Commit e6c02ad4 authored by Bruno Haible's avatar Bruno Haible

Detect round() bug on NetBSD 3.0/x86.

parent 5c20ddee
2007-11-11 Bruno Haible <bruno@clisp.org>
* m4/round.m4 (gl_FUNC_ROUND): Test against NetBSD 3.0 bug.
* doc/functions/round.texi: Mention the NetBSD 3.0 bug.
2007-11-11 Bruno Haible <bruno@clisp.org>
* tests/test-argmatch.c (ARGMATCH_DIE): Undefine.
......@@ -11,6 +11,9 @@ Portability problems fixed by Gnulib:
@item
This function is missing on some platforms:
FreeBSD 5.2.1, OpenBSD 3.8, AIX 5.1, IRIX 6.5, OSF/1 4.0, Solaris 9, Interix 3.5.
@item
This functions returns a wrong result for x = 1/2 - 2^-54 on some platforms:
NetBSD 3.0.
@end itemize
Portability problems not fixed by Gnulib:
......
# round.m4 serial 4
# round.m4 serial 5
dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
......@@ -13,6 +13,44 @@ AC_DEFUN([gl_FUNC_ROUND],
if test "$ac_cv_have_decl_round" = yes; then
gl_CHECK_MATH_LIB([ROUND_LIBM], [x = round (x);])
fi
if test "$ac_cv_have_decl_round" = yes && test "$ROUND_LIBM" != missing; then
dnl Test whether round() produces correct results. On NetBSD 3.0, for
dnl x = 1/2 - 2^-54, the system's round() returns a wrong result.
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether round works], [gl_cv_func_round_works],
[
save_LIBS="$LIBS"
LIBS="$LIBS $ROUND_LIBM"
AC_TRY_RUN([
#include <float.h>
#include <math.h>
int main()
{
/* 2^DBL_MANT_DIG. */
static const double TWO_MANT_DIG =
/* Assume DBL_MANT_DIG <= 5 * 31.
Use the identity
n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */
(double) (1U << (DBL_MANT_DIG / 5))
* (double) (1U << ((DBL_MANT_DIG + 1) / 5))
* (double) (1U << ((DBL_MANT_DIG + 2) / 5))
* (double) (1U << ((DBL_MANT_DIG + 3) / 5))
* (double) (1U << ((DBL_MANT_DIG + 4) / 5));
volatile double x = 0.5 - 0.5 / TWO_MANT_DIG;
exit (x < 0.5 && round (x) != 0.0);
}], [gl_cv_func_round_works=yes], [gl_cv_func_round_works=no],
[case "$host_os" in
netbsd*) gl_cv_func_round_works="guessing no";;
*) gl_cv_func_round_works="guessing yes";;
esac
])
LIBS="$save_LIBS"
])
case "$gl_cv_func_round_works" in
*no) ROUND_LIBM=missing ;;
esac
fi
if test "$ac_cv_have_decl_round" != yes || test "$ROUND_LIBM" = missing; then
REPLACE_ROUND=1
AC_LIBOBJ([round])
......@@ -20,4 +58,5 @@ AC_DEFUN([gl_FUNC_ROUND],
gl_FUNC_CEIL_LIBS
ROUND_LIBM="$FLOOR_LIBM $CEIL_LIBM"
fi
AC_SUBST([ROUND_LIBM])])
AC_SUBST([ROUND_LIBM])
])
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