>From e5462c3304ef7f373bfb7c6a976dc25730412a7a Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Sun, 20 Jan 2019 23:48:18 +0100 Subject: [PATCH 5/6] log10l: Work around inaccurate implementation on NetBSD. * m4/log10l.m4 (gl_FUNC_LOG10L_WORKS): Add test for a certain accuracy. * lib/log10l.c: Comment out too simplistic override. * doc/posix-functions/log10l.texi: Mention the NetBSD bug. --- ChangeLog | 7 ++++ doc/posix-functions/log10l.texi | 4 ++ lib/log10l.c | 2 +- m4/log10l.m4 | 87 +++++++++++++++++++++++++++++++++-------- 4 files changed, 82 insertions(+), 18 deletions(-) diff --git a/ChangeLog b/ChangeLog index 98702e2..00516b2 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,12 @@ 2019-01-20 Bruno Haible + log10l: Work around inaccurate implementation on NetBSD. + * m4/log10l.m4 (gl_FUNC_LOG10L_WORKS): Add test for a certain accuracy. + * lib/log10l.c: Comment out too simplistic override. + * doc/posix-functions/log10l.texi: Mention the NetBSD bug. + +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. diff --git a/doc/posix-functions/log10l.texi b/doc/posix-functions/log10l.texi index b26a249..ac42644 100644 --- a/doc/posix-functions/log10l.texi +++ b/doc/posix-functions/log10l.texi @@ -26,6 +26,10 @@ IRIX 6.5. @item This function returns an unnormalized positive infinity for a positive infinite argument on some platforms: IRIX 6.5. 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/log10l.c b/lib/log10l.c index 765d485..4ac6085 100644 --- a/lib/log10l.c +++ b/lib/log10l.c @@ -27,7 +27,7 @@ log10l (long double x) return log10 (x); } -#elif HAVE_LOG10L +#elif 0 /* was: HAVE_LOG10L */ # include diff --git a/m4/log10l.m4 b/m4/log10l.m4 index af0afaf..80835f6 100644 --- a/m4/log10l.m4 +++ b/m4/log10l.m4 @@ -1,4 +1,4 @@ -# log10l.m4 serial 5 +# log10l.m4 serial 6 dnl Copyright (C) 2011-2019 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -60,6 +60,7 @@ dnl 0xFFF00000000000007FF0000000000000, should be dnl 0xFFF00000000000000000000000000000. dnl On AIX 5.1, log10l(-0.0L) is finite if it's not the first log10l call dnl in the program. +dnl On NetBSD 8.0, the result is accurate to only 16 digits. AC_DEFUN([gl_FUNC_LOG10L_WORKS], [ AC_REQUIRE([AC_PROG_CC]) @@ -68,36 +69,88 @@ AC_DEFUN([gl_FUNC_LOG10L_WORKS], [ AC_RUN_IFELSE( [AC_LANG_SOURCE([[ +#ifndef __NO_MATH_INLINES +# define __NO_MATH_INLINES 1 /* for glibc */ +#endif +#include #include -#ifndef log10l /* for AIX */ +/* 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 log10l /* for AIX */ extern #ifdef __cplusplus "C" #endif long double log10l (long double); -#endif -volatile long double x; -long double y; -int main () +static long double dummy (long double x) { return 0; } +volatile long double gx; +long double gy; +int main (int argc, char *argv[]) { + long double (* volatile my_log10l) (long double) = argc ? log10l : dummy; + int result = 0; /* Dummy call, to trigger the AIX 5.1 bug. */ - x = 0.6L; - y = log10l (x); + gx = 0.6L; + gy = log10l (gx); /* This test fails on AIX 5.1, IRIX 6.5, OSF/1 5.1. */ - x = -0.0L; - y = log10l (x); - if (!(y + y == y)) - return 1; - return 0; + { + gx = -0.0L; + gy = log10l (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 = 7.90097792256024576L; + long double err = (my_log10l (x) + my_log10l (1.0L / x)) * TWO_LDBL_MANT_DIG; + if (!(err >= -100.0L && err <= 100.0L)) + result |= 2; + } + return result; } ]])], [gl_cv_func_log10l_works=yes], [gl_cv_func_log10l_works=no], [case "$host_os" in - aix* | irix* | osf*) gl_cv_func_log10l_works="guessing no" ;; - # Guess yes on native Windows. - mingw*) gl_cv_func_log10l_works="guessing yes" ;; - *) gl_cv_func_log10l_works="guessing yes" ;; + # Guess yes on glibc systems. + *-gnu* | gnu*) gl_cv_func_log10l_works="guessing yes" ;; + # Guess yes on native Windows. + mingw*) gl_cv_func_log10l_works="guessing yes" ;; + # If we don't know, assume the worst. + *) gl_cv_func_log10l_works="guessing no" ;; esac ]) ]) -- 2.7.4