"sei()" not executed but "SREG |= _BV(SREG_I)" is

[rubienr]

example:
compile code for -mmcu=atmega16 with or without size optimization (-Os), run avrora with: -monitors=calls,interrupts -invocations-only=false -show-interrupts=true

code:

int main(void) {
    sei();
    ...
    cli(); // vs SREG |= _BV(SREG_I);
}

expected:
"disable interrupts" is reported by the monitor as expected by executing "cli()"
"enable interrupts" is not reported by executing "sei()" but by exceuting "SREG |= _BV(SREG_I)"