void Search::init() {
for (int i = 1; i < MAX_MOVES; ++i)
- Reductions[i] = int(22.9 * std::log(i));
+ Reductions[i] = int(22.9 * std::log(i));
}
minScore = std::min(minScore, th->rootMoves[0].score);
// Vote according to score and depth, and select the best thread
- int64_t bestVote = 0;
for (Thread* th : Threads)
{
votes[th->rootMoves[0].pv[0]] +=
- (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
+ (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
- if (votes[th->rootMoves[0].pv[0]] > bestVote)
- {
- bestVote = votes[th->rootMoves[0].pv[0]];
+ if (votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
bestThread = th;
- }
}
}
bool ttHit, ttPv, inCheck, givesCheck, improving;
bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
Piece movedPiece;
- int moveCount, captureCount, quietCount;
+ int moveCount, captureCount, quietCount, singularLMR;
// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
Color us = pos.side_to_move();
- moveCount = captureCount = quietCount = ss->moveCount = 0;
+ moveCount = captureCount = quietCount = singularLMR = ss->moveCount = 0;
bestValue = -VALUE_INFINITE;
maxValue = VALUE_INFINITE;
// starts with statScore = 0. Later grandchildren start with the last calculated
// statScore of the previous grandchild. This influences the reduction rules in
// LMR which are based on the statScore of parent position.
- if (rootNode)
- (ss + 4)->statScore = 0;
- else
- (ss + 2)->statScore = 0;
+ if (rootNode)
+ (ss + 4)->statScore = 0;
+ else
+ (ss + 2)->statScore = 0;
// Step 4. Transposition table lookup. We don't want the score of a partial
// search to overwrite a previous full search TT value, so we use a different
ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
ttMove = rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
: ttHit ? tte->move() : MOVE_NONE;
- ttPv = (ttHit && tte->is_pv()) || (PvNode && depth > 4 * ONE_PLY);
+ ttPv = PvNode || (ttHit && tte->is_pv());
// At non-PV nodes we check for an early TT cutoff
if ( !PvNode
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
moveCountPruning = false;
ttCapture = ttMove && pos.capture_or_promotion(ttMove);
- int singularExtensionLMRmultiplier = 0;
// Step 12. Loop through all pseudo-legal moves until no moves remain
// or a beta cutoff occurs.
ss->excludedMove = MOVE_NONE;
if (value < singularBeta)
- {
+ {
extension = ONE_PLY;
- singularExtensionLMRmultiplier++;
+ singularLMR++;
+
if (value < singularBeta - std::min(3 * depth / ONE_PLY, 39))
- singularExtensionLMRmultiplier++;
- }
+ singularLMR++;
+ }
// Multi-cut pruning
// Our ttMove is assumed to fail high, and now we failed high also on a reduced
if ( !captureOrPromotion
&& !givesCheck
- && !pos.advanced_pawn_push(move))
+ && (!pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
{
// Move count based pruning (~30 Elo)
if (moveCountPruning)
if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
continue;
}
- else if (!pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
+ else if ((!givesCheck || !(pos.blockers_for_king(~us) & from_sq(move)))
+ && !pos.see_ge(move, -PawnValueEg * (depth / ONE_PLY))) // (~20 Elo)
continue;
}
// Decrease reduction if opponent's move count is high (~10 Elo)
if ((ss-1)->moveCount > 15)
r -= ONE_PLY;
+
// Decrease reduction if move has been singularly extended
- r -= singularExtensionLMRmultiplier * ONE_PLY;
+ r -= singularLMR * ONE_PLY;
if (!captureOrPromotion)
{
r -= ss->statScore / 20000 * ONE_PLY;
}
- Depth d = std::max(newDepth - std::max(r, DEPTH_ZERO), ONE_PLY);
+ Depth d = clamp(newDepth - r, ONE_PLY, newDepth);
value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
// Don't search moves with negative SEE values
if ( (!inCheck || evasionPrunable)
+ && (!givesCheck || !(pos.blockers_for_king(~pos.side_to_move()) & from_sq(move)))
&& !pos.see_ge(move))
continue;
void update_capture_stats(const Position& pos, Move move,
Move* captures, int captureCount, int bonus) {
- CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
+ CapturePieceToHistory& captureHistory = pos.this_thread()->captureHistory;
Piece moved_piece = pos.moved_piece(move);
PieceType captured = type_of(pos.piece_on(to_sq(move)));
if (dtz_available || rootMoves[0].tbScore <= VALUE_DRAW)
Cardinality = 0;
}
- else
- {
- // Assign the same rank to all moves
- for (auto& m : rootMoves)
- m.tbRank = 0;
- }
}