1# isfinite.m4 serial 17 2dnl Copyright (C) 2007-2020 Free Software Foundation, Inc. 3dnl This file is free software; the Free Software Foundation 4dnl gives unlimited permission to copy and/or distribute it, 5dnl with or without modifications, as long as this notice is preserved. 6 7AC_DEFUN([gl_ISFINITE], 8[ 9 AC_REQUIRE([gl_MATH_H_DEFAULTS]) 10 AC_REQUIRE([AC_CANONICAL_HOST]) 11 dnl Persuade glibc <math.h> to declare isfinite. 12 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) 13 AC_CHECK_DECLS([isfinite], , , [[#include <math.h>]]) 14 if test "$ac_cv_have_decl_isfinite" = yes; then 15 gl_CHECK_MATH_LIB([ISFINITE_LIBM], 16 [x = isfinite (x) + isfinite ((float) x);]) 17 if test "$ISFINITE_LIBM" != missing; then 18 dnl Test whether isfinite() on 'long double' works. 19 gl_ISFINITEL_WORKS 20 case "$gl_cv_func_isfinitel_works" in 21 *yes) ;; 22 *) ISFINITE_LIBM=missing;; 23 esac 24 dnl Also, isfinite() on 'double' does not work on Linux/ia64 (because of 25 dnl signalling NaNs). But this does not have to be tested, since 26 dnl isfinite(long double) also does not work in this situation. 27 fi 28 fi 29 dnl On Solaris 10, with CC in C++ mode, isfinite is not available although 30 dnl is with cc in C mode. This cannot be worked around by defining 31 dnl _XOPEN_SOURCE=600, because the latter does not work in C++ mode on 32 dnl Solaris 11.0. Therefore use the replacement functions on Solaris. 33 if test "$ac_cv_have_decl_isfinite" != yes \ 34 || test "$ISFINITE_LIBM" = missing \ 35 || { case "$host_os" in solaris*) true;; *) false;; esac; }; then 36 REPLACE_ISFINITE=1 37 dnl No libraries are needed to link lib/isfinite.c. 38 ISFINITE_LIBM= 39 fi 40 AC_SUBST([ISFINITE_LIBM]) 41]) 42 43dnl Test whether isfinite() on 'long double' recognizes all canonical values 44dnl which are neither finite nor infinite. 45AC_DEFUN([gl_ISFINITEL_WORKS], 46[ 47 AC_REQUIRE([AC_PROG_CC]) 48 AC_REQUIRE([gl_BIGENDIAN]) 49 AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE]) 50 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles 51 AC_CACHE_CHECK([whether isfinite(long double) works], [gl_cv_func_isfinitel_works], 52 [ 53 AC_RUN_IFELSE([AC_LANG_SOURCE([[ 54#include <float.h> 55#include <limits.h> 56#include <math.h> 57#define NWORDS \ 58 ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int)) 59typedef union { unsigned int word[NWORDS]; long double value; } 60 memory_long_double; 61/* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the 62 runtime type conversion. */ 63#ifdef __sgi 64static long double NaNl () 65{ 66 double zero = 0.0; 67 return zero / zero; 68} 69#else 70# define NaNl() (0.0L / 0.0L) 71#endif 72int main () 73{ 74 int result = 0; 75 76 { 77 memory_long_double m; 78 unsigned int i; 79 80 /* The isfinite macro should be immune against changes in the sign bit and 81 in the mantissa bits. The xor operation twiddles a bit that can only be 82 a sign bit or a mantissa bit (since the exponent never extends to 83 bit 31). */ 84 m.value = NaNl (); 85 m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1); 86 for (i = 0; i < NWORDS; i++) 87 m.word[i] |= 1; 88 if (isfinite (m.value)) 89 result |= 1; 90 } 91 92#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 93/* Representation of an 80-bit 'long double' as an initializer for a sequence 94 of 'unsigned int' words. */ 95# ifdef WORDS_BIGENDIAN 96# define LDBL80_WORDS(exponent,manthi,mantlo) \ 97 { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \ 98 ((unsigned int) (manthi) << 16) | ((unsigned int) (mantlo) >> 16), \ 99 (unsigned int) (mantlo) << 16 \ 100 } 101# else 102# define LDBL80_WORDS(exponent,manthi,mantlo) \ 103 { mantlo, manthi, exponent } 104# endif 105 { /* Quiet NaN. */ 106 static memory_long_double x = 107 { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) }; 108 if (isfinite (x.value)) 109 result |= 2; 110 } 111 { 112 /* Signalling NaN. */ 113 static memory_long_double x = 114 { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) }; 115 if (isfinite (x.value)) 116 result |= 2; 117 } 118 /* isfinite should return something even for noncanonical values. */ 119 { /* Pseudo-NaN. */ 120 static memory_long_double x = 121 { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) }; 122 if (isfinite (x.value) && !isfinite (x.value)) 123 result |= 4; 124 } 125 { /* Pseudo-Infinity. */ 126 static memory_long_double x = 127 { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) }; 128 if (isfinite (x.value) && !isfinite (x.value)) 129 result |= 8; 130 } 131 { /* Pseudo-Zero. */ 132 static memory_long_double x = 133 { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) }; 134 if (isfinite (x.value) && !isfinite (x.value)) 135 result |= 16; 136 } 137 { /* Unnormalized number. */ 138 static memory_long_double x = 139 { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) }; 140 if (isfinite (x.value) && !isfinite (x.value)) 141 result |= 32; 142 } 143 { /* Pseudo-Denormal. */ 144 static memory_long_double x = 145 { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) }; 146 if (isfinite (x.value) && !isfinite (x.value)) 147 result |= 64; 148 } 149#endif 150 151 return result; 152}]])], 153 [gl_cv_func_isfinitel_works=yes], 154 [gl_cv_func_isfinitel_works=no], 155 [case "$host_os" in 156 # Guess no on native Windows. 157 mingw*) gl_cv_func_isfinitel_works="guessing no" ;; 158 *) gl_cv_func_isfinitel_works="guessing yes" ;; 159 esac 160 ]) 161 ]) 162]) 163