// Function prototypes
template<bool Trace>
- Value do_evaluate(const Position& pos, Value& margin);
+ Value do_evaluate(const Position& pos);
template<Color Us>
void init_eval_info(const Position& pos, EvalInfo& ei);
Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score* mobility);
template<Color Us, bool Trace>
- Score evaluate_king(const Position& pos, const EvalInfo& ei, Value margins[]);
+ Score evaluate_king(const Position& pos, const EvalInfo& ei);
template<Color Us, bool Trace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei);
/// values, an endgame score and a middle game score, and interpolates
/// between them based on the remaining material.
- Value evaluate(const Position& pos, Value& margin) {
- return do_evaluate<false>(pos, margin);
+ Value evaluate(const Position& pos) {
+ return do_evaluate<false>(pos);
}
namespace {
template<bool Trace>
-Value do_evaluate(const Position& pos, Value& margin) {
+Value do_evaluate(const Position& pos) {
assert(!pos.checkers());
EvalInfo ei;
- Value margins[COLOR_NB];
Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
Thread* th = pos.this_thread();
- // margins[] store the uncertainty estimation of position's evaluation
- // that typically is used by the search for pruning decisions.
- margins[WHITE] = margins[BLACK] = VALUE_ZERO;
-
// Initialize score by reading the incrementally updated scores included
// in the position object (material + piece square tables) and adding
// Tempo bonus. Score is computed from the point of view of white.
// If we have a specialized evaluation function for the current material
// configuration, call it and return.
if (ei.mi->specialized_eval_exists())
- {
- margin = VALUE_ZERO;
return ei.mi->evaluate(pos);
- }
// Probe the pawn hash table
ei.pi = Pawns::probe(pos, th->pawnsTable);
// Evaluate kings after all other pieces because we need complete attack
// information when computing the king safety evaluation.
- score += evaluate_king<WHITE, Trace>(pos, ei, margins)
- - evaluate_king<BLACK, Trace>(pos, ei, margins);
+ score += evaluate_king<WHITE, Trace>(pos, ei)
+ - evaluate_king<BLACK, Trace>(pos, ei);
// Evaluate tactical threats, we need full attack information including king
score += evaluate_threats<WHITE, Trace>(pos, ei)
sf = ScaleFactor(50);
}
- margin = margins[pos.side_to_move()];
Value v = interpolate(score, ei.mi->game_phase(), sf);
// In case of tracing add all single evaluation contributions for both white and black
Score b = ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei);
Tracing::add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
Tracing::add(TOTAL, score);
- Tracing::stream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
- << ", Black: " << to_cp(margins[BLACK])
- << "\nScaling: " << std::noshowpos
+ Tracing::stream << "\nScaling: " << std::noshowpos
<< std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
<< std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
<< std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
// evaluate_king() assigns bonuses and penalties to a king of a given color
template<Color Us, bool Trace>
- Score evaluate_king(const Position& pos, const EvalInfo& ei, Value margins[]) {
+ Score evaluate_king(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
attackUnits = std::min(99, std::max(0, attackUnits));
// Finally, extract the king danger score from the KingDanger[]
- // array and subtract the score from evaluation. Set also margins[]
- // value that will be used for pruning because this value can sometimes
- // be very big, and so capturing a single attacking piece can therefore
- // result in a score change far bigger than the value of the captured piece.
+ // array and subtract the score from evaluation.
