Bulat Ziganshin wrote:
Hello Simon,
Friday, October 20, 2006, 1:38:39 PM, you wrote:
-O2 -funbox-strict-fields
I'm not sure that -funbox-strict-fields always improves performance,
we search for solution that improves performance ON AVERAGE
Not really: would you turn on an optimisation that makes 100 programs 1% better, and 1 program 200% worse? I'm being slightly hypocritical because we already do that kind of thing with full laziness. But the rule of thumb should be that -O/-O2 never takes risks that might seriously hurt performance. I'd say -funbox-strict-fields is too much of a risk to have on by default, but it's a difficult call to make. Measurements over lots of programs would help us decide - the nofib suite isn't much good here because most of the programs are from a time before strict fields were invented. Cheers, Simon