#include "book.h"
#include "evaluate.h"
#include "history.h"
-#include "maxgain.h"
#include "misc.h"
#include "movegen.h"
#include "movepick.h"
IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
+ // Search window management
+ int AspirationDelta;
+
// MultiPV mode
int MultiPV;
// History table
History H;
- // MaxGain table
- MaxGain MG;
-
/// Functions
Value id_loop(const Position& pos, Move searchMoves[]);
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta);
+ Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta);
Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
bool ok_to_prune(const Position& pos, Move m, Move threat);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
+ Depth calculate_reduction(double baseReduction, int moveCount, Depth depth, double reductionInhibitor);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
+ void update_gains(const Position& pos, Move move, Value before, Value after);
bool fail_high_ply_1();
int current_search_time();
// Initialize
TT.new_search();
H.clear();
- MG.clear();
init_ss_array(ss);
IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
Iteration = 1;
int prevDelta1 = IterationInfo[Iteration - 1].speculatedValue - IterationInfo[Iteration - 2].speculatedValue;
int prevDelta2 = IterationInfo[Iteration - 2].speculatedValue - IterationInfo[Iteration - 3].speculatedValue;
- int delta = Max(2 * abs(prevDelta1) + abs(prevDelta2), ProblemMargin);
+ int delta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16);
+
+ delta = (delta + 7) / 8 * 8; // Round to match grainSize
+ AspirationDelta = delta;
alpha = Max(IterationInfo[Iteration - 1].value - delta, -VALUE_INFINITE);
beta = Min(IterationInfo[Iteration - 1].value + delta, VALUE_INFINITE);
// similar to search_pv except that it uses a different move ordering
// scheme and prints some information to the standard output.
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta) {
+ Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value& oldAlpha, Value& beta) {
- Value oldAlpha = alpha;
- Value value = -VALUE_INFINITE;
+ Value alpha = oldAlpha;
+ Value value;
CheckInfo ci(pos);
+ int researchCount = 0;
bool isCheck = pos.is_check();
// Evaluate the position statically
else
ss[0].eval = VALUE_NONE;
+ while(1) // Fail low loop
+ {
+
// Loop through all the moves in the root move list
for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
{
ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
newDepth = depth + ext;
+ value = - VALUE_INFINITE;
+
+ while (1) // Fail high loop
+ {
+
// Make the move, and search it
pos.do_move(move, st, ci, moveIsCheck);
- if (i < MultiPV)
+ if (i < MultiPV || value > alpha)
{
// Aspiration window is disabled in multi-pv case
if (MultiPV > 1)
pos.undo_move(move);
+ if (AbortSearch || value < beta)
+ break; // We are not failing high
+
+ // We are failing high and going to do a research. It's important to update score
+ // before research in case we run out of time while researching.
+ rml.set_move_score(i, value);
+ update_pv(ss, 0);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
+ rml.set_move_pv(i, ss[0].pv);
+
+ // Print search information to the standard output
+ cout << "info depth " << Iteration
+ << " score " << value_to_string(value)
+ << ((value >= beta) ? " lowerbound" :
+ ((value <= alpha)? " upperbound" : ""))
+ << " time " << current_search_time()
+ << " nodes " << nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
+ cout << ss[0].pv[j] << " ";
+
+ cout << endl;
+
+ if (UseLogFile)
+ {
+ ValueType type = (value >= beta ? VALUE_TYPE_LOWER
+ : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
+
+ LogFile << pretty_pv(pos, current_search_time(), Iteration,
+ nodes_searched(), value, type, ss[0].pv) << endl;
+ }
+
+ // Prepare for research
+ researchCount++;
+ beta = Min(beta + AspirationDelta * (1 << researchCount), VALUE_INFINITE);
+
+ } // End of fail high loop
+
// Finished searching the move. If AbortSearch is true, the search
// was aborted because the user interrupted the search or because we
// ran out of time. In this case, the return value of the search cannot
FailLow = (alpha == oldAlpha);
}
+
+ if (AbortSearch || alpha > oldAlpha)
+ break; // End search, we are not failing low
+
+ // Prepare for research
+ researchCount++;
+ alpha = Max(alpha - AspirationDelta * (1 << researchCount), -VALUE_INFINITE);
+ oldAlpha = alpha;
+
+ } // Fail low loop
+
return alpha;
}
tte = TT.retrieve(pos.get_key());
}
- // Evaluate the position statically
isCheck = pos.is_check();
- EvalInfo ei;
if (!isCheck)
{
+ // Update gain statistics of the previous move that lead
+ // us in this position.
