Fwd: Questions on PA machine description?

[Jerry Quinn]

Richard Henderson wrote:
> 
> On Sat, Mar 20, 1999 at 12:46:46AM -0700, Jeffrey A Law wrote:
> > That's basically what I've had in mind.  In addition to checking the
> > target macro, I think we'd want to check the ready delay and only do
> > this if it's zero.
> 
> Hum.  I suppose that's resonable.  We would even not need a target
> macro then -- just make sure that all sane targets ADJUST_COST
> anti-dependancies to zero.

I started trying to look at the haifa_sched.c file.  I can't really see
where insns dependent on the current one in the ready queue are
removed.  I'm looking in the loop on ready[] in schedule_block().  My
guess is that somehow schedule_insn does this, but I'm not sure.

My first thought is that instead of removing dependent instructions from
ready to insn_queue, move them to a temporary queue when the delay
(cost?) is 0.  Then, if the ready queue is empty but can_issue_more is
still live, pull one insn from the temp queue.  Repeat this second loop
until can_issue_more is empty or the temp queue is empty.  The return
everything else back to the insn_queue.

I may just be babbling.  Does this make any sense?  How is the ready
queue sorted?


-- 
Jerry Quinn                             Tel: (514) 761-8737
jquinn@nortelnetworks.com               Fax: (514) 761-8505
Speech Recognition Research