Re: [gnugo-devel] GNU Go 3.5.7 and latest CVS crash in KGS game

[Gunnar Farnebäck]

Tom wrote:
> My robot (GnuGoCVS) blew chunks on move 127 of the attached game.  The 
> following will cause an assertion failure with 3.5.7 and the latest CVS:
> 
> # gnugo -l 2004-06-03-R-no-GnuGoCVS.sgf -L 127
> 
> ***assertion failure:
> owl.c:1408 - board[move] == EMPTY near J19***

Thanks for the report. This seems to be a fairly serious problem,
where the tactical reading retrieves an occupied attack point from the
(non-persistent) cache. If someone wants to help with it, add the
patch below to get an assertion error closer to where the problem is.

Btw, this is nothing that valgrind catches.

/Gunnar

Index: engine/reading.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/reading.c,v
retrieving revision 1.145
diff -u -r1.145 reading.c
--- engine/reading.c    2 Jun 2004 20:28:45 -0000       1.145
+++ engine/reading.c    6 Jun 2004 02:43:43 -0000
@@ -2962,6 +2962,9 @@
                &retval, NULL, &xpos) == 2) {
     TRACE_CACHED_RESULT(retval, xpos);
     SGFTRACE(xpos, retval, "cached");
+    if (retval != 0) {
+      ASSERT1(board[xpos] == EMPTY, xpos);
+    }
     if (move)
       *move = xpos;
     return retval;