> -----Original Message----- > From: Bernd Schmidt [mailto:ber...@codesourcery.com] > Sent: 05 November 2012 16:52 > To: Paulo Matos > Cc: gcc@gcc.gnu.org > Subject: Re: Defining scheduling resource constraint > > Depends on why it schedules them in the same cycle. Either there's an > output dependency, in which case your target's adjust_cost needs to > ensure it doesn't have cost zero. Or maybe the scheduler proved that the > conditions are mutually exclusive and didn't add such a dependency. In > that case, if the machine really disallows this case, you'll probably > need to define the sched_reorg hooks and maybe variable_issue and do the > bookkeeping yourself - keep track of which registers have been set in > the current cycle, and ensure insns which set the same registers go to > the back of the queue and aren't considered anymore until the next cycle. >
I am following your advice and using sched.reorg to remove the instruction from the ready list. What I am doing is checking the register written in ready[n_ready - 1] (if any) and look for the remainder of the ready list for insns writing to the same register. If I find one such insn, in index k, then I remove the insn by moving all insns from 0 -> k-1 to 1-> k (essentially shifting right all instructions below k. However this is getting me into trouble with an ice. I feel like I should instead be moving the instruction from ready to pending instead of simply removing it from ready, however I have no access to Haifa-sched.c internals from the backend. Any suggestions on how to remove this instruction? Or do I need to keep more scheduling state in the backend in order to do this properly? Cheers, Paulo Matos
