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Use equations for PushAway and PushClose

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A functional simplification replacing the corresponding arrays. Tested in two variants,
also the simpler one performs well, even though differences to master should be minimal.

STC
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 57864 W: 11092 L: 11001 D: 35771
Ptnml(0-2): 826, 6458, 14320, 6455, 873
http://tests.stockfishchess.org/tests/view/5e5da5b6e42a5c3b3ca2e05c

LTC
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 7198 W: 982 L: 883 D: 5333
Ptnml(0-2): 33, 575, 2296, 650, 45
http://tests.stockfishchess.org/tests/view/5e5df13ae42a5c3b3ca2e077

LTC (This exact version. . . more simplified)
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 5392 W: 729 L: 631 D: 4032
Ptnml(0-2): 23, 405, 1751, 485, 32
http://tests.stockfishchess.org/tests/view/5e5ead99e42a5c3b3ca2e0e4

closes https://github.com/official-stockfish/Stockfish/pull/2570

Bench 5123316
This commit is contained in:
protonspring 2020-03-02 17:32:02 -07:00 • committed by Joost VandeVondele
parent 960d59d541
commit 5a7b45eac9
1 changed files with 8 additions and 8 deletions
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16
src/endgame.cpp
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@ -54,9 +54,9 @@ namespace {
4160, 4480, 4800, 5120, 5440, 5760, 6080, 6400
};
// Tables used to drive a piece towards or away from another piece
constexpr int PushClose[8] = { 0, 0, 100, 80, 60, 40, 20, 10 };
constexpr int PushAway [8] = { 0, 5, 20, 40, 60, 80, 90, 100 };
// Drive a piece close to or away from another piece
inline int push_close(Square s1, Square s2) { return 140 - 20 * distance(s1, s2); }
inline int push_away(Square s1, Square s2) { return 120 - push_close(s1, s2); }
// Pawn Rank based scaling factors used in KRPPKRP endgame
constexpr int KRPPKRPScaleFactors[RANK_NB] = { 0, 9, 10, 14, 21, 44, 0, 0 };
@ -130,7 +130,7 @@ Value Endgame<KXK>::operator()(const Position& pos) const {
Value result = pos.non_pawn_material(strongSide)
+ pos.count<PAWN>(strongSide) * PawnValueEg
+ PushToEdges[loserKSq]
+ PushClose[distance(winnerKSq, loserKSq)];
+ push_close(winnerKSq, loserKSq);
if ( pos.count<QUEEN>(strongSide)
|| pos.count<ROOK>(strongSide)
@ -159,7 +159,7 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
// to drive to opposite corners (A8/H1).
Value result = VALUE_KNOWN_WIN
+ PushClose[distance(winnerKSq, loserKSq)]
+ push_close(winnerKSq, loserKSq)
+ PushToCorners[opposite_colors(bishopSq, SQ_A1) ? ~loserKSq : loserKSq];
assert(abs(result) < VALUE_TB_WIN_IN_MAX_PLY);
@ -258,7 +258,7 @@ Value Endgame<KRKN>::operator()(const Position& pos) const {
Square bksq = pos.square<KING>(weakSide);
Square bnsq = pos.square<KNIGHT>(weakSide);
Value result = Value(PushToEdges[bksq] + PushAway[distance(bksq, bnsq)]);
Value result = Value(PushToEdges[bksq] + push_away(bksq, bnsq));
return strongSide == pos.side_to_move() ? result : -result;
}
@ -277,7 +277,7 @@ Value Endgame<KQKP>::operator()(const Position& pos) const {
Square loserKSq = pos.square<KING>(weakSide);
Square pawnSq = pos.square<PAWN>(weakSide);
Value result = Value(PushClose[distance(winnerKSq, loserKSq)]);
Value result = Value(push_close(winnerKSq, loserKSq));
if ( relative_rank(weakSide, pawnSq) != RANK_7
|| distance(loserKSq, pawnSq) != 1
@ -304,7 +304,7 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
Value result = QueenValueEg
- RookValueEg
+ PushToEdges[loserKSq]
+ PushClose[distance(winnerKSq, loserKSq)];
+ push_close(winnerKSq, loserKSq);
return strongSide == pos.side_to_move() ? result : -result;
}