Re: Make max_issue honor issue_rate

[Jie Zhang <jie at codesourcery dot com>]

On 10/23/2010 02:35 AM, Jie Zhang wrote:
> On 10/21/2010 12:41 AM, Jie Zhang wrote:
> > Hi,
> >
> > This patch is an improvement of the patch I posted before:
> >
> > http://gcc.gnu.org/ml/gcc/2010-10/msg00278.html
> >
> > According to the replies to that email, it seems both dropping
> > ISSUE_POINTS and making max_issue honor issue_rate are good. So I clean
> > it up and resubmit it here for review and approval.
> >
> > This new patch does not enable "gcc_assert (more_issue >= 0);" since
> > it's belongs to another issue and I have sent a patch for that.
> >
> > I also added a new gcc_assert:
> >
> > gcc_assert (memcmp (top->state, state, dfa_state_size) != 0);
> >
> > This is mainly for testing purpose. I will remove it if the test results
> > are good.
> >
> > It's already bootstrapped on x86_64-unknown-linux-gnu. The regression
> > testing is going on. Is it OK if no regressions are found?
> The regression testing is OK on x86_64-unknown-linux-gnu. The updated
> patch is attached. OK?
Update the patch against the latest SVN trunk.


--
Jie Zhang
CodeSourcery

	* haifa-sched.c (ISSUE_POINTS): Remove.
	(struct choice_entry): Remove field n.
	(max_issue): Don't issue more than issue_rate instructions.

Index: haifa-sched.c
===================================================================
--- haifa-sched.c	(revision 165924)
+++ haifa-sched.c	(working copy)
@@ -199,10 +199,6 @@ struct common_sched_info_def *common_sch
 /* The minimal value of the INSN_TICK of an instruction.  */
 #define MIN_TICK (-max_insn_queue_index)
 
-/* Issue points are used to distinguish between instructions in max_issue ().
-   For now, all instructions are equally good.  */
-#define ISSUE_POINTS(INSN) 1
-
 /* List of important notes we must keep around.  This is a pointer to the
    last element in the list.  */
 rtx note_list;
@@ -2401,8 +2397,6 @@ struct choice_entry
   int index;
   /* The number of the rest insns whose issues we should try.  */
   int rest;
-  /* The number of issued essential insns.  */
-  int n;
   /* State after issuing the insn.  */
   state_t state;
 };
@@ -2444,8 +2438,7 @@ static int cached_issue_rate = 0;
    insns is insns with the best rank (the first insn in READY).  To
    make this function tries different samples of ready insns.  READY
    is current queue `ready'.  Global array READY_TRY reflects what
-   insns are already issued in this try.  MAX_POINTS is the sum of points
-   of all instructions in READY.  The function stops immediately,
+   insns are already issued in this try.  The function stops immediately,
    if it reached the such a solution, that all instruction can be issued.
    INDEX will contain index of the best insn in READY.  The following
    function is used only for first cycle multipass scheduling.
@@ -2458,7 +2451,7 @@ int
 max_issue (struct ready_list *ready, int privileged_n, state_t state,
 	   int *index)
 {
-  int n, i, all, n_ready, best, delay, tries_num, max_points;
+  int i, all, n_ready, best, delay, tries_num;
   int more_issue;
   struct choice_entry *top;
   rtx insn;
@@ -2477,19 +2470,9 @@ max_issue (struct ready_list *ready, int
     }
 
   /* Init max_points.  */
-  max_points = 0;
   more_issue = issue_rate - cycle_issued_insns;
   gcc_assert (more_issue >= 0);
 
-  for (i = 0; i < n_ready; i++)
-    if (!ready_try [i])
-      {
-	if (more_issue-- > 0)
-	  max_points += ISSUE_POINTS (ready_element (ready, i));
-	else
-	  break;
-      }
-
   /* The number of the issued insns in the best solution.  */
   best = 0;
 
@@ -2498,7 +2481,6 @@ max_issue (struct ready_list *ready, int
   /* Set initial state of the search.  */
   memcpy (top->state, state, dfa_state_size);
   top->rest = dfa_lookahead;
-  top->n = 0;
 
   /* Count the number of the insns to search among.  */
   for (all = i = 0; i < n_ready; i++)
@@ -2514,16 +2496,23 @@ max_issue (struct ready_list *ready, int
 	     been asked...  */
 	  top->rest == 0
 	  /* Or have nothing else to try.  */
-	  || i >= n_ready)
+	  || i >= n_ready
+	  /* Or can't issue more.  */
+	  || top - choice_stack >= more_issue)
 	{
 	  /* ??? (... || i == n_ready).  */
 	  gcc_assert (i <= n_ready);
 
+	  /* We should not issue more than issue_rate instructions.  */
+	  gcc_assert (top - choice_stack <= more_issue);
+
 	  if (top == choice_stack)
 	    break;
 
 	  if (best < top - choice_stack)
 	    {
+	      int n;
+
 	      if (privileged_n)
 		{
 		  n = privileged_n;
@@ -2541,7 +2530,7 @@ max_issue (struct ready_list *ready, int
 		  /* This is the index of the insn issued first in this
 		     solution.  */
 		  *index = choice_stack [1].index;
-		  if (top->n == max_points || best == all)
+		  if (top - choice_stack == more_issue || best == all)
 		    break;
 		}
 	    }
@@ -2572,16 +2561,11 @@ max_issue (struct ready_list *ready, int
 	      else
 		top->rest--;
 
-	      n = top->n;
-	      if (memcmp (top->state, state, dfa_state_size) != 0)
-		n += ISSUE_POINTS (insn);
-
 	      /* Advance to the next choice_entry.  */
 	      top++;
 	      /* Initialize it.  */
 	      top->rest = dfa_lookahead;
 	      top->index = i;
-	      top->n = n;
 	      memcpy (top->state, state, dfa_state_size);
 
 	      ready_try [i] = 1;