Hi Paolo,
The mathl module uses the idiom x != x
to test for a NaN. The IRIX 6.5 cc compiler, however, simplifies this expression
to false, both for 'double' and 'long double' variables. The two workarounds
that I found are:
- Use the isnanl function,
- Copy one of the operands into a 'volatile' variable:
volatile double y = x;
if (x != y) ...
Also, do you know which are the operations that can be performed on a
signalling NaN without getting an exception? Only an isnanl test? Or also
comparisons?
So, your opinion about the following patch?
2007-03-25 Bruno Haible <[EMAIL PROTECTED]>
* lib/atanl.c: Include isnanl.h.
(atanl): Use isnanl, instead of the x != x idiom.
* lib/ldexpl.c: Include isnanl.h.
(ldexpl): Use isnanl, instead of the x != x idiom.
* lib/logl.c: Include isnanl.h.
(logl): Use isnanl, instead of the x != x idiom.
* lib/sinl.c: Include isnanl.h.
(sinl): Use isnanl, instead of the x != x idiom.
* lib/sqrtl.c: Include isnanl.h.
(sqrtl): Use isnanl, instead of the x != x idiom.
* lib/tanl.c: Include isnanl.h.
(tanl): Use isnanl, instead of the x != x idiom.
* lib/trigl.c: Include isnanl.h.
(ieee754_rem_pio2l): Use isnanl, instead of the x != x idiom.
* modules/mathl (Depends-on): Add isnanl.
--- lib/atanl.c 18 Feb 2007 15:10:28 -0000 1.4
+++ lib/atanl.c 25 Mar 2007 20:34:50 -0000
@@ -64,6 +64,7 @@
*
*/
+#include "isnanl.h"
/* arctan(k/8), k = 0, ..., 82 */
static const long double atantbl[84] = {
@@ -178,12 +179,12 @@
int k, sign;
long double t, u, p, q;
- sign = x < 0.0;
-
/* Check for zero or NaN. */
- if (x != x || x == 0.0)
+ if (isnanl (x) || x == 0.0)
return x + x;
+ sign = x < 0.0;
+
if (x + x == x)
{
/* Infinity. */
--- lib/ldexpl.c 18 Feb 2007 15:10:28 -0000 1.5
+++ lib/ldexpl.c 25 Mar 2007 20:34:50 -0000
@@ -25,6 +25,7 @@
#include <math.h>
#include <float.h>
+#include "isnanl.h"
long double
ldexpl(long double x, int exp)
@@ -33,7 +34,7 @@
int bit;
/* Check for zero, nan and infinity. */
- if (x != x || x + x == x )
+ if (isnanl (x) || x + x == x)
return x;
if (exp < 0)
--- lib/logl.c 18 Feb 2007 15:10:28 -0000 1.4
+++ lib/logl.c 25 Mar 2007 20:34:50 -0000
@@ -64,6 +64,8 @@
*
*/
+#include "isnanl.h"
+
/* log(1+x) = x - .5 x^2 + x^3 l(x)
-.0078125 <= x <= +.0078125
peak relative error 1.2e-37 */
@@ -207,7 +209,7 @@
return (x - x) / ZERO;
}
/* log (infinity or NaN) */
- if (x + x == x || x != x)
+ if (isnanl (x) || x + x == x)
{
return x + x;
}
--- lib/sinl.c 18 Feb 2007 15:10:28 -0000 1.3
+++ lib/sinl.c 25 Mar 2007 20:34:50 -0000
@@ -52,6 +52,7 @@
#include "trigl.h"
#include "trigl.c"
#include "sincosl.c"
+#include "isnanl.h"
long double
sinl (long double x)
@@ -65,7 +66,7 @@
return kernel_sinl (x, z, 0);
/* sinl(Inf or NaN) is NaN, sinl(0) is 0 */
- else if (x + x == x || x != x)
+ else if (isnanl (x) || x + x == x)
return x - x; /* NaN */
/* argument reduction needed */
--- lib/sqrtl.c 18 Feb 2007 15:10:28 -0000 1.4
+++ lib/sqrtl.c 25 Mar 2007 20:34:50 -0000
@@ -25,6 +25,7 @@
#include <math.h>
#include <float.h>
+#include "isnanl.h"
/* A simple Newton-Raphson method. */
long double
@@ -38,7 +39,7 @@
return (long double) sqrt(-1);
/* Check for zero, NANs and infinites */
- if (x + x == x || x != x)
+ if (isnanl (x) || x + x == x)
return x;
frexpl (x, &exponent);
--- lib/tanl.c 18 Feb 2007 15:10:28 -0000 1.3
+++ lib/tanl.c 25 Mar 2007 20:34:50 -0000
@@ -55,6 +55,7 @@
#include "trigl.c"
#endif
#endif
+#include "isnanl.h"
/*
* ====================================================
@@ -197,7 +198,7 @@
return kernel_tanl (x, z, 1);
/* tanl(Inf or NaN) is NaN, tanl(0) is 0 */
- else if (x + x == x || x != x)
+ else if (isnanl (x) || x + x == x)
return x - x; /* NaN */
/* argument reduction needed */
--- lib/trigl.c 25 Mar 2007 18:03:15 -0000 1.5
+++ lib/trigl.c 25 Mar 2007 20:34:50 -0000
@@ -23,6 +23,7 @@
#include <math.h>
#include <float.h>
+#include "isnanl.h"
/* Table of constants for 2/pi, 5628 hexadecimal digits of 2/pi */
static const int two_over_pi[] = {
@@ -233,7 +234,7 @@
return -1;
}
- if (x + x == x || x != x) /* x is +=oo or NaN */
+ if (isnanl (x) || x + x == x) /* x is +=oo or NaN */
{
y[0] = x - x;
y[1] = y[0];
--- modules/mathl 23 Mar 2007 01:26:24 -0000 1.7
+++ modules/mathl 25 Mar 2007 20:34:50 -0000
@@ -22,6 +22,7 @@
Depends-on:
math
frexpl
+isnanl
configure.ac:
gl_FUNC_LONG_DOUBLE_MATH
