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Minor simplifications and cleanup in search

Browse source 
STC: https://tests.stockfishchess.org/tests/view/629d6775593a4a9b6482c1ec
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 77416 W: 20683 L: 20589 D: 36144
Ptnml(0-2): 317, 8690, 20620, 8744, 337

LTC: https://tests.stockfishchess.org/tests/view/629db4be593a4a9b6482ceef
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 106544 W: 28752 L: 28705 D: 49087
Ptnml(0-2): 97, 10692, 31641, 10751, 91

closes https://github.com/official-stockfish/Stockfish/pull/4059

Bench: 5913510
This commit is contained in:
mstembera 2022-06-05 19:32:05 -07:00 • committed by Joost VandeVondele
parent d54b85b4bd
commit 2d5dcf3d18
1 changed files with 18 additions and 22 deletions
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40
src/search.cpp
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@ -85,8 +85,8 @@ namespace {
}
// Add a small random component to draw evaluations to avoid 3-fold blindness
Value value_draw(Thread* thisThread) {
return VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
Value value_draw(const Thread* thisThread) {
return VALUE_DRAW - 1 + Value(thisThread->nodes & 0x2);
}
// Skill structure is used to implement strength limit. If we have an uci_elo then
@ -116,7 +116,7 @@ namespace {
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, Move* childPv);
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_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,
@ -635,10 +635,9 @@ namespace {
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
&& ss->ttHit
&& tte->depth() > depth - (thisThread->id() % 2 == 1)
&& tte->depth() > depth - ((int)thisThread->id() & 0x1)
&& ttValue != VALUE_NONE // Possible in case of TT access race
&& (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
: (tte->bound() & BOUND_UPPER)))
&& (tte->bound() & (ttValue >= beta ? BOUND_LOWER : BOUND_UPPER)))
{
// If ttMove is quiet, update move sorting heuristics on TT hit (~1 Elo)
if (ttMove)
@ -896,12 +895,11 @@ namespace {
if (value >= probCutBeta)
{
// if transposition table doesn't have equal or more deep info write probCut data into it
if ( !(ss->ttHit
&& tte->depth() >= depth - 3
&& ttValue != VALUE_NONE))
if (!( ss->ttHit
&& tte->depth() >= depth - 3
&& ttValue != VALUE_NONE))
tte->save(posKey, value_to_tt(value, ss->ply), ttPv,
BOUND_LOWER,
depth - 3, move, ss->staticEval);
BOUND_LOWER, depth - 3, move, ss->staticEval);
return value;
}
}
@ -1172,7 +1170,7 @@ moves_loop: // When in check, search starts here
// Decrease reduction for PvNodes based on depth
if (PvNode)
r -= 1 + 15 / ( 3 + depth );
r -= 1 + 15 / (3 + depth);
// Increase reduction if next ply has a lot of fail high else reset count to 0
if ((ss+1)->cutoffCnt > 3 && !PvNode)
@ -1450,8 +1448,7 @@ moves_loop: // When in check, search starts here
&& ss->ttHit
&& tte->depth() >= ttDepth
&& ttValue != VALUE_NONE // Only in case of TT access race
&& (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
: (tte->bound() & BOUND_UPPER)))
&& (tte->bound() & (ttValue >= beta ? BOUND_LOWER : BOUND_UPPER)))
return ttValue;
// Evaluate the position statically
@ -1567,14 +1564,14 @@ moves_loop: // When in check, search starts here
[to_sq(move)];
// Continuation history based pruning (~2 Elo)
if ( !capture
if ( !capture
&& bestValue > VALUE_TB_LOSS_IN_MAX_PLY
&& (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold
&& (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold)
continue;
// movecount pruning for quiet check evasions
if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY
if ( bestValue > VALUE_TB_LOSS_IN_MAX_PLY
&& quietCheckEvasions > 1
&& !capture
&& ss->inCheck)
@ -1675,7 +1672,7 @@ moves_loop: // When in check, search starts here
// update_pv() adds current move and appends child pv[]
void update_pv(Move* pv, Move move, Move* childPv) {
void update_pv(Move* pv, Move move, const Move* childPv) {
for (*pv++ = move; childPv && *childPv != MOVE_NONE; )
*pv++ = *childPv++;
@ -1688,19 +1685,18 @@ moves_loop: // When in check, search starts here
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) {
int bonus1, bonus2;
Color us = pos.side_to_move();
Thread* thisThread = pos.this_thread();
CapturePieceToHistory& captureHistory = thisThread->captureHistory;
Piece moved_piece = pos.moved_piece(bestMove);
PieceType captured = type_of(pos.piece_on(to_sq(bestMove)));
bonus1 = stat_bonus(depth + 1);
bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus
: stat_bonus(depth); // smaller bonus
int bonus1 = stat_bonus(depth + 1);
if (!pos.capture(bestMove))
{
int bonus2 = bestValue > beta + PawnValueMg ? bonus1 // larger bonus
: stat_bonus(depth); // smaller bonus
// Increase stats for the best move in case it was a quiet move
update_quiet_stats(pos, ss, bestMove, bonus2);