Re: [gnugo-devel] Crash report for OS X Segmentation fault

[Arend Bayer]

Gunnar wrote:
> Dan wrote:
> > > Yes, declaring it static fixes the problem. I'm not familiar with 
> > > contributing code or patches to gnugo, so could please one of you guys 
> > > fix it? Thanks.
> > 
> > It's already changed in the CVS. See the patch:
> > 
> > http://www.gnu.org/software/gnugo/patches/static_moyo_1_20.1
> 
> Here's a different solution which substantially reduces the memory
> requirements for that function.

As the gnu mail server seems to have some problems (e.g. I got trevor's latest
patch with 2 days delay) I don't know whether you already got my previous
message where I mentioned a similar patch in preparation. My patch just
reduces the array size in the declaration of moyo_is_adjacent to the size
actually needed. (When I wrote the original declaration, I must have
assumed that the moyo size is stored in the draon array, not the dragon2
array.)

Compared to Gunnar's solution, this patch may need a little more memory
but should be slightly faster. I have no strong feelings about which one
might be preferrable.

-Arend


Index: engine/dragon.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/dragon.c,v
retrieving revision 1.44
diff -u -r1.44 dragon.c
--- engine/dragon.c     8 Jan 2002 22:34:14 -0000       1.44
+++ engine/dragon.c     10 Jan 2002 22:41:25 -0000
@@ -1577,32 +1577,34 @@
   int i, j;
   int pos;
   int m, n;
-  int result[MAX_BOARD * MAX_BOARD];
-  static int moyo_is_adjacent[MAX_BOARD * MAX_BOARD][MAX_MOYOS + 1];
+  int result[number_of_dragons];
   struct moyo_data moyos;
 
   influence_get_moyo_segmentation(opposite, &moyos);
-  for (i = 0; i < number_of_dragons; i++) {
-    result[i] = 0;
-    for (j = 1; j <= moyos.number; j++)
-      moyo_is_adjacent[i][j] = 0;
-  }
-  
-  for (m = 0; m < board_size; m++)
-    for (n = 0; n < board_size; n++) {
-      pos = POS(m, n);
-      if (moyos.segmentation[pos] != 0
-          && board[pos] == moyos.owner[moyos.segmentation[pos]])
-        moyo_is_adjacent[dragon[pos].id][moyos.segmentation[pos]] = 1; 
+  {
+    int moyo_is_adjacent[number_of_dragons][moyos.number + 1];
+    for (i = 0; i < number_of_dragons; i++) {
+      result[i] = 0;
+      for (j = 1; j <= moyos.number; j++)
+        moyo_is_adjacent[i][j] = 0;
     }
   
-  for (i = 0; i < number_of_dragons; i++) {
-    for (j = 1; j <= moyos.number; j++) {
-      if (moyo_is_adjacent[i][j])
-         result[i] += moyos.size[j];
+    for (m = 0; m < board_size; m++)
+      for (n = 0; n < board_size; n++) {
+        pos = POS(m, n);
+        if (moyos.segmentation[pos] != 0
+            && board[pos] == moyos.owner[moyos.segmentation[pos]])
+          moyo_is_adjacent[dragon[pos].id][moyos.segmentation[pos]] = 1; 
+      }
+  
+    for (i = 0; i < number_of_dragons; i++) {
+      for (j = 1; j <= moyos.number; j++) {
+        if (moyo_is_adjacent[i][j])
+           result[i] += moyos.size[j];
+      }
+      if (result[i] < dragon2[i].moyo)
+         dragon2[i].moyo = result[i];
     }
-    if (result[i] < dragon2[i].moyo)
-       dragon2[i].moyo = result[i];
   }
 }