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Code Issues Releases Wiki Activity

Remove lowPly history

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Seems that after pull request #3731 (Capping stat bonus at 2000) this
heuristic is no longer useful.

STC:
https://tests.stockfishchess.org/tests/view/61b8d0e2dffbe89a35815444
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 30672 W: 7974 L: 7812 D: 14886
Ptnml(0-2): 106, 3436, 8072, 3634, 88

LTC:
https://tests.stockfishchess.org/tests/view/61b8e90cdffbe89a35815a67
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 42448 W: 10884 L: 10751 D: 20813
Ptnml(0-2): 23, 4394, 12267, 4507, 33

closes https://github.com/official-stockfish/Stockfish/pull/3853

bench: 4474950
This commit is contained in:
pb00067 2021-12-15 08:49:44 +01:00 • committed by Stéphane Nicolet
parent 0889210262
commit dc5d9bdfee
5 changed files with 27 additions and 52 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

28
src/movepick.cpp
View file

@ -56,11 +56,14 @@ namespace {
/// ordering is at the current node.
/// MovePicker constructor for the main search
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const LowPlyHistory* lp,
const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, const Move* killers, int pl)
: pos(p), mainHistory(mh), lowPlyHistory(lp), captureHistory(cph), continuationHistory(ch),
ttMove(ttm), refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d), ply(pl) {
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
const CapturePieceToHistory* cph,
const PieceToHistory** ch,
Move cm,
const Move* killers)
: pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch),
ttMove(ttm), refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}}, depth(d)
{
assert(d > 0);
stage = (pos.checkers() ? EVASION_TT : MAIN_TT) +
@ -69,9 +72,11 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist
/// MovePicker constructor for quiescence search
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
const CapturePieceToHistory* cph, const PieceToHistory** ch, Square rs)
: pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch), ttMove(ttm), recaptureSquare(rs), depth(d) {
const CapturePieceToHistory* cph,
const PieceToHistory** ch,
Square rs)
: pos(p), mainHistory(mh), captureHistory(cph), continuationHistory(ch), ttMove(ttm), recaptureSquare(rs), depth(d)
{
assert(d <= 0);
stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) +
@ -83,8 +88,8 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist
/// MovePicker constructor for ProbCut: we generate captures with SEE greater
/// than or equal to the given threshold.
MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph)
: pos(p), captureHistory(cph), ttMove(ttm), threshold(th) {
: pos(p), captureHistory(cph), ttMove(ttm), threshold(th)
{
assert(!pos.checkers());
stage = PROBCUT_TT + !(ttm && pos.capture(ttm)
@ -110,8 +115,7 @@ void MovePicker::score() {
+ 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
+ (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
+ (*continuationHistory[3])[pos.moved_piece(m)][to_sq(m)]
+ (*continuationHistory[5])[pos.moved_piece(m)][to_sq(m)]
+ (ply < MAX_LPH ? 6 * (*lowPlyHistory)[ply][from_to(m)] : 0);
+ (*continuationHistory[5])[pos.moved_piece(m)][to_sq(m)];
else // Type == EVASIONS
{

22
src/movepick.h
View file

@ -88,12 +88,6 @@ enum StatsType { NoCaptures, Captures };
/// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
typedef Stats<int16_t, 14365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
/// At higher depths LowPlyHistory records successful quiet moves near the root
/// and quiet moves which are/were in the PV (ttPv). LowPlyHistory is populated during
/// iterative deepening and at each new search the data is shifted down by 2 plies
constexpr int MAX_LPH = 4;
typedef Stats<int16_t, 10692, MAX_LPH, int(SQUARE_NB) * int(SQUARE_NB)> LowPlyHistory;
/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
/// move, see www.chessprogramming.org/Countermove_Heuristic
typedef Stats<Move, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;
@ -123,18 +117,16 @@ class MovePicker {
public:
MovePicker(const MovePicker&) = delete;
MovePicker& operator=(const MovePicker&) = delete;
MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
const CapturePieceToHistory*,
const PieceToHistory**,
Move,
const Move*);
MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
const CapturePieceToHistory*,
const PieceToHistory**,
Square);
MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
const LowPlyHistory*,
const CapturePieceToHistory*,
const PieceToHistory**,
Move,
const Move*,
int);
MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
Move next_move(bool skipQuiets = false);
private:
@ -145,7 +137,6 @@ private:
const Position& pos;
const ButterflyHistory* mainHistory;
const LowPlyHistory* lowPlyHistory;
const CapturePieceToHistory* captureHistory;
const PieceToHistory** continuationHistory;
Move ttMove;
@ -154,7 +145,6 @@ private:
Square recaptureSquare;
Value threshold;
Depth depth;
int ply;
ExtMove moves[MAX_MOVES];
};

