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.
1868599f8d