Merge branch 'master' into clusterMergeMaster5

.travis.yml

@@ -55,6 +55,9 @@ script:
   - make clean && make -j2 ARCH=x86-64 optimize=no debug=yes build && ../tests/signature.sh $benchref
   - make clean && make -j2 ARCH=x86-32 optimize=no debug=yes build && ../tests/signature.sh $benchref
   - make clean && make -j2 ARCH=x86-32 build && ../tests/signature.sh $benchref
+
+  # Verify bench number is ONE_PLY independent by doubling its value
+  - sed -i'.bak' 's/.*\(ONE_PLY = [0-9]*\),.*/\1 * 2,/g' types.h
   - make clean && make -j2 ARCH=x86-64 build && ../tests/signature.sh $benchref
   #
   # Check perft and reproducible search

src/Makefile

@@ -490,7 +490,7 @@ config-sanity:
 	@echo "Testing config sanity. If this fails, try 'make help' ..."
 	@echo ""
 	@test "$(debug)" = "yes" || test "$(debug)" = "no"
-	@test "$(sanitize)" = "undefined" || test "$(sanitize)" = "thread" || test "$(sanitize)" = "no"
+	@test "$(sanitize)" = "undefined" || test "$(sanitize)" = "thread" || test "$(sanitize)" = "address" || test "$(sanitize)" = "no"
 	@test "$(optimize)" = "yes" || test "$(optimize)" = "no"
 	@test "$(arch)" = "any" || test "$(arch)" = "x86_64" || test "$(arch)" = "i386" || \
 	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || test "$(arch)" = "armv7"

src/bitbase.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 #include <numeric>
 #include <vector>

src/bitboard.cpp

@@ -18,8 +18,8 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <bitset>
+#include <algorithm>
 
 #include "bitboard.h"
 #include "misc.h"
@@ -27,13 +27,10 @@
 uint8_t PopCnt16[1 << 16];
 uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
-Bitboard SquareBB[SQUARE_NB];
-Bitboard ForwardRanksBB[COLOR_NB][RANK_NB];
-Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 Bitboard LineBB[SQUARE_NB][SQUARE_NB];
-Bitboard DistanceRingBB[SQUARE_NB][8];
 Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
+Bitboard SquareBB[SQUARE_NB];
 
 Bitboard KingFlank[FILE_NB] = {
   QueenSide ^ FileDBB, QueenSide, QueenSide,
@@ -85,10 +82,7 @@ void Bitboards::init() {
 
   for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
       for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
-          {
               SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
-              DistanceRingBB[s1][SquareDistance[s1][s2]] |= s2;
-          }
 
   int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } };
 
@@ -122,10 +116,7 @@ void Bitboards::init() {
       for (PieceType pt : { BISHOP, ROOK })
           for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
               if (PseudoAttacks[pt][s1] & s2)
-              {
                   LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
-                  BetweenBB[s1][s2] = attacks_bb(pt, s1, SquareBB[s2]) & attacks_bb(pt, s2, SquareBB[s1]);
-              }
   }
 }
 

src/bitboard.h

@@ -68,13 +68,11 @@ constexpr Bitboard Center      = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
 extern uint8_t PopCnt16[1 << 16];
 extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
-extern Bitboard SquareBB[SQUARE_NB];
-extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
-extern Bitboard DistanceRingBB[SQUARE_NB][8];
 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
 extern Bitboard KingFlank[FILE_NB];
+extern Bitboard SquareBB[SQUARE_NB];
 
 
 /// Magic holds all magic bitboards relevant data for a single square
@@ -102,34 +100,19 @@ struct Magic {
 extern Magic RookMagics[SQUARE_NB];
 extern Magic BishopMagics[SQUARE_NB];
 
+inline Bitboard square_bb(Square s) {
+  assert(s >= SQ_A1 && s <= SQ_H8);
+  return SquareBB[s];
+}
 
 /// Overloads of bitwise operators between a Bitboard and a Square for testing
 /// whether a given bit is set in a bitboard, and for setting and clearing bits.
 