27
src/search.cpp
View file

@ -141,7 +141,7 @@ namespace {
Value value_from_tt(Value v, int ply, int r50c);
void update_pv(Move* pv, Move move, Move* childPv);
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth);
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus);
void update_all_stats(const Position& pos, Stack* ss, Move bestMove, Value bestValue, Value beta, Square prevSq,
Move* quietsSearched, int quietCount, Move* capturesSearched, int captureCount, Depth depth);
@ -317,9 +317,6 @@ void Thread::search() {
mainThread->iterValue[i] = mainThread->bestPreviousScore;
}
std::copy(&lowPlyHistory[2][0], &lowPlyHistory.back().back() + 1, &lowPlyHistory[0][0]);
std::fill(&lowPlyHistory[MAX_LPH - 2][0], &lowPlyHistory.back().back() + 1, 0);
size_t multiPV = size_t(Options["MultiPV"]);
Skill skill(Options["Skill Level"], Options["UCI_LimitStrength"] ? int(Options["UCI_Elo"]) : 0);
@ -666,14 +663,6 @@ namespace {
if (!excludedMove)
ss->ttPv = PvNode || (ss->ttHit && tte->is_pv());
// Update low ply history for previous move if we are near root and position is or has been in PV
if ( ss->ttPv
&& depth > 12
&& ss->ply - 1 < MAX_LPH
&& !priorCapture
&& is_ok((ss-1)->currentMove))
thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5);
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
&& ss->ttHit
@ -689,7 +678,7 @@ namespace {
{
// Bonus for a quiet ttMove that fails high
if (!ttCapture)
update_quiet_stats(pos, ss, ttMove, stat_bonus(depth), depth);
update_quiet_stats(pos, ss, ttMove, stat_bonus(depth));
// Extra penalty for early quiet moves of the previous ply
if ((ss-1)->moveCount <= 2 && !priorCapture)
@ -973,12 +962,10 @@ moves_loop: // When in check, search starts here
Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
&thisThread->lowPlyHistory,
&captureHistory,
contHist,
countermove,
ss->killers,
ss->ply);
ss->killers);
value = bestValue;
moveCountPruning = false;
@ -1708,7 +1695,7 @@ moves_loop: // When in check, search starts here
if (!pos.capture_or_promotion(bestMove))
{
// Increase stats for the best move in case it was a quiet move
update_quiet_stats(pos, ss, bestMove, bonus2, depth);
update_quiet_stats(pos, ss, bestMove, bonus2);
// Decrease stats for all non-best quiet moves
for (int i = 0; i < quietCount; ++i)
@ -1755,7 +1742,7 @@ moves_loop: // When in check, search starts here
// update_quiet_stats() updates move sorting heuristics
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus, int depth) {
void update_quiet_stats(const Position& pos, Stack* ss, Move move, int bonus) {
// Update killers
if (ss->killers[0] != move)
@ -1775,10 +1762,6 @@ moves_loop: // When in check, search starts here
Square prevSq = to_sq((ss-1)->currentMove);
thisThread->counterMoves[pos.piece_on(prevSq)][prevSq] = move;
}
// Update low ply history
if (depth > 11 && ss->ply < MAX_LPH)
thisThread->lowPlyHistory[ss->ply][from_to(move)] << stat_bonus(depth - 7);
}
// When playing with strength handicap, choose best move among a set of RootMoves

1
src/thread.cpp
View file

@ -59,7 +59,6 @@ void Thread::clear() {
counterMoves.fill(MOVE_NONE);
mainHistory.fill(0);
lowPlyHistory.fill(0);
captureHistory.fill(0);
for (bool inCheck : { false, true })

1
src/thread.h
View file

@ -77,7 +77,6 @@ public:
Value rootDelta;
CounterMoveHistory counterMoves;
ButterflyHistory mainHistory;
LowPlyHistory lowPlyHistory;
CapturePieceToHistory captureHistory;
ContinuationHistory continuationHistory[2][2];
Score trend;