> > FreeBSD 6.4: > > > > test-isinf.c:151: assertion failed > > Abort trap (core dumped) > > FAIL: test-isinf > > This test failure occurs because lib/isinf.c relies on LDBL_MAX, and on > FreeBSD/x86, LDBL_MAX is Infinity. Ouch.
We had known about this bug, see <http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00118.html>, but not added a workaround. The bug on FreeBSD/x86 is that the compiler thinks that 'long double's have 53 bits of precision, but they really have 64 bits of precision. When LDBL_MAX is defined to 0x0.ffffffffffffffffp16384L, gcc converts it to Infinity. Whereas when LDBL_MAX is defined to 0x0.fffffffffffff8p16384L, it is possible to multiply it with (1 + 2^-54) or so, and get finite 'long double' values that are greater than LDBL_MAX. What can we do? The only workaround that I found (and that also disables GCC optimizations) is to define LDBL_MAX as a variable in a separate file. On AIX 7.1 with gcc 4.2 - a platform with a "double double" representation for 'long double' - the situation is similar: The real LDBL_MAX value is { 0x7FEFFFFF, 0xFFFFFFFF, 0x7C8FFFFF, 0xFFFFFFFF }, but the largest value that GCC allows us to define through a constant expression is { 0x7FEFFFFF, 0xFFFFFFFF, 0x7C8FFFFF, 0xFFFFFFFE }. Here too the fix is to define LDBL_MAX externally. On IRIX 6.5 - another platform with a "double double" representation for 'long double' - the situation is simpler. The cc compiler gets LDBL_MANT_DIG wrong, and gcc gets LDBL_MIN_EXP, LDBL_MIN, LDBL_EPSILON wrong. I'm applying these fixes. Unfortunately, it attaches an AC_LIBOBJ to a header file, and unfortunately LDBL_MAX is not a constant expression any more on all platforms. But that's the best we can get. 2011-06-20 Bruno Haible <br...@clisp.org> float: Work around <float.h> bugs on FreeBSD/x86, AIX with GCC, IRIX. * lib/float.in.h: Add workarounds for FreeBSD/x86, AIX with GCC, IRIX. * lib/float.c: New file. * m4/float_h.m4 (gl_FLOAT_H): Also handle FreeBSD, AIX, IRIX. Set REPLACE_FLOAT_LDBL. * modules/float (Files): Add lib/float.c. (configure.ac): Invoke AC_LIBOBJ. * doc/posix-headers/float.texi: Mention problems on FreeBSD, AIX, IRIX. ================================= lib/float.c ================================= /* Auxiliary definitions for <float.h>. Copyright (C) 2011 Free Software Foundation, Inc. Written by Bruno Haible <br...@clisp.org>, 2011. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <config.h> /* Specification. */ #include <float.h> #if (defined _ARCH_PPC || defined _POWER) && defined _AIX && (LDBL_MANT_DIG == 106) && defined __GNUC__ const union gl_long_double_union gl_LDBL_MAX = { { DBL_MAX, DBL_MAX / (double)134217728UL / (double)134217728UL } }; #elif defined __i386__ const union gl_long_double_union gl_LDBL_MAX = { { 0xFFFFFFFF, 0xFFFFFFFF, 32766 } }; #else /* This declaration is solely to ensure that after preprocessing this file is never empty. */ typedef int dummy; #endif =============================================================================== --- doc/posix-headers/float.texi.orig Mon Jun 20 12:33:40 2011 +++ doc/posix-headers/float.texi Mon Jun 20 12:33:23 2011 @@ -12,6 +12,10 @@ On OpenBSD 4.0, MirBSD 10, and BeOS, they are the same as the values of the @code{DBL_*} macros, although @samp{long double} is a larger type than @samp{double}. +On