+ EvalInfo ei;
ss[ply].eval = evaluate(pos, ei, threadID);
-
- // Store gain statistics
- Move m = ss[ply - 1].currentMove;
- if ( m != MOVE_NULL
- && pos.captured_piece() == NO_PIECE_TYPE
- && !move_is_castle(m)
- && !move_is_promotion(m))
- MG.store(pos.piece_on(move_to(m)), move_from(m), move_to(m), ss[ply - 1].eval, -ss[ply].eval);
-
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
}
// Initialize a MovePicker object for the current position, and prepare
ss[ply].eval = staticValue;
futilityValue = staticValue + PostFutilityValueMargin; //FIXME: Remove me, only for split
staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible
-
- // Store gain statistics
- Move m = ss[ply - 1].currentMove;
- if ( m != MOVE_NULL
- && pos.captured_piece() == NO_PIECE_TYPE
- && !move_is_castle(m)
- && !move_is_promotion(m))
- MG.store(pos.piece_on(move_to(m)), move_from(m), move_to(m), ss[ply - 1].eval, -ss[ply].eval);
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
}
- // Post futility pruning
- if (depth < SelectiveDepth && staticValue - PostFutilityValueMargin >= beta)
- return (staticValue - PostFutilityValueMargin);
+ // Do a "stand pat". If we are above beta by a good margin then
+ // return immediately.
+ // FIXME: test with added condition 'allowNullmove || depth <= OnePly' and !value_is_mate(beta)
+ // FIXME: test with modified condition 'depth < RazorDepth'
+ if ( !isCheck
+ && depth < SelectiveDepth
+ && staticValue - PostFutilityValueMargin >= beta)
+ return staticValue - PostFutilityValueMargin;
// Null move search
if ( allowNullmove
movesSearched[moveCount++] = ss[ply].currentMove = move;
// Futility pruning for captures
+ // FIXME: test disabling 'Futility pruning for captures'
+ // FIXME: test with 'newDepth < RazorDepth'
Color them = opposite_color(pos.side_to_move());
if ( !isCheck
if (newDepth >= OnePly)
preFutilityValueMargin = 112 * bitScanReverse32(int(newDepth) * int(newDepth) / 2);
- if (ss[ply].eval + pos.endgame_value_of_piece_on(move_to(move)) + preFutilityValueMargin + ei.futilityMargin + 90 < beta)
+ Value futilityCaptureValue = ss[ply].eval + pos.endgame_value_of_piece_on(move_to(move)) + preFutilityValueMargin + ei.futilityMargin + 90;
+
+ if (futilityCaptureValue < beta)
+ {
+ if (futilityCaptureValue > bestValue)
+ bestValue = futilityCaptureValue;
continue;
+ }
}
-
// Futility pruning
if ( !isCheck
&& !dangerous
if (predictedDepth >= OnePly)
preFutilityValueMargin = 112 * bitScanReverse32(int(predictedDepth) * int(predictedDepth) / 2);
- preFutilityValueMargin += MG.retrieve(pos.piece_on(move_from(move)), move_from(move), move_to(move)) + 45;
+ preFutilityValueMargin += H.gain(pos.piece_on(move_from(move)), move_from(move), move_to(move)) + 45;
futilityValueScaled = ss[ply].eval + preFutilityValueMargin - moveCount * IncrementalFutilityMargin;
if (!isCheck)
{
ss[ply].eval = staticValue;
- // Store gain statistics
- Move m = ss[ply - 1].currentMove;
- if ( m != MOVE_NULL
- && pos.captured_piece() == NO_PIECE_TYPE
- && !move_is_castle(m)
- && !move_is_promotion(m))
- MG.store(pos.piece_on(move_to(m)), move_from(m), move_to(m), ss[ply - 1].eval, -ss[ply].eval);
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
}
-
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
bestValue = staticValue;
SearchStack* ss = sp->sstack[threadID];
Value value = -VALUE_INFINITE;
Move move;
+ int moveCount;
bool isCheck = pos.is_check();
bool useFutilityPruning = sp->depth < SelectiveDepth
&& !isCheck;
const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8));
- while ( sp->bestValue < sp->beta
+ while ( lock_grab_bool(&(sp->lock))
+ && sp->bestValue < sp->beta
&& !thread_should_stop(threadID)
- && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
+ && (move = sp->mp->get_next_move()) != MOVE_NONE)
{
+ moveCount = ++sp->moves;
+ lock_release(&(sp->lock));
+
assert(move_is_ok(move));
bool moveIsCheck = pos.move_is_check(move, ci);
bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
- lock_grab(&(sp->lock));
- int moveCount = ++sp->moves;
- lock_release(&(sp->lock));
-
ss[sp->ply].currentMove = move;
- // Decide the new search depth.