-inline Bitboard operator&(Bitboard b, Square s) {
+inline Bitboard  operator&( Bitboard  b, Square s) { return b &  square_bb(s); }
-  assert(s >= SQ_A1 && s <= SQ_H8);
+inline Bitboard  operator|( Bitboard  b, Square s) { return b |  square_bb(s); }
-  return b & SquareBB[s];
+inline Bitboard  operator^( Bitboard  b, Square s) { return b ^  square_bb(s); }
-}
+inline Bitboard& operator|=(Bitboard& b, Square s) { return b |= square_bb(s); }
-
+inline Bitboard& operator^=(Bitboard& b, Square s) { return b ^= square_bb(s); }
-inline Bitboard operator|(Bitboard b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b | SquareBB[s];
-}
-
-inline Bitboard operator^(Bitboard b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b ^ SquareBB[s];
-}
-
-inline Bitboard& operator|=(Bitboard& b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b |= SquareBB[s];
-}
-
-inline Bitboard& operator^=(Bitboard& b, Square s) {
-  assert(s >= SQ_A1 && s <= SQ_H8);
-  return b ^= SquareBB[s];
-}
 
 constexpr bool more_than_one(Bitboard b) {
   return b & (b - 1);
@@ -200,13 +183,12 @@ inline Bitboard adjacent_files_bb(File f) {
 }
 
 
-/// between_bb() returns a bitboard representing all the squares between the two
+/// between_bb() returns squares that are linearly between the given squares
-/// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
+/// If the given squares are not on a same file/rank/diagonal, return 0.
-/// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank,
-/// file or diagonal, 0 is returned.
 
 inline Bitboard between_bb(Square s1, Square s2) {
-  return BetweenBB[s1][s2];
+  return LineBB[s1][s2] & ( (AllSquares << (s1 +  (s1 < s2)))
+                           ^(AllSquares << (s2 + !(s1 < s2))));
 }
 
 
@@ -254,15 +236,16 @@ inline bool aligned(Square s1, Square s2, Square s3) {
 
 
 /// distance() functions return the distance between x and y, defined as the
-/// number of steps for a king in x to reach y. Works with squares, ranks, files.
+/// number of steps for a king in x to reach y.
 
-template<typename T> inline int distance(T x, T y) { return std::abs(x - y); }
+template<typename T1 = Square> inline int distance(Square x, Square y);
+template<> inline int distance<File>(Square x, Square y) { return std::abs(file_of(x) - file_of(y)); }
+template<> inline int distance<Rank>(Square x, Square y) { return std::abs(rank_of(x) - rank_of(y)); }
 template<> inline int distance<Square>(Square x, Square y) { return SquareDistance[x][y]; }
 
-template<typename T1, typename T2> inline int distance(T2 x, T2 y);
+template<class T> constexpr const T& clamp(const T& v, const T& lo, const T&  hi) {
-template<> inline int distance<File>(Square x, Square y) { return distance(file_of(x), file_of(y)); }
+  return v < lo ? lo : v > hi ? hi : v;
-template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
+}
-
 
 /// attacks_bb() returns a bitboard representing all the squares attacked by a
 /// piece of type Pt (bishop or rook) placed on 's'.

src/endgame.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 
 #include "bitboard.h"
@@ -77,10 +76,7 @@ namespace {
     if (file_of(pos.square<PAWN>(strongSide)) >= FILE_E)
         sq = Square(sq ^ 7); // Mirror SQ_H1 -> SQ_A1
 
-    if (strongSide == BLACK)
+    return strongSide == WHITE ? sq : ~sq;
-        sq = ~sq;
-
-    return sq;
   }
 
 } // namespace
@@ -286,18 +282,18 @@ Value Endgame<KQKR>::operator()(const Position& pos) const {
 }
 
 
-/// KNN vs KP. Simply push the opposing king to the corner.
+/// KNN vs KP. Simply push the opposing king to the corner
 template<>
 Value Endgame<KNNKP>::operator()(const Position& pos) const {
 
-    assert(verify_material(pos, strongSide, 2 * KnightValueMg, 0));
+  assert(verify_material(pos, strongSide, 2 * KnightValueMg, 0));
-    assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
+  assert(verify_material(pos, weakSide, VALUE_ZERO, 1));
 
-    Value result =  2 * KnightValueEg
+  Value result =  2 * KnightValueEg
-                  - PawnValueEg
+                - PawnValueEg
-                  + PushToEdges[pos.square<KING>(weakSide)];
+                + PushToEdges[pos.square<KING>(weakSide)];
 
