X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fisfinite.m4;h=5f6119d33c5279268933f1cc21abceebb2a86247;hb=0963898828c9a6b76a2cf959f34b4e758fc4e265;hp=acffccbfdc875aab67c1c80db00aef112a0e5c3e;hpb=28d9a006c64dcc3e831f8a5149eed0739a89df12;p=gnulib.git

diff --git a/m4/isfinite.m4 b/m4/isfinite.m4
index acffccbfd..5f6119d33 100644
--- a/m4/isfinite.m4
+++ b/m4/isfinite.m4
@@ -1,5 +1,5 @@
-# isfinite.m4 serial 2
-dnl Copyright (C) 2007 Free Software Foundation, Inc.
+# isfinite.m4 serial 6
+dnl Copyright (C) 2007-2009 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.
@@ -12,6 +12,17 @@ AC_DEFUN([gl_ISFINITE],
   AC_CHECK_DECLS([isfinite], , , [#include <math.h>])
   if test "$ac_cv_have_decl_isfinite" = yes; then
     gl_CHECK_MATH_LIB([ISFINITE_LIBM], [x = isfinite (x);])
+    if test "$ISFINITE_LIBM" != missing; then
+      dnl Test whether isfinite() on 'long double' works.
+      gl_ISFINITEL_WORKS
+      case "$gl_cv_func_isfinitel_works" in
+        *yes) ;;
+        *)    ISFINITE_LIBM=missing;;
+      esac
+      dnl Also, isfinite() on 'double' does not work on Linux/ia64 (because of
+      dnl signalling NaNs). But this does not have to be tested, since
+      dnl isfinite(long double) also does not work in this situation.
+    fi
   fi
   if test "$ac_cv_have_decl_isfinite" != yes ||
      test "$ISFINITE_LIBM" = missing; then
@@ -22,3 +33,128 @@ AC_DEFUN([gl_ISFINITE],
   AC_SUBST([REPLACE_ISFINITE])
   AC_SUBST([ISFINITE_LIBM])
 ])
+
+dnl Test whether isfinite() on 'long double' recognizes all numbers which are
+dnl neither finite nor infinite. This test fails e.g. on i686, x86_64, ia64,
+dnl because of
+dnl - pseudo-denormals on x86_64,
+dnl - pseudo-zeroes, unnormalized numbers, and pseudo-denormals on i686,
+dnl - pseudo-NaN, pseudo-Infinity, pseudo-zeroes, unnormalized numbers, and
+dnl   pseudo-denormals on ia64.
+AC_DEFUN([gl_ISFINITEL_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([gl_BIGENDIAN])
+  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 ()
+{
+  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))
+    return 1;
+
+#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
+/* 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))
+      return 1;
+  }
+  {
+    /* Signalling NaN.  */
+    static memory_long_double x =
+      { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
+    if (isfinite (x.value))
+      return 1;
+  }
+  /* The isfinite macro should recognize Pseudo-NaNs, Pseudo-Infinities,
+     Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals, as defined in
+       Intel IA-64 Architecture Software Developer's Manual, Volume 1:
+       Application Architecture.
+       Table 5-2 "Floating-Point Register Encodings"
+       Figure 5-6 "Memory to Floating-Point Register Data Translation"
+   */
+  { /* Pseudo-NaN.  */
+    static memory_long_double x =
+      { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
+    if (isfinite (x.value))
+      return 1;
+  }
+  { /* Pseudo-Infinity.  */
+    static memory_long_double x =
+      { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
+    if (isfinite (x.value))
+      return 1;
+  }
+  { /* Pseudo-Zero.  */
+    static memory_long_double x =
+      { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
+    if (isfinite (x.value))
+      return 1;
+  }
+  { /* Unnormalized number.  */
+    static memory_long_double x =
+      { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
+    if (isfinite (x.value))
+      return 1;
+  }
+  { /* Pseudo-Denormal.  */
+    static memory_long_double x =
+      { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
+    if (isfinite (x.value))
+      return 1;
+  }
+#endif
+
+  return 0;
+}]])], [gl_cv_func_isfinitel_works=yes], [gl_cv_func_isfinitel_works=no],
+      [case "$host_cpu" in
+                               # Guess no on ia64, x86_64, i386.
+         ia64 | x86_64 | i*86) gl_cv_func_isnanl_works="guessing no";;
+         *)                    gl_cv_func_isnanl_works="guessing yes";;
+       esac
+      ])
+    ])
+])