[gnugo-devel] clear_cache mystery

[Gunnar Farnebäck]

Apply the patch at
http://trac.gnugo.org/gnugo/attachment/ticket/199/gunnar_7_12.9.diff
which is no more complex than this:

--- a/engine/owl.c
+++ b/engine/owl.c
@@ -1027,7 +1027,10 @@ do_owl_analyze_semeai(int apos, int bpos,

       if (board[pos] == EMPTY && !mw[pos]) {
        if (liberty_of_goal(pos, owlb)) {
-         if (!liberty_of_goal(pos, owla)) {
+         int origin = owlb->my_eye[pos].origin;
+         if (!liberty_of_goal(pos, owla)
+             && !(owlb->my_eye[origin].color == owlb->color
+                  && max_eyes(&owlb->my_eye[origin].value) > 0)) {
            /* outside liberty */
            if (safe_move(pos, color) == WIN) {
              safe_outside_liberty_found = 1;

Then build and go to the regression directory. Start GNU Go with

../interface/gnugo --mode gtp

and paste in the following commands:

1 loadsgf games/CrazyStone1.sgf 56
2 analyze_semeai D9 G3
3 analyze_semeai D9 G3
4 clear_cache
5 analyze_semeai D9 G3

The result turns out to be:

=1 white

=2 1 1 H2

=3 1 1 H2

=4

=5 1 2 H2

I.e. after doing clear_cache the semeai reading changes result. What's
going on here? Am I doing something stupid in my patch or is something
broken with clear_cache?

(This is testcase semeai:133 and contrary to the test suite the
correct result is 1 1 H2. But that's beside the point here.)

/Gunnar