Problem with interpreted double operations on IA64

Tue Apr 9 09:37:00 GMT 2002

Could someone point me at a description of exactly how type __java_double
should differ from double? As far as I can tell, __java_double is used
primarily by the interpreter? On X86 this seems to work correctly. On IA64
(and perhaps other 64-bit platforms?), it seems to get confused about the
low order bits. This means that "double precision" results in the
interpreter are computed at most to single precision accuracy. Here's a C++
example to demonstrate the issue. Gij runs into the same problems, causing
scimark to fail, etc. (This is with a very recent 3.1 tree.)
[hboehm@plasma ~/tests]$ cat double.cc
#include <stdio.h>
__java_double jdiv (__java_double x, __java_double y) {
 return x/y;
}
double div (double x, double y) {
 return x/y;
}
int main()
{
 __java_double jx=2.0, jy=3.0;
 double x=2.0, y=3.0;
 double result, jresult;
 jresult = jdiv(jx, jy);
 result = div(x, y);
 printf("%20.15f %20.15f\n", result, jresult);
}
[hboehm@plasma ~/tests]$ g++ double.cc
[hboehm@plasma ~/tests]$ ./a.out
 0.666666666666667 0.666666686534882
Hans