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Simplify pawn asymmetry (remove use of semiopen files). (#2054)

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This is a functional simplification.

To me, the exclusive OR of semiopenFiles here is quite convoluted. Looks like it can be removed.

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 43885 W: 9731 L: 9653 D: 24501
http://tests.stockfishchess.org/tests/view/5c9041680ebc5925cfff10ea

LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 68437 W: 11577 L: 11533 D: 45327
http://tests.stockfishchess.org/tests/view/5c9101740ebc5925cfff1cbf

bench 3575627
This commit is contained in:
protonspring 2019-03-24 10:41:25 -06:00 • committed by Marco Costalba
parent 2f11c03bbf
commit 7133598a98
3 changed files with 6 additions and 7 deletions
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6
src/evaluate.cpp
View file

@ -743,12 +743,12 @@ namespace {
&& (pos.pieces(PAWN) & KingSide); && (pos.pieces(PAWN) & KingSide);
// Compute the initiative bonus for the attacking side // Compute the initiative bonus for the attacking side
int complexity = 9 * pe->pawn_asymmetry() int complexity = 9 * pe->passed_count()
+ 11 * pos.count<PAWN>() + 11 * pos.count<PAWN>()
+ 9 * outflanking + 9 * outflanking
+ 18 * pawnsOnBothFlanks + 18 * pawnsOnBothFlanks
+ 49 * !pos.non_pawn_material() + 49 * !pos.non_pawn_material()
-121 ; -103 ;
// Now apply the bonus: note that we find the attacking side by extracting // Now apply the bonus: note that we find the attacking side by extracting
// the sign of the endgame value, and that we carefully cap the bonus so // the sign of the endgame value, and that we carefully cap the bonus so
@ -776,7 +776,7 @@ namespace {
if ( pos.opposite_bishops() if ( pos.opposite_bishops()
&& pos.non_pawn_material(WHITE) == BishopValueMg && pos.non_pawn_material(WHITE) == BishopValueMg
&& pos.non_pawn_material(BLACK) == BishopValueMg) && pos.non_pawn_material(BLACK) == BishopValueMg)
sf = 8 + 4 * pe->pawn_asymmetry(); sf = 16 + 4 * pe->passed_count();
else else
sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide), sf); sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide), sf);

3
src/pawns.cpp
View file

@ -185,8 +185,7 @@ Entry* probe(const Position& pos) {
e->key = key; e->key = key;
e->scores[WHITE] = evaluate<WHITE>(pos, e); e->scores[WHITE] = evaluate<WHITE>(pos, e);
e->scores[BLACK] = evaluate<BLACK>(pos, e); e->scores[BLACK] = evaluate<BLACK>(pos, e);
e->asymmetry = popcount( (e->passedPawns[WHITE] | e->passedPawns[BLACK]) e->passedCount= popcount(e->passedPawns[WHITE] | e->passedPawns[BLACK]);
| (e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]));
return e; return e;
} }

4
src/pawns.h
View file

@ -38,7 +38,7 @@ struct Entry {
Bitboard passed_pawns(Color c) const { return passedPawns[c]; } Bitboard passed_pawns(Color c) const { return passedPawns[c]; }
Bitboard pawn_attacks_span(Color c) const { return pawnAttacksSpan[c]; } Bitboard pawn_attacks_span(Color c) const { return pawnAttacksSpan[c]; }
int weak_unopposed(Color c) const { return weakUnopposed[c]; } int weak_unopposed(Color c) const { return weakUnopposed[c]; }
int pawn_asymmetry() const { return asymmetry; } int passed_count() const { return passedCount; }
int semiopen_file(Color c, File f) const { int semiopen_file(Color c, File f) const {
return semiopenFiles[c] & (1 << f); return semiopenFiles[c] & (1 << f);
@ -71,7 +71,7 @@ struct Entry {
int castlingRights[COLOR_NB]; int castlingRights[COLOR_NB];
int semiopenFiles[COLOR_NB]; int semiopenFiles[COLOR_NB];
int pawnsOnSquares[COLOR_NB][COLOR_NB]; // [color][light/dark squares] int pawnsOnSquares[COLOR_NB][COLOR_NB]; // [color][light/dark squares]
int asymmetry; int passedCount;
}; };
typedef HashTable<Entry, 16384> Table; typedef HashTable<Entry, 16384> Table;