Before revision:  Although this is a time consuming process, our approach eventually constructs a simple variation of -O3, which we call -Ocm3, that realizes nearly two thirds of the known available gains on the CM3 architecture (beyond -O3) and significantly outperforms a far more complex state-of-the-art predictive method . Our approach suggests that 26 flags should be removed from -O3 while three other flags should be added. We analyze in detail two of the former and explain why turning them off improves performance on this processor .
After revision:  Although this is a time consuming process, our approach eventually constructs a simple variation of -O3, which we call -Ocm3, that realizes nearly two thirds of the known available gains on the CM3 architecture (beyond -O3) and significantly outperforms a far more complex state-of-the-art predictive method in cross-validation experiments. Finally, we demonstrate our method on additional platforms by constructing two more optimization levels that find even more significant speed-ups on the ARM Cortex-A8 and 8-bit AVR processors .