+ // Decide the new search depth
bool dangerous;
Depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
if (thread_should_stop(threadID))
+ {
+ lock_grab(&(sp->lock));
break;
+ }
// New best move?
if (value > sp->bestValue) // Less then 2% of cases
}
}
- lock_grab(&(sp->lock));
+ /* Here we have the lock still grabbed */
// 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.
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
Value value = -VALUE_INFINITE;
+ int moveCount;
Move move;
- while ( sp->alpha < sp->beta
+ while ( lock_grab_bool(&(sp->lock))
+ && sp->alpha < sp->beta
&& !thread_should_stop(threadID)
- && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
+ && (move = sp->mp->get_next_move()) != MOVE_NONE)
{
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ moveCount = ++sp->moves;
+ lock_release(&(sp->lock));
assert(move_is_ok(move));
- lock_grab(&(sp->lock));
- int moveCount = ++sp->moves;
- lock_release(&(sp->lock));
+ bool moveIsCheck = pos.move_is_check(move, ci);
+ bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
ss[sp->ply].currentMove = move;
- // Decide the new search depth.
+ // Decide the new search depth
bool dangerous;
Depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
Depth newDepth = sp->depth - OnePly + ext;
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
if (thread_should_stop(threadID))
+ {
+ lock_grab(&(sp->lock));
break;
+ }
// New best move?
if (value > sp->bestValue) // Less then 2% of cases
}
}
- lock_grab(&(sp->lock));
+ /* Here we have the lock still grabbed */
// 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.
return defaultEval;
}
+ // calculate_reduction() returns reduction in plies based on
+ // moveCount and depth. Reduction is always at least one ply.
+
+ Depth calculate_reduction(double baseReduction, int moveCount, Depth depth, double reductionInhibitor) {
+
+ double red = baseReduction + ln(moveCount) * ln(depth / 2) / reductionInhibitor;
+
+ if (red >= 1.0)
+ return Depth(int(floor(red * int(OnePly))));
+ else
+ return Depth(0);
+
+ }
+
// update_history() registers a good move that produced a beta-cutoff
// in history and marks as failures all the other moves of that ply.
}
+ // update_gains() updates the gains table of a non-capture move given
+ // the static position evaluation before and after the move.
+
+ void update_gains(const Position& pos, Move m, Value before, Value after) {
+
+ if ( m != MOVE_NULL
+ && before != VALUE_NONE
+ && after != VALUE_NONE
+ && pos.captured_piece() == NO_PIECE_TYPE
+ && !move_is_castle(m)
+ && !move_is_promotion(m))
+ H.set_gain(pos.piece_on(move_to(m)), move_from(m), move_to(m), -(before + after));
+ }
+
+
// fail_high_ply_1() checks if some thread is currently resolving a fail
// high at ply 1 at the node below the first root node. This information
// is used for time management.
projects / stockfish / blobdiff