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Re: [PATCH] PowerPC: modf optimization


On 03/25/2013 06:43 PM, Adhemerval Zanella wrote:
This patch implements modf/modff optimization for POWER by focus
on FP operations instead of relying in integer ones.

For POWER7 it shows a leverage of about 50% for modf ppc32, 40% for
modff ppc32, 65% for modf ppc64, and 60% for modff ppc64.

How are you measuring the speed up? Is it possible to add these tests to the benchmark testsuite that was just started?


Any though, tips, advices?

---

2013-03-25  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/fpu/Makefile: Add s_floor[f] and s_ceil[f] for
	powerpc64/POWER4 builds.


diff --git a/sysdeps/powerpc/fpu/Makefile b/sysdeps/powerpc/fpu/Makefile
index fda59f9..fe1eadc 100644
--- a/sysdeps/powerpc/fpu/Makefile
+++ b/sysdeps/powerpc/fpu/Makefile
@@ -1,6 +1,8 @@
  ifeq ($(subdir),math)
  libm-support += fenv_const fe_nomask fe_mask t_sqrt

+# modf needs floof and ceil for powerpc64/POWER4
+sysdep_routines += s_floor s_ceil s_floorf s_ceilf

So, you're moving s_floor and s_ceil into libc.so? That looks wrong to me. Are you sure that those are not exported?

Andreas

  # libm needs ld.so to access dl_hwcap
  $(objpfx)libm.so: $(elfobjdir)/ld.so
  endif
diff --git a/sysdeps/powerpc/fpu/s_modf.c b/sysdeps/powerpc/fpu/s_modf.c
new file mode 100644
index 0000000..b45bf66
--- /dev/null
+++ b/sysdeps/powerpc/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/fpu/s_modff.c b/sysdeps/powerpc/fpu/s_modff.c
new file mode 100644
index 0000000..55759cd
--- /dev/null
+++ b/sysdeps/powerpc/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)



--
 Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
  SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
   GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg)
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