Re: DFA scheduler patch for review

[law at redhat dot com]

In message <20020430171056.GQ18000@atrey.karlin.mff.cuni.cz>, Jan Hubicka write
s:
 > > In message <322710000.1020184857@gandalf.codesourcery.com>, Mark Mitchell 
 > write
 > > s:
 > >  > > Anyway, I really don't expect the DFA scheduler to have the kind of
 > >  > > negative impact that the inliner had.
 > >  > 
 > >  > I agree.
 > >  > 
 > >  > The flip side of Jeff's point (that you only get the DFA scheduler wher
 > e
 > >  > it's turned on) is that we now again have two schedulers.  It would be
 > >  > good if people would collaborate to do DFA schedulers for all the ports
 > >  > so that we can lose the old new scheduler.
 > > More correctly, we have two methods for describing a processor pipeline an
 > d
 > > two methods for the scheduler to query that information from the backend.
 > 
 > Even more corectly, we even do have two schedulers.  We do have the region
 > based global scheduler comming from Haifa and EBB scheduler sharing majority
 > of code.
Building of scheduling regions in the haifa scheduler should largely (if not
completely) be the same problem as building EBBs.  In fact, if you refer back
to the old documents from IBM Haifa, they're just building EBBS.

The implementation of building regions left a lot to be desired and has never
worked as it was supposed to.  It's ripe for being ripped out and rewritten.

Can you describe in a little more detail what you've done?  It's likely we
can use it to simply replace the lame code from Haifa.

 > On the branch I made EBB scheduler to update CFG and I will modify it soon
 > to update liveness as well.
Under what circumstances did you need to update the CFG?  The CFG should be
unaffected by scheduling.  Liveness can change as instructions move between
blocks, but that's already handled.

jeff