const Value FutilityMarginQS = Value(0x80);
// Each move futility margin is decreased
- const Value IncrementalFutilityMargin = Value(0x8);
+ const Value IncrementalFutilityMargin = Value(0x4);
- // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
- const Value FutilityMargins[12] = { Value(0x100), Value(0x120), Value(0x200), Value(0x220), Value(0x250), Value(0x270),
- // 4 ply 4.5 ply 5 ply 5.5 ply 6 ply 6.5 ply
- Value(0x2A0), Value(0x2C0), Value(0x340), Value(0x360), Value(0x3A0), Value(0x3C0) };
// Razoring
const Depth RazorDepth = 4*OnePly;
// LSN filtering. Used only for developing purpose. Disabled by default.
- if (UseLSNFiltering)
+ if ( UseLSNFiltering
+ && loseOnTime)
{
// Step 2. If after last move we decided to lose on time, do it now!
- if ( loseOnTime
- && myTime < LSNTime // double check: catches some very rear false positives!
- && myIncrement == 0
- && movesToGo == 0)
- {
- while (SearchStartTime + myTime + 1000 > get_system_time())
- ; // wait here
- } else if (loseOnTime) // false positive, reset flag
- loseOnTime = false;
+ while (SearchStartTime + myTime + 1000 > get_system_time())
+ ; // wait here
}
// We're ready to start thinking. Call the iterative deepening loop function
// LSN filtering. Used only for developing purpose. Disabled by default.
if (UseLSNFiltering)
{
- // Step 1. If this is sudden death game and our position is hopeless, decide to lose on time.
+ // Step 1. If this is sudden death game and our position is hopeless,
+ // decide to lose on time.
if ( !loseOnTime // If we already lost on time, go to step 3.
&& myTime < LSNTime
&& myIncrement == 0
return alpha;
// Transposition table lookup. At PV nodes, we don't use the TT for
- // pruning, but only for move ordering.
+ // pruning, but only for move ordering. This is to avoid problems in
+ // the following areas:
+ //
+ // * Repetition draw detection
+ // * Fifty move rule detection
+ // * Searching for a mate
+ // * Printing of full PV line
+ //
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
{
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
ttMove = ss[ply].pv[ply];
+ tte = TT.retrieve(pos.get_key());
+
+ // If tte->move() != MOVE_NONE then it equals ttMove
+ assert(!(tte && tte->move()) || tte->move() == ttMove);
}
// Initialize a MovePicker object for the current position, and prepare
// To verify this we do a reduced search on all the other moves but the ttMove,
// if result is lower then TT value minus a margin then we assume ttMove is the
// only one playable. It is a kind of relaxed single reply extension.
- if ( depth >= 4 * OnePly
- && move == ttMove
+ if ( depth >= 6 * OnePly
+ && tte
+ && move == tte->move()
&& ext < OnePly
&& is_lower_bound(tte->type())
&& tte->depth() >= depth - 3 * OnePly)
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Depth d = Max(Min(depth / 2, depth - 4 * OnePly), OnePly);
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, d, ply, false, threadID, ttMove);
+ Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
// If search result is well below the foreseen score of the ttMove then we
// assume ttMove is the only one realistically playable and we extend it.
if (tte && ok_to_use_TT(tte, depth, beta, ply))
{
- ss[ply].currentMove = ttMove; // can be MOVE_NONE
+ ss[ply].currentMove = ttMove; // Can be MOVE_NONE
return value_from_tt(tte->value(), ply);
}
{
search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
ttMove = ss[ply].pv[ply];
+ tte = TT.retrieve(pos.get_key());
}
// Initialize a MovePicker object for the current position, and prepare
futilityValue = VALUE_NONE;
useFutilityPruning = depth < SelectiveDepth && !isCheck;
+ // Calculate depth dependant futility pruning parameters
+ const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
+ const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
+
// Avoid calling evaluate() if we already have the score in TT
if (tte && (tte->type() & VALUE_TYPE_EVAL))
- futilityValue = value_from_tt(tte->value(), ply) + FutilityMargins[int(depth) - 2];
-
- // Move count pruning limit
- const int MCLimit = 3 + (1 << (3*int(depth)/8));
+ futilityValue = value_from_tt(tte->value(), ply) + FutilityValueMargin;
// Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
// To verify this we do a reduced search on all the other moves but the ttMove,
// if result is lower then TT value minus a margin then we assume ttMove is the
// only one playable. It is a kind of relaxed single reply extension.
- if ( depth >= 4 * OnePly
- && !excludedMove // do not allow recursive single-reply search
- && move == ttMove
+ if ( depth >= 8 * OnePly
+ && tte
+ && move == tte->move()
+ && !excludedMove // Do not allow recursive single-reply search
&& ext < OnePly
&& is_lower_bound(tte->type())
&& tte->depth() >= depth - 3 * OnePly)
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Depth d = Max(Min(depth / 2, depth - 4 * OnePly), OnePly);
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, d, ply, false, threadID, ttMove);
+ Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
// If search result is well below the foreseen score of the ttMove then we
// assume ttMove is the only one realistically playable and we extend it.
if (excValue < ttValue - SingleReplyMargin)
- ext = (depth >= 8 * OnePly) ? OnePly : ext + OnePly / 2;
+ ext = OnePly;
}
}
&& move != ttMove)
{
// History pruning. See ok_to_prune() definition
- if ( moveCount >= MCLimit
+ if ( moveCount >= FutilityMoveCountMargin
&& ok_to_prune(pos, move, ss[ply].threatMove, depth)
&& bestValue > value_mated_in(PLY_MAX))
continue;
if (approximateEval < beta)
{
if (futilityValue == VALUE_NONE)
- futilityValue = evaluate(pos, ei, threadID)
- + 64*(2+bitScanReverse32(int(depth) * int(depth)));
+ futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID);
}
else
- value = beta; // Just to trigger next condition
+ value = beta; // Just to trigger next condition
if (value >= beta) // Go with full depth non-pv search
{
// New best move?
if (value > bestValue)
{
- bestValue = value;
- if (value >= beta)
- update_pv(ss, ply);
+ bestValue = value;
+ if (value >= beta)
+ update_pv(ss, ply);
- if (value == value_mate_in(ply + 1))
- ss[ply].mateKiller = move;
+ if (value == value_mate_in(ply + 1))
+ ss[ply].mateKiller = move;
}
// Split?
&& !thread_should_stop(threadID)
&& split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval,
depth, &moveCount, &mp, threadID, false))
- break;
+ break;
}
// All legal moves have been searched. A special case: If there were
}
ttMove = (tte ? tte->move() : MOVE_NONE);
- // Evaluate the position statically
isCheck = pos.is_check();
ei.futilityMargin = Value(0); // Manually initialize futilityMargin
+ // Evaluate the position statically
if (isCheck)
staticValue = -VALUE_INFINITE;
// Use the cached evaluation score if possible
assert(ei.futilityMargin == Value(0));
- staticValue = tte->value();
+ staticValue = value_from_tt(tte->value(), ply);
}
else
staticValue = evaluate(pos, ei, threadID);
bool useFutilityPruning = sp->depth < SelectiveDepth
&& !isCheck;
+ const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2);
+
while ( sp->bestValue < sp->beta
&& !thread_should_stop(threadID)
&& (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
if (sp->futilityValue == VALUE_NONE)
{
EvalInfo ei;
- sp->futilityValue = evaluate(pos, ei, threadID)
- + FutilityMargins[int(sp->depth) - 2];
+ sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
}
if (sp->futilityValue < sp->beta)
projects / stockfish / blobdiff