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Candidate passed pawns

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Detect safe candidate passers.

STC: http://tests.stockfishchess.org/tests/view/5882395c0ebc5915193f78b3
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 53569 W: 9925 L: 9570 D: 34074

LTC: http://tests.stockfishchess.org/tests/view/5882b4fb0ebc5915193f78e2
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 77576 W: 10387 L: 10014 D: 57175

Bench: 5325829
This commit is contained in:
Stefan Geschwentner 2017-01-19 18:16:23 +01:00 • committed by Marco Costalba
parent 58c181de9a
commit 471f7a1b5c
2 changed files with 20 additions and 8 deletions
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15
src/evaluate.cpp
View file

@ -606,10 +606,11 @@ namespace {
} }
// evaluate_passed_pawns() evaluates the passed pawns of the given color // evaluate_passer_pawns() evaluates the passed pawns and candidate passed
// pawns of the given color.
template<Color Us, bool DoTrace> template<Color Us, bool DoTrace>
Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) { Score evaluate_passer_pawns(const Position& pos, const EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE); const Color Them = (Us == WHITE ? BLACK : WHITE);
@ -622,7 +623,6 @@ namespace {
{ {
Square s = pop_lsb(&b); Square s = pop_lsb(&b);
assert(pos.pawn_passed(Us, s));
assert(!(pos.pieces(PAWN) & forward_bb(Us, s))); assert(!(pos.pieces(PAWN) & forward_bb(Us, s)));
bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them)); bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
@ -683,6 +683,11 @@ namespace {
if (!pos.non_pawn_material(Them)) if (!pos.non_pawn_material(Them))
ebonus += 20; ebonus += 20;
// Scale down bonus for candidate passers which need more than one pawn
// push to become passed.
if (!pos.pawn_passed(Us, s + pawn_push(Us)))
mbonus /= 2, ebonus /= 2;
score += make_score(mbonus, ebonus) + PassedFile[file_of(s)]; score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
} }
@ -844,8 +849,8 @@ Value Eval::evaluate(const Position& pos) {
- evaluate_threats<BLACK, DoTrace>(pos, ei); - evaluate_threats<BLACK, DoTrace>(pos, ei);
// Evaluate passed pawns, we need full attack information including king // Evaluate passed pawns, we need full attack information including king
score += evaluate_passed_pawns<WHITE, DoTrace>(pos, ei) score += evaluate_passer_pawns<WHITE, DoTrace>(pos, ei)
- evaluate_passed_pawns<BLACK, DoTrace>(pos, ei); - evaluate_passer_pawns<BLACK, DoTrace>(pos, ei);
// Evaluate space for both sides, only during opening // Evaluate space for both sides, only during opening
if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222) if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)

13
src/pawns.cpp
View file

@ -99,8 +99,9 @@ namespace {
const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST); const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
Bitboard b, neighbours, stoppers, doubled, supported, phalanx; Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
Bitboard lever, leverPush, connected;
Square s; Square s;
bool opposed, lever, connected, backward; bool opposed, backward;
Score score = SCORE_ZERO; Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us); const Square* pl = pos.squares<PAWN>(Us);
const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
@ -129,6 +130,7 @@ namespace {
opposed = theirPawns & forward_bb(Us, s); opposed = theirPawns & forward_bb(Us, s);
stoppers = theirPawns & passed_pawn_mask(Us, s); stoppers = theirPawns & passed_pawn_mask(Us, s);
lever = theirPawns & pawnAttacksBB[s]; lever = theirPawns & pawnAttacksBB[s];
leverPush = theirPawns & pawnAttacksBB[s + Up];
doubled = ourPawns & (s + Up); doubled = ourPawns & (s + Up);
neighbours = ourPawns & adjacent_files_bb(f); neighbours = ourPawns & adjacent_files_bb(f);
phalanx = neighbours & rank_bb(s); phalanx = neighbours & rank_bb(s);
@ -153,8 +155,13 @@ namespace {
} }
// Passed pawns will be properly scored in evaluation because we need // Passed pawns will be properly scored in evaluation because we need
// full attack info to evaluate them. // full attack info to evaluate them. Include also not passed pawns
if (!stoppers && !(ourPawns & forward_bb(Us, s))) // which could become passed after one or two pawn pushes when are
// not attacked more times than defended.
if ( !(stoppers ^ lever ^ leverPush)
&& !(ourPawns & forward_bb(Us, s))
&& popcount(supported) >= popcount(lever)
&& popcount(phalanx) >= popcount(leverPush))
e->passedPawns[Us] |= s; e->passedPawns[Us] |= s;
// Score this pawn // Score this pawn