On Wed, Jul 21, 2010 at 4:44 PM, Bernd Schmidt <ber...@codesourcery.com> wrote: > On 07/21/2010 03:06 PM, Steven Bosscher wrote: >> 3. GCC now has better alias analysis than it used to, especially with >> the alias-exporting stuff that exports the GIMPLE points-to analysis >> results, but also just all the other little things that were >> contributed over the last 10 years (little things like tree-ssa :) > [...] >> It looks like ~9% extra !true_dependence cases are found with cselib, >> with is not insignificant: > > So, if you want to do something useful in this area, try finding out why > cselib is still useful despite your point 3 above. Maybe alias analysis > can be improved?
Yes, this is what I planned to do anyway. > If that can't be improved, I think that rather than remove cselib from > the scheduler, the question should be: if it's useful, why don't we use > it for other schedulers rather than only sched-ebb? Well, for one thing: It currently breaks things. See PRs I referenced. We end up not translating the VALUE rtx'en to normal addresses, and missing real true dependencies. Ciao! Steven