score -= KingDanger[Us == Search::RootColor][attackUnits];
- margins[Us] += mg_value(KingDanger[Us == Search::RootColor][attackUnits]);
}
if (Trace)
stream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
std::memset(scores, 0, 2 * (TOTAL + 1) * sizeof(Score));
- Value margin;
- do_evaluate<true>(pos, margin);
+ do_evaluate<true>(pos);
std::string totals = stream.str();
stream.str("");
inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); }
// Futility lookup tables (initialized at startup) and their access functions
- Value FutilityMargins[16][64]; // [depth][moveNumber]
int FutilityMoveCounts[2][32]; // [improving][depth]
- inline Value futility_margin(Depth d, int mn) {
-
- return d < 7 * ONE_PLY ? FutilityMargins[std::max(int(d), 1)][std::min(mn, 63)]
- : 2 * VALUE_INFINITE;
+ inline Value futility_margin(Depth d) {
+ return Value(100 * int(d));
}
// Reduction lookup tables (initialized at startup) and their access function
double BestMoveChanges;
Value DrawValue[COLOR_NB];
HistoryStats History;
- GainsStats Gains;
CountermovesStats Countermoves;
template <NodeType NT>
Reductions[0][0][hd][mc] += ONE_PLY / 2;
}
- // Init futility margins array
- for (d = 1; d < 16; ++d) for (mc = 0; mc < 64; ++mc)
- FutilityMargins[d][mc] = Value(112 * int(2.9 * log(double(d))) - 8 * mc + 45);
-
// Init futility move count array
for (d = 0; d < 32; ++d)
{
Value bestValue, alpha, beta, delta;
std::memset(ss-2, 0, 5 * sizeof(Stack));
- (ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
depth = 0;
BestMoveChanges = 0;
TT.new_search();
History.clear();
- Gains.clear();
Countermoves.clear();
PVSize = Options["MultiPV"];
Move ttMove, move, excludedMove, bestMove, threatMove;
Depth ext, newDepth;
Value bestValue, value, ttValue;
- Value eval, nullValue, futilityValue;
+ Value eval, nullValue;
bool inCheck, givesCheck, pvMove, singularExtensionNode, improving;
bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount, quietCount;
bestValue = -VALUE_INFINITE;
ss->currentMove = threatMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
ss->ply = (ss-1)->ply + 1;
- ss->futilityMoveCount = 0;
(ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
// Step 5. Evaluate the position statically and update parent's gain statistics
if (inCheck)
{
- ss->staticEval = ss->evalMargin = eval = VALUE_NONE;
+ ss->staticEval = eval = VALUE_NONE;
goto moves_loop;
}
else if (tte)
{
// Never assume anything on values stored in TT
- if ( (ss->staticEval = eval = tte->eval_value()) == VALUE_NONE
- ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE)
- eval = ss->staticEval = evaluate(pos, ss->evalMargin);
+ if ((ss->staticEval = eval = tte->eval_value()) == VALUE_NONE)
+ eval = ss->staticEval = evaluate(pos);
// Can ttValue be used as a better position evaluation?
if (ttValue != VALUE_NONE)
}
else
{
- eval = ss->staticEval = evaluate(pos, ss->evalMargin);
- TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
- ss->staticEval, ss->evalMargin);
- }
-
- // Update gain for the parent non-capture move given the static position
- // evaluation before and after the move.
- if ( !pos.captured_piece_type()
- && ss->staticEval != VALUE_NONE
- && (ss-1)->staticEval != VALUE_NONE
- && (move = (ss-1)->currentMove) != MOVE_NULL
- && type_of(move) == NORMAL)
- {
- Square to = to_sq(move);
- Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
+ eval = ss->staticEval = evaluate(pos);
+ TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval);
}
// Step 6. Razoring (skipped when in check)
return v;
}
- // Step 7. Static null move pruning (skipped when in check)
- // We're betting that the opponent doesn't have a move that will reduce
- // the score by more than futility_margin(depth) if we do a null move.
+ // Step 7. Futility pruning: child node (skipped when in check)
if ( !PvNode
&& !ss->skipNullMove
- && depth < 4 * ONE_PLY
- && eval - futility_margin(depth, (ss-1)->futilityMoveCount) >= beta
+ && depth < 7 * ONE_PLY
+ && eval - futility_margin(depth) >= beta
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
&& abs(eval) < VALUE_KNOWN_WIN
&& pos.non_pawn_material(pos.side_to_move()))
- return eval - futility_margin(depth, (ss-1)->futilityMoveCount);
+ return eval - futility_margin(depth);
// Step 8. Null move search with verification search (is omitted in PV nodes)
if ( !PvNode
// Update current move (this must be done after singular extension search)
newDepth = depth - ONE_PLY + ext;
- // Step 13. Futility pruning (is omitted in PV nodes)
+ // Step 13. Pruning at shallow depth (exclude PV nodes)
if ( !PvNode
&& !captureOrPromotion
&& !inCheck
continue;
}
- // Value based pruning
- // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth,
- // but fixing this made program slightly weaker.
