Simplify qsearch stages in MovePicker
The difference between QCAPTURES_1 and QCAPTURES_2 quiescence search stages boils down to a simple check of depth. The way it's being done now is unnecessarily complex. This patch is simpler, clearer, and easier to understand. Passed SPRT[-3..1] test at STC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 99755 W: 22158 L: 22192 D: 55405 http://tests.stockfishchess.org/tests/view/5a71f41c0ebc590f2c86e9cb No functional change.pull/1393/head
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@ -28,9 +28,7 @@ namespace {
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MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES,
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EVASION, EVASIONS_INIT, ALL_EVASIONS,
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PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES,
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QSEARCH_WITH_CHECKS, QCAPTURES_1_INIT, QCAPTURES_1, QCHECKS,
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QSEARCH_NO_CHECKS, QCAPTURES_2_INIT, QCAPTURES_2,
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QSEARCH_RECAPTURES, QRECAPTURES
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QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS, QSEARCH_RECAPTURES, QRECAPTURES
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};
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// partial_insertion_sort() sorts moves in descending order up to and including
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@ -81,18 +79,15 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist
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/// MovePicker constructor for quiescence search
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MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const CapturePieceToHistory* cph, Square s)
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: pos(p), mainHistory(mh), captureHistory(cph) {
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: pos(p), mainHistory(mh), captureHistory(cph), depth(d) {
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assert(d <= DEPTH_ZERO);
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if (pos.checkers())
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stage = EVASION;
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else if (d > DEPTH_QS_NO_CHECKS)
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stage = QSEARCH_WITH_CHECKS;
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else if (d > DEPTH_QS_RECAPTURES)
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stage = QSEARCH_NO_CHECKS;
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stage = QSEARCH;
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else
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{
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@ -161,8 +156,7 @@ Move MovePicker::next_move(bool skipQuiets) {
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switch (stage) {
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case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS:
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case QSEARCH_NO_CHECKS: case PROBCUT:
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case MAIN_SEARCH: case EVASION: case QSEARCH: case PROBCUT:
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++stage;
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return ttMove;
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@ -280,21 +274,21 @@ Move MovePicker::next_move(bool skipQuiets) {
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}
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break;
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case QCAPTURES_1_INIT: case QCAPTURES_2_INIT:
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case QCAPTURES_INIT:
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cur = moves;
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endMoves = generate<CAPTURES>(pos, cur);
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score<CAPTURES>();
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++stage;
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/* fallthrough */
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case QCAPTURES_1: case QCAPTURES_2:
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case QCAPTURES:
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while (cur < endMoves)
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{
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move = pick_best(cur++, endMoves);
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if (move != ttMove)
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return move;
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}
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if (stage == QCAPTURES_2)
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if (depth <= DEPTH_QS_NO_CHECKS)
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break;
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cur = moves;
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endMoves = generate<QUIET_CHECKS>(pos, cur);
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