-    return strongSide == pos.side_to_move() ? result : -result;
+  return strongSide == pos.side_to_move() ? result : -result;
 }
 
 
@@ -639,8 +635,6 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
   Square ksq = pos.square<KING>(weakSide);
   Square psq1 = pos.squares<PAWN>(strongSide)[0];
   Square psq2 = pos.squares<PAWN>(strongSide)[1];
-  Rank r1 = rank_of(psq1);
-  Rank r2 = rank_of(psq2);
   Square blockSq1, blockSq2;
 
   if (relative_rank(strongSide, psq1) > relative_rank(strongSide, psq2))
@@ -674,7 +668,7 @@ ScaleFactor Endgame<KBPPKB>::operator()(const Position& pos) const {
         && opposite_colors(ksq, wbsq)
         && (   bbsq == blockSq2
             || (pos.attacks_from<BISHOP>(blockSq2) & pos.pieces(weakSide, BISHOP))
-            || distance(r1, r2) >= 2))
+            || distance<Rank>(psq1, psq2) >= 2))
         return SCALE_FACTOR_DRAW;
 
     else if (   ksq == blockSq2

src/evaluate.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 #include <cstring>   // For std::memset
 #include <iomanip>
@@ -229,6 +228,8 @@ namespace {
 
     const Square ksq = pos.square<KING>(Us);
 
+    Bitboard dblAttackByPawn = pawn_double_attacks_bb<Us>(pos.pieces(Us, PAWN));
+
     // Find our pawns that are blocked or on the first two ranks
     Bitboard b = pos.pieces(Us, PAWN) & (shift<Down>(pos.pieces()) | LowRanks);
 
@@ -240,7 +241,8 @@ namespace {
     attackedBy[Us][KING] = pos.attacks_from<KING>(ksq);
     attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
     attackedBy[Us][ALL_PIECES] = attackedBy[Us][KING] | attackedBy[Us][PAWN];
-    attackedBy2[Us]            = attackedBy[Us][KING] & attackedBy[Us][PAWN];
+    attackedBy2[Us]            = (attackedBy[Us][KING] & attackedBy[Us][PAWN])
+                                 | dblAttackByPawn;
 
     // Init our king safety tables
     kingRing[Us] = attackedBy[Us][KING];
@@ -257,7 +259,7 @@ namespace {
     kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
 
     // Remove from kingRing[] the squares defended by two pawns
-    kingRing[Us] &= ~pawn_double_attacks_bb<Us>(pos.pieces(Us, PAWN));
+    kingRing[Us] &= ~dblAttackByPawn;
   }
 
 
@@ -326,7 +328,7 @@ namespace {
                 // bishop, bigger when the center files are blocked with pawns.
                 Bitboard blocked = pos.pieces(Us, PAWN) & shift<Down>(pos.pieces());
 
-                score -= BishopPawns * pe->pawns_on_same_color_squares(Us, s)
+                score -= BishopPawns * pos.pawns_on_same_color_squares(Us, s)
                                      * (1 + popcount(blocked & CenterFiles));
 
                 // Bonus for bishop on a long diagonal which can "see" both center squares
@@ -356,8 +358,8 @@ namespace {
                 score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
 
             // Bonus for rook on an open or semi-open file
-            if (pe->semiopen_file(Us, file_of(s)))
+            if (pos.semiopen_file(Us, file_of(s)))
-                score += RookOnFile[bool(pe->semiopen_file(Them, file_of(s)))];
+                score += RookOnFile[bool(pos.semiopen_file(Them, file_of(s)))];
 
             // Penalty when trapped by the king, even more if the king cannot castle
             else if (mob <= 3)
@@ -465,15 +467,16 @@ namespace {
                  +  69 * kingAttacksCount[Them]
                  + 185 * popcount(kingRing[Us] & weak)
                  - 100 * bool(attackedBy[Us][KNIGHT] & attackedBy[Us][KING])
+                 -  35 * bool(attackedBy[Us][BISHOP] & attackedBy[Us][KING])
                  + 150 * popcount(pos.blockers_for_king(Us) | unsafeChecks)
                  - 873 * !pos.count<QUEEN>(Them)
                  -   6 * mg_value(score) / 8
                  +       mg_value(mobility[Them] - mobility[Us])
                  +   5 * kingFlankAttacks * kingFlankAttacks / 16
-                 -   25;
+                 -   7;
 
