avoid gcc 3.4.3 bug on long double NaN on Irix 6.5

[gnulib.git] / m4 / isfinite.m4

diff --git a/m4/isfinite.m4 b/m4/isfinite.m4
index 055ba82..019eb95 100644 (file)
--- a/m4/isfinite.m4
+++ b/m4/isfinite.m4
@@ -1,4 +1,4 @@
-# isfinite.m4 serial 4
+# isfinite.m4 serial 5
 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,
@@ -56,6 +56,17 @@ AC_DEFUN([gl_ISFINITEL_WORKS],
   ((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;
@@ -65,7 +76,7 @@ int main ()
      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 = 0.0L / 0.0L;
+  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;