// when the static evaluation is at most IIDMargin below beta.
const Value IIDMargin = Value(0x100);
- // Use easy moves?
- const bool UseEasyMove = true;
-
// Easy move margin. An easy move candidate must be at least this much
// better than the second best move.
const Value EasyMoveMargin = Value(0x200);
bool UseQSearchFutilityPruning = true;
bool UseFutilityPruning = true;
- // Margins for futility pruning in the quiescence search, at frontier
- // nodes, and at pre-frontier nodes
- Value FutilityMargin0 = Value(0x80);
- Value FutilityMargin1 = Value(0x100);
- Value FutilityMargin2 = Value(0x300);
+ // Margins for futility pruning in the quiescence search, and at frontier
+ // and near frontier nodes
+ Value FutilityMarginQS = Value(0x80);
+ Value FutilityMargins[6] = { Value(0x100), Value(0x200), Value(0x250),
+ Value(0x2A0), Value(0x340), Value(0x3A0) };
// Razoring
Depth RazorDepth = 4*OnePly;
UseQSearchFutilityPruning = get_option_value_bool("Futility Pruning (Quiescence Search)");
UseFutilityPruning = get_option_value_bool("Futility Pruning (Main Search)");
- FutilityMargin0 = value_from_centipawns(get_option_value_int("Futility Margin 0"));
- FutilityMargin1 = value_from_centipawns(get_option_value_int("Futility Margin 1"));
- FutilityMargin2 = value_from_centipawns(get_option_value_int("Futility Margin 2"));
+ FutilityMarginQS = value_from_centipawns(get_option_value_int("Futility Margin (Quiescence Search)"));
+ int fmScale = get_option_value_int("Futility Margin (Main Serach)");
+ for (int i = 0; i < 6; i++)
+ FutilityMargins[i] = (FutilityMargins[i] * fmScale) / 100;
RazorDepth = (get_option_value_int("Maximum Razoring Depth") + 1) * OnePly;
RazorMargin = value_from_centipawns(get_option_value_int("Razoring Margin"));
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
- if (AbortSearch || thread_should_stop(threadID))
- return Value(0);
-
if (depth < OnePly)
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
+ // Initialize, and make an early exit in case of an aborted search,
+ // an instant draw, maximum ply reached, etc.
init_node(pos, ss, ply, threadID);
+ // After init_node() that calls poll()
+ if (AbortSearch || thread_should_stop(threadID))
+ return Value(0);
+
if (pos.is_draw())
return VALUE_DRAW;
movesSearched[moveCount++] = ss[ply].currentMove = move;
if (moveIsCapture)
- ss[ply].currentMoveCaptureValue = pos.midgame_value_of_piece_on(move_to(move));
- else if (move_is_ep(move))
- ss[ply].currentMoveCaptureValue = PawnValueMidgame;
+ ss[ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
else
ss[ply].currentMoveCaptureValue = Value(0);
else
value = alpha + 1; // Just to trigger next condition
- if (value > alpha) // Go with full depth pv search
+ if (value > alpha) // Go with full depth non-pv search
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
// (from the computer's point of view) since the previous iteration:
- if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ if ( ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
Problem = true;
}
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
+ if (depth < OnePly)
+ return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(pos, ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- if (depth < OnePly)
- return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
-
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
+ EvalInfo ei;
+
if (ply >= PLY_MAX - 1)
return evaluate(pos, ei, threadID);
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 there is a good possibility that this is a cut-node.
- // We will do an IID later to find a ttMove.
+ // 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
}
}
// Null move search not allowed, try razoring
- else if ( !isCheck
- && !value_is_mate(beta)
- && ( (approximateEval < beta - RazorMargin && depth < RazorDepth)
- ||(approximateEval < beta - PawnValueMidgame && depth <= OnePly)))
+ else if ( !value_is_mate(beta)
+ && approximateEval < beta - RazorMargin
+ && depth < RazorDepth
+ && depth > OnePly
+ && ttMove == MOVE_NONE
+ && !pos.has_pawn_on_7th(pos.side_to_move()))
{
Value v = qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
- if (v < beta)
+ if (v < beta - RazorMargin / 2 - int(depth - OnePly) * RazorMargin / 8)
return v;
}
{
// 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 is a cut-node. So it's a good time to search for a ttMove.
