Bug in egcs-2.91.66 - double comparisons

[Richard Bielak]

Hi,

I'm using egcs-2.91.66 on a RH 6.0 system:

	Linux chippewa 2.2.9 #20 SMP Thu May 20 00:01:37 PDT 1999 i686 unknown

and I compile this program:

----------------------------------------------------------
#include <stdio.h>

int main (int argc, char **argv) {

  double t1, t2, t3, t4;

  t1 = 0.040000000000000008;
  t2 = 0.20000000000000001;
  t3 = 0.20000000000000001;


  /* The comparison fails here */
  if (t1 <= t3 * t2) {
	printf ("Seems OK \n");
  }
  else {
	printf ("Seems wrong \n");
  }


  t4 = t3 * t2;

  /* Comparison OK here */
  if (t1 <= t4) {
	printf ("Seems OK \n");
  }
  else {
	printf ("Seems wrong \n");
  }


  printf ("t1=%E t2=%E t3=%E t3*t2=%E \n", t1, t2, t3, t2 * t3);

}

--------------------------------------------------------

Depending on the kind of optimization I use the answers come out differently.
Here is what I type:

[richieb on chippewa] numbers > gcc -o doubles doubles.c
[richieb on chippewa] numbers > ./doubles 
Seems wrong 
Seems OK 
t1=4.000000E-02 t2=2.000000E-01 t3=2.000000E-01 t3*t2=4.000000E-02 
[richieb on chippewa] numbers > 
[richieb on chippewa] numbers > gcc -O -o doubles doubles.c
[richieb on chippewa] numbers > ./doubles 
Seems OK 
Seems wrong 
t1=4.000000E-02 t2=2.000000E-01 t3=2.000000E-01 t3*t2=4.000000E-02 
[richieb on chippewa] numbers > 
[richieb on chippewa] numbers > gcc -O2 -o doubles doubles.c
[richieb on chippewa] numbers > ./doubles 
Seems OK 
Seems OK 
t1=4.000000E-02 t2=2.000000E-01 t3=2.000000E-01 t3*t2=4.000000E-02 
[richieb on chippewa] numbers > 
[richieb on chippewa] numbers > 
[richieb on chippewa] numbers > gcc -O3 -o doubles doubles.c
[richieb on chippewa] numbers > ./doubles 
Seems OK 
Seems OK 
t1=4.000000E-02 t2=2.000000E-01 t3=2.000000E-01 t3*t2=4.000000E-02 
[richieb on chippewa] numbers > 



The correct answer is that both comparisons should come out the same.

This code works OK with earlier versions of GCC (2.8.1).

Thanks for any help...

...richie