FreeBSD/x86 6.4, they represent the incorrect 53-bit precision assumptions +in the compiler, not the real 64-bit precision at runtime. +On AIX 7.1 with GCC 4.2 and on IRIX 6.5, they don't reflect the +``double double'' representation of @code{long double} correctly. @end itemize Portability problems not fixed by Gnulib: --- lib/float.in.h.orig Mon Jun 20 12:33:40 2011 +++ lib/float.in.h Mon Jun 20 12:11:55 2011 @@ -29,6 +29,7 @@ #define _@GUARD_PREFIX@_FLOAT_H /* 'long double' properties. */ + #if defined __i386__ && (defined __BEOS__ || defined __OpenBSD__) /* Number of mantissa units, in base FLT_RADIX. */ # undef LDBL_MANT_DIG @@ -59,5 +60,115 @@ # define LDBL_MAX_10_EXP 4932 #endif +/* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of + precision in the compiler but 64 bits of precision at runtime. See + <http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00063.html>. */ +#if defined __i386__ && defined __FreeBSD__ +/* Number of mantissa units, in base FLT_RADIX. */ +# undef LDBL_MANT_DIG +# define LDBL_MANT_DIG 64 +/* Number of decimal digits that is sufficient for representing a number. */ +# undef LDBL_DIG +# define LDBL_DIG 18 +/* x-1 where x is the smallest representable number > 1. */ +# undef LDBL_EPSILON +# define LDBL_EPSILON 1.084202172485504434007452800869941711426e-19L /* 2^-63 */ +/* Minimum e such that FLT_RADIX^(e-1) is a normalized number. */ +# undef LDBL_MIN_EXP +# define LDBL_MIN_EXP (-16381) +/* Maximum e such that FLT_RADIX^(e-1) is a representable finite number. */ +# undef LDBL_MAX_EXP +# define LDBL_MAX_EXP 16384 +/* Minimum positive normalized number. */ +# undef LDBL_MIN +# define LDBL_MIN 3.3621031431120935E-4932L /* = 0x1p-16382L */ +/* Maximum representable finite number. */ +# undef LDBL_MAX +/* LDBL_MAX is represented as { 0xFFFFFFFF, 0xFFFFFFFF, 32766 }. + But the largest literal that GCC allows us to write is + 0x0.fffffffffffff8p16384L = { 0xFFFFF800, 0xFFFFFFFF, 32766 }. + So, define it like this through a reference to an external variable + + const unsigned int LDBL_MAX[3] = { 0xFFFFFFFF, 0xFFFFFFFF, 32766 }; + extern const long double LDBL_MAX; + + Unfortunately, this is not a constant expression. */ +union gl_long_double_union + { + struct { unsigned int lo; unsigned int hi; unsigned int exponent; } xd; + long double ld; + }; +extern const union gl_long_double_union gl_LDBL_MAX; +# define LDBL_MAX (gl_LDBL_MAX.ld) +/* Minimum e such that 10^e is in the range of normalized numbers. */ +# undef LDBL_MIN_10_EXP +# define LDBL_MIN_10_EXP (-4931) +/* Maximum e such that 10^e is in the range of representable finite numbers. */ +# undef LDBL_MAX_10_EXP +# define LDBL_MAX_10_EXP 4932 +#endif + +/* On AIX 7.1 with gcc 4.2, the values of LDBL_MIN_EXP, LDBL_MIN, LDBL_MAX are + wrong. */ +#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 +# undef LDBL_MIN_10_EXP +# define LDBL_MIN_10_EXP DBL_MIN_10_EXP +# undef LDBL_MIN +# define LDBL_MIN 2.22507385850720138309023271733240406422e-308L /* DBL_MIN = 2^-1022 */ +# undef LDBL_MAX +/* LDBL_MAX is represented as { 0x7FEFFFFF, 0xFFFFFFFF, 0x7C8FFFFF, 0xFFFFFFFF }. + It is not easy to define: + #define LDBL_MAX 1.79769313486231580793728971405302307166e308L + is too small, whereas + #define LDBL_MAX 1.79769313486231580793728971405302307167e308L + is too large. Apparently a bug in GCC