1# isnanl.m4 serial 22
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_FUNC_ISNANL],
8[
9  AC_REQUIRE([gl_MATH_H_DEFAULTS])
10  ISNANL_LIBM=
11  gl_HAVE_ISNANL_NO_LIBM
12  if test $gl_cv_func_isnanl_no_libm = no; then
13    gl_HAVE_ISNANL_IN_LIBM
14    if test $gl_cv_func_isnanl_in_libm = yes; then
15      ISNANL_LIBM=-lm
16    fi
17  fi
18  dnl The variable gl_func_isnanl set here is used by isnan.m4.
19  if test $gl_cv_func_isnanl_no_libm = yes \
20     || test $gl_cv_func_isnanl_in_libm = yes; then
21    save_LIBS="$LIBS"
22    LIBS="$LIBS $ISNANL_LIBM"
23    gl_FUNC_ISNANL_WORKS
24    LIBS="$save_LIBS"
25    case "$gl_cv_func_isnanl_works" in
26      *yes) gl_func_isnanl=yes ;;
27      *)    gl_func_isnanl=no; ISNANL_LIBM= ;;
28    esac
29  else
30    gl_func_isnanl=no
31  fi
32  if test $gl_func_isnanl != yes; then
33    HAVE_ISNANL=0
34  fi
35  AC_SUBST([ISNANL_LIBM])
36])
37
38AC_DEFUN([gl_FUNC_ISNANL_NO_LIBM],
39[
40  gl_HAVE_ISNANL_NO_LIBM
41  gl_func_isnanl_no_libm=$gl_cv_func_isnanl_no_libm
42  if test $gl_func_isnanl_no_libm = yes; then
43    gl_FUNC_ISNANL_WORKS
44    case "$gl_cv_func_isnanl_works" in
45      *yes) ;;
46      *)    gl_func_isnanl_no_libm=no ;;
47    esac
48  fi
49  if test $gl_func_isnanl_no_libm = yes; then
50    AC_DEFINE([HAVE_ISNANL_IN_LIBC], [1],
51      [Define if the isnan(long double) function is available in libc.])
52  fi
53])
54
55dnl Prerequisites of replacement isnanl definition. It does not need -lm.
56AC_DEFUN([gl_PREREQ_ISNANL],
57[
58  gl_LONG_DOUBLE_EXPONENT_LOCATION
59  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
60])
61
62dnl Test whether isnanl() can be used without libm.
63AC_DEFUN([gl_HAVE_ISNANL_NO_LIBM],
64[
65  AC_CACHE_CHECK([whether isnan(long double) can be used without linking with libm],
66    [gl_cv_func_isnanl_no_libm],
67    [
68      AC_LINK_IFELSE(
69        [AC_LANG_PROGRAM(
70           [[#include <math.h>
71             #if (__GNUC__ >= 4) || (__clang_major__ >= 4)
72             # undef isnanl
73             # define isnanl(x) __builtin_isnan ((long double)(x))
74             #elif defined isnan
75             # undef isnanl
76             # define isnanl(x) isnan ((long double)(x))
77             #endif
78             long double x;]],
79           [[return isnanl (x);]])],
80        [gl_cv_func_isnanl_no_libm=yes],
81        [gl_cv_func_isnanl_no_libm=no])
82    ])
83])
84
85dnl Test whether isnanl() can be used with libm.
86AC_DEFUN([gl_HAVE_ISNANL_IN_LIBM],
87[
88  AC_CACHE_CHECK([whether isnan(long double) can be used with libm],
89    [gl_cv_func_isnanl_in_libm],
90    [
91      save_LIBS="$LIBS"
92      LIBS="$LIBS -lm"
93      AC_LINK_IFELSE(
94        [AC_LANG_PROGRAM(
95           [[#include <math.h>
96             #if (__GNUC__ >= 4) || (__clang_major__ >= 4)
97             # undef isnanl
98             # define isnanl(x) __builtin_isnan ((long double)(x))
99             #elif defined isnan
100             # undef isnanl
101             # define isnanl(x) isnan ((long double)(x))
102             #endif
103             long double x;]],
104           [[return isnanl (x);]])],
105        [gl_cv_func_isnanl_in_libm=yes],
106        [gl_cv_func_isnanl_in_libm=no])
107      LIBS="$save_LIBS"
108    ])
109])
110
111dnl Test whether isnanl() recognizes all canonical numbers which are neither
112dnl finite nor infinite.
