On 23 April 2007 19:07, Diego Novillo wrote:
> Mark Mitchell wrote on 04/23/07 13:56:
>
>> So, I think there's a middle ground between "exactly the same passes on
>> all targets" and "use Acovea for every CPU to pick what -O2 means".
>> Using Acovea to reveal some of the suprising, but beneficial results,
>> seems like a fine idea, though.
>
> I'm hoping to hear something along those lines at the next GCC Summit. I
> have heard of a bunch of work in academia doing extensive optimization
> space searches looking for combinations of pass sequencing and
> repetition to achieve optimal results.
>
> My naive idea is for someone to test all these different combinations
> and give us a set of -Ox recipes that we can use by default in the compiler.
Has any of the Acovea research demonstrated whether there actually is any
such thing as a "good default set of flags in all cases"? If the results
obtained diverge significantly according to the nature/coding
style/architecture/other uncontrolled variable factors of the application, we
may be labouring under a false premise wrt. the entire idea, mightn't we?
cheers,
DaveK
--
Can't think of a witty .sigline today....
