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Code Issues Releases Wiki Activity

Introduce separate butterfly history table for sorting root moves

Browse source 
Idea of this patch comes from the fact that current history heuristics
are mostly populated by low depth entries since our stat bonus reaches
maximum value at depth 5-6 and number of low depth nodes is much bigger
than number of high depth nodes. But it doesn't make a whole lost of
sense to use this low-depth centered histories to sort moves at root.
Current patch introduces special history table that is used exclusively
at root, it remembers which quiet moves were good and which quiet moves
were not good there and uses this information for move ordering.

Passed STC:
https://tests.stockfishchess.org/tests/view/66dda74adc53972b68218cc9
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 127680 W: 33579 L: 33126 D: 60975
Ptnml(0-2): 422, 15098, 32391, 15463, 466

Passed LTC:
https://tests.stockfishchess.org/tests/view/66dead2adc53972b68218d34
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 381978 W: 96958 L: 95923 D: 189097
Ptnml(0-2): 277, 42165, 105089, 43162, 296

closes https://github.com/official-stockfish/Stockfish/pull/5595

Bench: 1611283
This commit is contained in:
Michael Chaly 2024-09-14 08:22:32 +03:00 • committed by Disservin
parent 5ce7f866a5
commit 240a5b1c72
4 changed files with 53 additions and 24 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
src/movepick.cpp
View file

@ -82,16 +82,20 @@ MovePicker::MovePicker(const Position& p,
Move ttm,
Depth d,
const ButterflyHistory* mh,
const ButterflyHistory* rh,
const CapturePieceToHistory* cph,
const PieceToHistory** ch,
const PawnHistory* ph) :
const PawnHistory* ph,
bool rn) :
pos(p),
mainHistory(mh),
rootHistory(rh),
captureHistory(cph),
continuationHistory(ch),
pawnHistory(ph),
ttMove(ttm),
depth(d) {
depth(d),
rootNode(rn) {
if (pos.checkers())
stage = EVASION_TT + !(ttm && pos.pseudo_legal(ttm));
@ -174,6 +178,9 @@ void MovePicker::score() {
m.value -= (pt == QUEEN ? bool(to & threatenedByRook) * 49000
: pt == ROOK ? bool(to & threatenedByMinor) * 24335
: bool(to & threatenedByPawn) * 14900);
if (rootNode)
m.value += 4 * (*rootHistory)[pos.side_to_move()][m.from_to()];
}
else // Type == EVASIONS

6
src/movepick.h
View file

@ -171,9 +171,11 @@ class MovePicker {
Move,
Depth,
const ButterflyHistory*,
const ButterflyHistory*,
const CapturePieceToHistory*,
const PieceToHistory**,
const PawnHistory*);
const PawnHistory*,
bool);
MovePicker(const Position&, Move, int, const CapturePieceToHistory*);
Move next_move(bool skipQuiets = false);
@ -187,6 +189,7 @@ class MovePicker {
const Position& pos;
const ButterflyHistory* mainHistory;
const ButterflyHistory* rootHistory;
const CapturePieceToHistory* captureHistory;
const PieceToHistory** continuationHistory;
const PawnHistory* pawnHistory;
@ -195,6 +198,7 @@ class MovePicker {
int stage;
int threshold;
Depth depth;
bool rootNode;
ExtMove moves[MAX_MOVES];
};

