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Revert "Move draw by material check"

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Possible regression

bench: 4554579
This commit is contained in:
Marco Costalba 2013-09-12 08:41:28 +02:00
parent 45b0aea875
commit 27f2ce8f6e
3 changed files with 14 additions and 15 deletions
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2
src/endgame.h
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@ -43,7 +43,7 @@ enum EndgameType {
KQKP, // KQ vs KP
KQKR, // KQ vs KR
KBBKN, // KBB vs KN
KmmKm, // K and one or two minors vs K and zero or one minor
KmmKm, // K and two minors vs K and one or two minors
// Scaling functions

15
src/material.cpp
View file

@ -173,18 +173,10 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
return e;
}
// Draw by insufficient material (trivial draws like KK, KBK and KNK)
if ( !pos.pieces(PAWN)
&& pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) <= BishopValueMg)
{
e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
return e;
}
// Minor piece endgame with at least one minor piece per side and
// no pawns. Note that the case KmmK is already handled by KXK.
if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
{
// Minor piece endgame with at least one minor piece per side and
// no pawns. Note that the case KmmK is already handled by KXK.
assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP)));
assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP)));
@ -248,7 +240,8 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
}
}
// No pawns makes it difficult to win, even with a material advantage
// No pawns makes it difficult to win, even with a material advantage. This
// catches some trivial draws like KK, KBK and KNK
if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
{
e->factor[WHITE] = (uint8_t)

12
src/position.cpp
View file

@ -1255,11 +1255,17 @@ Value Position::compute_non_pawn_material(Color c) const {
}
/// Position::is_draw() tests whether the position is drawn by 50 moves rule
/// or by repetition. It does not detect stalemates.
/// 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.
bool Position::is_draw() const {
// Draw by material?
if ( !pieces(PAWN)
&& (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg))
return true;
// Draw by the 50 moves rule?
if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;