>From 27f3a1709d027b85bcf5ff91e604818978377af4 Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Sun, 20 Jan 2019 22:57:41 +0100 Subject: [PATCH 4/6] logl: Work around inaccurate implementation on NetBSD. * m4/logl.m4 (gl_FUNC_LOGL_WORKS): Add test for a certain accuracy. * lib/logl.c: Comment out unused code. * doc/posix-functions/logl.texi: Mention the NetBSD bug. --- ChangeLog | 7 ++++ doc/posix-functions/logl.texi | 4 ++ lib/logl.c | 2 +- m4/logl.m4 | 88 ++++++++++++++++++++++++++++++++++++------- 4 files changed, 87 insertions(+), 14 deletions(-) diff --git a/ChangeLog b/ChangeLog index 07f3cc4..98702e2 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,12 @@ 2019-01-20 Bruno Haible + logl: Work around inaccurate implementation on NetBSD. + * m4/logl.m4 (gl_FUNC_LOGL_WORKS): Add test for a certain accuracy. + * lib/logl.c: Comment out unused code. + * doc/posix-functions/logl.texi: Mention the NetBSD bug. + +2019-01-20 Bruno Haible + expm1l: Work around inaccurate implementation on NetBSD. * lib/math.in.h (expm1l): Test also REPLACE_EXPM1L. * m4/expm1l.m4 (gl_FUNC_EXPM1L): Add test for a certain accuracy. Set diff --git a/doc/posix-functions/logl.texi b/doc/posix-functions/logl.texi index 51e2081..a82c3af 100644 --- a/doc/posix-functions/logl.texi +++ b/doc/posix-functions/logl.texi @@ -23,6 +23,10 @@ glibc 2.7 on Linux/SPARC64. @item This function returns a wrong value for a minus zero argument on some platforms: OSF/1 5.1. address@hidden +This function produces results which are accurate to only 16 digits on some +platforms: +NetBSD 8.0. @end itemize Portability problems not fixed by Gnulib: diff --git a/lib/logl.c b/lib/logl.c index 07cc7aa..0e8162f 100644 --- a/lib/logl.c +++ b/lib/logl.c @@ -26,7 +26,7 @@ logl (long double x) return log (x); } -#elif HAVE_LOGL +#elif 0 /* was: HAVE_LOGL */ long double logl (long double x) diff --git a/m4/logl.m4 b/m4/logl.m4 index 12b7081..a3576cb 100644 --- a/m4/logl.m4 +++ b/m4/logl.m4 @@ -1,4 +1,4 @@ -# logl.m4 serial 10 +# logl.m4 serial 11 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, @@ -103,6 +103,7 @@ AC_DEFUN([gl_FUNC_LOGL], dnl Test whether logl() works. dnl On OSF/1 5.1, logl(-0.0L) is NaN. +dnl On NetBSD 8.0, the result is accurate to only 16 digits. AC_DEFUN([gl_FUNC_LOGL_WORKS], [ AC_REQUIRE([AC_PROG_CC]) @@ -111,25 +112,86 @@ AC_DEFUN([gl_FUNC_LOGL_WORKS], [ AC_RUN_IFELSE( [AC_LANG_SOURCE([[ +#ifndef __NO_MATH_INLINES +# define __NO_MATH_INLINES 1 /* for glibc */ +#endif +#include #include -volatile long double x; -long double y; -int main () +/* 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 logl +extern +#ifdef __cplusplus +"C" +#endif +long double logl (long double); +static long double dummy (long double x) { return 0; } +volatile long double gx; +long double gy; +int main (int argc, char *argv[]) { - x = -0.0L; - y = logl (x); - if (!(y + y == y)) - return 1; - return 0; + long double (* volatile my_logl) (long double) = argc ? logl : dummy; + int result = 0; + /* This test fails on OSF/1 5.1. */ + { + gx = -0.0L; + gy = logl (gx); + if (!(gy + gy == gy)) + result |= 1; + } + /* 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 = 16.981137113807045L; + long double err = (my_logl (x) + my_logl (1.0L / x)) * TWO_LDBL_MANT_DIG; + if (!(err >= -100.0L && err <= 100.0L)) + result |= 2; + } + + return result; } ]])], [gl_cv_func_logl_works=yes], [gl_cv_func_logl_works=no], [case "$host_os" in - osf*) gl_cv_func_logl_works="guessing no" ;; - # Guess yes on native Windows. - mingw*) gl_cv_func_logl_works="guessing yes" ;; - *) gl_cv_func_logl_works="guessing yes" ;; + # Guess yes on glibc systems. + *-gnu* | gnu*) gl_cv_func_logl_works="guessing yes" ;; + # Guess yes on native Windows. + mingw*) gl_cv_func_logl_works="guessing yes" ;; + # If we don't know, assume the worst. + *) gl_cv_func_logl_works="guessing no" ;; esac ]) ]) -- 2.7.4