59
src/search.cpp
View file

@ -101,16 +101,21 @@ Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply, int r50c);
void update_pv(Move* pv, Move move, const Move* childPv);
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
void update_quiet_histories(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus);
void update_all_stats(const Position& pos,
Stack* ss,
Search::Worker& workerThread,
Move bestMove,
Square prevSq,
ValueList<Move, 32>& quietsSearched,
ValueList<Move, 32>& capturesSearched,
Depth depth);
void update_quiet_histories(const Position& pos,
Stack* ss,
Search::Worker& workerThread,
Move move,
int bonus,
bool rootNode);
void update_all_stats(const Position& pos,
Stack* ss,
Search::Worker& workerThread,
Move bestMove,
Square prevSq,
ValueList<Move, 32>& quietsSearched,
ValueList<Move, 32>& capturesSearched,
Depth depth,
bool rootNode);
} // namespace
@ -264,6 +269,8 @@ void Search::Worker::iterative_deepening() {
int searchAgainCounter = 0;
rootHistory.fill(0);
// Iterative deepening loop until requested to stop or the target depth is reached
while (++rootDepth < MAX_PLY && !threads.stop
&& !(limits.depth && mainThread && rootDepth > limits.depth))
@ -488,6 +495,7 @@ void Search::Worker::iterative_deepening() {
// Reset histories, usually before a new game
void Search::Worker::clear() {
mainHistory.fill(0);
rootHistory.fill(0);
captureHistory.fill(-753);
pawnHistory.fill(-1152);
pawnCorrectionHistory.fill(0);
@ -622,7 +630,7 @@ Value Search::Worker::search(
{
// Bonus for a quiet ttMove that fails high (~2 Elo)
if (!ttCapture)
update_quiet_histories(pos, ss, *this, ttData.move, stat_bonus(depth));
update_quiet_histories(pos, ss, *this, ttData.move, stat_bonus(depth), rootNode);
// Extra penalty for early quiet moves of
// the previous ply (~1 Elo on STC, ~2 Elo on LTC)
@ -912,8 +920,8 @@ moves_loop: // When in check, search starts here
(ss - 6)->continuationHistory};
MovePicker mp(pos, ttData.move, depth, &thisThread->mainHistory, &thisThread->captureHistory,
contHist, &thisThread->pawnHistory);
MovePicker mp(pos, ttData.move, depth, &thisThread->mainHistory, &thisThread->rootHistory,
&thisThread->captureHistory, contHist, &thisThread->pawnHistory, rootNode);
value = bestValue;
@ -1339,7 +1347,8 @@ moves_loop: // When in check, search starts here
// If there is a move that produces search value greater than alpha,
// we update the stats of searched moves.
else if (bestMove)
update_all_stats(pos, ss, *this, bestMove, prevSq, quietsSearched, capturesSearched, depth);
update_all_stats(pos, ss, *this, bestMove, prevSq, quietsSearched, capturesSearched, depth,
rootNode);
// Bonus for prior countermove that caused the fail low
else if (!priorCapture && prevSq != SQ_NONE)
@ -1533,8 +1542,9 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta)
// Initialize a MovePicker object for the current position, and prepare to search
// the moves. We presently use two stages of move generator in quiescence search:
// captures, or evasions only when in check.
MovePicker mp(pos, ttData.move, DEPTH_QS, &thisThread->mainHistory, &thisThread->captureHistory,
contHist, &thisThread->pawnHistory);
MovePicker mp(pos, ttData.move, DEPTH_QS, &thisThread->mainHistory, &thisThread->rootHistory,
&thisThread->captureHistory, contHist, &thisThread->pawnHistory,
nodeType == Root);
// Step 5. Loop through all pseudo-legal moves until no moves remain or a beta
// cutoff occurs.
@ -1751,7 +1761,8 @@ void update_all_stats(const Position& pos,
Square prevSq,
ValueList<Move, 32>& quietsSearched,
ValueList<Move, 32>& capturesSearched,
Depth depth) {
Depth depth,
bool rootNode) {
CapturePieceToHistory& captureHistory = workerThread.captureHistory;
Piece moved_piece = pos.moved_piece(bestMove);
@ -1762,11 +1773,11 @@ void update_all_stats(const Position& pos,
if (!pos.capture_stage(bestMove))
{
update_quiet_histories(pos, ss, workerThread, bestMove, quietMoveBonus);
update_quiet_histories(pos, ss, workerThread, bestMove, quietMoveBonus, rootNode);
// Decrease stats for all non-best quiet moves
for (Move move : quietsSearched)
update_quiet_histories(pos, ss, workerThread, move, -quietMoveMalus);
update_quiet_histories(pos, ss, workerThread, move, -quietMoveMalus, rootNode);
}
else
{
@ -1808,11 +1819,17 @@ void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
// Updates move sorting heuristics
void update_quiet_histories(
const Position& pos, Stack* ss, Search::Worker& workerThread, Move move, int bonus) {
void update_quiet_histories(const Position& pos,
Stack* ss,
Search::Worker& workerThread,
Move move,
int bonus,
bool rootNode) {
Color us = pos.side_to_move();
workerThread.mainHistory[us][move.from_to()] << bonus;
if (rootNode)
workerThread.rootHistory[us][move.from_to()] << bonus;
update_continuation_histories(ss, pos.moved_piece(move), move.to_sq(), bonus);

1
src/search.h
View file

@ -278,6 +278,7 @@ class Worker {
// Public because they need to be updatable by the stats
ButterflyHistory mainHistory;
ButterflyHistory rootHistory;
CapturePieceToHistory captureHistory;
ContinuationHistory continuationHistory[2][2];
PawnHistory pawnHistory;