Tweak dynamic contempt (the birthday patch)

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index bc1cf38af9c2706f54b793967866f632aa5c65c0..84f3d97748d4003c62afce8e57773956ed089bfe 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -72,7 +72,7 @@ namespace {
     constexpr Direction Up   = (Us == WHITE ? NORTH : SOUTH);
 
     Bitboard neighbours, stoppers, support, phalanx, opposed;
-    Bitboard lever, leverPush;
+    Bitboard lever, leverPush, blocked;
     Square s;
     bool backward, passed, doubled;
     Score score = SCORE_ZERO;
@@ -83,9 +83,9 @@ namespace {
 
     Bitboard doubleAttackThem = pawn_double_attacks_bb<Them>(theirPawns);
 
-    e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
+    e->passedPawns[Us] = 0;
     e->kingSquares[Us] = SQ_NONE;
-    e->pawnAttacks[Us] = pawn_attacks_bb<Us>(ourPawns);
+    e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb<Us>(ourPawns);
 
     // Loop through all pawns of the current color and score each pawn
     while ((s = *pl++) != SQ_NONE)
@@ -96,6 +96,7 @@ namespace {
 
         // Flag the pawn
         opposed    = theirPawns & forward_file_bb(Us, s);
+        blocked    = theirPawns & (s + Up);
         stoppers   = theirPawns & passed_pawn_span(Us, s);
         lever      = theirPawns & PawnAttacks[Us][s];
         leverPush  = theirPawns & PawnAttacks[Us][s + Up];
@@ -105,21 +106,13 @@ namespace {
         support    = neighbours & rank_bb(s - Up);
 
         // A pawn is backward when it is behind all pawns of the same color on
-        // the adjacent files and cannot safely advance. Phalanx and isolated
-        // pawns will be excluded when the pawn is scored.
-        backward =  !(neighbours & forward_ranks_bb(Them, s))
-                  && (stoppers & (leverPush | (s + Up)));
-
-        // Span of backward pawns and span behind opposing pawns are not included
-        // in the pawnAttacksSpan bitboard.
-        if (!backward || phalanx)
-        {
-            if (opposed)
-                e->pawnAttacksSpan[Us] |=  pawn_attack_span(Us, s) &
-                                          ~pawn_attack_span(Us, frontmost_sq(Them, opposed));
-            else
-                e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
-        }
+        // the adjacent files and cannot safely advance.
+        backward =  !(neighbours & forward_ranks_bb(Them, s + Up))
+                  && (leverPush | blocked);
+
+        // Compute additional span if pawn is not backward nor blocked
+        if (!backward && !blocked)
+            e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
 
         // A pawn is passed if one of the three following conditions is true:
         // (a) there is no stoppers except some levers
@@ -128,7 +121,7 @@ namespace {
         passed =   !(stoppers ^ lever)
                 || (   !(stoppers ^ leverPush)
                     && popcount(phalanx) >= popcount(leverPush))
-                || (   stoppers == square_bb(s + Up) && r >= RANK_5
+                || (   stoppers == blocked && r >= RANK_5
                     && (shift<Up>(support) & ~(theirPawns | doubleAttackThem)));
 
         // Passed pawns will be properly scored later in evaluation when we have
@@ -231,7 +224,7 @@ Score Entry::do_king_safety(const Position& pos) {
   Square ksq = pos.square<KING>(Us);
   kingSquares[Us] = ksq;
   castlingRights[Us] = pos.castling_rights(Us);
-  auto compare = [](Score a, Score b) { return mg_value(a) <= mg_value(b); };
+  auto compare = [](Score a, Score b) { return mg_value(a) < mg_value(b); };
 
   Score shelter = evaluate_shelter<Us>(pos, ksq);