powerpc: round/roundf refactor

This patches consolidates all the powerpc round{f} implementations on
the generic sysdeps/powerpc/fpu/s_round{f}.  The generic implementation
uses either the compiler builts for ISA 2.03+ (which generates the
frim instruction) or a generic implementation which uses FP only
operations.

The IFUNC organization for powerpc64 is also change to be enabled only
for powerpc64 and not for powerpc64le (since minium ISA of 2.08 does not
require the fallback generic implementation).

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/fpu/round_to_integer.h (set_fenv_mode): Add
	ROUND handling.
	(round_mode): Add definition for ROUND.
	(round_to_integer_float): Likewise.
	* sysdeps/powerpc/fpu/s_round.c: New file.
	* sysdeps/powerpc/fpu/s_roundf.c: New file.
	* sysdeps/powerpc/powerpc32/fpu/s_round.S: Remove file.
	* sysdeps/powerpc/powerpc32/fpu/s_roundf.S: Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_round-power5+.S:
	Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_round-ppc32.S:
	Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_roundf-power5+.S:
	Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_roundf-ppc32.S:
	Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_round-power5+.c: New
	file.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_round-ppc32.c:
	Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_roundf-power5+.c:
	Likewise.
	* sysdep/powerpc/powepc32/power4/fpu/multiarch/s_roundf-ppc32.c:
	Likewise.
	* sysdep/powerpc/powerpc32/power5+/fpu/s_round.S: Remove file.
	* sysdep/powerpc/powerpc32/power5+/fpu/s_roundf.S: Likewise.
	* sysdep/powerpc/powerpc64/be/fpu/multiarch/Makefile
	(libm-sysdep_routines): Add s_round-power5+, s_round-ppc64,
	s_roundf-power5+, and s_roundf-ppc64.
	(CFLAGS-s_round-power5+.c, CFLAGS-s_roundf-power5+.c): New rule.
	* sysdep/powerpc/powercp64/be/fpu/multiarch/s_round-power5+.c: New
	file.
	* sysdep/powerpc/powercp64/be/fpu/multiarch/s_round-ppc64.c: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_round.c: Move to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_round.c: ... here.
	* sysdep/powerpc/powercp64/be/fpu/multiarch/s_roundf-power5+.c: New
	file.
	* sysdep/powerpc/powercp64/be/fpu/multiarch/s_roundf-ppc64.c:
	Likewise.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/s_roundf.c: Move to ...
	* sysdeps/powerpc/powerpc64/be/fpu/multiarch/s_roundf.c: ... here.
	* sysdeps/powerpc/powerpc64/fpu/multiarch/Makefile
	(libm-sysdep_routines): Remove s_round-power5+, s_round-ppc64,
	s_roundf-power5+, and s_roundf-ppc64.
	* sysdep/powerpc/powerpc64/fpu/multiarch/s_round-power5+.S: Remove
	file.
	* sysdep/powerpc/powerpc64/fpu/multiarch/s_round-ppc64.S: Likewise.
	* sysdep/powerpc/powerpc64/fpu/multiarch/s_roundf-power5+.S:
	Likewise.
	* sysdep/powerpc/powerpc64/fpu/multiarch/s_roundf-ppc64.S: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_round.S: Likewise.
	* sysdeps/powerpc/powerpc64/fpu/s_roundf.S: Likewise.
	* sysdep/powerpc/powerpc64/power5+/fpu/s_round.S: Likewise.
	* sysdep/powerpc/powerpc64/power5+/fpu/s_roundf.S: Likewise.

