Cache king shelter info in pawns structure

It does not change often and is not so fast
to calculate.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 59b605eca2665f12b40f4a816d71badc9fa6c449..88ab5ff67f5ef079b76bd1d68fa2c95c4009ec9d 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -709,11 +709,19 @@ namespace {
     // King shelter
     if (relative_rank(us, s) <= RANK_4)
     {
-        Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
-        Rank r = square_rank(s);
-        for (int i = 1; i < 4; i++)
-            shelter += count_1s_8bit(shiftRowsDown(pawns, r+i*sign)) * (128>>i);
-
+        // Shelter cache lookup
+        shelter = ei.pi->kingShelter(us, s);
+        if (shelter == -1)
+        {
+            shelter = 0;
+            Bitboard pawns = p.pawns(us) & this_and_neighboring_files_bb(s);
+            Rank r = square_rank(s);
+            for (int i = 1; i < 4; i++)
+                shelter += count_1s_8bit(shiftRowsDown(pawns, r+i*sign)) * (128>>i);
+
+            // Cache shelter value in pawn info
+            ei.pi->setKingShelter(us, s, shelter);
+        }
         ei.mgValue += sign * Value(shelter);
     }
 

diff --git a/src/pawns.h b/src/pawns.h
index ba337a8d64a3726fbf91273e30800093d548839c..8f88b57732001174120e35b4f21ca05ce068a0e5 100644 (file)
--- a/src/pawns.h
+++ b/src/pawns.h
@@ -53,12 +53,16 @@ public:
   int file_is_half_open(Color c, File f) const;
   int has_open_file_to_left(Color c, File f) const;
   int has_open_file_to_right(Color c, File f) const;
+  int kingShelter(Color c, Square ksq) const;
+  void setKingShelter(Color c, Square ksq, int value);
 
 private:
   void clear();
 
   Key key;
   Bitboard passedPawns;
+  Square kingSquares[2];
+  int16_t kingShelters[2];
   int16_t mgValue, egValue;
   int16_t ksStormValue[2], qsStormValue[2];
   uint8_t halfOpenFiles[2];
@@ -120,6 +124,15 @@ inline int PawnInfo::has_open_file_to_right(Color c, File f) const {
   return halfOpenFiles[c] & ~((1 << int(f+1)) - 1);
 }
 
+inline int PawnInfo::kingShelter(Color c, Square ksq) const {
+  return (kingSquares[c] == ksq ?  kingShelters[c] : -1);
+}
+
+inline void PawnInfo::setKingShelter(Color c, Square ksq, int value) {
+  kingSquares[c] = ksq;
+  kingShelters[c] = (int16_t)value;
+}
+
 inline void PawnInfo::clear() {
 
   passedPawns = EmptyBoardBB;
@@ -127,6 +140,7 @@ inline void PawnInfo::clear() {
   ksStormValue[WHITE] = ksStormValue[BLACK] = 0;
   qsStormValue[WHITE] = qsStormValue[BLACK] = 0;
   halfOpenFiles[WHITE] = halfOpenFiles[BLACK] = 0xFF;
+  kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE;
 }