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Use two counter moves instead of one

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Very good at long 60"+0.05 TC
LLR: 2.95 (-2.94,2.94)
Total: 5954 W: 1151 L: 1016 D: 3787

[edit: slightly changed form original patch to avoid useless loop
 across killers when killer is MOVE_NONE]

bench: 4327405
This commit is contained in:
Joona Kiiski
2013-05-15 20:31:45 +01:00
committed by Marco Costalba
parent 148490f04c
commit f7c013edd0
2 changed files with 27 additions and 7 deletions
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18
src/movepick.cpp
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@@ -90,7 +90,8 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats&
killers[0].move = ss->killers[0];
killers[1].move = ss->killers[1];
Square prevSq = to_sq((ss-1)->currentMove);
killers[2].move = cm[pos.piece_on(prevSq)][prevSq];
killers[2].move = cm[pos.piece_on(prevSq)][prevSq].first;
killers[3].move = cm[pos.piece_on(prevSq)][prevSq].second;
// Consider sligtly negative captures as good if at low depth and far from beta
if (ss && ss->staticEval < beta - PawnValueMg && d < 3 * ONE_PLY)
@@ -239,7 +240,17 @@ void MovePicker::generate_next() {
case KILLERS_S1:
cur = killers;
end = cur + 3 - (killers[2].move == killers[0].move || killers[2].move == killers[1].move);
end = cur + 2;
if ((cur+3)->move && (cur+3)->move == (cur+2)->move) // Due to a SMP race
(cur+3)->move = MOVE_NONE;
// Be sure countermoves are different from killers
if ((cur+2)->move != cur->move && (cur+2)->move != (cur+1)->move)
end++;
if ((cur+3)->move != cur->move && (cur+3)->move != (cur+1)->move)
(end++)->move = (cur+3)->move;
return;
case QUIETS_1_S1:
@@ -332,7 +343,8 @@ Move MovePicker::next_move<false>() {
if ( move != ttMove
&& move != killers[0].move
&& move != killers[1].move
&& move != killers[2].move)
&& move != killers[2].move
&& move != killers[3].move)
return move;
break;