Re: [gnugo-devel] Owl threats

[Gunnar Farneback]

Dan wrote (on January 19):
> Previously I put up a patch called owl_threats_1_22.1 which
> made the owl threat computation optional. I added this
> to the CVS.
> 
> Taking out the owl threat computation gives a very
> substantial speedup. It does break some regressions.
> 
> The version I tested it on omits some patches that are now
> in the CVS so you probably won't get identical results.
> I ran two similarly patched GNU Go processes and with
> the owl threats disabled we got 74 PASS and 42 FAIL
> where the version which computed the owl threats gave
> 59 PASS and 16 FAIL.

There's a bug in the patch giving the effect that also worm threats
have been disabled, which I don't think was the purpose. This breaks
e.g. Arend:36. Trevor later added a pattern CF3 in endgame.db to solve
this test case, but with worm threats working the pattern is
redundant.

The patch below fixes the bug and makes the
disable_threat_computations variable (needed by aftermath) independent
from the owl_threats variable.

/Gunnar

Index: engine/aftermath.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/aftermath.c,v
retrieving revision 1.19
diff -u -r1.19 aftermath.c
--- engine/aftermath.c  19 Jan 2002 16:11:16 -0000      1.19
+++ engine/aftermath.c  4 Feb 2002 12:02:41 -0000
@@ -727,8 +727,7 @@
   }
   
   /* Reenable worm and dragon threats and endgame patterns. */
-  if (owl_threats)
-    disable_threat_computation = 0;
+  disable_threat_computation = 0;
   disable_endgame_patterns   = 0;
 }
 
Index: engine/dragon.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/dragon.c,v
retrieving revision 1.50
diff -u -r1.50 dragon.c
--- engine/dragon.c     2 Feb 2002 10:27:16 -0000       1.50
+++ engine/dragon.c     4 Feb 2002 12:02:42 -0000
@@ -500,7 +500,8 @@
            dragon[ii].owl_defense_point = NO_MOVE;
            dragon[ii].owl_defense_code = 0;
            if (level >= 8
-               && !disable_threat_computation) {
+               && !disable_threat_computation
+               && owl_threats) {
              if (owl_threaten_defense(ii, &defense_point,
                                       &second_defense_point)) {
                dragon[ii].owl_threat_status = CAN_THREATEN_DEFENSE;
@@ -527,7 +528,8 @@
          dragon[ii].owl_attack_point = NO_MOVE;
          dragon[ii].owl_attack_code = 0;
          if (level >= 8
-             && !disable_threat_computation) {
+             && !disable_threat_computation
+             && owl_threats) {
            if (owl_threaten_attack(ii, &attack_point, &second_attack_point)) {
              dragon[ii].owl_threat_status = CAN_THREATEN_ATTACK;
              dragon[ii].owl_attack_point = attack_point;
Index: engine/genmove.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/genmove.c,v
retrieving revision 1.27
diff -u -r1.27 genmove.c
--- engine/genmove.c    2 Feb 2002 19:05:12 -0000       1.27
+++ engine/genmove.c    4 Feb 2002 12:02:42 -0000
@@ -341,8 +341,6 @@
   val = -1; 
   if (get_level(&level))
     fprintf(stderr, "level = %d\n", level);
-  if (!owl_threats)
-    disable_threat_computation = 1;
   
   /* experimental level adapter */
   clock_adapt_level(&level, color);