1 # isfinite.m4 serial 13
2 dnl Copyright (C) 2007-2012 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_ISFINITE],
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
10 dnl Persuade glibc <math.h> to declare isfinite.
11 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
12 AC_CHECK_DECLS([isfinite], , , [[#include <math.h>]])
13 if test "$ac_cv_have_decl_isfinite" = yes; then
14 gl_CHECK_MATH_LIB([ISFINITE_LIBM],
15 [x = isfinite (x) + isfinite ((float) x);])
16 if test "$ISFINITE_LIBM" != missing; then
17 dnl Test whether isfinite() on 'long double' works.
19 case "$gl_cv_func_isfinitel_works" in
21 *) ISFINITE_LIBM=missing;;
23 dnl Also, isfinite() on 'double' does not work on Linux/ia64 (because of
24 dnl signalling NaNs). But this does not have to be tested, since
25 dnl isfinite(long double) also does not work in this situation.
28 if test "$ac_cv_have_decl_isfinite" != yes ||
29 test "$ISFINITE_LIBM" = missing; then
31 dnl No libraries are needed to link lib/isfinite.c.
34 AC_SUBST([ISFINITE_LIBM])
37 dnl Test whether isfinite() on 'long double' recognizes all numbers which are
38 dnl neither finite nor infinite. This test fails e.g. on i686, x86_64, ia64,
40 dnl - pseudo-denormals on x86_64,
41 dnl - pseudo-zeroes, unnormalized numbers, and pseudo-denormals on i686,
42 dnl - pseudo-NaN, pseudo-Infinity, pseudo-zeroes, unnormalized numbers, and
43 dnl pseudo-denormals on ia64.
44 AC_DEFUN([gl_ISFINITEL_WORKS],
46 AC_REQUIRE([AC_PROG_CC])
47 AC_REQUIRE([gl_BIGENDIAN])
48 AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
49 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
50 AC_CACHE_CHECK([whether isfinite(long double) works], [gl_cv_func_isfinitel_works],
52 AC_RUN_IFELSE([AC_LANG_SOURCE([[
57 ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
58 typedef union { unsigned int word[NWORDS]; long double value; }
60 /* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the
61 runtime type conversion. */
63 static long double NaNl ()
69 # define NaNl() (0.0L / 0.0L)
79 /* The isfinite macro should be immune against changes in the sign bit and
80 in the mantissa bits. The xor operation twiddles a bit that can only be
81 a sign bit or a mantissa bit (since the exponent never extends to
84 m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
85 for (i = 0; i < NWORDS; i++)
87 if (isfinite (m.value))
91 #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
92 /* Representation of an 80-bit 'long double' as an initializer for a sequence
93 of 'unsigned int' words. */
94 # ifdef WORDS_BIGENDIAN
95 # define LDBL80_WORDS(exponent,manthi,mantlo) \
96 { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
97 ((unsigned int) (manthi) << 16) | (unsigned int) (mantlo) >> 16), \
98 (unsigned int) (mantlo) << 16 \
101 # define LDBL80_WORDS(exponent,manthi,mantlo) \
102 { mantlo, manthi, exponent }
105 static memory_long_double x =
106 { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
107 if (isfinite (x.value))
111 /* Signalling NaN. */
112 static memory_long_double x =
113 { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
114 if (isfinite (x.value))
117 /* The isfinite macro should recognize Pseudo-NaNs, Pseudo-Infinities,
118 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals, as defined in
119 Intel IA-64 Architecture Software Developer's Manual, Volume 1:
120 Application Architecture.
121 Table 5-2 "Floating-Point Register Encodings"
122 Figure 5-6 "Memory to Floating-Point Register Data Translation"
125 static memory_long_double x =
126 { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
127 if (isfinite (x.value))
130 { /* Pseudo-Infinity. */
131 static memory_long_double x =
132 { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
133 if (isfinite (x.value))
137 static memory_long_double x =
138 { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
139 if (isfinite (x.value))
142 { /* Unnormalized number. */
143 static memory_long_double x =
144 { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
145 if (isfinite (x.value))
148 { /* Pseudo-Denormal. */
149 static memory_long_double x =
150 { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
151 if (isfinite (x.value))
157 }]])], [gl_cv_func_isfinitel_works=yes], [gl_cv_func_isfinitel_works=no],
159 # Guess no on ia64, x86_64, i386.
160 ia64 | x86_64 | i*86) gl_cv_func_isfinitel_works="guessing no";;
161 *) gl_cv_func_isfinitel_works="guessing yes";;