From e86cbc4644f41ea3a7b5c898790264e93191a49e Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Sun, 20 Jan 2019 21:45:29 +0100 Subject: [PATCH 1/6] exp2l: Work around inaccurate implementation on NetBSD. * m4/exp2l.m4 (gl_FUNC_EXP2L): Add test for a certain accuracy. * doc/posix-functions/exp2l.texi: Mention the NetBSD bug. --- ChangeLog | 6 +++ doc/posix-functions/exp2l.texi | 4 ++ m4/exp2l.m4 | 90 +++++++++++++++++++++++++++++++++++++++++- 3 files changed, 99 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index 6e02f8a..a8c6797 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,11 @@ 2019-01-20 Bruno Haible + exp2l: Work around inaccurate implementation on NetBSD. + * m4/exp2l.m4 (gl_FUNC_EXP2L): Add test for a certain accuracy. + * doc/posix-functions/exp2l.texi: Mention the NetBSD bug. + +2019-01-20 Bruno Haible + floor, floorl: Avoid autoconf warnings. * modules/floor (configure.ac): Use AC_REQUIRE. * modules/floorl (configure.ac): Likewise. diff --git a/doc/posix-functions/exp2l.texi b/doc/posix-functions/exp2l.texi index a0f7841..672b4de 100644 --- a/doc/posix-functions/exp2l.texi +++ b/doc/posix-functions/exp2l.texi @@ -14,6 +14,10 @@ FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, older IRIX @item This function is not declared on some platforms: IRIX 6.5. +@item +This function produces results which are accurate to only 16 digits on some +platforms: +NetBSD 8.0. @end itemize Portability problems fixed by Gnulib module @code{exp2l-ieee}: diff --git a/m4/exp2l.m4 b/m4/exp2l.m4 index 20630cc..8a065d9 100644 --- a/m4/exp2l.m4 +++ b/m4/exp2l.m4 @@ -1,4 +1,4 @@ -# exp2l.m4 serial 6 +# exp2l.m4 serial 7 dnl Copyright (C) 2010-2019 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -26,6 +26,94 @@ AC_DEFUN([gl_FUNC_EXP2L], dnl Also check whether it's declared. dnl IRIX 6.5 has exp2l() in libm but doesn't declare it in . AC_CHECK_DECL([exp2l], , [HAVE_DECL_EXP2L=0], [[#include ]]) + if test $REPLACE_EXP2L = 0; then + AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles + AC_CACHE_CHECK([whether exp2l works], + [gl_cv_func_exp2l_works], + [ + save_LIBS="$LIBS" + LIBS="$LIBS $EXP2L_LIBM" + AC_RUN_IFELSE( + [AC_LANG_SOURCE([[ +#ifndef __NO_MATH_INLINES +# define __NO_MATH_INLINES 1 /* for glibc */ +#endif +#include +#include +/* Override the values of , like done in float.in.h. */ +#if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__) +# undef LDBL_MANT_DIG +# define LDBL_MANT_DIG 64 +# undef LDBL_MIN_EXP +# define LDBL_MIN_EXP (-16381) +# undef LDBL_MAX_EXP +# define LDBL_MAX_EXP 16384 +#endif +#if defined __i386__ && (defined __FreeBSD__ || defined __DragonFly__) +# undef LDBL_MANT_DIG +# define LDBL_MANT_DIG 64 +# undef LDBL_MIN_EXP +# define LDBL_MIN_EXP (-16381) +# undef LDBL_MAX_EXP +# define LDBL_MAX_EXP 16384 +#endif +#if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__ +# undef LDBL_MIN_EXP +# define LDBL_MIN_EXP DBL_MIN_EXP +#endif +#if defined __sgi && (LDBL_MANT_DIG >= 106) +# undef LDBL_MANT_DIG +# define LDBL_MANT_DIG 106 +# if defined __GNUC__ +# undef LDBL_MIN_EXP +# define LDBL_MIN_EXP DBL_MIN_EXP +# endif +#endif +#undef exp2l +extern +#ifdef __cplusplus +"C" +#endif +long double exp2l (long double); +static long double dummy (long double x) { return 0; } +int main (int argc, char *argv[]) +{ + long double (* volatile my_exp2l) (long double) = argc ? exp2l : dummy; + int result = 0; + /* This test fails on NetBSD 8.0. */ + { + const long double TWO_LDBL_MANT_DIG = /* 2^LDBL_MANT_DIG */ + (long double) (1U << ((LDBL_MANT_DIG - 1) / 5)) + * (long double) (1U << ((LDBL_MANT_DIG - 1 + 1) / 5)) + * (long double) (1U << ((LDBL_MANT_DIG - 1 + 2) / 5)) + * (long double) (1U << ((LDBL_MANT_DIG - 1 + 3) / 5)) + * (long double) (1U << ((LDBL_MANT_DIG - 1 + 4) / 5)); + long double x = 11.358L; + long double err = (my_exp2l (x) * my_exp2l (- x) - 1.0L) * TWO_LDBL_MANT_DIG; + if (!(err >= -100.0L && err <= 100.0L)) + result |= 1; + } + return result; +} + ]])], + [gl_cv_func_exp2l_works=yes], + [gl_cv_func_exp2l_works=no], + [case "$host_os" in + # Guess yes on glibc systems. + *-gnu* | gnu*) gl_cv_func_exp2l_works="guessing yes" ;; + # Guess yes on native Windows. + mingw*) gl_cv_func_exp2l_works="guessing yes" ;; + # If we don't know, assume the worst. + *) gl_cv_func_exp2l_works="guessing no" ;; + esac + ]) + LIBS="$save_LIBS" + ]) + case "$gl_cv_func_exp2l_works" in + *yes) ;; + *) REPLACE_EXP2L=1 ;; + esac + fi m4_ifdef([gl_FUNC_EXP2L_IEEE], [ if test $gl_exp2l_required = ieee && test $REPLACE_EXP2L = 0; then AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles -- 2.7.4