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Description of problem:
When I compile the simple C-program below under RedHat 6.2 (egcs-2.91.66)
or 
RedHat 7.0 (gcc-2.96) I get the following problem: 

> gcc -O3 testc.c -lm -o testc
> ./testc
1: x1!=x2
1: x1!=x2  -0.227202 -0.227202 0.000000e+00

If a comparison of variables is made, as the first operation, the 
values are not loaded into the varibles before comparison. 

If I compile without the -O3 flag, the problem disappears. On an 
alpha-architecture (gcc 2.8.1) the problem is not present. 

test program:

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
int main(){
  double x1;
  double x2;

  x1 = cos(1.7);
  x2 = cos(1.7);

  if(x1!=x2) printf("1: x1!=x2\n");
  if(x1!=x2) printf("2: x1!=x2\n");
  if(x1!=x2) printf("3: x1!=x2\n");

  x1 = cos(1.8);
  x2 = cos(1.8);

  if(x1!=x2) printf("1: x1!=x2  %f %f %e\n", x1, x2, x1-x2);
  if(x1!=x2) printf("2: x1!=x2  %f %f %e\n", x1, x2, x1-x2);
  if(x1!=x2) printf("3: x1!=x2  %f %f %e\n", x1, x2, x1-x2);

  exit(0);
}



How reproducible:
Always

Steps to Reproduce:
1. gcc -O3 testc.c -lm -o testc
2. ./testc
3.
	

Actual Results:  When compiled with optimization O1, O2, O3, ... the test
program fails to compare 
two double the first time they are used. When compiled with O0, the program 
works without problem. 


Additional info: