/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
+ Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <algorithm>
#include <cassert>
-#include <iterator>
#include <utility>
#include "bitboard.h"
MAIN_TT,
CAPTURE_INIT,
GOOD_CAPTURE,
- REFUTATION,
QUIET_INIT,
- QUIET,
+ GOOD_QUIET,
BAD_CAPTURE,
+ BAD_QUIET,
// generate evasion moves
EVASION_TT,
// generate qsearch moves
QSEARCH_TT,
QCAPTURE_INIT,
- QCAPTURE,
- QCHECK_INIT,
- QCHECK
+ QCAPTURE
};
-// Sort moves in descending order up to and including
-// a given limit. The order of moves smaller than the limit is left unspecified.
+// Sort moves in descending order up to and including a given limit.
+// The order of moves smaller than the limit is left unspecified.
void partial_insertion_sort(ExtMove* begin, ExtMove* end, int limit) {
for (ExtMove *sortedEnd = begin, *p = begin + 1; p < end; ++p)
// Constructors of the MovePicker class. As arguments, we pass information
-// to help it return the (presumably) good moves first, to decide which
-// moves to return (in the quiescence search, for instance, we only want to
-// search captures, promotions, and some checks) and how important a good
-// move ordering is at the current node.
+// to decide which class of moves to emit, to help sorting the (presumably)
+// good moves first, and how important move ordering is at the current node.
-// MovePicker constructor for the main search
+// MovePicker constructor for the main search and for the quiescence search
MovePicker::MovePicker(const Position& p,
Move ttm,
Depth d,
const ButterflyHistory* mh,
const CapturePieceToHistory* cph,
const PieceToHistory** ch,
- Move cm,
- const Move* killers) :
+ const PawnHistory* ph) :
pos(p),
mainHistory(mh),
captureHistory(cph),
continuationHistory(ch),
+ pawnHistory(ph),
ttMove(ttm),
- refutations{{killers[0], 0}, {killers[1], 0}, {cm, 0}},
depth(d) {
- assert(d > 0);
- stage = (pos.checkers() ? EVASION_TT : MAIN_TT) + !(ttm && pos.pseudo_legal(ttm));
-}
-
-// Constructor for quiescence search
-MovePicker::MovePicker(const Position& p,
- Move ttm,
- Depth d,
- const ButterflyHistory* mh,
- const CapturePieceToHistory* cph,
- const PieceToHistory** ch,
- Square rs) :
- pos(p),
- mainHistory(mh),
- captureHistory(cph),
- continuationHistory(ch),
- ttMove(ttm),
- recaptureSquare(rs),
- depth(d) {
- assert(d <= 0);
+ if (pos.checkers())
+ stage = EVASION_TT + !(ttm && pos.pseudo_legal(ttm));
- stage = (pos.checkers() ? EVASION_TT : QSEARCH_TT) + !(ttm && pos.pseudo_legal(ttm));
+ else
+ stage = (depth > 0 ? MAIN_TT : QSEARCH_TT) + !(ttm && pos.pseudo_legal(ttm));
}
-// Constructor for ProbCut: we generate captures with SEE greater
-// than or equal to the given threshold.
-MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph) :
+// MovePicker constructor for ProbCut: we generate captures with Static Exchange
+// Evaluation (SEE) greater than or equal to the given threshold.
+MovePicker::MovePicker(const Position& p, Move ttm, int th, const CapturePieceToHistory* cph) :
pos(p),
captureHistory(cph),
ttMove(ttm),
+ !(ttm && pos.capture_stage(ttm) && pos.pseudo_legal(ttm) && pos.see_ge(ttm, threshold));
}
-// Assigns a numerical value to each move in a list, used
-// for sorting. Captures are ordered by Most Valuable Victim (MVV), preferring
-// captures with a good history. Quiets moves are ordered using the history tables.
+// Assigns a numerical value to each move in a list, used for sorting.
