gcc/config/math.m4
Jakub Jelinek 1868599f8d libgfortran: Provide some further math library fallbacks [PR94694]
The following patch provides some further math library fallbacks.
fmaf can be implemented using fma if available, fma and fmal can use
x * y + z as fallback, it is not perfect, but e.g. glibc on various arches
has been using that as fallback for many years,
and copysign/copysignl/fabs/fabsl can be implemented using corresponding
__builtin_* if we make sure that gcc expands it inline instead of using
a library call (these days it is expanded inline on most targets).

2020-04-22  Jakub Jelinek  <jakub@redhat.com>

	PR libfortran/94694
	PR libfortran/94586
	* configure.ac: Add math func checks for fmaf, fma and fmal.  Add
	HAVE_INLINE_BUILTIN_COPYSIGN check.
	* c99_protos.h (copysign, fmaf, fma, fmal): Provide fallback
	prototypes.
	(HAVE_COPYSIGN, HAVE_FMAF, HAVE_FMA, HAVE_FMAL): Define if not
	defined and fallback version is provided.
	* intrinsics/c99_functions.c (copysign, fmaf, fma, fmal): Provide
	fallback implementations if possible
	* configure: Regenerated.
	* config.h.in: Regenerated.

	* math.m4 (GCC_CHECK_MATH_INLINE_BUILTIN_FALLBACK1,
	GCC_CHECK_MATH_INLINE_BUILTIN_FALLBACK2): New.
2020-04-22 21:34:19 +02:00

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dnl GCC_CHECK_LIBM
dnl
dnl Check whether -lm is available. This is a pre-requisite for
dnl GCC_CHECK_MATH_FUNC so that it will link with -lm.
AC_DEFUN([GCC_CHECK_LIBM],
[AC_CHECK_LIB([m],[sin])])
dnl GCC_CHECK_MATH_HEADERS
dnl
dnl Check for math.h and complex.h. This is a pre-requisite for
dnl GCC_CHECK_MATH_FUNC so that it includes the right headers.
dnl (Some systems, such as AIX or OpenVMS may define macro for math
dnl functions).
AC_DEFUN([GCC_CHECK_MATH_HEADERS],
[AC_CHECK_HEADERS_ONCE(math.h complex.h)])
dnl GCC_CHECK_MATH_FUNC([name])
dnl
dnl Check whether math function NAME is available on the system (by compiling
dnl and linking a C program) and run define HAVE_name on success.
dnl
dnl Note that OpenVMS system insists on including complex.h before math.h
AC_DEFUN([GCC_CHECK_MATH_FUNC],
[
AC_REQUIRE([GCC_CHECK_LIBM])
AC_REQUIRE([GCC_CHECK_MATH_HEADERS])
AC_CACHE_CHECK([for $1], [gcc_cv_math_func_$1],
[AC_LINK_IFELSE([AC_LANG_SOURCE([
#ifdef HAVE_COMPLEX_H
#include <complex.h>
#endif
#ifdef HAVE_MATH_H
#include <math.h>
#endif
int (*ptr)() = (int (*)())$1;
int
main ()
{
return 0;
}
])],
[gcc_cv_math_func_$1=yes],
[gcc_cv_math_func_$1=no])])
if test $gcc_cv_math_func_$1 = yes; then
AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_$1),[1],
[Define to 1 if you have the `$1' function.])
fi
])
dnl GCC_CHECK_MATH_INLINE_BUILTIN_FALLBACK1([name], [type])
dnl
dnl Check if math function NAME fallback for function with single
dnl TYPE argument and TYPE result can be implemented using
dnl __builtin_NAME expanded inline without needing unavailable math
dnl library function.
AC_DEFUN([GCC_CHECK_MATH_INLINE_BUILTIN_FALLBACK1],
[
AC_REQUIRE([GCC_CHECK_LIBM])
if test $gcc_cv_math_func_$1 = no; then
AC_CACHE_CHECK([for inline __builtin_$1], [gcc_cv_math_inline_builtin_$1],
[AC_LINK_IFELSE([AC_LANG_SOURCE([
$2
$1_fallback ($2 x)
{
return __builtin_$1 (x);
}
int
main ()
{
return 0;
}
])],
[gcc_cv_math_inline_builtin_$1=yes],
[gcc_cv_math_inline_builtin_$1=no])])
if test $gcc_cv_math_inline_builtin_$1 = yes; then
AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_INLINE_BUILTIN_$1),[1],
[Define to 1 if `__builtin_$1' is expanded inline.])
fi
fi])
dnl GCC_CHECK_MATH_INLINE_BUILTIN_FALLBACK2([name], [type])
dnl
dnl Check if math function NAME fallback for function with two
dnl TYPE arguments and TYPE result can be implemented using
dnl __builtin_NAME expanded inline without needing unavailable math
dnl library function.
AC_DEFUN([GCC_CHECK_MATH_INLINE_BUILTIN_FALLBACK2],
[
AC_REQUIRE([GCC_CHECK_LIBM])
if test $gcc_cv_math_func_$1 = no; then
AC_CACHE_CHECK([for inline __builtin_$1], [gcc_cv_math_inline_builtin_$1],
[AC_LINK_IFELSE([AC_LANG_SOURCE([
$2
$1_fallback ($2 x, $2 y)
{
return __builtin_$1 (x, y);
}
int
main ()
{
return 0;
}
])],
[gcc_cv_math_inline_builtin_$1=yes],
[gcc_cv_math_inline_builtin_$1=no])])
if test $gcc_cv_math_inline_builtin_$1 = yes; then
AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_INLINE_BUILTIN_$1),[1],
[Define to 1 if `__builtin_$1' is expanded inline.])
fi
fi])