On Linux/ia64 (RHEL 5.11, a glibc 2.5 system), I see this test failure:
../../gltests/test-isfinite.c:174: assertion '!isfinite (m.value)' failed
FAIL test-isfinite (exit status: 134)
It's a bug in the isfinite() macro from glibc. From 2008-04-27 to 2015-02-21,
this bug was worked around, due to the configure test
checking whether isfinite(long double) works... no
But since 2015-02-21, this configure test produces
checking whether isfinite(long double) works... yes
The patch below fixes it, by strengthening the configure test, so that it
again produces
checking whether isfinite(long double) works... no
For this purpose, it uses a value that gdb prints as
{word = {0, 1073741825, 327679, 536870912}, value = -nan(0x4000000100000000)}
2023-10-08 Bruno Haible <br...@clisp.org>
isfinite: Work around a bug with 'long double' in glibc 2.5/ia64.
* m4/isfinite.m4 (gl_ISFINITEL_WORKS): Require
gl_LONG_DOUBLE_EXPONENT_LOCATION. Test also another NaN value.
* modules/isfinite (Files): Add m4/exponentl.m4.
* doc/posix-functions/isfinite.texi: Mention also a 'long double'
problem on ia64.
diff --git a/doc/posix-functions/isfinite.texi
b/doc/posix-functions/isfinite.texi
index d6ea43f818..8278c9449a 100644
--- a/doc/posix-functions/isfinite.texi
+++ b/doc/posix-functions/isfinite.texi
@@ -12,9 +12,9 @@
This macro is missing on some platforms:
macOS 11.1, OpenBSD 6.7, AIX 5.1, IRIX 6.5, Solaris 11.4.
@item
-This macro incorrectly yields true for some @samp{double} arguments, on some
-platforms:
-Linux/ia64 (signalling NaNs).
+This macro incorrectly yields true for some @samp{double} and for some
+@samp{long double} arguments, on some platforms:
+Linux/ia64 (NaNs).
@end itemize
Portability problems not fixed by Gnulib:
diff --git a/m4/isfinite.m4 b/m4/isfinite.m4
index 6170890d25..47e945a0ce 100644
--- a/m4/isfinite.m4
+++ b/m4/isfinite.m4
@@ -1,4 +1,4 @@
-# isfinite.m4 serial 18
+# isfinite.m4 serial 19
dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -46,6 +46,7 @@ AC_DEFUN([gl_ISFINITEL_WORKS]
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([gl_BIGENDIAN])
+ AC_REQUIRE([gl_LONG_DOUBLE_EXPONENT_LOCATION])
AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether isfinite(long double) works],
[gl_cv_func_isfinitel_works],
@@ -87,6 +88,31 @@ AC_DEFUN([gl_ISFINITEL_WORKS]
m.word[i] |= 1;
if (isfinite (m.value))
result |= 1;
+
+#if defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
+ /* Another NaN, more precisely crafted. */
+ m.value = NaNl ();
+ #if defined __powerpc__ && LDBL_MANT_DIG == 106
+ /* This is PowerPC "double double", a pair of two doubles. Inf and NaN
are
+ represented as the corresponding 64-bit IEEE values in the first
double;
+ the second is ignored. Manipulate only the first double. */
+ #define HNWORDS \
+ ((sizeof (double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
+ #else
+ #define HNWORDS NWORDS
+ #endif
+ #if LDBL_EXPBIT0_BIT > 0
+ m.word[LDBL_EXPBIT0_WORD] ^= (unsigned int) 1 << (LDBL_EXPBIT0_BIT - 1);
+ #else
+ m.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD < HNWORDS / 2 ? 1 : - 1)]
+ ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
+ #endif
+ m.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD < HNWORDS / 2 ? 1 : - 1)]
+ |= (unsigned int) 1 << LDBL_EXPBIT0_BIT;
+ #undef HNWORDS
+ if (isfinite (m.value))
+ result |= 1;
+#endif
}
#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined
_M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
diff --git a/modules/isfinite b/modules/isfinite
index 9933109cb0..0e801457bd 100644
--- a/modules/isfinite
+++ b/modules/isfinite
@@ -5,6 +5,7 @@ Files:
lib/isfinite.c
m4/isfinite.m4
m4/check-math-lib.m4
+m4/exponentl.m4
Depends-on:
math