+// Captures are ordered by Most Valuable Victim (MVV), preferring captures
+// with a good history. Quiets moves are ordered using the history tables.
template<GenType Type>
void MovePicker::score() {
for (auto& m : *this)
if constexpr (Type == CAPTURES)
m.value =
- (7 * int(PieceValue[pos.piece_on(to_sq(m))])
- + (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))])
- / 16;
+ 7 * int(PieceValue[pos.piece_on(m.to_sq())])
+ + (*captureHistory)[pos.moved_piece(m)][m.to_sq()][type_of(pos.piece_on(m.to_sq()))];
else if constexpr (Type == QUIETS)
{
Piece pc = pos.moved_piece(m);
- PieceType pt = type_of(pos.moved_piece(m));
- Square from = from_sq(m);
- Square to = to_sq(m);
+ PieceType pt = type_of(pc);
+ Square from = m.from_sq();
+ Square to = m.to_sq();
// histories
- m.value = 2 * (*mainHistory)[pos.side_to_move()][from_to(m)];
+ m.value = (*mainHistory)[pos.side_to_move()][m.from_to()];
+ m.value += 2 * (*pawnHistory)[pawn_structure_index(pos)][pc][to];
m.value += 2 * (*continuationHistory[0])[pc][to];
m.value += (*continuationHistory[1])[pc][to];
- m.value += (*continuationHistory[2])[pc][to] / 4;
+ m.value += (*continuationHistory[2])[pc][to] / 3;
m.value += (*continuationHistory[3])[pc][to];
m.value += (*continuationHistory[5])[pc][to];
m.value += bool(pos.check_squares(pt) & to) * 16384;
// bonus for escaping from capture
- m.value += threatenedPieces & from ? (pt == QUEEN && !(to & threatenedByRook) ? 50000
- : pt == ROOK && !(to & threatenedByMinor) ? 25000
- : !(to & threatenedByPawn) ? 15000
+ m.value += threatenedPieces & from ? (pt == QUEEN && !(to & threatenedByRook) ? 51700
+ : pt == ROOK && !(to & threatenedByMinor) ? 25600
+ : !(to & threatenedByPawn) ? 14450
: 0)
: 0;
// malus for putting piece en prise
- m.value -= !(threatenedPieces & from)
- ? (pt == QUEEN ? bool(to & threatenedByRook) * 50000
- + bool(to & threatenedByMinor) * 10000
- + bool(to & threatenedByPawn) * 20000
- : pt == ROOK ? bool(to & threatenedByMinor) * 25000
- + bool(to & threatenedByPawn) * 10000
- : pt != PAWN ? bool(to & threatenedByPawn) * 15000
- : 0)
- : 0;
+ m.value -= (pt == QUEEN ? bool(to & threatenedByRook) * 49000
+ : pt == ROOK ? bool(to & threatenedByMinor) * 24335
+ : bool(to & threatenedByPawn) * 14900);
}
else // Type == EVASIONS
{
if (pos.capture_stage(m))
- m.value = PieceValue[pos.piece_on(to_sq(m))] - Value(type_of(pos.moved_piece(m)))
- + (1 << 28);
+ m.value =
+ PieceValue[pos.piece_on(m.to_sq())] - type_of(pos.moved_piece(m)) + (1 << 28);
else
- m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
- + (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)];
+ m.value = (*mainHistory)[pos.side_to_move()][m.from_to()]
+ + (*continuationHistory[0])[pos.moved_piece(m)][m.to_sq()]
+ + (*pawnHistory)[pawn_structure_index(pos)][pos.moved_piece(m)][m.to_sq()];
}
}
// Returns the next move satisfying a predicate function.
-// It never returns the TT move.
+// This never returns the TT move, as it was emitted before.
template<MovePicker::PickType T, typename Pred>
Move MovePicker::select(Pred filter) {
cur++;
}
- return MOVE_NONE;
+ return Move::none();
}
-// Most important method of the MovePicker class. It
-// returns a new pseudo-legal move every time it is called until there are no more
-// moves left, picking the move with the highest score from a list of generated moves.
