Skip to content

Commit

Permalink
VVLTC search tune
Browse files Browse the repository at this point in the history 
Parameters were tuned in 2 stages:
1. 127k games at VVLTC:
   https://tests.stockfishchess.org/tests/view/6649f8dfb8fa20e74c39f52a.
2. 106k games at VVLTC:
   https://tests.stockfishchess.org/tests/view/664bfb77830eb9f886615a9d.

Passed VVLTC 1st sprt:
https://tests.stockfishchess.org/tests/view/664e8dd9928b1fb18de4e410
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 20466 W: 5340 L: 5093 D: 10033
Ptnml(0-2): 0, 1796, 6397, 2037, 3

Passed VVLTC 2nd sprt:
https://tests.stockfishchess.org/tests/view/664eb4aa928b1fb18de4e47d
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 15854 W: 4186 L: 3934 D: 7734
Ptnml(0-2): 1, 1367, 4938, 1621, 0

closes official-stockfish#5286

Bench: 1558110
  • Loading branch information
@XInTheDark @Disservin
XInTheDark authored and Disservin committed May 23, 2024
1 parent 365aa85 commit 61acbfc
Showing 1 changed file with 44 additions and 44 deletions.
88 changes: 44 additions & 44 deletions src/search.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,9 +60,9 @@ static constexpr double EvalLevel[10] = {0.981, 0.956, 0.895, 0.949, 0.913,

// Futility margin
Value futility_margin(Depth d, bool noTtCutNode, bool improving, bool oppWorsening) {
Value futilityMult = 127 - 48 * noTtCutNode;
Value improvingDeduction = 65 * improving * futilityMult / 32;
Value worseningDeduction = 334 * oppWorsening * futilityMult / 1024;
Value futilityMult = 129 - 43 * noTtCutNode;
Value improvingDeduction = 56 * improving * futilityMult / 32;
Value worseningDeduction = 336 * oppWorsening * futilityMult / 1024;

return futilityMult * d - improvingDeduction - worseningDeduction;
}
Expand All @@ -74,15 +74,15 @@ constexpr int futility_move_count(bool improving, Depth depth) {
// Add correctionHistory value to raw staticEval and guarantee evaluation does not hit the tablebase range
Value to_corrected_static_eval(Value v, const Worker& w, const Position& pos) {
auto cv = w.correctionHistory[pos.side_to_move()][pawn_structure_index<Correction>(pos)];
v += cv * std::abs(cv) / 6047;
v += cv * std::abs(cv) / 5435;
return std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
}

// History and stats update bonus, based on depth
int stat_bonus(Depth d) { return std::clamp(187 * d - 288, 17, 1548); }
int stat_bonus(Depth d) { return std::clamp(205 * d - 283, 18, 1544); }

// History and stats update malus, based on depth
int stat_malus(Depth d) { return (d < 4 ? 630 * d - 281 : 1741); }
int stat_malus(Depth d) { return (d < 4 ? 767 * d - 275 : 1911); }

// Add a small random component to draw evaluations to avoid 3-fold blindness
Value value_draw(size_t nodes) { return VALUE_DRAW - 1 + Value(nodes & 0x2); }
Expand Down Expand Up @@ -312,12 +312,12 @@ void Search::Worker::iterative_deepening() {

// Reset aspiration window starting size
Value avg = rootMoves[pvIdx].averageScore;
delta = 10 + avg * avg / 9828;
delta = 9 + avg * avg / 10502;
alpha = std::max(avg - delta, -VALUE_INFINITE);
beta = std::min(avg + delta, VALUE_INFINITE);

// Adjust optimism based on root move's averageScore (~4 Elo)
optimism[us] = 116 * avg / (std::abs(avg) + 84);
optimism[us] = 122 * avg / (std::abs(avg) + 92);
optimism[~us] = -optimism[us];

