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Micro-optimize perft

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Avoid to call perft function when we just need to count
moves, at leaf nodes.

Speed up of almost 2%

No functional change.
This commit is contained in:
Marco Costalba 2013-06-21 09:10:03 +02:00
parent e95e69515a
commit e215a88cdd
1 changed files with 2 additions and 6 deletions
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8
src/search.cpp
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@ -155,21 +155,17 @@ void Search::init() {
size_t Search::perft(Position& pos, Depth depth) { size_t Search::perft(Position& pos, Depth depth) {
// At the last ply just return the number of legal moves (leaf nodes)
if (depth == ONE_PLY)
return MoveList<LEGAL>(pos).size();
StateInfo st; StateInfo st;
size_t cnt = 0; size_t cnt = 0;
CheckInfo ci(pos); CheckInfo ci(pos);
const bool leaf = depth == 2 * ONE_PLY;
for (MoveList<LEGAL> it(pos); *it; ++it) for (MoveList<LEGAL> it(pos); *it; ++it)
{ {
pos.do_move(*it, st, ci, pos.move_gives_check(*it, ci)); pos.do_move(*it, st, ci, pos.move_gives_check(*it, ci));
cnt += perft(pos, depth - ONE_PLY); cnt += leaf ? MoveList<LEGAL>(pos).size() : perft(pos, depth - ONE_PLY);
pos.undo_move(*it); pos.undo_move(*it);
} }
return cnt; return cnt;
} }