Cleaned up MakeIndex()

The index order in kpp_board_index[][] is reversed to be more optimal for the access pattern

STC https://tests.stockfishchess.org/tests/view/5fbd74f967cbf42301d6b24f
LLR: 2.93 (-2.94,2.94) {-1.25,0.25}
Total: 27504 W: 2686 L: 2607 D: 22211
Ptnml(0-2): 84, 2001, 9526, 2034, 107

closes https://github.com/official-stockfish/Stockfish/pull/3233

No functional change

diff --git a/src/nnue/evaluate_nnue.cpp b/src/nnue/evaluate_nnue.cpp
index b0ed7d2f5a4f78e0092603edf4756402c69de2ae..382d8ff9d0623a7d5744a1ac7c89e22c1e181a22 100644 (file)
--- a/src/nnue/evaluate_nnue.cpp
+++ b/src/nnue/evaluate_nnue.cpp
@@ -31,27 +31,6 @@
 
 namespace Eval::NNUE {
 
-  const uint32_t kpp_board_index[PIECE_NB][COLOR_NB] = {
-   // convention: W - us, B - them
-   // viewed from other side, W and B are reversed
-      { PS_NONE,     PS_NONE     },
-      { PS_W_PAWN,   PS_B_PAWN   },
-      { PS_W_KNIGHT, PS_B_KNIGHT },
-      { PS_W_BISHOP, PS_B_BISHOP },
-      { PS_W_ROOK,   PS_B_ROOK   },
-      { PS_W_QUEEN,  PS_B_QUEEN  },
-      { PS_W_KING,   PS_B_KING   },
-      { PS_NONE,     PS_NONE     },
-      { PS_NONE,     PS_NONE     },
-      { PS_B_PAWN,   PS_W_PAWN   },
-      { PS_B_KNIGHT, PS_W_KNIGHT },
-      { PS_B_BISHOP, PS_W_BISHOP },
-      { PS_B_ROOK,   PS_W_ROOK   },
-      { PS_B_QUEEN,  PS_W_QUEEN  },
-      { PS_B_KING,   PS_W_KING   },
-      { PS_NONE,     PS_NONE     }
-  };
-
   // Input feature converter
   LargePagePtr<FeatureTransformer> feature_transformer;
 

diff --git a/src/nnue/features/half_kp.cpp b/src/nnue/features/half_kp.cpp
index 116157cc19d1b6e555fb39a39dd18ee1822fd9a3..29322f040893fc9f40161b64f3a6527961b078ca 100644 (file)
--- a/src/nnue/features/half_kp.cpp
+++ b/src/nnue/features/half_kp.cpp
@@ -28,12 +28,9 @@ namespace Eval::NNUE::Features {
     return Square(int(s) ^ (bool(perspective) * 63));
   }
 
-  // Find the index of the feature quantity from the king position and PieceSquare
-  template <Side AssociatedKing>
-  inline IndexType HalfKP<AssociatedKing>::MakeIndex(
-      Color perspective, Square s, Piece pc, Square ksq) {
-
-    return IndexType(orient(perspective, s) + kpp_board_index[pc][perspective] + PS_END * ksq);
+  // Index of a feature for a given king position and another piece on some square
+  inline IndexType make_index(Color perspective, Square s, Piece pc, Square ksq) {
+    return IndexType(orient(perspective, s) + kpp_board_index[perspective][pc] + PS_END * ksq);
   }
 
   // Get a list of indices for active features
@@ -45,7 +42,7 @@ namespace Eval::NNUE::Features {
     Bitboard bb = pos.pieces() & ~pos.pieces(KING);
     while (bb) {
       Square s = pop_lsb(&bb);
-      active->push_back(MakeIndex(perspective, s, pos.piece_on(s), ksq));
+      active->push_back(make_index(perspective, s, pos.piece_on(s), ksq));
     }
   }
 
@@ -60,9 +57,9 @@ namespace Eval::NNUE::Features {
       Piece pc = dp.piece[i];
       if (type_of(pc) == KING) continue;
       if (dp.from[i] != SQ_NONE)
-        removed->push_back(MakeIndex(perspective, dp.from[i], pc, ksq));
+        removed->push_back(make_index(perspective, dp.from[i], pc, ksq));
       if (dp.to[i] != SQ_NONE)
-        added->push_back(MakeIndex(perspective, dp.to[i], pc, ksq));
+        added->push_back(make_index(perspective, dp.to[i], pc, ksq));
     }
   }
 

diff --git a/src/nnue/features/half_kp.h b/src/nnue/features/half_kp.h
index 52a83eecf3b77bfa94b885a56bb6615e7496412d..708fd7ea0badd445cb2f83af418cf44c79037058 100644 (file)
--- a/src/nnue/features/half_kp.h
+++ b/src/nnue/features/half_kp.h
@@ -52,10 +52,6 @@ namespace Eval::NNUE::Features {
     // Get a list of indices for recently changed features
     static void AppendChangedIndices(const Position& pos, const DirtyPiece& dp, Color perspective,
                                      IndexList* removed, IndexList* added);
-
-   private:
-    // Index of a feature for a given king position and another piece on some square
-    static IndexType MakeIndex(Color perspective, Square s, Piece pc, Square sq_k);
   };
 
 }  // namespace Eval::NNUE::Features

diff --git a/src/nnue/nnue_common.h b/src/nnue/nnue_common.h
index a9664262a47f0232643d17f1f59b77c3971c6a03..f9ff2bc81ee8f919903fef0f37217379a1304262 100644 (file)
--- a/src/nnue/nnue_common.h
+++ b/src/nnue/nnue_common.h
@@ -90,7 +90,14 @@ namespace Eval::NNUE {
     PS_END2     = 12 * SQUARE_NB + 1
   };
 
-  extern const uint32_t kpp_board_index[PIECE_NB][COLOR_NB];
+  constexpr uint32_t kpp_board_index[COLOR_NB][PIECE_NB] = {
+    // convention: W - us, B - them
+    // viewed from other side, W and B are reversed
+    { PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_W_KING, PS_NONE,
+      PS_NONE, PS_B_PAWN, PS_B_KNIGHT, PS_B_BISHOP, PS_B_ROOK, PS_B_QUEEN, PS_B_KING, PS_NONE },
+    { PS_NONE, PS_B_PAWN, PS_B_KNIGHT, PS_B_BISHOP, PS_B_ROOK, PS_B_QUEEN, PS_B_KING, PS_NONE,
+      PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_W_KING, PS_NONE }
+  };
 
   // Type of input feature after conversion
   using TransformedFeatureType = std::uint8_t;