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Implement post futility pruning

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and prevent futility pruning from pruning
castling moves

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski
2010-01-21 19:03:06 +02:00
committed by Marco Costalba
parent 22b8dc8c98
commit 05a8c318b8
1 changed files with 11 additions and 10 deletions
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21
src/search.cpp
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@@ -703,6 +703,7 @@ namespace {
// Initialize
TT.new_search();
H.clear();
MG.clear();
init_ss_array(ss);
IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
Iteration = 1;
@@ -1428,6 +1429,10 @@ namespace {
MG.store(pos.piece_on(move_to(m)), move_from(m), move_to(m), ss[ply - 1].eval, -ss[ply].eval);
}
// Post futility pruning
if (staticValue - FutilityValueMargin >= beta)
return (staticValue - FutilityValueMargin);
// Null move search
if ( allowNullmove
&& depth > OnePly
@@ -1555,6 +1560,7 @@ namespace {
if ( useFutilityPruning
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
&& move != ttMove)
{
// Move count based pruning
@@ -2509,9 +2515,8 @@ namespace {
Square mfrom, mto, tfrom, tto;
// Prune if there isn't any threat move and
// is not a castling move (common case).
if (threat == MOVE_NONE && !move_is_castle(m))
// Prune if there isn't any threat move
if (threat == MOVE_NONE)
return true;
mfrom = move_from(m);
@@ -2519,15 +2524,11 @@ namespace {
tfrom = move_from(threat);
tto = move_to(threat);
// Case 1: Castling moves are never pruned
if (move_is_castle(m))
return false;
// Case 2: Don't prune moves which move the threatened piece
// Case 1: Don't prune moves which move the threatened piece
if (mfrom == tto)
return false;
// Case 3: If the threatened piece has value less than or equal to the
// Case 2: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune move which defend it.
if ( pos.move_is_capture(threat)
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
@@ -2535,7 +2536,7 @@ namespace {
&& pos.move_attacks_square(m, tto))
return false;
// Case 4: If the moving piece in the threatened move is a slider, don't
// Case 3: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
if ( piece_is_slider(pos.piece_on(tfrom))
&& bit_is_set(squares_between(tfrom, tto), mto)