// Start with a small aspiration window and, in the case of a fail
Expand Down Expand Up @@ -507,7 +507,7 @@ void Search::Worker::clear() {
h->fill(-60);

for (size_t i = 1; i < reductions.size(); ++i)
reductions[i] = int((21.69 + std::log(size_t(options["Threads"])) / 2) * std::log(i));
reductions[i] = int((19.90 + std::log(size_t(options["Threads"])) / 2) * std::log(i));

refreshTable.clear(networks);
}
Expand Down Expand Up @@ -740,7 +740,7 @@ Value Search::Worker::search(
// Use static evaluation difference to improve quiet move ordering (~9 Elo)
if (((ss - 1)->currentMove).is_ok() && !(ss - 1)->inCheck && !priorCapture)
{
int bonus = std::clamp(-11 * int((ss - 1)->staticEval + ss->staticEval), -1729, 1517);
int bonus = std::clamp(-11 * int((ss - 1)->staticEval + ss->staticEval), -1592, 1390);
bonus = bonus > 0 ? 2 * bonus : bonus / 2;
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()] << bonus;
if (type_of(pos.piece_on(prevSq)) != PAWN && ((ss - 1)->currentMove).type_of() != PROMOTION)
Expand All @@ -762,7 +762,7 @@ Value Search::Worker::search(
// Step 7. Razoring (~1 Elo)
// If eval is really low check with qsearch if it can exceed alpha, if it can't,
// return a fail low.
if (eval < alpha - 474 - 324 * depth * depth)
if (eval < alpha - 501 - 305 * depth * depth)
{
value = qsearch<NonPV>(pos, ss, alpha - 1, alpha);
if (value < alpha)
Expand All @@ -771,23 +771,23 @@ Value Search::Worker::search(

// Step 8. Futility pruning: child node (~40 Elo)
// The depth condition is important for mate finding.
if (!ss->ttPv && depth < 11
if (!ss->ttPv && depth < 12
&& eval - futility_margin(depth, cutNode && !ss->ttHit, improving, opponentWorsening)
- (ss - 1)->statScore / 252
- (ss - 1)->statScore / 248
>= beta
&& eval >= beta && eval < VALUE_TB_WIN_IN_MAX_PLY && (!ttMove || ttCapture))
return beta > VALUE_TB_LOSS_IN_MAX_PLY ? (eval + beta) / 2 : eval;

// Step 9. Null move search with verification search (~35 Elo)
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 15246
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 366 && !excludedMove
if (!PvNode && (ss - 1)->currentMove != Move::null() && (ss - 1)->statScore < 13999
&& eval >= beta && ss->staticEval >= beta - 21 * depth + 390 && !excludedMove
&& pos.non_pawn_material(us) && ss->ply >= thisThread->nmpMinPly
&& beta > VALUE_TB_LOSS_IN_MAX_PLY)
{
assert(eval - beta >= 0);

// Null move dynamic reduction based on depth and eval
Depth R = std::min(int(eval - beta) / 152, 6) + depth / 3 + 5;
Depth R = std::min(int(eval - beta) / 177, 6) + depth / 3 + 5;

ss->currentMove = Move::null();
ss->continuationHistory = &thisThread->continuationHistory[0][0][NO_PIECE][0];
Expand Down Expand Up @@ -845,7 +845,7 @@ Value Search::Worker::search(
// Step 11. ProbCut (~10 Elo)
// If we have a good enough capture (or queen promotion) and a reduced search returns a value
// much above beta, we can (almost) safely prune the previous move.
probCutBeta = beta + 176 - 65 * improving;
probCutBeta = beta + 185 - 60 * improving;
if (
!PvNode && depth > 3
&& std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY
Expand Down Expand Up @@ -901,7 +901,7 @@ Value Search::Worker::search(
moves_loop: // When in check, search starts here

// Step 12. A small Probcut idea, when we are in check (~4 Elo)
probCutBeta = beta + 440;
probCutBeta = beta + 361;
if (ss->inCheck && !PvNode && ttCapture && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 4 && ttValue >= probCutBeta
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && std::abs(beta) < VALUE_TB_WIN_IN_MAX_PLY)
Expand Down Expand Up @@ -985,15 +985,15 @@ Value Search::Worker::search(
// Futility pruning for captures (~2 Elo)
if (!givesCheck && lmrDepth < 7 && !ss->inCheck)
{
Value futilityValue = ss->staticEval + 276 + 256 * lmrDepth
Value futilityValue = ss->staticEval + 283 + 235 * lmrDepth
+ PieceValue[capturedPiece] + captHist / 7;
if (futilityValue <= alpha)
continue;
}