+ // 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);
&& !moveIsCapture
&& !move_promotion(move))
{
- // History pruning. See ok_to_prune() definition.
+ // History pruning. See ok_to_prune() definition
if ( moveCount >= 2 + int(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove, depth))
continue;
- // Value based pruning.
- if (depth < 3 * OnePly && approximateEval < beta)
+ // Value based pruning
+ if (depth < 7 * OnePly && approximateEval < beta)
{
if (futilityValue == VALUE_NONE)
futilityValue = evaluate(pos, ei, threadID)
- + (depth < 2 * OnePly ? FutilityMargin1 : FutilityMargin2);
+ + FutilityMargins[int(depth)/2 - 1]
+ + 32 * (depth & 1);
if (futilityValue < beta)
{
assert(ply >= 0 && ply < PLY_MAX);
assert(threadID >= 0 && threadID < ActiveThreads);
- EvalInfo ei;
-
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
+ init_node(pos, ss, ply, threadID);
+
+ // After init_node() that calls poll()
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
- init_node(pos, ss, ply, threadID);
-
if (pos.is_draw())
return VALUE_DRAW;
return value_from_tt(tte->value(), ply);
// Evaluate the position statically
+ EvalInfo ei;
bool isCheck = pos.is_check();
Value staticValue = (isCheck ? -VALUE_INFINITE : evaluate(pos, ei, threadID));
Value futilityValue = staticValue
+ Max(pos.midgame_value_of_piece_on(move_to(move)),
pos.endgame_value_of_piece_on(move_to(move)))
- + FutilityMargin0
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0))
+ + FutilityMarginQS
+ ei.futilityMargin;
if (futilityValue < alpha)
assert(move_is_ok(move));
- ss[sp->ply].currentMoveCaptureValue = move_is_ep(move)?
- PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ if (moveIsCapture)
+ ss[sp->ply].currentMoveCaptureValue =
+ move_is_ep(move)? PawnValueMidgame : pos.midgame_value_of_piece_on(move_to(move));
+ else
+ ss[sp->ply].currentMoveCaptureValue = Value(0);
lock_grab(&(sp->lock));
int moveCount = ++sp->moves;
}
// If we are at ply 1, and we are searching the first root move at
// ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration:
- if (Iteration >= 2 && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
+ // (from the computer's point of view) since the previous iteration.
+ if ( sp->ply == 1
+ && Iteration >= 2
+ && -value <= ValueByIteration[Iteration-1] - ProblemMargin)
Problem = true;
}
lock_release(&(sp->lock));
lock_grab(&(sp->lock));
// If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads:
+ // a beta cutoff higher up in the tree, stop all slave threads.
if (sp->master == threadID && thread_should_stop(threadID))
for (int i = 0; i < ActiveThreads; i++)
if (sp->slaves[i])
Depth extension(const Position &pos, Move m, bool pvNode, bool check,
bool singleReply, bool mateThreat, bool* dangerous) {
+ assert(m != MOVE_NONE);
+
Depth result = Depth(0);
*dangerous = check || singleReply || mateThreat;
*dangerous = true;
}
- if ( pos.midgame_value_of_piece_on(move_to(m)) >= RookValueMidgame
+ if ( pos.move_is_capture(m)
+ && pos.type_of_piece_on(move_to(m)) != PAWN
&& ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
- pos.midgame_value_of_piece_on(move_to(m)) == Value(0))
- && !move_promotion(m))
+ && !move_promotion(m)
+ && !move_is_ep(m))
{
result += PawnEndgameExtension[pvNode];
*dangerous = true;
// value of the threatening piece, don't prune move which defend it.
if ( !PruneDefendingMoves
&& threat != MOVE_NONE
- && pos.type_of_piece_on(tto) != NO_PIECE_TYPE
+ && pos.move_is_capture(threat)
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
|| pos.type_of_piece_on(tfrom) == KING)
&& pos.move_attacks_square(m, tto))
if ( !PruneBlockingMoves
&& threat != MOVE_NONE
&& piece_is_slider(pos.piece_on(tfrom))
- && bit_is_set(squares_between(tfrom, tto), mto) && pos.see(m) >= 0)
+ && bit_is_set(squares_between(tfrom, tto), mto)
+ && pos.see(m) >= 0)
return false;
return true;
projects / stockfish / blobdiff