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Diffstat (limited to 'm4/isfinite.m4')
-rw-r--r-- | m4/isfinite.m4 | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/m4/isfinite.m4 b/m4/isfinite.m4 new file mode 100644 index 000000000..8f18ae8d6 --- /dev/null +++ b/m4/isfinite.m4 @@ -0,0 +1,162 @@ +# isfinite.m4 serial 17 +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, +dnl with or without modifications, as long as this notice is preserved. + +AC_DEFUN([gl_ISFINITE], +[ + AC_REQUIRE([gl_MATH_H_DEFAULTS]) + AC_REQUIRE([AC_CANONICAL_HOST]) + dnl Persuade glibc <math.h> to declare isfinite. + AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) + AC_CHECK_DECLS([isfinite], , , [[#include <math.h>]]) + if test "$ac_cv_have_decl_isfinite" = yes; then + gl_CHECK_MATH_LIB([ISFINITE_LIBM], + [x = isfinite (x) + isfinite ((float) x);]) + if test "$ISFINITE_LIBM" != missing; then + dnl Test whether isfinite() on 'long double' works. + gl_ISFINITEL_WORKS + case "$gl_cv_func_isfinitel_works" in + *yes) ;; + *) ISFINITE_LIBM=missing;; + esac + dnl Also, isfinite() on 'double' does not work on Linux/ia64 (because of + dnl signalling NaNs). But this does not have to be tested, since + dnl isfinite(long double) also does not work in this situation. + fi + fi + dnl On Solaris 10, with CC in C++ mode, isfinite is not available although + dnl is with cc in C mode. This cannot be worked around by defining + dnl _XOPEN_SOURCE=600, because the latter does not work in C++ mode on + dnl Solaris 11.0. Therefore use the replacement functions on Solaris. + if test "$ac_cv_have_decl_isfinite" != yes \ + || test "$ISFINITE_LIBM" = missing \ + || { case "$host_os" in solaris*) true;; *) false;; esac; }; then + REPLACE_ISFINITE=1 + dnl No libraries are needed to link lib/isfinite.c. + ISFINITE_LIBM= + fi + AC_SUBST([ISFINITE_LIBM]) +]) + +dnl Test whether isfinite() on 'long double' recognizes all canonical values +dnl which are neither finite nor infinite. +AC_DEFUN([gl_ISFINITEL_WORKS], +[ + AC_REQUIRE([AC_PROG_CC]) + AC_REQUIRE([gl_BIGENDIAN]) + 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], + [ + AC_RUN_IFELSE([AC_LANG_SOURCE([[ +#include <float.h> +#include <limits.h> +#include <math.h> +#define NWORDS \ + ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int)) +typedef union { unsigned int word[NWORDS]; long double value; } + memory_long_double; +/* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the + runtime type conversion. */ +#ifdef __sgi +static long double NaNl () +{ + double zero = 0.0; + return zero / zero; +} +#else +# define NaNl() (0.0L / 0.0L) +#endif +int main () +{ + int result = 0; + + { + memory_long_double m; + unsigned int i; + + /* The isfinite macro 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 (since the exponent never extends to + bit 31). */ + m.value = NaNl (); + m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1); + for (i = 0; i < NWORDS; i++) + m.word[i] |= 1; + if (isfinite (m.value)) + result |= 1; + } + +#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 +/* Representation of an 80-bit 'long double' as an initializer for a sequence + of 'unsigned int' words. */ +# ifdef WORDS_BIGENDIAN +# define LDBL80_WORDS(exponent,manthi,mantlo) \ + { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \ + ((unsigned int) (manthi) << 16) | ((unsigned int) (mantlo) >> 16), \ + (unsigned int) (mantlo) << 16 \ + } +# else +# define LDBL80_WORDS(exponent,manthi,mantlo) \ + { mantlo, manthi, exponent } +# endif + { /* Quiet NaN. */ + static memory_long_double x = + { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) }; + if (isfinite (x.value)) + result |= 2; + } + { + /* Signalling NaN. */ + static memory_long_double x = + { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) }; + if (isfinite (x.value)) + result |= 2; + } + /* isfinite should return something even for noncanonical values. */ + { /* Pseudo-NaN. */ + static memory_long_double x = + { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) }; + if (isfinite (x.value) && !isfinite (x.value)) + result |= 4; + } + { /* Pseudo-Infinity. */ + static memory_long_double x = + { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) }; + if (isfinite (x.value) && !isfinite (x.value)) + result |= 8; + } + { /* Pseudo-Zero. */ + static memory_long_double x = + { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) }; + if (isfinite (x.value) && !isfinite (x.value)) + result |= 16; + } + { /* Unnormalized number. */ + static memory_long_double x = + { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) }; + if (isfinite (x.value) && !isfinite (x.value)) + result |= 32; + } + { /* Pseudo-Denormal. */ + static memory_long_double x = + { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) }; + if (isfinite (x.value) && !isfinite (x.value)) + result |= 64; + } +#endif + + return result; +}]])], + [gl_cv_func_isfinitel_works=yes], + [gl_cv_func_isfinitel_works=no], + [case "$host_os" in + # Guess no on native Windows. + mingw*) gl_cv_func_isfinitel_works="guessing no" ;; + *) gl_cv_func_isfinitel_works="guessing yes" ;; + esac + ]) + ]) +]) |