Add isinf optimized for 64-bit.

ChangeLog

@@ -1,5 +1,7 @@
 2009-08-26  Ulrich Drepper  <drepper@redhat.com>
 
+	* sysdeps/ieee754/dbl-64/wordsize-64/s_isinf.c: New file.
+
 	* sysdeps/ieee754/dbl-64/wordsize-64/s_isnan.c: New file.
 
 2009-08-25  Ulrich Drepper  <drepper@redhat.com>

sysdeps/ieee754/dbl-64/wordsize-64/s_isinf.c

@@ -0,0 +1,30 @@
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Changed to return -1 for -Inf by Ulrich Drepper <drepper@cygnus.com>.
+ * Public domain.
+ */
+
+/*
+ * isinf(x) returns 1 is x is inf, -1 if x is -inf, else 0;
+ * no branching!
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+int
+__isinf (double x)
+{
+	int64_t ix;
+	EXTRACT_WORDS64(ix,x);
+	int64_t t = ix & UINT64_C(0x7fffffffffffffff);
+	t ^= UINT64_C(0x7ff0000000000000);
+	t |= -t;
+	return ~(t >> 63) & (ix >> 62);
+}
+hidden_def (__isinf)
+weak_alias (__isinf, isinf)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__isinf, __isinfl)
+weak_alias (__isinf, isinfl)
+#endif