Avoid exponential runtime

From-SVN: r40145

gcc/ChangeLog

+2001-03-01  Bernd Schmidt  <bernds@redhat.com>
+
+	* sched-int.h (struct haifa_insn_data): Add new member priority_known.
+	(INSN_PRIORITY_KNOWN): New accessor macro.
+	* haifa-sched.c (priority): Use it instead of testing priority against
+	zero.
+
 2001-02-28  DJ Delorie  <dj@redhat.com>
 
 	* config/m68k/m68k.h (MOVE_BY_PIECES_P): Avoid pushing bytes,

gcc/haifa-sched.c

@@ -719,38 +719,43 @@ static int
 priority (insn)
      rtx insn;
 {
-  int this_priority;
   rtx link;
 
   if (! INSN_P (insn))
     return 0;
 
-  if ((this_priority = INSN_PRIORITY (insn)) == 0)
+  if (! INSN_PRIORITY_KNOWN (insn))
     {
+      int this_priority = 0;
+
       if (INSN_DEPEND (insn) == 0)
 	this_priority = insn_cost (insn, 0, 0);
       else
-	for (link = INSN_DEPEND (insn); link; link = XEXP (link, 1))
-	  {
-	    rtx next;
-	    int next_priority;
+	{
+	  for (link = INSN_DEPEND (insn); link; link = XEXP (link, 1))
+	    {
+	      rtx next;
+	      int next_priority;
 
-	    if (RTX_INTEGRATED_P (link))
-	      continue;
+	      if (RTX_INTEGRATED_P (link))
+		continue;
 
-	    next = XEXP (link, 0);
+	      next = XEXP (link, 0);
 
-	    /* Critical path is meaningful in block boundaries only.  */
-	    if (! (*current_sched_info->contributes_to_priority) (next, insn))
-	      continue;
+	      /* Critical path is meaningful in block boundaries only.  */
+	      if (! (*current_sched_info->contributes_to_priority) (next, insn))
+		continue;
 
-	    next_priority = insn_cost (insn, link, next) + priority (next);
-	    if (next_priority > this_priority)
-	      this_priority = next_priority;
-	  }
+	      next_priority = insn_cost (insn, link, next) + priority (next);
+	      if (next_priority > this_priority)
+		this_priority = next_priority;
+	    }
+	}
       INSN_PRIORITY (insn) = this_priority;
+      INSN_PRIORITY_KNOWN (insn) = 1;
     }
-  return this_priority;
+
+  return INSN_PRIORITY (insn);
 }
 
 /* Macros and functions for keeping the priority queue sorted, and

gcc/sched-int.h

@@ -198,6 +198,9 @@ struct haifa_insn_data
      moved load insn and this one.  */
   unsigned int fed_by_spec_load : 1;
   unsigned int is_load_insn : 1;
+
+  /* Nonzero if priority has been computed already.  */
+  unsigned int priority_known : 1;
 };
 
 extern struct haifa_insn_data *h_i_d;
@@ -209,6 +212,7 @@ extern struct haifa_insn_data *h_i_d;
 #define CANT_MOVE(insn)		(h_i_d[INSN_UID (insn)].cant_move)
 #define INSN_DEP_COUNT(INSN)	(h_i_d[INSN_UID (INSN)].dep_count)
 #define INSN_PRIORITY(INSN)	(h_i_d[INSN_UID (INSN)].priority)
+#define INSN_PRIORITY_KNOWN(INSN) (h_i_d[INSN_UID (INSN)].priority_known)
 #define INSN_COST(INSN)		(h_i_d[INSN_UID (INSN)].cost)
 #define INSN_UNIT(INSN)		(h_i_d[INSN_UID (INSN)].units)
 #define INSN_REG_WEIGHT(INSN)	(h_i_d[INSN_UID (INSN)].reg_weight)