "modf"
> +#include "bench-skeleton.c"
> diff --git a/sysdeps/powerpc/power5/fpu/s_modf.c b/sysdeps/powerpc/power5/fpu/s_modf.c
> new file mode 100644
> index 0000000..b45bf66
> --- /dev/null
> +++ b/sysdeps/powerpc/power5/fpu/s_modf.c
> @@ -0,0 +1,58 @@
> +/* Copyright (C) 2013 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 Library General Public License as
> +   published by the Free Software Foundation; either version 2 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
> +   Library General Public License for more details.
> +
> +   You should have received a copy of the GNU Library General Public
> +   License along with the GNU C Library; see the file COPYING.LIB.  If
> +   not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <math.h>
> +#include <math_private.h>
> +#include <math_ldbl_opt.h>
> +
> +double
> +__modf (double x, double *iptr)
> +{
> +  if (__builtin_isinf (x))
> +    {
> +      *iptr = x;
> +      return __copysign (0.0, x);
> +    }
> +  else if (__builtin_isnan (x))
> +    {
> +      *iptr = NAN;
> +      return NAN;
> +    }
> +
> +  if (x >= 0.0)
> +    {
> +      *iptr = __floor (x);
> +      return (x - *iptr);
> +    }
> +  else
> +    {
> +      *iptr = __ceil (x);
> +      return (x - *iptr);
> +    }
> +}
> +weak_alias (__modf, modf)
> +#ifdef NO_LONG_DOUBLE
> +strong_alias (__modf, __modfl)
> +weak_alias (__modf, modfl)
> +#endif
> +#ifdef IS_IN_libm
> +# if LONG_DOUBLE_COMPAT(libm, GLIBC_2_0)
> +compat_symbol (libm, __modf, modfl, GLIBC_2_0);
> +# endif
> +#elif LONG_DOUBLE_COMPAT(libc, GLIBC_2_0)
> +compat_symbol (libc, __modf, modfl, GLIBC_2_0);
> +#endif
> diff --git a/sysdeps/powerpc/power5/fpu/s_modff.c b/sysdeps/powerpc/power5/fpu/s_modff.c
> new file mode 100644
> index 0000000..55759cd
> --- /dev/null
> +++ b/sysdeps/powerpc/power5/fpu/s_modff.c
> @@ -0,0 +1,46 @@
> +/* Copyright (C) 2013 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 Library General Public License as
> +   published by the Free Software Foundation; either version 2 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
> +   Library General Public License for more details.
> +
> +   You should have received a copy of the GNU Library General Public
> +   License along with the GNU C Library; see the file COPYING.LIB.  If
> +   not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <math.h>
> +#include <math_private.h>
> +
> +float
> +__modff (float x, float *iptr)
> +{
> +  if (__builtin_isinff (x))
> +    {
> +      *iptr = x;
> +      return __copysignf (0.0, x);
> +    }
> +  else if (__builtin_isnanf (x))
> +    {
> +      *iptr = NAN;
> +      return NAN;
> +    }
> +
> +  if (x >= 0.0)
> +    {
> +      *iptr = __floorf (x);
> +      return (x - *iptr);
> +    }
> +  else
> +    {
> +      *iptr = __ceilf (x);
> +      return (x - *iptr);
> +    }
> +}
> +weak_alias (__modff, modff)
> diff --git a/sysdeps/powerpc/powerpc32/power5/Implies b/sysdeps/powerpc/powerpc32/power5/Implies
> index 17139bf..17949d4 100644
> --- a/sysdeps/powerpc/powerpc32/power5/Implies
> +++ b/sysdeps/powerpc/powerpc32/power5/Implies
> @@ -1,2 +1,4 @@
> +powerpc/power5/fpu
> +powerpc/power5
>  powerpc/powerpc32/power4/fpu
>  powerpc/powerpc32/power4
> diff --git a/sysdeps/powerpc/powerpc64/power5/Implies b/sysdeps/powerpc/powerpc64/power5/Implies
> index bedb20b..b36831e 100644
> --- a/sysdeps/powerpc/powerpc64/power5/Implies
> +++ b/sysdeps/powerpc/powerpc64/power5/Implies
> @@ -1,2 +1,4 @@
> +powerpc/power5/fpu
> +powerpc/power5
>  powerpc/powerpc64/power4/fpu
>  powerpc/powerpc64/power4
>