libjava configure question

Wed May 25 15:37:00 GMT 2005

Bryce McKinlay writes:
 > 
 > In fact GCJ already has the ability to inline Math.* calls directly 
 > into native FPU instructions in some cases.
One other thing: I don't think we can do this in general and meet even
the more relaxed requirements of java.lang.Math, because the x86 has a
restricted range of allowable arguments to its trig functions.
Try this with -ffast-math:
public class trial
{
 static public void main (String[] argv)
 {
 System.out.println(Math.sin(Math.pow(2.0, 90.0)));
 }
}
zapata:~ $ gcj trial.java --main=trial -ffast-math -O 
zapata:~ $ ./a.out 
1.2379400392853803E27
zapata:~ $ gcj trial.java --main=trial -ffast-math 
zapata:~ $ ./a.out 
-0.9044312486086016
I think that we can agree the error is more than 1 ulp!
Andrew.