// SEE based pruning for captures and checks (~11 Elo)
int seeHist = std::clamp(captHist / 32, -177 * depth, 175 * depth);
if (!pos.see_ge(move, -183 * depth - seeHist))
int seeHist = std::clamp(captHist / 32, -183 * depth, 162 * depth);
if (!pos.see_ge(move, -166 * depth - seeHist))
continue;
}
else
Expand All @@ -1004,18 +1004,18 @@ Value Search::Worker::search(
+ thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()];

// Continuation history based pruning (~2 Elo)
if (lmrDepth < 6 && history < -4076 * depth)
if (lmrDepth < 6 && history < -4427 * depth)
continue;

history += 2 * thisThread->mainHistory[us][move.from_to()];

lmrDepth += history / 4401;
lmrDepth += history / 3670;

Value futilityValue =
ss->staticEval + (bestValue < ss->staticEval - 53 ? 151 : 57) + 140 * lmrDepth;
ss->staticEval + (bestValue < ss->staticEval - 51 ? 149 : 55) + 141 * lmrDepth;

// Futility pruning: parent node (~13 Elo)
if (!ss->inCheck && lmrDepth < 10 && futilityValue <= alpha)
if (!ss->inCheck && lmrDepth < 11 && futilityValue <= alpha)
{
if (bestValue <= futilityValue && std::abs(bestValue) < VALUE_TB_WIN_IN_MAX_PLY
&& futilityValue < VALUE_TB_WIN_IN_MAX_PLY)
Expand Down Expand Up @@ -1049,11 +1049,11 @@ Value Search::Worker::search(
// margins scale well.

if (!rootNode && move == ttMove && !excludedMove
&& depth >= 4 - (thisThread->completedDepth > 35) + ss->ttPv
&& depth >= 4 - (thisThread->completedDepth > 38) + ss->ttPv
&& std::abs(ttValue) < VALUE_TB_WIN_IN_MAX_PLY && (tte->bound() & BOUND_LOWER)
&& tte->depth() >= depth - 3)
{
Value singularBeta = ttValue - (57 + 50 * (ss->ttPv && !PvNode)) * depth / 64;
Value singularBeta = ttValue - (58 + 64 * (ss->ttPv && !PvNode)) * depth / 64;
Depth singularDepth = newDepth / 2;

ss->excludedMove = move;
Expand All @@ -1063,15 +1063,15 @@ Value Search::Worker::search(

if (value < singularBeta)
{
int doubleMargin = 298 * PvNode - 209 * !ttCapture;
int tripleMargin = 117 + 252 * PvNode - 270 * !ttCapture + 111 * ss->ttPv;
int quadMargin = 471 + 343 * PvNode - 281 * !ttCapture + 217 * ss->ttPv;
int doubleMargin = 304 * PvNode - 203 * !ttCapture;
int tripleMargin = 117 + 259 * PvNode - 296 * !ttCapture + 97 * ss->ttPv;
int quadMargin = 486 + 343 * PvNode - 273 * !ttCapture + 232 * ss->ttPv;

extension = 1 + (value < singularBeta - doubleMargin)
+ (value < singularBeta - tripleMargin)
+ (value < singularBeta - quadMargin);

depth += ((!PvNode) && (depth < 15));
depth += ((!PvNode) && (depth < 16));
}

// Multi-cut pruning
Expand Down Expand Up @@ -1101,7 +1101,7 @@ Value Search::Worker::search(
else if (PvNode && move == ttMove && move.to_sq() == prevSq
&& thisThread->captureHistory[movedPiece][move.to_sq()]
[type_of(pos.piece_on(move.to_sq()))]
> 3748)
> 3988)
extension = 1;
}

Expand Down Expand Up @@ -1157,10 +1157,10 @@ Value Search::Worker::search(

ss->statScore = 2 * thisThread->mainHistory[us][move.from_to()]
+ (*contHist[0])[movedPiece][move.to_sq()]
+ (*contHist[1])[movedPiece][move.to_sq()] - 5266;
+ (*contHist[1])[movedPiece][move.to_sq()] - 5169;

