-# isnanf.m4 serial 1
-dnl Copyright (C) 2007 Free Software Foundation, Inc.
+# isnanf.m4 serial 10
+dnl Copyright (C) 2007-2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
+dnl Check how to get or define isnanf().
+
+AC_DEFUN([gl_FUNC_ISNANF],
+[
+ AC_REQUIRE([gl_MATH_H_DEFAULTS])
+ ISNANF_LIBM=
+ gl_HAVE_ISNANF_NO_LIBM
+ if test $gl_cv_func_isnanf_no_libm = no; then
+ gl_HAVE_ISNANF_IN_LIBM
+ if test $gl_cv_func_isnanf_in_libm = yes; then
+ ISNANF_LIBM=-lm
+ fi
+ fi
+ if test $gl_cv_func_isnanf_no_libm = yes \
+ || test $gl_cv_func_isnanf_in_libm = yes; then
+ save_LIBS="$LIBS"
+ LIBS="$LIBS $ISNANF_LIBM"
+ gl_ISNANF_WORKS
+ LIBS="$save_LIBS"
+ case "$gl_cv_func_isnanf_works" in
+ *yes) gl_func_isnanf=yes ;;
+ *) gl_func_isnanf=no; ISNANF_LIBM= ;;
+ esac
+ else
+ gl_func_isnanf=no
+ fi
+ if test $gl_func_isnanf != yes; then
+ HAVE_ISNANF=0
+ gl_BUILD_ISNANF
+ fi
+ AC_SUBST([ISNANF_LIBM])
+])
+
dnl Check how to get or define isnanf() without linking with libm.
AC_DEFUN([gl_FUNC_ISNANF_NO_LIBM],
[
gl_HAVE_ISNANF_NO_LIBM
if test $gl_cv_func_isnanf_no_libm = yes; then
- AC_DEFINE([HAVE_ISNANF_IN_LIBC], 1,
+ gl_ISNANF_WORKS
+ fi
+ if test $gl_cv_func_isnanf_no_libm = yes \
+ && { case "$gl_cv_func_isnanf_works" in
+ *yes) true;;
+ *) false;;
+ esac
+ }; then
+ AC_DEFINE([HAVE_ISNANF_IN_LIBC], [1],
[Define if the isnan(float) function is available in libc.])
else
- AC_LIBOBJ([isnanf])
- gl_FLOAT_EXPONENT_LOCATION
+ gl_BUILD_ISNANF
fi
])
+dnl Pull in replacement isnanf definition. It does not need -lm.
+AC_DEFUN([gl_BUILD_ISNANF],
+[
+ AC_LIBOBJ([isnanf])
+ gl_FLOAT_EXPONENT_LOCATION
+])
+
dnl Test whether isnanf() can be used without libm.
AC_DEFUN([gl_HAVE_ISNANF_NO_LIBM],
[
[gl_cv_func_isnanf_no_libm],
[
AC_TRY_LINK([#include <math.h>
- #ifdef isnan
+ #if __GNUC__ >= 4
+ # undef isnanf
+ # define isnanf(x) __builtin_isnanf ((float)(x))
+ #elif defined isnan
# undef isnanf
# define isnanf(x) isnan ((float)(x))
#endif
])
])
-AC_DEFUN([gl_FLOAT_EXPONENT_LOCATION],
+dnl Test whether isnanf() can be used with libm.
+AC_DEFUN([gl_HAVE_ISNANF_IN_LIBM],
+[
+ AC_CACHE_CHECK([whether isnan(float) can be used with libm],
+ [gl_cv_func_isnanf_in_libm],
+ [
+ save_LIBS="$LIBS"
+ LIBS="$LIBS -lm"
+ AC_TRY_LINK([#include <math.h>
+ #if __GNUC__ >= 4
+ # undef isnanf
+ # define isnanf(x) __builtin_isnanf ((float)(x))
+ #elif defined isnan
+ # undef isnanf
+ # define isnanf(x) isnan ((float)(x))
+ #endif
+ float x;],
+ [return isnanf (x);],
+ [gl_cv_func_isnanf_in_libm=yes],
+ [gl_cv_func_isnanf_in_libm=no])
+ LIBS="$save_LIBS"
+ ])
+])
+
+dnl Test whether isnanf() rejects Infinity (this fails on Solaris 2.5.1),
+dnl recognizes a NaN (this fails on IRIX 6.5 with cc), and recognizes a NaN
+dnl with in-memory representation 0x7fbfffff (this fails on IRIX 6.5).
