Giovanni Bajo wrote:
I believe you are missing my point. What is the GCC command line option for "try to optimize as best as you can, please, I don't care compiletime"? I believe that should be -O3. Otherwise let's make -O4. Or -O666. The only real argument I heard till now is that -funroll-loops isn't valuable without profile feedback. My experience is that it isn't true, I for sure use it for profit in my code. But it looks like the only argument that could make a difference is SPEC, and SPEC is not freely available. So I'd love if someone could SPEC -funroll-loops for me.
It is not at all the case that SPEC is the only good argument, in fact SPEC on its own is a bad argument. Much more important is impact on real life applications, so your data point that it makes a significant difference for your application is more interesting than SPEC marks. When it comes to GCC, we are more interested in performance than good SPEC figures!
Giovanni Bajo
