// Depth limit for selective search:
Depth SelectiveDepth = 7*OnePly;
+ // Use dynamic LMR?
+ const bool UseDynamicLMR = false;
+
// Use internal iterative deepening?
const bool UseIIDAtPVNodes = true;
const bool UseIIDAtNonPVNodes = false;
- // Use null move driven internal iterative deepening?
- bool UseNullDrivenIID = false;
-
// Internal iterative deepening margin. At Non-PV moves, when
// UseIIDAtNonPVNodes is true, we do an internal iterative deepening search
// when the static evaluation is at most IIDMargin below beta.
// Iteration counters
int Iteration;
- bool LastIterations;
BetaCounterType BetaCounter;
// Scores and number of times the best move changed for each iteration:
int SearchStartTime;
int MaxNodes, MaxDepth;
int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime;
- Move BestRootMove, PonderMove, EasyMove;
+ Move EasyMove;
int RootMoveNumber;
bool InfiniteSearch;
bool PonderSearch;
// Initialize global search variables
Idle = false;
SearchStartTime = get_system_time();
- BestRootMove = MOVE_NONE;
- PonderMove = MOVE_NONE;
EasyMove = MOVE_NONE;
for (int i = 0; i < THREAD_MAX; i++)
{
if (UseLogFile)
LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
- UseNullDrivenIID = get_option_value_bool("Null driven IID");
UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
ValueByIteration[0] = Value(0);
ValueByIteration[1] = rml.get_move_score(0);
Iteration = 1;
- LastIterations = false;
EasyMove = rml.scan_for_easy_move();
ExtraSearchTime = BestMoveChangesByIteration[Iteration] * (MaxSearchTime / 2)
+ BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
- // Try to guess if the current iteration is the last one or the last two
- LastIterations = (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*58) / 128);
-
// Stop search if most of MaxSearchTime is consumed at the end of the
// iteration. We probably don't have enough time to search the first
// move at the next iteration anyway.
<< " hashfull " << TT.full() << std::endl;
// Print the best move and the ponder move to the standard output
+ if (ss[0].pv[0] == MOVE_NONE)
+ {
+ ss[0].pv[0] = rml.get_move(0);
+ ss[0].pv[1] = MOVE_NONE;
+ }
std::cout << "bestmove " << ss[0].pv[0];
if (ss[0].pv[1] != MOVE_NONE)
std::cout << " ponder " << ss[0].pv[1];
Value approximateEval = quick_evaluate(pos);
bool mateThreat = false;
- bool nullDrivenIID = false;
bool isCheck = pos.is_check();
// Null move search
Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
- // Check for a null capture artifact, if the value without the null capture
- // is above beta then mark the node as a suspicious failed low. We will verify
- // later if we are really under threat.
- if ( UseNullDrivenIID
- && nullValue < beta
- && depth > 6 * OnePly
- &&!value_is_mate(nullValue)
- && ttMove == MOVE_NONE
- && ss[ply + 1].currentMove != MOVE_NONE
- && pos.move_is_capture(ss[ply + 1].currentMove)
- && pos.see(ss[ply + 1].currentMove) + nullValue >= beta)
- nullDrivenIID = true;
-
pos.undo_null_move();
if (value_is_mate(nullValue))
// low score (which will cause the reduced move to fail high in the
// parent node, which will trigger a re-search with full depth).
if (nullValue == value_mated_in(ply + 2))
- {
mateThreat = true;
- nullDrivenIID = false;
- }
+
ss[ply].threatMove = ss[ply + 1].currentMove;
if ( depth < ThreatDepth
&& ss[ply - 1].reduction
{
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
if ( (v < beta - RazorMargin - RazorMargin / 4)
- || (depth < 3*OnePly && v < beta - RazorMargin)
- || (depth < 2*OnePly && v < beta - RazorMargin / 2))
+ || (depth <= 2*OnePly && v < beta - RazorMargin)
+ || (depth <= OnePly && v < beta - RazorMargin / 2))
return v;
}
search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
ttMove = ss[ply].pv[ply];
}
- else if (nullDrivenIID)
- {
- // The null move failed low due to a suspicious capture. Perhaps we
- // are facing a null capture artifact due to the side to move change
- // and this position should fail high. So do a normal search with a
- // reduced depth to get a good ttMove to use in the following full
- // depth search.