// Decrease/increase reduction for moves with a good/bad history (~8 Elo)
r -= ss->statScore / (14519 - std::min(depth, 15) * 103);
r -= ss->statScore / (12219 - std::min(depth, 13) * 120);

// Step 17. Late moves reduction / extension (LMR, ~117 Elo)
if (depth >= 2 && moveCount > 1 + rootNode)
Expand All @@ -1179,7 +1179,7 @@ Value Search::Worker::search(
{
// Adjust full-depth search based on LMR results - if the result
// was good enough search deeper, if it was bad enough search shallower.
const bool doDeeperSearch = value > (bestValue + 40 + 2 * newDepth); // (~1 Elo)
const bool doDeeperSearch = value > (bestValue + 36 + 2 * newDepth); // (~1 Elo)
const bool doShallowerSearch = value < bestValue + newDepth; // (~2 Elo)

newDepth += doDeeperSearch - doShallowerSearch;
Expand Down Expand Up @@ -1340,9 +1340,9 @@ Value Search::Worker::search(
// Bonus for prior countermove that caused the fail low
else if (!priorCapture && prevSq != SQ_NONE)
{
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -13241)
+ ((ss - 1)->moveCount > 10) + (!ss->inCheck && bestValue <= ss->staticEval - 127)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 74);
int bonus = (depth > 4) + (depth > 5) + (PvNode || cutNode) + ((ss - 1)->statScore < -14144)
+ ((ss - 1)->moveCount > 9) + (!ss->inCheck && bestValue <= ss->staticEval - 115)
+ (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 81);
update_continuation_histories(ss - 1, pos.piece_on(prevSq), prevSq,
stat_bonus(depth) * bonus);
thisThread->mainHistory[~us][((ss - 1)->currentMove).from_to()]
Expand Down Expand Up @@ -1513,7 +1513,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
if (bestValue > alpha)
alpha = bestValue;

futilityBase = ss->staticEval + 264;
futilityBase = ss->staticEval + 279;
}

const PieceToHistory* contHist[] = {(ss - 1)->continuationHistory,
Expand Down Expand Up @@ -1585,11 +1585,11 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
+ (*contHist[1])[pos.moved_piece(move)][move.to_sq()]
+ thisThread->pawnHistory[pawn_structure_index(pos)][pos.moved_piece(move)]
[move.to_sq()]
<= 4348)
<= 4181)
continue;

// Do not search moves with bad enough SEE values (~5 Elo)
if (!pos.see_ge(move, -63))
if (!pos.see_ge(move, -67))
continue;
}

Expand Down Expand Up @@ -1655,7 +1655,7 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,

Depth Search::Worker::reduction(bool i, Depth d, int mn, int delta) {
int reductionScale = reductions[d] * reductions[mn];
return (reductionScale + 1147 - delta * 755 / rootDelta) / 1024 + (!i && reductionScale > 1125);
return (reductionScale + 1222 - delta * 733 / rootDelta) / 1024 + (!i && reductionScale > 1231);
}

// elapsed() returns the time elapsed since the search started. If the
Expand Down Expand Up @@ -1758,7 +1758,7 @@ void update_all_stats(const Position& pos,

if (!pos.capture_stage(bestMove))
{
int bestMoveBonus = bestValue > beta + 165 ? quietMoveBonus // larger bonus
int bestMoveBonus = bestValue > beta + 176 ? quietMoveBonus // larger bonus
: stat_bonus(depth); // smaller bonus

update_quiet_stats(pos, ss, workerThread, bestMove, bestMoveBonus);
Expand Down Expand Up @@ -1796,7 +1796,7 @@ void update_all_stats(const Position& pos,
// by moves at ply -1, -2, -3, -4, and -6 with current move.
void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {

bonus = bonus * 45 / 64;
bonus = bonus * 47 / 64;

for (int i : {1, 2, 3, 4, 6})
{
Expand Down

0 comments on commit 61acbfc

Please sign in to comment.