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# fabsl.m4 serial 3
dnl Copyright (C) 2011-2018 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_FUNC_FABSL],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
dnl Persuade glibc <math.h> to declare fabsl().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Determine FABSL_LIBM.
gl_MATHFUNC([fabsl], [long double], [(long double)])
if test $gl_cv_func_fabsl_no_libm = yes \
|| test $gl_cv_func_fabsl_in_libm = yes; then
save_LIBS="$LIBS"
LIBS="$LIBS $FABSL_LIBM"
gl_FUNC_FABSL_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_fabsl_works" in
*yes) ;;
*) REPLACE_FABSL=1 ;;
esac
else
HAVE_FABSL=0
fi
if test $HAVE_FABSL = 0 || test $REPLACE_FABSL = 1; then
dnl Find libraries needed to link lib/fabsl.c.
if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
AC_REQUIRE([gl_FUNC_FABS])
FABSL_LIBM="$FABS_LIBM"
else
FABSL_LIBM=
fi
fi
AC_SUBST([FABSL_LIBM])
])
dnl Test whether fabsl() works on a minus zero.
dnl On IRIX 6.5, with gcc 4.2.4 and without -fno-builtin-fabsl, the value is a
dnl minus zero rather than a positive zero.
AC_DEFUN([gl_FUNC_FABSL_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether fabsl works], [gl_cv_func_fabsl_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <float.h>
#include <math.h>
#include <string.h>
volatile long double x;
long double y;
long double zero = 0.0L;
int main ()
{
x = - (LDBL_MIN * LDBL_MIN * LDBL_MIN);
y = fabsl (x);
return (memcmp (&y, &zero, sizeof y) != 0);
}
]])],
[gl_cv_func_fabsl_works=yes],
[gl_cv_func_fabsl_works=no],
[case "$host_os" in
irix*) gl_cv_func_fabsl_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_fabsl_works="guessing yes" ;;
*) gl_cv_func_fabsl_works="guessing yes" ;;
esac
])
])
])
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