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Skip draw by repetition check in qsearch

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Cut in half the time spent in pos.draw() that accounts
for a whopping 1% of total time !

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-06-04 11:29:54 +01:00
parent 91407f4f74
commit 3b2bcee0a8
3 changed files with 13 additions and 8 deletions
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13
src/position.cpp
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@@ -1778,7 +1778,7 @@ Value Position::compute_non_pawn_material(Color c) const {
/// Position::is_draw() tests whether the position is drawn by material,
/// repetition, or the 50 moves rule. It does not detect stalemates, this
/// must be done by the search.
template<bool SkipRepetition>
bool Position::is_draw() const {
// Draw by material?
@@ -1791,13 +1791,18 @@ bool Position::is_draw() const {
return true;
// Draw by repetition?
for (int i = 4, e = Min(Min(st->gamePly, st->rule50), st->pliesFromNull); i <= e; i += 2)
if (history[st->gamePly - i] == st->key)
return true;
if (!SkipRepetition)
for (int i = 4, e = Min(Min(st->gamePly, st->rule50), st->pliesFromNull); i <= e; i += 2)
if (history[st->gamePly - i] == st->key)
return true;
return false;
}
// Explicit template instantiations
template bool Position::is_draw<false>() const;
template bool Position::is_draw<true>() const;
/// Position::is_mate() returns true or false depending on whether the
/// side to move is checkmated.