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Don't prune discovered checks

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Don't prune and eventually extend check moves of type
DISCO_CHECK (pun intended, Lucas will understand :-) ).

Patch from Lucas Braesch that has also tested it:

Result: 879-661-2137, score=52.96%, LOS=100.00% (time 10"+0.1")

I have started a verification test right now.

bench: 6004966
This commit is contained in:
Marco Costalba
2012-11-07 18:20:39 +01:00
parent 3b87314331
commit 96d3b1c92b
4 changed files with 22 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
src/position.cpp
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@@ -657,7 +657,7 @@ bool Position::is_pseudo_legal(const Move m) const {
/// Position::move_gives_check() tests whether a pseudo-legal move gives a check
bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
CheckType Position::move_gives_check(Move m, const CheckInfo& ci) const {
assert(is_ok(m));
assert(ci.dcCandidates == discovered_check_candidates());
@@ -669,7 +669,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
// Direct check ?
if (ci.checkSq[pt] & to)
return true;
return DIRECT_CHECK;
// Discovery check ?
if (ci.dcCandidates && (ci.dcCandidates & from))
@@ -677,19 +677,19 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
// For pawn and king moves we need to verify also direction
if ( (pt != PAWN && pt != KING)
|| !squares_aligned(from, to, king_square(~sideToMove)))
return true;
return DISCO_CHECK;
}
// Can we skip the ugly special cases ?
if (type_of(m) == NORMAL)
return false;
return NO_CHECK;
Color us = sideToMove;
Square ksq = king_square(~us);
// Promotion with check ?
if (type_of(m) == PROMOTION)
return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq;
return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq ? DIRECT_CHECK : NO_CHECK;
// En passant capture with check ? We have already handled the case
// of direct checks and ordinary discovered check, the only case we
@@ -701,7 +701,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
Bitboard b = (pieces() ^ from ^ capsq) | to;
return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK))
| (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP));
| (attacks_bb<BISHOP>(ksq, b) & pieces(us, QUEEN, BISHOP)) ? DISCO_CHECK : NO_CHECK;
}
// Castling with check ?
@@ -713,10 +713,10 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1);
Bitboard b = (pieces() ^ kfrom ^ rfrom) | rto | kto;
return attacks_bb<ROOK>(rto, b) & ksq;
return attacks_bb<ROOK>(rto, b) & ksq ? DIRECT_CHECK : NO_CHECK;
}
return false;
return NO_CHECK;
}