Mercurial > gnulib
changeset 40114:d871c219134f
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.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Sun, 20 Jan 2019 22:57:41 +0100 |
parents | 7ca21aacb634 |
children | d53c98a8c061 |
files | ChangeLog doc/posix-functions/logl.texi lib/logl.c m4/logl.m4 |
diffstat | 4 files changed, 87 insertions(+), 14 deletions(-) [+] |
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line diff
--- a/ChangeLog Sun Jan 20 22:28:37 2019 +0100 +++ b/ChangeLog Sun Jan 20 22:57:41 2019 +0100 @@ -1,3 +1,10 @@ +2019-01-20 Bruno Haible <bruno@clisp.org> + + 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 <bruno@clisp.org> expm1l: Work around inaccurate implementation on NetBSD.
--- a/doc/posix-functions/logl.texi Sun Jan 20 22:28:37 2019 +0100 +++ b/doc/posix-functions/logl.texi Sun Jan 20 22:57:41 2019 +0100 @@ -23,6 +23,10 @@ @item This function returns a wrong value for a minus zero argument on some platforms: OSF/1 5.1. +@item +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:
--- a/lib/logl.c Sun Jan 20 22:28:37 2019 +0100 +++ b/lib/logl.c Sun Jan 20 22:57:41 2019 +0100 @@ -26,7 +26,7 @@ return log (x); } -#elif HAVE_LOGL +#elif 0 /* was: HAVE_LOGL */ long double logl (long double x)
--- a/m4/logl.m4 Sun Jan 20 22:28:37 2019 +0100 +++ b/m4/logl.m4 Sun Jan 20 22:57:41 2019 +0100 @@ -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 @@ 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_RUN_IFELSE( [AC_LANG_SOURCE([[ +#ifndef __NO_MATH_INLINES +# define __NO_MATH_INLINES 1 /* for glibc */ +#endif +#include <float.h> #include <math.h> -volatile long double x; -long double y; -int main () +/* Override the values of <float.h>, 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 ]) ])