Add eg component to evaluate_shelter() #2137

Add an endgame component to the blockedstorm penalty
so that the penalty applies more uniformly through the game.

STC 10+0.1 th 1 :
LLR: -2.95 (-2.94,2.94) [0.50,4.50]
Total: 94063 W: 21426 L: 21118 D: 51519
http://tests.stockfishchess.org/tests/view/5cd4605c0ebc5925cf04bf43

LTC 60+0.6 th 1 :
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 188232 W: 32808 L: 32090 D: 123334
http://tests.stockfishchess.org/tests/view/5cd47d0a0ebc5925cf04c4fd

Refactored code with higher constant values gave a more convincing LTC result:
LLR: 2.96 (-2.94,2.94) [0.00,3.50]
Total: 30050 W: 5330 L: 5066 D: 19654
http://tests.stockfishchess.org/tests/view/5cd6a0000ebc5925cf050653

Bench: 3687700

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 0a88c9f1ba37b07a3738800fea6d11f0c003ec09..8d6f812a6d56cf5607e06f51c903f96cad0fc01f 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -172,7 +172,7 @@ Entry* probe(const Position& pos) {
 /// penalty for a king, looking at the king file and the two closest files.
 
 template<Color Us>
 /// penalty for a king, looking at the king file and the two closest files.
 
 template<Color Us>

-Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
+void Entry::evaluate_shelter(const Position& pos, Square ksq, Score& shelter) {

 
   constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
   constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
 
   constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
   constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);


@@ -183,7 +183,8 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
   Bitboard ourPawns = b & pos.pieces(Us);
   Bitboard theirPawns = b & pos.pieces(Them);
 
   Bitboard ourPawns = b & pos.pieces(Us);
   Bitboard theirPawns = b & pos.pieces(Them);
 

-  Value safety = (shift<Down>(theirPawns) & BlockSquares & ksq) ? Value(374) : Value(5);
+  Value bonus[] = { (shift<Down>(theirPawns) & BlockSquares & ksq) ? Value(374) : Value(5),
+                    VALUE_ZERO };

 
   File center = clamp(file_of(ksq), FILE_B, FILE_G);
   for (File f = File(center - 1); f <= File(center + 1); ++f)
 
   File center = clamp(file_of(ksq), FILE_B, FILE_G);
   for (File f = File(center - 1); f <= File(center + 1); ++f)


@@ -195,12 +196,16 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
       Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
 
       int d = std::min(f, ~f);
       Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
 
       int d = std::min(f, ~f);

-      safety += ShelterStrength[d][ourRank];
-      safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3)
-                                                        : UnblockedStorm[d][theirRank];
+      bonus[MG] += ShelterStrength[d][ourRank];
+
+      if (ourRank && (ourRank == theirRank - 1))
+          bonus[MG] -= 82 * (theirRank == RANK_3), bonus[EG] -= 82 * (theirRank == RANK_3);
+      else
+          bonus[MG] -= UnblockedStorm[d][theirRank];

   }
 
   }
 

-  return safety;
+  if (bonus[MG] > mg_value(shelter))
+      shelter = make_score(bonus[MG], bonus[EG]);

 }
 
 
 }
 
 


@@ -223,16 +228,17 @@ Score Entry::do_king_safety(const Position& pos) {
   else while (pawns)
       minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
 
   else while (pawns)
       minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
 

-  Value bonus = evaluate_shelter<Us>(pos, ksq);
+  Score shelter = make_score(-VALUE_INFINITE, VALUE_ZERO);
+  evaluate_shelter<Us>(pos, ksq, shelter);

 
   // If we can castle use the bonus after the castling if it is bigger
   if (pos.can_castle(Us | KING_SIDE))
 
   // If we can castle use the bonus after the castling if it is bigger
   if (pos.can_castle(Us | KING_SIDE))

-      bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)));
+      evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1), shelter);

 
   if (pos.can_castle(Us | QUEEN_SIDE))
 
   if (pos.can_castle(Us | QUEEN_SIDE))

-      bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)));
+      evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1), shelter);

 
 

-  return make_score(bonus, -16 * minPawnDist);
+  return shelter - make_score(VALUE_ZERO, 16 * minPawnDist);

 }
 
 // Explicit template instantiation
 }
 
 // Explicit template instantiation

diff --git a/src/pawns.h b/src/pawns.h
index 76c5ffc95100bcf9a4b45a7e788f8d874b55153c..771e9cd353069a8ebdadcf652ca16806df6ce2e3 100644 (file)
--- a/src/pawns.h
+++ b/src/pawns.h
@@ -50,7 +50,7 @@ struct Entry {
   Score do_king_safety(const Position& pos);
 
   template<Color Us>
   Score do_king_safety(const Position& pos);
 
   template<Color Us>

-  Value evaluate_shelter(const Position& pos, Square ksq);
+  void evaluate_shelter(const Position& pos, Square ksq, Score& shelter);

 
   Key key;
   Score scores[COLOR_NB];
 
   Key key;
   Score scores[COLOR_NB];