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Introduce 'follow up' moves

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When we have a fail-high of a quiet move, store it in
a Followupmoves table indexed by the previous move of
the same color (instead of immediate previous move as
is in countermoves case).

Then use this table for quiet moves ordering in the same
way we are already doing with countermoves.

These followup moves will be tried just after countermoves
and before remaining quiet moves.

Passed both short TC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 10350 W: 1998 L: 1866 D: 6486

And long TC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 14066 W: 2303 L: 2137 D: 9626

bench: 7205153
This commit is contained in:
Stefan Geschwentner
2014-01-12 22:42:16 +01:00
committed by unknown
parent 402a7ae151
commit 53ab32ef0b
4 changed files with 42 additions and 13 deletions
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src/search.cpp
+18 -7
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@@ -83,7 +83,7 @@ namespace {
Value DrawValue[COLOR_NB];
HistoryStats History;
GainsStats Gains;
CountermovesStats Countermoves;
MovesStats Countermoves, Followupmoves;
template <NodeType NT>
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
@@ -304,6 +304,7 @@ namespace {
History.clear();
Gains.clear();
Countermoves.clear();
Followupmoves.clear();
PVSize = Options["MultiPV"];
Skill skill(Options["Skill Level"]);
@@ -499,7 +500,7 @@ namespace {
moveCount = quietCount = 0;
bestValue = -VALUE_INFINITE;
ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
(ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
@@ -532,7 +533,7 @@ namespace {
excludedMove = ss->excludedMove;
posKey = excludedMove ? pos.exclusion_key() : pos.key();
tte = TT.probe(posKey);
ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
// At PV nodes we check for exact scores, whilst at non-PV nodes we check for
@@ -550,7 +551,7 @@ namespace {
TT.refresh(tte);
ss->currentMove = ttMove; // Can be MOVE_NONE
// If ttMove is quiet, update killers, history, and counter move on TT hit
// If ttMove is quiet, update killers, history, counter move and followup move on TT hit
if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove) && !inCheck)
update_stats(pos, ss, ttMove, depth, NULL, 0);
@@ -712,7 +713,11 @@ moves_loop: // When in check and at SpNode search starts from here
Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first,
Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second };
MovePicker mp(pos, ttMove, depth, History, countermoves, ss);
Square prevOwnMoveSq = to_sq((ss-2)->currentMove);
Move followupmoves[] = { Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].first,
Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].second };
MovePicker mp(pos, ttMove, depth, History, countermoves, followupmoves, ss);
CheckInfo ci(pos);
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
improving = ss->staticEval >= (ss-2)->staticEval
@@ -1029,7 +1034,7 @@ moves_loop: // When in check and at SpNode search starts from here
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
depth, bestMove, ss->staticEval);
// Quiet best move: update killers, history and countermoves
// Quiet best move: update killers, history, countermoves and followupmoves
if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
@@ -1264,7 +1269,7 @@ moves_loop: // When in check and at SpNode search starts from here
}
// update_stats() updates killers, history and countermoves stats after a fail-high
// update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
// of a quiet move.
void update_stats(Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
@@ -1290,6 +1295,12 @@ moves_loop: // When in check and at SpNode search starts from here
Square prevMoveSq = to_sq((ss-1)->currentMove);
Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, move);
}
if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove)
{
Square prevOwnMoveSq = to_sq((ss-2)->currentMove);
Followupmoves.update(pos.piece_on(prevOwnMoveSq), prevOwnMoveSq, move);
}
}