Gcc -O(1-3) produce worse code on MPC5200

[Amir Bukhari]

I use macraiger gcc port for PPC. When I compile my software with gcc -O0
zero the program work as excpected
But I as soon as I use optimization option like -O2 my software crash. I
can't figure what case this until now. My assumtion is that the stack is got
currupted.

I use uC-II RTOS as a kernel.

Has someone experience such case? 
Have someone some hints for me?

Thanks,
Amir