+// This is the most important method of the MovePicker class. We emit one
+// new pseudo-legal move on every call until there are no more moves left,
+// picking the move with the highest score from a list of generated moves.
Move MovePicker::next_move(bool skipQuiets) {
+ auto quiet_threshold = [](Depth d) { return -3560 * d; };
+
top:
switch (stage)
{
case GOOD_CAPTURE :
if (select<Next>([&]() {
- return pos.see_ge(*cur, Value(-cur->value))
- ?
- // Move losing capture to endBadCaptures to be tried later
- true
- : (*endBadCaptures++ = *cur, false);
+ // Move losing capture to endBadCaptures to be tried later
+ return pos.see_ge(*cur, -cur->value / 18) ? true
+ : (*endBadCaptures++ = *cur, false);
}))
return *(cur - 1);
- // Prepare the pointers to loop over the refutations array
- cur = std::begin(refutations);
- endMoves = std::end(refutations);
-
- // If the countermove is the same as a killer, skip it
- if (refutations[0].move == refutations[2].move
- || refutations[1].move == refutations[2].move)
- --endMoves;
-
- ++stage;
- [[fallthrough]];
-
- case REFUTATION :
- if (select<Next>([&]() {
- return *cur != MOVE_NONE && !pos.capture_stage(*cur) && pos.pseudo_legal(*cur);
- }))
- return *(cur - 1);
++stage;
[[fallthrough]];
if (!skipQuiets)
{
cur = endBadCaptures;
- endMoves = generate<QUIETS>(pos, cur);
+ endMoves = beginBadQuiets = endBadQuiets = generate<QUIETS>(pos, cur);
score<QUIETS>();
- partial_insertion_sort(cur, endMoves, -3000 * depth);
+ partial_insertion_sort(cur, endMoves, quiet_threshold(depth));
}
++stage;
[[fallthrough]];
- case QUIET :
- if (!skipQuiets && select<Next>([&]() {
- return *cur != refutations[0].move && *cur != refutations[1].move
- && *cur != refutations[2].move;
- }))
- return *(cur - 1);
+ case GOOD_QUIET :
+ if (!skipQuiets && select<Next>([]() { return true; }))
+ {
+ if ((cur - 1)->value > -7998 || (cur - 1)->value <= quiet_threshold(depth))
+ return *(cur - 1);
+
+ // Remaining quiets are bad
+ beginBadQuiets = cur - 1;
+ }
// Prepare the pointers to loop over the bad captures
cur = moves;
[[fallthrough]];
case BAD_CAPTURE :
- return select<Next>([]() { return true; });
+ if (select<Next>([]() { return true; }))
+ return *(cur - 1);
+
+ // Prepare the pointers to loop over the bad quiets
+ cur = beginBadQuiets;
+ endMoves = endBadQuiets;
+
+ ++stage;
+ [[fallthrough]];
+
+ case BAD_QUIET :
+ if (!skipQuiets)
+ return select<Next>([]() { return true; });
+
+ return Move::none();
case EVASION_INIT :
cur = moves;
return select<Next>([&]() { return pos.see_ge(*cur, threshold); });
case QCAPTURE :
- if (select<Next>(
- [&]() { return depth > DEPTH_QS_RECAPTURES || to_sq(*cur) == recaptureSquare; }))
- return *(cur - 1);
-
- // If we did not find any move and we do not try checks, we have finished
- if (depth != DEPTH_QS_CHECKS)
- return MOVE_NONE;
-
- ++stage;
- [[fallthrough]];
-
- case QCHECK_INIT :
- cur = moves;
- endMoves = generate<QUIET_CHECKS>(pos, cur);
-
- ++stage;
- [[fallthrough]];
-
- case QCHECK :
return select<Next>([]() { return true; });
}
assert(false);
- return MOVE_NONE; // Silence warning
+ return Move::none(); // Silence warning
}
} // namespace Stockfish
projects / stockfish / blobdiff