uint64_t perft(Position& pos, Depth depth) {
StateInfo st;
- ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+ ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
uint64_t cnt, nodes = 0;
const bool leaf = (depth == 2);
Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64];
StateInfo st;
- ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+ ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
TTEntry* tte;
Key posKey;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
- ss->inCheck = pos.checkers();
- priorCapture = pos.captured_piece();
- Color us = pos.side_to_move();
- moveCount = captureCount = quietCount = ss->moveCount = 0;
- bestValue = -VALUE_INFINITE;
- maxValue = VALUE_INFINITE;
- ss->distanceFromPv = (PvNode ? 0 : ss->distanceFromPv);
+ ss->inCheck = pos.checkers();
+ priorCapture = pos.captured_piece();
+ Color us = pos.side_to_move();
+ moveCount = captureCount = quietCount = ss->moveCount = 0;
+ bestValue = -VALUE_INFINITE;
+ maxValue = VALUE_INFINITE;
// Check for the available remaining time
if (thisThread == Threads.main())
return probCutBeta;
assert(probCutBeta < VALUE_INFINITE);
+
MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
int probCutCount = 0;
bool ttPv = ss->ttPv;
{
Value singularBeta = ttValue - ((formerPv + 4) * depth) / 2;
Depth singularDepth = (depth - 1 + 3 * formerPv) / 2;
+
ss->excludedMove = move;
value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, singularDepth, cutNode);
ss->excludedMove = MOVE_NONE;
{
extension = 1;
singularQuietLMR = !ttCapture;
+ if (!PvNode && value < singularBeta - 140)
+ extension = 2;
}
// Multi-cut pruning
}
}
- // Check extension (~2 Elo)
- else if ( givesCheck
- && (pos.is_discovered_check_on_king(~us, move) || pos.see_ge(move)))
- extension = 1;
-
- // Last captures extension
- else if ( PieceValue[EG][pos.captured_piece()] > PawnValueEg
- && pos.non_pawn_material() <= 2 * RookValueMg)
- extension = 1;
-
// Add extension to new depth
newDepth += extension;
// Step 15. Make the move
pos.do_move(move, st, givesCheck);
- (ss+1)->distanceFromPv = ss->distanceFromPv + moveCount - 1;
-
// Step 16. Late moves reduction / extension (LMR, ~200 Elo)
// We use various heuristics for the sons of a node after the first son has
// been searched. In general we would like to reduce them, but there are many
|| ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
|| cutNode
|| (!PvNode && !formerPv && captureHistory[movedPiece][to_sq(move)][type_of(pos.captured_piece())] < 3678)
- || thisThread->ttHitAverage < 432 * TtHitAverageResolution * TtHitAverageWindow / 1024))
+ || thisThread->ttHitAverage < 432 * TtHitAverageResolution * TtHitAverageWindow / 1024)
+ && (!PvNode || ss->ply > 1 || thisThread->id() % 4 != 3))
{
Depth r = reduction(improving, depth, moveCount);
// Decrease reduction if position is or has been on the PV
// and node is not likely to fail low. (~10 Elo)
- if (ss->ttPv && !likelyFailLow)
+ if ( ss->ttPv
+ && !likelyFailLow)
r -= 2;
// Increase reduction at root and non-PV nodes when the best move does not change frequently
- if ((rootNode || !PvNode) && thisThread->rootDepth > 10 && thisThread->bestMoveChanges <= 2)
+ if ( (rootNode || !PvNode)
+ && thisThread->rootDepth > 10
+ && thisThread->bestMoveChanges <= 2)
r++;
// More reductions for late moves if position was not in previous PV
- if (moveCountPruning && !formerPv)
+ if ( moveCountPruning
+ && !formerPv)
r++;
// Decrease reduction if opponent's move count is high (~5 Elo)
if (captureOrPromotion)
{
- // Unless giving check, this capture is likely bad
+ // Increase reduction for non-checking captures likely to be bad
if ( !givesCheck
&& ss->staticEval + PieceValue[EG][pos.captured_piece()] + 210 * depth <= alpha)
r++;
// Decrease reduction for moves that escape a capture. Filter out
// castling moves, because they are coded as "king captures rook" and
- // hence break make_move(). (~2 Elo)
+ // hence break reverse_move() (~2 Elo)
else if ( type_of(move) == NORMAL
&& !pos.see_ge(reverse_move(move)))
r -= 2 + ss->ttPv - (type_of(movedPiece) == PAWN);
r -= ss->statScore / 14790;
}
- // In general we want to cap the LMR depth search at newDepth. But for nodes
- // close to the principal variation the cap is at (newDepth + 1), which will
- // allow these nodes to be searched deeper than the pv (up to 4 plies deeper).
- Depth d = std::clamp(newDepth - r, 1, newDepth + ((ss+1)->distanceFromPv <= 4));
+ // In general we want to cap the LMR depth search at newDepth. But if
+ // reductions are really negative and movecount is low, we allow this move
+ // to be searched deeper than the first move.
+ Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && moveCount <= 5));
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
assert(moveCount || !ss->inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
if (!moveCount)
- bestValue = excludedMove ? alpha
- : ss->inCheck ? mated_in(ss->ply) : VALUE_DRAW;
+ bestValue = excludedMove ? alpha :
+ ss->inCheck ? mated_in(ss->ply)
+ : VALUE_DRAW;
// If there is a move which produces search value greater than alpha we update stats of searched moves
else if (bestMove)
Move pv[MAX_PLY+1];
StateInfo st;
- ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+ ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
TTEntry* tte;
Key posKey;
bool RootMove::extract_ponder_from_tt(Position& pos) {
StateInfo st;
- ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+ ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
bool ttHit;
projects / stockfish / blobdiff