     // Transform the kingDanger units into a Score, and subtract it from the evaluation
-    if (kingDanger > 0)
+    if (kingDanger > 100)
         score -= make_score(kingDanger * kingDanger / 4096, kingDanger / 16);
 
     // Penalty when our king is on a pawnless flank
@@ -718,7 +721,7 @@ namespace {
 
     int bonus = popcount(safe) + popcount(behind & safe);
     int weight =  pos.count<ALL_PIECES>(Us)
-                - 2 * popcount(pe->semiopenFiles[WHITE] & pe->semiopenFiles[BLACK]);
+               - (16 - pos.count<PAWN>()) / 4;
 
     Score score = make_score(bonus * weight * weight / 16, 0);
 
@@ -743,12 +746,12 @@ namespace {
                             && (pos.pieces(PAWN) & KingSide);
 
     // Compute the initiative bonus for the attacking side
-    int complexity =   9 * pe->pawn_asymmetry()
+    int complexity =   9 * pe->passed_count()
                     + 11 * pos.count<PAWN>()
                     +  9 * outflanking
                     + 18 * pawnsOnBothFlanks
                     + 49 * !pos.non_pawn_material()
-                    -121 ;
+                    -103 ;
 
     // Now apply the bonus: note that we find the attacking side by extracting
     // the sign of the endgame value, and that we carefully cap the bonus so
@@ -776,7 +779,7 @@ namespace {
         if (   pos.opposite_bishops()
             && pos.non_pawn_material(WHITE) == BishopValueMg
             && pos.non_pawn_material(BLACK) == BishopValueMg)
-            sf = 8 + 4 * pe->pawn_asymmetry();
+            sf = 16 + 4 * pe->passed_count();
         else
             sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide), sf);
 

src/main.cpp

@@ -44,7 +44,6 @@ int main(int argc, char* argv[]) {
   Position::init();
   Bitbases::init();
   Search::init();
-  Pawns::init();
   Threads.set(Options["Threads"]);
   Search::clear(); // After threads are up
 

src/material.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm> // For std::min
 #include <cassert>
 #include <cstring>   // For std::memset
 
@@ -70,14 +69,12 @@ namespace {
 
   bool is_KBPsK(const Position& pos, Color us) {
     return   pos.non_pawn_material(us) == BishopValueMg
-          && pos.count<BISHOP>(us) == 1
           && pos.count<PAWN  >(us) >= 1;
   }
 
   bool is_KQKRPs(const Position& pos, Color us) {
     return  !pos.count<PAWN>(us)
           && pos.non_pawn_material(us) == QueenValueMg
-          && pos.count<QUEEN>(us) == 1
           && pos.count<ROOK>(~us) == 1
           && pos.count<PAWN>(~us) >= 1;
   }
@@ -132,7 +129,7 @@ Entry* probe(const Position& pos) {
 
   Value npm_w = pos.non_pawn_material(WHITE);
   Value npm_b = pos.non_pawn_material(BLACK);
-  Value npm = std::max(EndgameLimit, std::min(npm_w + npm_b, MidgameLimit));
+  Value npm   = clamp(npm_w + npm_b, EndgameLimit, MidgameLimit);
 
   // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME]
   e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
@@ -152,9 +149,9 @@ Entry* probe(const Position& pos) {
 
   // OK, we didn't find any special evaluation function for the current material
   // configuration. Is there a suitable specialized scaling function?
-  const EndgameBase<ScaleFactor>* sf;
+  const auto* sf = pos.this_thread()->endgames.probe<ScaleFactor>(key);
 
-  if ((sf = pos.this_thread()->endgames.probe<ScaleFactor>(key)) != nullptr)
+  if (sf)
   {
       e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned
       return e;

src/misc.h

@@ -53,7 +53,7 @@ struct HashTable {
   Entry* operator[](Key key) { return &table[(uint32_t)key & (Size - 1)]; }
 
 private:
-  std::vector<Entry> table = std::vector<Entry>(Size);
+  std::vector<Entry> table = std::vector<Entry>(Size); // Allocate on the heap
 };
 
