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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
Download Patch File Download Diff File Expand all files Collapse all files
src/search.cpp
+5 -22
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