glibc/sysdeps/powerpc/bits/floatn.h
Gabriel F. T. Gomes 8466ee1cb7 float128: Add signbit alternative for old compilers
In math/math.h, __MATH_TG will expand signbit to __builtin_signbit*,
e.g.: __builtin_signbitf128, before GCC 6.  However, there has never
been a __builtin_signbitf128 in GCC and the type-generic builtin is
only available since GCC 6.  For older GCC, this patch defines
__builtin_signbitf128 to __signbitf128, so that the internal function
is used instead of the non-existent builtin.

This patch also changes the implementation of __signbitf128, because
it was reusing the implementation of __signbitl from ldbl-128, which
calls __builtin_signbitl.  Using the long double version of the
builtin is not correct on machines where _Float128 is ABI-distinct
from long double (i.e.: ia64, powerpc64le, x86, x86_84).  The new
implementation does not rely on builtins when being built with GCC
versions older than 6.0.

The new code does not currently affect powerpc64le builds, because
only GCC 6.2 fulfills the requirements from configure.  It might
affect powerpc64le builds if those requirements are backported to
older versions of the compiler.  The new code affects x86_64 builds,
since glibc is supposed to build correctly with older versions of GCC.

Tested for powerpc64le and x86_64.

	* include/math.h (__signbitf128): Define as hidden.
	* sysdeps/ieee754/float128/s_signbitf128.c (__signbitf128):
	Reimplement without builtins.
	* sysdeps/ia64/bits/floatn.h [!__GNUC_PREREQ (6, 0)]
	(__builtin_signbitf128): Define to __signbitf128.
	* sysdeps/powerpc/bits/floatn.h: Likewise.
	* sysdeps/x86/bits/floatn.h: Likewise.
2017-06-30 18:34:29 -03:00

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C

/* Macros to control TS 18661-3 glibc features on powerpc.
Copyright (C) 2017 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/>. */
#ifndef _BITS_FLOATN_H
#define _BITS_FLOATN_H
#include <features.h>
/* Defined to 1 if the current compiler invocation provides a
floating-point type with the IEEE 754 binary128 format, and this glibc
includes corresponding *f128 interfaces for it. */
#if defined _ARCH_PWR8 && defined __LITTLE_ENDIAN__ && (_CALL_ELF == 2) \
&& defined __FLOAT128__
# define __HAVE_FLOAT128 1
#else
# define __HAVE_FLOAT128 0
#endif
/* Defined to 1 if __HAVE_FLOAT128 is 1 and the type is ABI-distinct
from the default float, double and long double types in this glibc. */
#if __HAVE_FLOAT128
# define __HAVE_DISTINCT_FLOAT128 1
#else
# define __HAVE_DISTINCT_FLOAT128 0
#endif
/* Defined to concatenate the literal suffix to be used with _Float128
types, if __HAVE_FLOAT128 is 1. */
#if __HAVE_FLOAT128
# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
/* The literal suffix (f128) exist for powerpc only since GCC 7.0. */
# define __f128(x) x##q
# else
# define __f128(x) x##f128
# endif
#endif
/* Defined to a complex binary128 type if __HAVE_FLOAT128 is 1. */
#if __HAVE_FLOAT128
# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
/* Add a typedef for older GCC compilers which don't natively support
_Complex _Float128. */
typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__KC__)));
# define __CFLOAT128 __cfloat128
# else
# define __CFLOAT128 _Complex _Float128
# endif
#endif
/* The remaining of this file provides support for older compilers. */
#if __HAVE_FLOAT128
/* The type _Float128 exist for powerpc only since GCC 7.0. */
# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
typedef __float128 _Float128;
# endif
/* Builtin __builtin_huge_valf128 doesn't exist before GCC 7.0. */
# if !__GNUC_PREREQ (7, 0)
# define __builtin_huge_valf128() ((_Float128) __builtin_huge_val ())
# endif
/* The following builtins (suffixed with 'q') are available in GCC >= 6.2,
which is the minimum version required for float128 support on powerpc64le.
Since GCC 7.0 the builtins suffixed with f128 are also available, then
there is no need to redefined them. */
# if !__GNUC_PREREQ (7, 0)
# define __builtin_copysignf128 __builtin_copysignq
# define __builtin_fabsf128 __builtin_fabsq
# define __builtin_inff128 __builtin_infq
# define __builtin_nanf128 __builtin_nanq
# define __builtin_nansf128 __builtin_nansq
# endif
/* In math/math.h, __MATH_TG will expand signbit to __builtin_signbit*,
e.g.: __builtin_signbitf128, before GCC 6. However, there has never
been a __builtin_signbitf128 in GCC and the type-generic builtin is
only available since GCC 6. */
# if !__GNUC_PREREQ (6, 0)
# define __builtin_signbitf128 __signbitf128
# endif
#endif
#endif /* _BITS_FLOATN_H */