Re: [PATCH] haifa-sched: SCHED_GROUP_P ignored for queued insn

[Vladimir Makarov <vmakarov at redhat dot com>]

Andreas Krebbel wrote:

> Hi,
>
> (sorry for the last empty mail :(
>
> a scheduler bug makes insns of different LIBCALL/RETVAL blocks to get
> intermixed. 
>
> If a SCHED_GROUP_P insn gets queued due to a pipeline hazard, the scheduler 
> chooses an insn from the ready list without looking at the queued_list.
> If an insn which belongs to a sched group is available either on the ready list
> or on the queued list this insn has to be scheduled (according to the definition
> of sched groups).
> For insns queued due to data dependencies there is already a check 
> (haifa-sched.c:952) which advances the cycle count so that the queued 
> sched group insn comes to the ready list in the next turn and hence can 
> be choosen by choose_insn.
>
> The attached patch implements the same check for the other call of queue_insn
> (haifa-sched.c:2054).
>
> This fixes a testcase on s390x compiled with -O2, -m31 and -march=z990. Unfortunately
> the testcase is extremely vulnerable to compiler changes and therefore not 
> appropriate for the testsuite.
>  
Yes, that is a real problem of tests for insn scheduler.  Even if they 
are extracted and made small they become obsolete pretty soon because 
generated code changes every day.

> Bootstrapped and regtested on s390, s390x and i686.
>
> OK? Please commit at mainline if so.
>  
It could be used for solving the problem.  But it results in inaccuarate 
simulated clock and as consequence potentially worse code.  The insn in 
the group should be issued on right time.  So the problem should solved 
by advacning clock not changing cost.  I'll try to make a patch on this 
week and send you for testing.  If it is ok, we can commit it in the 
mainline.

Vlad

> Bye,
>
> -Andreas-
>
> 2005-02-08  Andreas Krebbel  <krebbel1@de.ibm.com>
>
> 	* gcc/haifa-sched.c (schedule_block): Make queued sched group 
> 	insns return to ready list in the next turn.
>
>
> Index: gcc/haifa-sched.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/haifa-sched.c,v
> retrieving revision 1.251
> diff -p -c -r1.251 haifa-sched.c
> *** gcc/haifa-sched.c	24 Nov 2004 11:32:22 -0000	1.251
> --- gcc/haifa-sched.c	8 Feb 2005 07:16:10 -0000
> *************** schedule_block (int b, int rgn_n_insns)
> *** 2052,2057 ****
> --- 2052,2063 ----
>  	  if (cost >= 1)
>  	    {
>  	      queue_insn (insn, cost);
> + 	      if (SCHED_GROUP_P (insn))
> + 		{
> + 		  advance = cost;
> + 		  break;
> + 		}
> + 
>  	      continue;
>  	    }
>  
>