Eclipse EDS optimizer ommitted delay loop?

Hello!

I was having this code for a simple LED blinking Nios II application based on a counter and some delays:

# include "sys/alt_stdio.h"# include "system.h"# include "altera_avalon_pio_regs.h"
int main()
{ 
    int count = 140;
    int delay1 = 0;
    int delay2 = 0;
    int delay3 = 0;
    int delay4 = 0;
  /* Event loop never exits. */
  while (1) {
      IOWR_ALTERA_AVALON_PIO_DATA(LEDS_BASE, count&0x02);
      delay1 = 0;
      while(delay1 < 900000) {
          delay2=0;
          while(delay2 < 900000) {
              delay3=0;
              while(delay3 < 900000) {
                  delay4=0;
                  while(delay4 < 900000) {
                        delay4++;
                    }
                  delay3++;
              }
              delay2++;
          }
          delay1++;
      }
      //alt_putstr("DELAY3\n");
      count++;
  }
  return 0;
}

The optimizer was set at level 2 and I was trying to run the program but for some reason I had no delay!! The LEDs were constantly ON. Then I tried to debug the code using a debug configuration in Eclipse and I saw only the count variable but no delay variables. Then I saw a remark somewhere "Optimized out"! When I switched the optimizer option to Off. I finally could see the difference.

My question is how can the optimizer change the functionality of the code like this? Doesn't the program become unreliable after this?

Regards