const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
- // Enhance position with TT value if possible
+ // Enhance score accuracy with TT value if possible
futilityValue = staticValue + FutilityValueMargin;
staticValue = refine_eval(tte, staticValue, ply);
if (move == excludedMove)
continue;
- singleEvasion = (isCheck && mp.number_of_evasions() == 1);
moveIsCheck = pos.move_is_check(move, ci);
+ singleEvasion = (isCheck && mp.number_of_evasions() == 1);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
// Decide the new search depth
break;
}
- // All legal moves have been searched. A special case: If there were
+ // All legal moves have been searched. A special case: If there were
// no legal moves, it must be mate or stalemate.
- if (moveCount == 0)
+ if (!moveCount)
return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
// If the search is not aborted, update the transposition table,
{
BetaCounter.add(pos.side_to_move(), depth, threadID);
move = ss[ply].pv[ply];
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
if (!pos.move_is_capture_or_promotion(move))
{
update_history(pos, move, depth, movesSearched, moveCount);
update_killers(move, ss[ply]);
}
- TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
+
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
EvalInfo ei;
StateInfo st;
Move ttMove, move;
- Value staticValue, bestValue, value, futilityValue;
+ Value staticValue, bestValue, value, futilityBase, futilityValue;
bool isCheck, enoughMaterial, moveIsCheck;
const TTEntry* tte = NULL;
int moveCount = 0;
if (pos.is_draw())
return VALUE_DRAW;
- // Transposition table lookup, only when not in PV
- if (!pvNode)
+ if (ply >= PLY_MAX - 1)
+ return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
+
+ // Transposition table lookup. At PV nodes, we don't use the TT for
+ // pruning, but only for move ordering.
+ tte = TT.retrieve(pos.get_key());
+ ttMove = (tte ? tte->move() : MOVE_NONE);
+
+ if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
{
- tte = TT.retrieve(pos.get_key());
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
- {
- assert(tte->type() != VALUE_TYPE_EVAL);
+ assert(tte->type() != VALUE_TYPE_EVAL);
- return value_from_tt(tte->value(), ply);
- }
+ ss[ply].currentMove = ttMove; // Can be MOVE_NONE
+ return value_from_tt(tte->value(), ply);
}
- ttMove = (tte ? tte->move() : MOVE_NONE);
isCheck = pos.is_check();
ei.futilityMargin = Value(0); // Manually initialize futilityMargin
// Evaluate the position statically
if (isCheck)
staticValue = -VALUE_INFINITE;
-
else if (tte && (tte->type() & VALUE_TYPE_EVAL))
- {
- // Use the cached evaluation score if possible
- assert(ei.futilityMargin == Value(0));
-
staticValue = value_from_tt(tte->value(), ply);
- }
else
staticValue = evaluate(pos, ei, threadID);
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
-
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
bestValue = staticValue;
MovePicker mp = MovePicker(pos, ttMove, depth, H);
CheckInfo ci(pos);
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
+ futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin;
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
{
assert(move_is_ok(move));
+ moveIsCheck = pos.move_is_check(move, ci);
+
+ // Update current move
moveCount++;
ss[ply].currentMove = move;
- moveIsCheck = pos.move_is_check(move, ci);
-
// Futility pruning
if ( enoughMaterial
&& !isCheck
&& !move_is_promotion(move)
&& !pos.move_is_passed_pawn_push(move))
{
- futilityValue = staticValue
- + Max(pos.midgame_value_of_piece_on(move_to(move)),
- pos.endgame_value_of_piece_on(move_to(move)))
- + (move_is_ep(move) ? PawnValueEndgame : Value(0))
- + FutilityMarginQS
- + ei.futilityMargin;
+ futilityValue = futilityBase
+ + pos.endgame_value_of_piece_on(move_to(move))
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0));
if (futilityValue < alpha)
{
}
}
- // All legal moves have been searched. A special case: If we're in check
+ // All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
if (!moveCount && pos.is_check()) // Mate!
return value_mated_in(ply);
- assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
-
// Update transposition table
- move = ss[ply].pv[ply];
- if (!pvNode)
+ Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ if (bestValue < beta)
{
- // If bestValue isn't changed it means it is still the static evaluation of
- // the node, so keep this info to avoid a future costly evaluation() call.
+ // If bestValue isn't changed it means it is still the static evaluation
+ // of the node, so keep this info to avoid a future evaluation() call.
ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
- Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
+ }
+ else
+ {
+ move = ss[ply].pv[ply];
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
- if (bestValue < beta)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
- else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
+ // Update killers only for good checking moves
+ if (!pos.move_is_capture_or_promotion(move))
+ update_killers(move, ss[ply]);
}
- // Update killers only for good check moves
- if (alpha >= beta && !pos.move_is_capture_or_promotion(move))
- update_killers(move, ss[ply]);
+ assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
return bestValue;
}
projects / stockfish / blobdiff