Reviewed-by: Gabriel F. T. Gomes <gabriel@inconstante.eti.br>

3 files changed, 89 insertions, 1 deletions

diff --git a/sysdeps/powerpc/fpu/round_to_integer.h b/sysdeps/powerpc/fpu/round_to_integer.h
index ff77dde394..b318e37190 100644
--- a/sysdeps/powerpc/fpu/round_to_integer.h
+++ b/sysdeps/powerpc/fpu/round_to_integer.h
@@ -24,7 +24,8 @@
 enum round_mode
 {
   CEIL,
-  FLOOR
+  FLOOR,
+  ROUND
 };
 
 static inline void
@@ -35,6 +36,7 @@ set_fenv_mode (enum round_mode mode)
   {
   case CEIL:  rmode = FE_UPWARD; break;
   case FLOOR: rmode = FE_DOWNWARD; break;
+  case ROUND: rmode = FE_TOWARDZERO; break;
   default:    rmode = FE_TONEAREST; break;
   }
   __fesetround_inline_nocheck (rmode);
@@ -57,12 +59,24 @@ round_to_integer_float (enum round_mode mode, float x)
   set_fenv_mode (mode);
   if (x > 0.0)
     {
+      /* IEEE 1003.1 round function.  IEEE specifies "round to the nearest
+	 integer value, rounding halfway cases away from zero, regardless of
+	 the current rounding mode."  However PowerPC Architecture defines
+	 "Round to Nearest" as "Choose the best approximation. In case of a
+	 tie, choose the one that is even (least significant bit o).".
+	 So we can't use the PowerPC "Round to Nearest" mode. Instead we set
+	 "Round toward Zero" mode and round by adding +-0.5 before rounding
+	 to the integer value.  */
+      if (mode == ROUND)
+	r += 0.5f;
       r += 0x1p+23;
       r -= 0x1p+23;
       r = fabs (r);
     }
   else if (x < 0.0)
     {
+      if (mode == ROUND)
+	r -= 0.5f;
       r -= 0x1p+23;
       r += 0x1p+23;
       r = -fabs (r);
@@ -89,12 +103,16 @@ round_to_integer_double (enum round_mode mode, double x)
   set_fenv_mode (mode);
   if (x > 0.0)
     {
+      if (mode == ROUND)
+	r += 0.5;
       r += 0x1p+52;
       r -= 0x1p+52;
       r = fabs (r);
     }
   else if (x < 0.0)
     {
+      if (mode == ROUND)
+	r -= 0.5;
       r -= 0x1p+52;
       r += 0x1p+52;
       r = -fabs (r);
diff --git a/sysdeps/powerpc/fpu/s_round.c b/sysdeps/powerpc/fpu/s_round.c
new file mode 100644
index 0000000000..cd105567ef
--- /dev/null
+++ b/sysdeps/powerpc/fpu/s_round.c
@@ -0,0 +1,35 @@
+/* Largest integral value not greater than argument.  PowerPC version.
+   Copyright (C) 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 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/>.  */
+
+#define NO_MATH_REDIRECT
+#include <math.h>
+#include <libm-alias-double.h>
+#include <round_to_integer.h>
+
+double
+__round (double x)
+{
+#ifdef _ARCH_PWR5X
+  return __builtin_round (x);
+#else
+  return round_to_integer_double (ROUND, x);
+#endif
+}
+#ifndef __round
+libm_alias_double (__round, round)
+#endif
diff --git a/sysdeps/powerpc/fpu/s_roundf.c b/sysdeps/powerpc/fpu/s_roundf.c
new file mode 100644
index 0000000000..418062adba
--- /dev/null
+++ b/sysdeps/powerpc/fpu/s_roundf.c
@@ -0,0 +1,35 @@
+/* Smallest integral value not less than argument.  PowerPC version.
+   Copyright (C) 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 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/>.  */
+
+#define NO_MATH_REDIRECT
+#include <math.h>
+#include <libm-alias-float.h>
+#include <round_to_integer.h>
+
+float
+__roundf (float x)
+{
+#ifdef _ARCH_PWR5X
+  return __builtin_roundf (x);
+#else
+  return round_to_integer_float (ROUND, x);
+#endif
+}
+#ifndef __roundf
+libm_alias_float (__round, round)
+#endif