Depth predictedDepth = newDepth - reduction<PvNode>(improving, depth, moveCount);
- futilityValue = ss->staticEval + ss->evalMargin + futility_margin(predictedDepth, moveCount)
- + Gains[pos.moved_piece(move)][to_sq(move)];
- if (futilityValue < beta)
+ // Futility pruning: parent node
+ if (predictedDepth < 7 * ONE_PLY)
{
- bestValue = std::max(bestValue, futilityValue);
+ Value futilityValue = ss->staticEval + futility_margin(predictedDepth) + Value(128);
- if (SpNode)
+ if (futilityValue <= alpha)
{
- splitPoint->mutex.lock();
- if (bestValue > splitPoint->bestValue)
- splitPoint->bestValue = bestValue;
+ bestValue = std::max(bestValue, futilityValue);
+
+ if (SpNode)
+ {
+ splitPoint->mutex.lock();
+ if (bestValue > splitPoint->bestValue)
+ splitPoint->bestValue = bestValue;
+ }
+ continue;
}
- continue;
}
// Prune moves with negative SEE at low depths
continue;
}
- // We have not pruned the move that will be searched, but remember how
- // far in the move list we are to be more aggressive in the child node.
- ss->futilityMoveCount = moveCount;
}
- else
- ss->futilityMoveCount = 0;
// Check for legality only before to do the move
if (!RootNode && !SpNode && !pos.legal(move, ci.pinned))
TT.store(posKey, value_to_tt(bestValue, ss->ply),
bestValue >= beta ? BOUND_LOWER :
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
- depth, bestMove, ss->staticEval, ss->evalMargin);
+ depth, bestMove, ss->staticEval);
// Quiet best move: update killers, history and countermoves
if ( bestValue >= beta
// Evaluate the position statically
if (InCheck)
{
- ss->staticEval = ss->evalMargin = VALUE_NONE;
+ ss->staticEval = VALUE_NONE;
bestValue = futilityBase = -VALUE_INFINITE;
}
else
if (tte)
{
// Never assume anything on values stored in TT
- if ( (ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE
- ||(ss->evalMargin = tte->eval_margin()) == VALUE_NONE)
- ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
+ if ((ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE)
+ ss->staticEval = bestValue = evaluate(pos);
// Can ttValue be used as a better position evaluation?
if (ttValue != VALUE_NONE)
bestValue = ttValue;
}
else
- ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
+ ss->staticEval = bestValue = evaluate(pos);
// Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta)
{
if (!tte)
TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER,
- DEPTH_NONE, MOVE_NONE, ss->staticEval, ss->evalMargin);
+ DEPTH_NONE, MOVE_NONE, ss->staticEval);
return bestValue;
}
if (PvNode && bestValue > alpha)
alpha = bestValue;
- futilityBase = bestValue + ss->evalMargin + Value(128);
+ futilityBase = bestValue + Value(128);
}
// Initialize a MovePicker object for the current position, and prepare
else // Fail high
{
TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER,
- ttDepth, move, ss->staticEval, ss->evalMargin);
+ ttDepth, move, ss->staticEval);
return value;
}
TT.store(posKey, value_to_tt(bestValue, ss->ply),
PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
- ttDepth, bestMove, ss->staticEval, ss->evalMargin);
+ ttDepth, bestMove, ss->staticEval);
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
tte = TT.probe(pos.key());
if (!tte || tte->move() != pv[ply]) // Don't overwrite correct entries
- TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], VALUE_NONE, VALUE_NONE);
+ TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[ply], VALUE_NONE);
assert(MoveList<LEGAL>(pos).contains(pv[ply]));