 

src/movepick.cpp

@@ -139,12 +139,12 @@ Move MovePicker::select(Pred filter) {
       if (T == Best)
           std::swap(*cur, *std::max_element(cur, endMoves));
 
-      move = *cur++;
+      if (*cur != ttMove && filter())
+          return *cur++;
 
-      if (move != ttMove && filter())
+      cur++;
-          return move;
   }
-  return move = MOVE_NONE;
+  return MOVE_NONE;
 }
 
 /// MovePicker::next_move() is the most important method of the MovePicker class. It
@@ -174,10 +174,10 @@ top:
 
   case GOOD_CAPTURE:
       if (select<Best>([&](){
-                       return pos.see_ge(move, Value(-55 * (cur-1)->value / 1024)) ?
+                       return pos.see_ge(*cur, Value(-55 * cur->value / 1024)) ?
                               // Move losing capture to endBadCaptures to be tried later
-                              true : (*endBadCaptures++ = move, false); }))
+                              true : (*endBadCaptures++ = *cur, false); }))
-          return move;
+          return *(cur - 1);
 
       // Prepare the pointers to loop over the refutations array
       cur = std::begin(refutations);
@@ -192,10 +192,10 @@ top:
       /* fallthrough */
 
   case REFUTATION:
-      if (select<Next>([&](){ return    move != MOVE_NONE
+      if (select<Next>([&](){ return    *cur != MOVE_NONE
-                                    && !pos.capture(move)
+                                    && !pos.capture(*cur)
-                                    &&  pos.pseudo_legal(move); }))
+                                    &&  pos.pseudo_legal(*cur); }))
-          return move;
+          return *(cur - 1);
       ++stage;
       /* fallthrough */
 
@@ -210,10 +210,10 @@ top:
 
   case QUIET:
       if (   !skipQuiets
-          && select<Next>([&](){return   move != refutations[0]
+          && select<Next>([&](){return   *cur != refutations[0].move
-                                      && move != refutations[1]
+                                      && *cur != refutations[1].move
-                                      && move != refutations[2];}))
+                                      && *cur != refutations[2].move;}))
-          return move;
+          return *(cur - 1);
 
       // Prepare the pointers to loop over the bad captures
       cur = moves;
@@ -237,12 +237,12 @@ top:
       return select<Best>([](){ return true; });
 
   case PROBCUT:
-      return select<Best>([&](){ return pos.see_ge(move, threshold); });
+      return select<Best>([&](){ return pos.see_ge(*cur, threshold); });
 
   case QCAPTURE:
       if (select<Best>([&](){ return   depth > DEPTH_QS_RECAPTURES
-                                    || to_sq(move) == recaptureSquare; }))
+                                    || to_sq(*cur) == recaptureSquare; }))
-          return move;
+          return *(cur - 1);
 
       // If we did not find any move and we do not try checks, we have finished
       if (depth != DEPTH_QS_CHECKS)

src/movepick.h

@@ -142,7 +142,6 @@ private:
   Move ttMove;
   ExtMove refutations[3], *cur, *endMoves, *endBadCaptures;
   int stage;
-  Move move;
   Square recaptureSquare;
   Value threshold;
   Depth depth;

src/pawns.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 
 #include "bitboard.h"
@@ -36,8 +35,8 @@ namespace {
   constexpr Score Doubled  = S(11, 56);
   constexpr Score Isolated = S( 5, 15);
 
-  // Connected pawn bonus by opposed, phalanx, #support and rank
+  // Connected pawn bonus
-  Score Connected[2][2][3][RANK_NB];
+  constexpr int Connected[RANK_NB] = { 0, 13, 17, 24, 59, 96, 171 };
 
   // Strength of pawn shelter for our king by [distance from edge][rank].
   // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
@@ -78,11 +77,8 @@ namespace {
     Bitboard theirPawns = pos.pieces(Them, PAWN);
 
     e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0;
-    e->semiopenFiles[Us] = 0xFF;
     e->kingSquares[Us]   = SQ_NONE;
     e->pawnAttacks[Us]   = pawn_attacks_bb<Us>(ourPawns);
-    e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
-    e->pawnsOnSquares[Us][WHITE] = pos.count<PAWN>(Us) - e->pawnsOnSquares[Us][BLACK];
 
