return value_from_tt(tte->value(), ply);
}
- // Step 5. Evaluate the position statically
- // At PV nodes we do this only to update gain statistics
+ // Step 5. Evaluate the position statically and
+ // update gain statistics of parent move.
isCheck = pos.is_check();
- if (!isCheck)
+ if (isCheck)
+ ss->eval = VALUE_NONE;
+ else if (tte)
{
- if (tte)
- {
- assert(tte->static_value() != VALUE_NONE);
+ assert(tte->static_value() != VALUE_NONE);
- ss->eval = tte->static_value();
- ei.kingDanger[pos.side_to_move()] = tte->king_danger();
- }
- else
- {
- ss->eval = evaluate(pos, ei);
- TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
- }
- refinedValue = refine_eval(tte, ss->eval, ply); // Enhance accuracy with TT value if possible
- update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
+ ss->eval = tte->static_value();
+ ei.kingDanger[pos.side_to_move()] = tte->king_danger();
+ refinedValue = refine_eval(tte, ss->eval, ply);
}
else
- ss->eval = VALUE_NONE;
+ {
+ refinedValue = ss->eval = evaluate(pos, ei);
+ TT.store(posKey, VALUE_NONE, VALUE_TYPE_NONE, DEPTH_NONE, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
+ }
+
+ // Save gain for the parent non-capture move
+ update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval);
// Step 6. Razoring (is omitted in PV nodes)
if ( !PvNode
if ( !PvNode
&& !ss->skipNullMove
&& depth < RazorDepth
- && refinedValue >= beta + futility_margin(depth, 0)
&& !isCheck
+ && refinedValue >= beta + futility_margin(depth, 0)
&& !value_is_mate(beta)
&& pos.non_pawn_material(pos.side_to_move()))
return refinedValue - futility_margin(depth, 0);
if ( !PvNode
&& !ss->skipNullMove
&& depth > OnePly
- && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)
&& !isCheck
+ && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0)
&& !value_is_mate(beta)
&& pos.non_pawn_material(pos.side_to_move()))
{
// singular extension search result is still valid.
if ( !PvNode
&& depth < SingularExtensionDepth[PvNode] + 5 * OnePly
- && ((ttx = TT.retrieve(pos.get_exclusion_key())) != NULL))
+ && (ttx = TT.retrieve(pos.get_exclusion_key())) != NULL)
{
if (is_upper_bound(ttx->type()))
ext = OnePly;
bestValue = value;
if (value > alpha)
{
- if (PvNode && value < beta) // This guarantees that always: alpha < beta
+ if (PvNode && value < beta) // We want always alpha < beta
alpha = value;
if (value == value_mate_in(ply + 1))
// no legal moves, it must be mate or stalemate.
// If one move was excluded return fail low score.
if (!moveCount)
- return excludedMove ? oldAlpha : (isCheck ? value_mated_in(ply) : VALUE_DRAW);
+ return excludedMove ? oldAlpha : isCheck ? value_mated_in(ply) : VALUE_DRAW;
// Step 20. Update tables
// If the search is not aborted, update the transposition table,
if (AbortSearch || TM.thread_should_stop(threadID))
return bestValue;
- ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
+ ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
move = (bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove);
- TT.store(posKey, value_to_tt(bestValue, ply), f, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
+ TT.store(posKey, value_to_tt(bestValue, ply), vt, depth, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
// Update killers and history only for non capture moves that fails high
if (bestValue >= beta)
if (tte)
{
assert(tte->static_value() != VALUE_NONE);
+
ei.kingDanger[pos.side_to_move()] = tte->king_danger();
bestValue = tte->static_value();
}
// Update transposition table
Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
- ValueType f = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), f, d, ss->bestMove, ss->eval, ei.kingDanger[pos.side_to_move()]);
+ ValueType vt = (bestValue <= oldAlpha ? VALUE_TYPE_UPPER : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), vt, d, ss->bestMove, ss->eval, ei.kingDanger[pos.side_to_move()]);
// Update killers only for checking moves that fails high
if ( bestValue >= beta
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
- if (!tte)
- return defaultEval;
+ assert(tte);
Value v = value_from_tt(tte->value(), ply);
&& before != VALUE_NONE
&& after != VALUE_NONE
&& pos.captured_piece() == NO_PIECE_TYPE
- && !move_is_castle(m)
- && !move_is_promotion(m))
+ && !move_is_special(m))
H.set_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after));
}