+AC_DEFUN([gl_ISNANF_WORKS],
[
- AC_CACHE_CHECK([where to find the exponent in a 'float'],
- [gl_cv_cc_float_expbit0],
+ AC_REQUIRE([AC_PROG_CC])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_REQUIRE([gl_FLOAT_EXPONENT_LOCATION])
+ AC_CACHE_CHECK([whether isnan(float) works], [gl_cv_func_isnanf_works],
[
AC_TRY_RUN([
-#include <float.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <string.h>
+#include <math.h>
+#if __GNUC__ >= 4
+# undef isnanf
+# define isnanf(x) __builtin_isnanf ((float)(x))
+#elif defined isnan
+# undef isnanf
+# define isnanf(x) isnan ((float)(x))
+#endif
+/* The Compaq (ex-DEC) C 6.4 compiler chokes on the expression 0.0 / 0.0. */
+#ifdef __DECC
+static float
+NaN ()
+{
+ static float zero = 0.0f;
+ return zero / zero;
+}
+#else
+# define NaN() (0.0f / 0.0f)
+#endif
#define NWORDS \
((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
-typedef union { float value; unsigned int word[NWORDS]; } memory_float;
-static unsigned int ored_words[NWORDS];
-static unsigned int anded_words[NWORDS];
-static void add_to_ored_words (float x)
+typedef union { unsigned int word[NWORDS]; float value; } memory_float;
+int main()
{
memory_float m;
- size_t i;
- /* Clear it first, in case
- sizeof (float) < sizeof (memory_float). */
- memset (&m, 0, sizeof (memory_float));
- m.value = x;
- for (i = 0; i < NWORDS; i++)
- {
- ored_words[i] |= m.word[i];
- anded_words[i] &= m.word[i];
- }
-}
-int main ()
-{
- size_t j;
- FILE *fp = fopen ("conftest.out", "w");
- if (fp == NULL)
+
+ if (isnanf (1.0f / 0.0f))
return 1;
- for (j = 0; j < NWORDS; j++)
- anded_words[j] = ~ (unsigned int) 0;
- add_to_ored_words (0.25f);
- add_to_ored_words (0.5f);
- add_to_ored_words (1.0f);
- add_to_ored_words (2.0f);
- add_to_ored_words (4.0f);
- /* Remove bits that are common (e.g. if representation of the first mantissa
- bit is explicit). */
- for (j = 0; j < NWORDS; j++)
- ored_words[j] &= ~anded_words[j];
- /* Now find the nonzero word. */
- for (j = 0; j < NWORDS; j++)
- if (ored_words[j] != 0)
- break;
- if (j < NWORDS)
+
+ if (!isnanf (NaN ()))
+ return 1;
+
+#if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
+ /* The isnanf function should be immune against changes in the sign bit and
+ in the mantissa bits. The xor operation twiddles a bit that can only be
+ a sign bit or a mantissa bit. */
+ if (FLT_EXPBIT0_WORD == 0 && FLT_EXPBIT0_BIT > 0)
{
- size_t i;
- for (i = j + 1; i < NWORDS; i++)
- if (ored_words[i] != 0)
- {
- fprintf (fp, "unknown");
- return (fclose (fp) != 0);
- }
- for (i = 0; ; i++)
- if ((ored_words[j] >> i) & 1)
- {
- fprintf (fp, "word %d bit %d", (int) j, (int) i);
- return (fclose (fp) != 0);
- }
+ m.value = NaN ();
+ /* Set the bits below the exponent to 01111...111. */
+ m.word[0] &= -1U << FLT_EXPBIT0_BIT;
+ m.word[0] |= 1U << (FLT_EXPBIT0_BIT - 1) - 1;
+ if (!isnanf (m.value))
+ return 1;
}
- fprintf (fp, "unknown");
- return (fclose (fp) != 0);
-}
- ],
- [gl_cv_cc_float_expbit0=`cat conftest.out`],
- [gl_cv_cc_float_expbit0="unknown"],
- [gl_cv_cc_double_expbit0="word 0 bit 23"])
- rm -f conftest.out
+#endif
+
+ return 0;
+}], [gl_cv_func_isnanf_works=yes], [gl_cv_func_isnanf_works=no],
+ [case "$host_os" in
+ irix* | solaris*) gl_cv_func_isnanf_works="guessing no";;
+ *) gl_cv_func_isnanf_works="guessing yes";;
+ esac
+ ])
])
- case "$gl_cv_cc_float_expbit0" in
- word*bit*)
- word=`echo "$gl_cv_cc_float_expbit0" | sed -e 's/word //' -e 's/ bit.*//'`
- bit=`echo "$gl_cv_cc_float_expbit0" | sed -e 's/word.*bit //'`
- AC_DEFINE_UNQUOTED([FLT_EXPBIT0_WORD], [$word],
- [Define as the word index where to find the exponent of 'float'.])
- AC_DEFINE_UNQUOTED([FLT_EXPBIT0_BIT], [$bit],
- [Define as the bit index in the word where to find bit 0 of the exponent of 'float'.])
- ;;
- esac
])