- Move tm = ss[ply].threatMove;
-
- assert(tm != MOVE_NONE);
- assert(ttMove == MOVE_NONE);
-
- search(pos, ss, beta, depth/2, ply, false, threadID);
- ttMove = ss[ply].pv[ply];
- ss[ply].threatMove = tm;
- }
// Initialize a MovePicker object for the current position, and prepare
// to search all moves:
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
- ss[ply].reduction = OnePly;
- value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID);
+ // LMR dynamic reduction
+ Depth R = UseDynamicLMR
+ && moveCount >= 2 * LMRNonPVMoves
+ && depth > 7*OnePly ? 2*OnePly : OnePly;
+
+ ss[ply].reduction = R;
+ value = -search(pos, ss, -(beta-1), newDepth-R, ply+1, true, threadID);
}
else
value = beta; // Just to trigger next condition
}
TT.store(pos, value_to_tt(bestValue, ply), depth, m, VALUE_TYPE_LOWER);
}
+
+ assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
+
return bestValue;
}
if (pos.is_draw())
return VALUE_DRAW;
- // Transposition table lookup
- const TTEntry* tte = TT.retrieve(pos);
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
- return value_from_tt(tte->value(), ply);
+ // Transposition table lookup, only when not in PV
+ TTEntry* tte = NULL;
+ bool pvNode = (beta - alpha != 1);
+ if (!pvNode)
+ {
+ tte = TT.retrieve(pos);
+ if (tte && ok_to_use_TT(tte, depth, beta, ply))
+ {
+ assert(tte->type() != VALUE_TYPE_EVAL);
+
+ return value_from_tt(tte->value(), ply);
+ }
+ }
// Evaluate the position statically
EvalInfo ei;
+ Value staticValue;
bool isCheck = pos.is_check();
- Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID));
+
+ if (isCheck)
+ staticValue = -VALUE_INFINITE;
+
+ else if (tte && tte->type() == VALUE_TYPE_EVAL)
+ {
+ // Use the cached evaluation score if possible
+ assert(tte->value() == evaluate(pos, ei, threadID));
+ assert(ei.futilityMargin == Value(0));
+
+ staticValue = tte->value();
+ ei.futilityMargin = Value(0); // manually initialize futilityMargin
+ }
+ else
+ staticValue = evaluate(pos, ei, threadID);
if (ply == PLY_MAX - 1)
return evaluate(pos, ei, threadID);
Value bestValue = staticValue;
if (bestValue >= beta)
+ {
+ // Store the score to avoid a future costly evaluation() call
+ if (!isCheck && !tte && ei.futilityMargin == 0)
+ TT.store(pos, value_to_tt(bestValue, ply), Depth(-127*OnePly), MOVE_NONE, VALUE_TYPE_EVAL);
+
return bestValue;
+ }
if (bestValue > alpha)
alpha = bestValue;
// Initialize a MovePicker object for the current position, and prepare
// to search the moves. Because the depth is <= 0 here, only captures,
// queen promotions and checks (only if depth == 0) will be generated.
- bool pvNode = (beta - alpha != 1);
- MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth, isCheck ? NULL : &ei);
+ MovePicker mp = MovePicker(pos, pvNode, MOVE_NONE, EmptySearchStack, depth);
Move move;
int moveCount = 0;
Bitboard dcCandidates = mp.discovered_check_candidates();
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
// Update transposition table
- TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT);
+ if (!pvNode)
+ {
+ Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ if (bestValue < beta)
+ TT.store(pos, value_to_tt(bestValue, ply), d, MOVE_NONE, VALUE_TYPE_UPPER);
+ else
+ TT.store(pos, value_to_tt(bestValue, ply), d, MOVE_NONE, VALUE_TYPE_LOWER);
+ }
// Update killers only for good check moves
Move m = ss[ply].currentMove;
|| ( !FailHigh && !fail_high_ply_1() && !Problem
&& t > 6*(MaxSearchTime + ExtraSearchTime));
- if ( (Iteration >= 2 && (!InfiniteSearch && overTime))
+ if ( (Iteration >= 3 && (!InfiniteSearch && overTime))
|| (ExactMaxTime && t >= ExactMaxTime)
|| (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
AbortSearch = true;
void ponderhit() {
int t = current_search_time();
PonderSearch = false;
- if(Iteration >= 2 &&
+ if(Iteration >= 3 &&
(!InfiniteSearch && (StopOnPonderhit ||
t > AbsoluteMaxSearchTime ||
(RootMoveNumber == 1 &&
projects / stockfish / blobdiff