113AC_DEFUN([gl_FUNC_ISNANL_WORKS],
114[
115  AC_REQUIRE([AC_PROG_CC])
116  AC_REQUIRE([gl_BIGENDIAN])
117  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
118  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
119  AC_CACHE_CHECK([whether isnanl works], [gl_cv_func_isnanl_works],
120    [
121      AC_RUN_IFELSE(
122        [AC_LANG_SOURCE([[
123#include <float.h>
124#include <limits.h>
125#include <math.h>
126#if (__GNUC__ >= 4) || (__clang_major__ >= 4)
127# undef isnanl
128# define isnanl(x) __builtin_isnan ((long double)(x))
129#elif defined isnan
130# undef isnanl
131# define isnanl(x) isnan ((long double)(x))
132#endif
133#define NWORDS \
134  ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
135typedef union { unsigned int word[NWORDS]; long double value; }
136        memory_long_double;
137/* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the
138   runtime type conversion.  */
139#ifdef __sgi
140static long double NaNl ()
141{
142  double zero = 0.0;
143  return zero / zero;
144}
145#else
146# define NaNl() (0.0L / 0.0L)
147#endif
148int main ()
149{
150  int result = 0;
151
152  if (!isnanl (NaNl ()))
153    result |= 1;
154
155  {
156    memory_long_double m;
157    unsigned int i;
158
159    /* The isnanl function should be immune against changes in the sign bit and
160       in the mantissa bits.  The xor operation twiddles a bit that can only be
161       a sign bit or a mantissa bit (since the exponent never extends to
162       bit 31).  */
163    m.value = NaNl ();
164    m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
165    for (i = 0; i < NWORDS; i++)
166      m.word[i] |= 1;
167    if (!isnanl (m.value))
168      result |= 1;
169  }
170
171#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
172/* Representation of an 80-bit 'long double' as an initializer for a sequence
173   of 'unsigned int' words.  */
174# ifdef WORDS_BIGENDIAN
175#  define LDBL80_WORDS(exponent,manthi,mantlo) \
176     { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
177       ((unsigned int) (manthi) << 16) | ((unsigned int) (mantlo) >> 16),   \
178       (unsigned int) (mantlo) << 16                                        \
179     }
180# else
181#  define LDBL80_WORDS(exponent,manthi,mantlo) \
182     { mantlo, manthi, exponent }
183# endif
184  { /* Quiet NaN.  */
185    static memory_long_double x =
186      { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
187    if (!isnanl (x.value))
188      result |= 2;
189  }
190  {
191    /* Signalling NaN.  */
192    static memory_long_double x =
193      { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
194    if (!isnanl (x.value))
195      result |= 2;
196  }
197  /* isnanl should return something even for noncanonical values.  */
198  { /* Pseudo-NaN.  */
199    static memory_long_double x =
200      { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
201    if (isnanl (x.value) && !isnanl (x.value))
202      result |= 4;
203  }
204  { /* Pseudo-Infinity.  */
205    static memory_long_double x =
206      { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
207    if (isnanl (x.value) && !isnanl (x.value))
208      result |= 8;
209  }
210  { /* Pseudo-Zero.  */
211    static memory_long_double x =
212      { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
213    if (isnanl (x.value) && !isnanl (x.value))
214      result |= 16;
215  }
216  { /* Unnormalized number.  */
217    static memory_long_double x =
218      { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
219    if (isnanl (x.value) && !isnanl (x.value))
220      result |= 32;
221  }
222  { /* Pseudo-Denormal.  */
223    static memory_long_double x =
224      { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
225    if (isnanl (x.value) && !isnanl (x.value))
226      result |= 64;
227  }
228#endif
229
230  return result;
231}]])],
232        [gl_cv_func_isnanl_works=yes],
233        [gl_cv_func_isnanl_works=no],
234        [case "$host_os" in
235           mingw*) # Guess yes on mingw, no on MSVC.
236             AC_EGREP_CPP([Known], [
237#ifdef __MINGW32__
238 Known
239#endif
240               ],
241               [gl_cv_func_isnanl_works="guessing yes"],
242               [gl_cv_func_isnanl_works="guessing no"])
243             ;;
244           *) gl_cv_func_isnanl_works="guessing yes" ;;
245         esac
246        ])
247    ])
248])
249