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Code Issues Releases Wiki Activity

Simplify qsearch stages in MovePicker

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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.
This commit is contained in:
protonspring 2018-02-04 14:57:57 +01:00 • committed by Stéphane Nicolet
parent 44a7db0f9a
commit d93baae220
1 changed files with 7 additions and 13 deletions
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20
src/movepick.cpp
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@ -28,9 +28,7 @@ namespace {
MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES, MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES,
EVASION, EVASIONS_INIT, ALL_EVASIONS, EVASION, EVASIONS_INIT, ALL_EVASIONS,
PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES, PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES,
QSEARCH_WITH_CHECKS, QCAPTURES_1_INIT, QCAPTURES_1, QCHECKS, QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS, QSEARCH_RECAPTURES, QRECAPTURES
QSEARCH_NO_CHECKS, QCAPTURES_2_INIT, QCAPTURES_2,
QSEARCH_RECAPTURES, QRECAPTURES
}; };
// partial_insertion_sort() sorts moves in descending order up to and including // partial_insertion_sort() sorts moves in descending order up to and including
@ -81,18 +79,15 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist
/// MovePicker constructor for quiescence search /// MovePicker constructor for quiescence search
MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const CapturePieceToHistory* cph, Square s) MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh, const CapturePieceToHistory* cph, Square s)
: pos(p), mainHistory(mh), captureHistory(cph) { : pos(p), mainHistory(mh), captureHistory(cph), depth(d) {
assert(d <= DEPTH_ZERO); assert(d <= DEPTH_ZERO);
if (pos.checkers()) if (pos.checkers())
stage = EVASION; stage = EVASION;
else if (d > DEPTH_QS_NO_CHECKS)
stage = QSEARCH_WITH_CHECKS;
else if (d > DEPTH_QS_RECAPTURES) else if (d > DEPTH_QS_RECAPTURES)
stage = QSEARCH_NO_CHECKS; stage = QSEARCH;
else else
{ {
@ -161,8 +156,7 @@ Move MovePicker::next_move(bool skipQuiets) {
switch (stage) { switch (stage) {
case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS: case MAIN_SEARCH: case EVASION: case QSEARCH: case PROBCUT:
case QSEARCH_NO_CHECKS: case PROBCUT:
++stage; ++stage;
return ttMove; return ttMove;
@ -280,21 +274,21 @@ Move MovePicker::next_move(bool skipQuiets) {
} }
break; break;
case QCAPTURES_1_INIT: case QCAPTURES_2_INIT: case QCAPTURES_INIT:
cur = moves; cur = moves;
endMoves = generate<CAPTURES>(pos, cur); endMoves = generate<CAPTURES>(pos, cur);
score<CAPTURES>(); score<CAPTURES>();
++stage; ++stage;
/* fallthrough */ /* fallthrough */
case QCAPTURES_1: case QCAPTURES_2: case QCAPTURES:
while (cur < endMoves) while (cur < endMoves)
{ {
move = pick_best(cur++, endMoves); move = pick_best(cur++, endMoves);
if (move != ttMove) if (move != ttMove)
return move; return move;
} }
if (stage == QCAPTURES_2) if (depth <= DEPTH_QS_NO_CHECKS)
break; break;
cur = moves; cur = moves;
endMoves = generate<QUIET_CHECKS>(pos, cur); endMoves = generate<QUIET_CHECKS>(pos, cur);