powerpc: refactor logb{f,l}

The power7 logb implementation does not show a performance gain on
ISA 2.07+ chips with faster floating-point to GRP instructions
(currently POWER8 and POWER9).

This patch moves the POWER7 implementation to generic one and enables
it for POWER7.  It also add some cleanup to use inline floating-point
number instead of define them using static const.

The performance difference is for POWER9:

  - Without patch:
  "logb": {
   "subnormal": {
    "duration": 4.99202e+09,
    "iterations": 8.83662e+08,
    "max": 75.194,
    "min": 5.501,
    "mean": 5.64925
   },
   "normal": {
    "duration": 4.97063e+09,
    "iterations": 9.97094e+08,
    "max": 46.489,
    "min": 4.956,
    "mean": 4.98512
   }
  }

  - With patch:
  "logb": {
   "subnormal": {
    "duration": 4.97226e+09,
    "iterations": 9.92036e+08,
    "max": 77.209,
    "min": 4.892,
    "mean": 5.01218
   },
   "normal": {
    "duration": 4.96192e+09,
    "iterations": 1.07545e+09,
    "max": 12.361,
    "min": 4.593,
    "mean": 4.61382
   }
  }

The ifunc implementation is also enabled only for powerpc64.

Checked on powerpc-linux-gnu (built without --with-cpu, with
--with-cpu=power4 and with --with-cpu=power5+ and --disable-multi-arch),
powerpc64-linux-gnu (built without --with-cp and with --with-cpu=power5+
and --disable-multi-arch).

	* sysdeps/powerpc/power7/fpu/s_logb.c: Move to ...
	* sysdeps/powerpc/fpu/s_logb.c: ... here.  Use inline FP constants.
	* sysdeps/powerpc/power7/fpu/s_logbf.c: Move to ...
	* sysdeps/powerpc/fpu/s_logbf.c: ... here.  Use inline FP constants.
	* sysdeps/powerpc/power7/fpu/s_logbl.c: Move to ...
	* sysdeps/powerpc/fpu/s_logbl.c: ... here.  Use inline FP constants.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_logb-power7.c:
	Adjust implementation path.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_logbf-power7.c:
	Adjust implementation path.
	* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_logbl-power7.c:
	Adjust implementation path.
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/Makefile
	(libm-sysdep_routines): Add s_log* objects.
	(CFLAGS-s_logbf-power7.c, CFLAGS-s_logbl-power7.c,
	CFLAGS-s_logb-power7.c): New fule.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logb-power7.c: Move
	to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logb-power7.c:
	... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logb-ppc64.c: Move
	to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logb-ppc64.c:
	... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logb.c: Move to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logb.c: ... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logbf-power7.c: Move
	to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logbf-power7.c:
	... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logbf-ppc64.c: Move
	to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logbf-ppc64.c:
	... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logbf.c: Move to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logbf.c: ... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logbl-power7.c: Move
	to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logbl-power7.c:
	... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logbl-ppc64.c: Move
	to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logbl-ppc64.c:
	... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_logbl.c: Move to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_logbl.c: ... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/Makefile: Remove file.
	* sysdeps/powerpc/powerpc64/power7/fpu/s_logb.c: Remove file.
	* sysdeps/powerpc/powerpc64/power7/fpu/s_logbf.c: Likewise.
	* sysdeps/powerpc/powerpc64/power7/fpu/s_logbl.c: Likewise.

Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>

3 files changed, 0 insertions, 217 deletions

diff --git a/sysdeps/powerpc/power7/fpu/s_logb.c b/sysdeps/powerpc/power7/fpu/s_logb.c
deleted file mode 100644
index 4cddc0f9c1..0000000000
--- a/sysdeps/powerpc/power7/fpu/s_logb.c
+++ /dev/null
@@ -1,74 +0,0 @@
-/* logb(). PowerPC/POWER7 version.
-   Copyright (C) 2012-2019 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 <math.h>
-#include <math_private.h>
-#include <math_ldbl_opt.h>
-#include <libm-alias-double.h>
-
-/* This implementation avoids FP to INT conversions by using VSX
-   bitwise instructions over FP values.  */
-
-static const double two1div52 = 2.220446049250313e-16;	/* 1/2**52  */
-static const double two10m1   = -1023.0;		/* 2**10 -1  */
-
-/* FP mask to extract the exponent.  */
-static const union {
-  unsigned long long mask;
-  double d;
-} mask = { 0x7ff0000000000000ULL };
-
-double
-__logb (double x)
-{
-  double ret;
-
-  if (__builtin_expect (x == 0.0, 0))
-    /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF].  */
-    return -1.0 / __builtin_fabs (x);
-
-  /* ret = x & 0x7ff0000000000000;  */
-  asm (
-    "xxland %x0,%x1,%x2\n"
-    "fcfid  %0,%0"
-    : "=f" (ret)
-    : "f" (x), "f" (mask.d));
-  /* ret = (ret >> 52) - 1023.0;  */
-  ret = (ret * two1div52) + two10m1;
-  if (__builtin_expect (ret > -two10m1, 0))
-    /* Multiplication is used to set logb (+-INF) = INF.  */
-    return (x * x);
-  else if (__builtin_expect (ret == two10m1, 0))
-    {
-      /* POSIX specifies that denormal numbers are treated as
-         though they were normalized.  */
-      int32_t lx, ix;
-      int ma;
-
-      EXTRACT_WORDS (ix, lx, x);
-      ix &= 0x7fffffff;
-      if (ix == 0)
-	ma = __builtin_clz (lx) + 32;
-      else
-	ma = __builtin_clz (ix);
-      return (double) (-1023 - (ma - 12));
-    }
-  /* Test to avoid logb_downward (0.0) == -0.0.  */
-  return ret == -0.0 ? 0.0 : ret;
-}
-libm_alias_double (__logb, logb)
diff --git a/sysdeps/powerpc/power7/fpu/s_logbf.c b/sysdeps/powerpc/power7/fpu/s_logbf.c
deleted file mode 100644
index b0d006b5c7..0000000000
--- a/sysdeps/powerpc/power7/fpu/s_logbf.c
+++ /dev/null
@@ -1,60 +0,0 @@
-/* logbf(). PowerPC/POWER7 version.
-   Copyright (C) 2012-2019 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 <libm-alias-float.h>
-
-/* This implementation avoids FP to INT conversions by using VSX
-   bitwise instructions over FP values.  */
-
-static const double two1div52 = 2.220446049250313e-16;	/* 1/2**52  */
-static const double two10m1   = -1023.0;		/* -2**10 + 1  */
-static const double two7m1    = -127.0;			/* -2**7 + 1  */
-
-/* FP mask to extract the exponent.  */
-static const union {
-  unsigned long long mask;
-  double d;
-} mask = { 0x7ff0000000000000ULL };
-
-float
-__logbf (float x)
-{
-  /* VSX operation are all done internally as double.  */
-  double ret;
-
-  if (__builtin_expect (x == 0.0, 0))
-    /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF].  */
-    return -1.0 / __builtin_fabsf (x);
-
-  /* ret = x & 0x7f800000;  */
-  asm (
-    "xxland %x0,%x1,%x2\n"
-    "fcfid  %0,%0"
-    : "=f"(ret)
-    : "f" (x), "f" (mask.d));
-  /* ret = (ret >> 52) - 1023.0, since ret is double.  */
-  ret = (ret * two1div52) + two10m1;
-  if (__builtin_expect (ret > -two7m1, 0))
-    /* Multiplication is used to set logb (+-INF) = INF.  */
-    return (x * x);
-  /* Since operations are done with double we don't need
-     additional tests for subnormal numbers.
-     The test is to avoid logb_downward (0.0) == -0.0.  */
-  return ret == -0.0 ? 0.0 : ret;
-}
-libm_alias_float (__logb, logb)
diff --git a/sysdeps/powerpc/power7/fpu/s_logbl.c b/sysdeps/powerpc/power7/fpu/s_logbl.c
deleted file mode 100644
index 76c29daeca..0000000000
--- a/sysdeps/powerpc/power7/fpu/s_logbl.c
+++ /dev/null
@@ -1,83 +0,0 @@
-/* logbl(). PowerPC/POWER7 version.
-   Copyright (C) 2012-2019 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 <math.h>
-#include <math_private.h>
-#include <math_ldbl_opt.h>
-
-/* This implementation avoids FP to INT conversions by using VSX
-   bitwise instructions over FP values.  */
-
-static const double two1div52 = 2.220446049250313e-16;	/* 1/2**52  */
-static const double two10m1   = -1023.0;		/* 2**10 -1  */
-
-/* FP mask to extract the exponent.  */
-static const union {
-  unsigned long long mask;
-  double d;
-} mask = { 0x7ff0000000000000ULL };
-
-long double
-__logbl (long double x)
-{
-  double xh, xl;
-  double ret;
-  int64_t hx;
-
-  if (__builtin_expect (x == 0.0L, 0))
-    /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF].  */
-    return -1.0L / __builtin_fabsl (x);
-
-  ldbl_unpack (x, &xh, &xl);
-  EXTRACT_WORDS64 (hx, xh);
-  /* ret = x & 0x7ff0000000000000;  */
-  asm (
-    "xxland %x0,%x1,%x2\n"
-    "fcfid  %0,%0"
-    : "=f" (ret)
-    : "f" (xh), "f" (mask.d));
-  /* ret = (ret >> 52) - 1023.0;  */
-  ret = (ret * two1div52) + two10m1;
-  if (__builtin_expect (ret > -two10m1, 0))
-    /* Multiplication is used to set logb (+-INF) = INF.  */
-    return (xh * xh);
-  else if (__builtin_expect (ret == two10m1, 0))
-    {
-      /* POSIX specifies that denormal number is treated as
-         though it were normalized.  */
-      return (long double) (- (__builtin_clzll (hx & 0x7fffffffffffffffLL) \
-			       - 12) - 1023);
-    }
-  else if ((hx & 0x000fffffffffffffLL) == 0)
-    {
-      /* If the high part is a power of 2, and the low part is nonzero
-	 with the opposite sign, the low part affects the
-	 exponent.  */
-      int64_t lx, rhx;
-      EXTRACT_WORDS64 (lx, xl);
-      rhx = (hx & 0x7ff0000000000000LL) >> 52;
-      if ((hx ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0)
-	rhx--;
-      return (long double) (rhx - 1023);
-    }
-  /* Test to avoid logb_downward (0.0) == -0.0.  */
-  return ret == -0.0 ? 0.0 : ret;
-}
-#ifndef __logbl
-long_double_symbol (libm, __logbl, logbl);
-#endif