decimal-to-binary conversion. + Also, I can't get values larger than + #define LDBL63 ((long double) (1ULL << 63)) + #define LDBL882 (LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63) + #define LDBL945 (LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63) + #define LDBL1008 (LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63 * LDBL63) + #define LDBL_MAX (LDBL1008 * 65535.0L + LDBL945 * (long double) 9223372036821221375ULL + LDBL882 * (long double) 4611686018427387904ULL) + which is represented as { 0x7FEFFFFF, 0xFFFFFFFF, 0x7C8FFFFF, 0xF8000000 }. + So, define it like this through a reference to an external variable + + const double LDBL_MAX[2] = { DBL_MAX, DBL_MAX / (double)134217728UL / (double)134217728UL }; + extern const long double LDBL_MAX; + + or through a pointer cast + + #define LDBL_MAX \ + (*(const long double *) (double[]) { DBL_MAX, DBL_MAX / (double)134217728UL / (double)134217728UL }) + + Unfortunately, this is not a constant expression, and the latter expression + does not work well when GCC is optimizing.. */ +union gl_long_double_union + { + struct { double hi; double lo; } dd; + long double ld; + }; +extern const union gl_long_double_union gl_LDBL_MAX; +# define LDBL_MAX (gl_LDBL_MAX.ld) +#endif + +/* On IRIX 6.5, with cc, the value of LDBL_MANT_DIG is wrong. + On IRIX 6.5, with gcc 4.2, the values of LDBL_MIN_EXP, LDBL_MIN, LDBL_EPSILON + are wrong. */ +#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 +# undef LDBL_MIN_10_EXP +# define LDBL_MIN_10_EXP DBL_MIN_10_EXP +# undef LDBL_MIN +# define LDBL_MIN 2.22507385850720138309023271733240406422e-308L /* DBL_MIN = 2^-1022 */ +# undef LDBL_EPSILON +# define LDBL_EPSILON 2.46519032881566189191165176650870696773e-32L /* 2^-105 */ +# endif +#endif + #endif /* _@GUARD_PREFIX@_FLOAT_H */ #endif /* _@GUARD_PREFIX@_FLOAT_H */ --- m4/float_h.m4.orig Mon Jun 20 12:33:40 2011 +++ m4/float_h.m4 Mon Jun 20 11:41:05 2011 @@ -1,4 +1,4 @@ -# float_h.m4 serial 6 +# float_h.m4 serial 7 dnl Copyright (C) 2007, 2009-2011 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -9,12 +9,41 @@ AC_REQUIRE([AC_PROG_CC]) AC_REQUIRE([AC_CANONICAL_HOST]) FLOAT_H= + REPLACE_FLOAT_LDBL=0 case "$host_os" in - beos* | openbsd* | mirbsd*) + aix* | beos* | openbsd* | mirbsd* | irix*) FLOAT_H=float.h - gl_NEXT_HEADERS([float.h]) + ;; + freebsd*) + case "$host_cpu" in +changequote(,)dnl + i[34567]86 ) +changequote([,])dnl + FLOAT_H=float.h + ;; + x86_64 ) + # On x86_64 systems, the C compiler may still be generating + # 32-bit code. + AC_EGREP_CPP([yes], + [#if defined __LP64__ || defined __x86_64__ || defined __amd64__ + yes + #endif], + [], + [FLOAT_H=float.h]) + ;; + esac + ;; + esac + case "$host_os" in + aix* | freebsd*) + if test -n "$FLOAT_H"; then + REPLACE_FLOAT_LDBL=1 + fi ;; esac + if test -n "$FLOAT_H"; then + gl_NEXT_HEADERS([float.h]) + fi AC_SUBST([FLOAT_H]) AM_CONDITIONAL([GL_GENERATE_FLOAT_H], [test -n "$FLOAT_H"]) ]) --- modules/float.orig Mon Jun 20 12:33:40 2011 +++ modules/float Mon Jun 20 02:23:42 2011 @@ -3,6 +3,7 @@ Files: lib/float.in.h +lib/float.c m4/float_h.m4 Depends-on: @@ -10,6 +11,9 @@ configure.ac: gl_FLOAT_H +if test $REPLACE_FLOAT_LDBL = 1; then + AC_LIBOBJ([float]) +fi Makefile.am: BUILT_SOURCES += $(FLOAT_H) -- In memoriam Neda Agha-Soltan <http://en.wikipedia.org/wiki/Neda_Agha-Soltan>
