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# ilogbl.m4 serial 6
dnl Copyright (C) 2010-2023 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_ILOGBL],
[
AC_REQUIRE([gl_MATH_H_DEFAULTS])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
AC_REQUIRE([gl_FUNC_ILOGB])
dnl Persuade glibc <math.h> to declare ilogbl().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether ilogbl() exists. Assume that ilogbl(), if it exists, is
dnl defined in the same library as ilogb().
save_LIBS="$LIBS"
LIBS="$LIBS $ILOGB_LIBM"
AC_CACHE_CHECK([for ilogbl],
[gl_cv_func_ilogbl],
[
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
int (*funcptr) (long double) = ilogbl;
long double x;]],
[[return (funcptr (x) % 2) == 0
|| (ilogbl (x) % 2) == 0;]])],
[gl_cv_func_ilogbl=yes],
[gl_cv_func_ilogbl=no])
])
LIBS="$save_LIBS"
if test $gl_cv_func_ilogbl = yes; then
ILOGBL_LIBM="$ILOGB_LIBM"
save_LIBS="$LIBS"
LIBS="$LIBS $ILOGBL_LIBM"
gl_FUNC_ILOGBL_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_ilogbl_works" in
*yes) ;;
*) REPLACE_ILOGBL=1 ;;
esac
else
HAVE_ILOGBL=0
fi
if test $HAVE_ILOGBL = 0 || test $REPLACE_ILOGBL = 1; then
dnl Find libraries needed to link lib/ilogbl.c.
if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
ILOGBL_LIBM="$ILOGB_LIBM"
else
AC_REQUIRE([gl_FUNC_FREXPL])
AC_REQUIRE([gl_FUNC_ISNANL])
ILOGBL_LIBM=
dnl Append $FREXPL_LIBM to ILOGBL_LIBM, avoiding gratuitous duplicates.
case " $ILOGBL_LIBM " in
*" $FREXPL_LIBM "*) ;;
*) ILOGBL_LIBM="$ILOGBL_LIBM $FREXPL_LIBM" ;;
esac
dnl Append $ISNANL_LIBM to ILOGBL_LIBM, avoiding gratuitous duplicates.
case " $ILOGBL_LIBM " in
*" $ISNANL_LIBM "*) ;;
*) ILOGBL_LIBM="$ILOGBL_LIBM $ISNANL_LIBM" ;;
esac
fi
fi
AC_SUBST([ILOGBL_LIBM])
])
dnl Test whether ilogbl() works.
dnl On Cygwin 2.9, ilogbl(0.0L) is wrong.
dnl On Cygwin 3.4.6, ilogbl(NaN) is wrong.
dnl On AIX 7.1 in 64-bit mode, ilogbl(2^(LDBL_MIN_EXP-1)) is wrong.
dnl On Haiku 2017, it returns i-2 instead of i-1 for values between
dnl ca. 2^-16444 and ca. 2^-16382.
AC_DEFUN([gl_FUNC_ILOGBL_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether ilogbl works], [gl_cv_func_ilogbl_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <float.h>
#include <math.h>
/* Override the values of <float.h>, like done in float.in.h. */
#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__)
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP (-16381)
#endif
#if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__)
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP (-16381)
#endif
#if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP DBL_MIN_EXP
#endif
#if defined __sgi && (LDBL_MANT_DIG >= 106)
# if defined __GNUC__
# undef LDBL_MIN_EXP
# define LDBL_MIN_EXP DBL_MIN_EXP
# endif
#endif
/* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the
runtime type conversion. */
#ifdef __sgi
static long double NaNl ()
{
double zero = 0.0;
return zero / zero;
}
#else
# define NaNl() (0.0L / 0.0L)
#endif
volatile long double x;
static int dummy (long double x) { return 0; }
int main (int argc, char *argv[])
{
int (* volatile my_ilogbl) (long double) = argc ? ilogbl : dummy;
int result = 0;
/* This test fails on Cygwin 2.9. */
{
x = 0.0L;
if (my_ilogbl (x) != FP_ILOGB0)
result |= 1;
}
/* This test fails on Cygwin 3.4.6. */
{
x = NaNl ();
if (my_ilogbl (x) != FP_ILOGBNAN)
result |= 2;
}
/* This test fails on AIX 7.1 in 64-bit mode. */
{
int i;
x = 0.5L;
for (i = LDBL_MIN_EXP - 1; i < 0; i++)
x = x * 0.5L;
if (x > 0.0L && my_ilogbl (x) != LDBL_MIN_EXP - 2)
result |= 4;
}
/* This test fails on Haiku 2017. */
{
int i;
for (i = 1, x = (long double)1.0; i >= LDBL_MIN_EXP-100 && x > (long double)0.0; i--, x *= (long double)0.5)
if (my_ilogbl (x) != i - 1)
{
result |= 8;
break;
}
}
return result;
}
]])],
[gl_cv_func_ilogbl_works=yes],
[gl_cv_func_ilogbl_works=no],
[case "$host_os" in
aix* | haiku*)
gl_cv_func_ilogbl_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_ilogbl_works="guessing yes" ;;
*) gl_cv_func_ilogbl_works="guessing yes" ;;
esac
])
])
])
|