     // Loop through all pawns of the current color and score each pawn
     while ((s = *pl++) != SQ_NONE)
@@ -90,8 +86,8 @@ namespace {
         assert(pos.piece_on(s) == make_piece(Us, PAWN));
 
         File f = file_of(s);
+        Rank r = relative_rank(Us, s);
 
-        e->semiopenFiles[Us]   &= ~(1 << f);
         e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
 
         // Flag the pawn
@@ -114,12 +110,11 @@ namespace {
         // which could become passed after one or two pawn pushes when are
         // not attacked more times than defended.
         if (   !(stoppers ^ lever ^ leverPush)
-            && popcount(support) >= popcount(lever) - 1
+            && (support || !more_than_one(lever))
             && popcount(phalanx) >= popcount(leverPush))
             e->passedPawns[Us] |= s;
 
-        else if (   stoppers == SquareBB[s + Up]
+        else if (stoppers == square_bb(s + Up) && r >= RANK_5)
-                 && relative_rank(Us, s) >= RANK_5)
         {
             b = shift<Up>(support) & ~theirPawns;
             while (b)
@@ -129,8 +124,11 @@ namespace {
 
         // Score this pawn
         if (support | phalanx)
-            score += Connected[opposed][bool(phalanx)][popcount(support)][relative_rank(Us, s)];
+        {
-
+            int v = (phalanx ? 3 : 2) * Connected[r];
+            v = 17 * popcount(support) + (v >> (opposed + 1));
+            score += make_score(v, v * (r - 2) / 4);
+        }
         else if (!neighbours)
             score -= Isolated, e->weakUnopposed[Us] += !opposed;
 
@@ -148,27 +146,6 @@ namespace {
 
 namespace Pawns {
 
-/// Pawns::init() initializes some tables needed by evaluation. Instead of using
-/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
-/// to reduce independent parameters and to allow easier tuning and better insight.
-
-void init() {
-
-  static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 };
-
-  for (int opposed = 0; opposed <= 1; ++opposed)
-      for (int phalanx = 0; phalanx <= 1; ++phalanx)
-          for (int support = 0; support <= 2; ++support)
-              for (Rank r = RANK_2; r < RANK_8; ++r)
-  {
-      int v = 17 * support;
-      v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
-
-      Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4);
-  }
-}
-
-
 /// Pawns::probe() looks up the current position's pawns configuration in
 /// the pawns hash table. It returns a pointer to the Entry if the position
 /// is found. Otherwise a new Entry is computed and stored there, so we don't
@@ -185,8 +162,6 @@ Entry* probe(const Position& pos) {
   e->key = key;
   e->scores[WHITE] = evaluate<WHITE>(pos, e);
   e->scores[BLACK] = evaluate<BLACK>(pos, e);
-  e->asymmetry = popcount(  (e->passedPawns[WHITE]   | e->passedPawns[BLACK])
-                          | (e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]));
 
   return e;
 }
@@ -209,7 +184,7 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
   Value safety = (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ?
                  Value(374) : Value(5);
 
-  File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
+  File center = clamp(file_of(ksq), FILE_B, FILE_G);
   for (File f = File(center - 1); f <= File(center + 1); ++f)
   {
       b = ourPawns & file_bb(f);
@@ -237,11 +212,15 @@ Score Entry::do_king_safety(const Position& pos) {
   Square ksq = pos.square<KING>(Us);
   kingSquares[Us] = ksq;
   castlingRights[Us] = pos.castling_rights(Us);
-  int minKingPawnDistance = 0;
 
   Bitboard pawns = pos.pieces(Us, PAWN);
-  if (pawns)
+  int minPawnDist = pawns ? 8 : 0;
-      while (!(DistanceRingBB[ksq][++minKingPawnDistance] & pawns)) {}
+
+  if (pawns & PseudoAttacks[KING][ksq])
+      minPawnDist = 1;
+
+  else while (pawns)
+      minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
 
   Value bonus = evaluate_shelter<Us>(pos, ksq);
 
@@ -252,7 +231,7 @@ Score Entry::do_king_safety(const Position& pos) {
   if (pos.can_castle(Us | QUEEN_SIDE))
       bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)));
 
-  return make_score(bonus, -16 * minKingPawnDistance);
+  return make_score(bonus, -16 * minPawnDist);
 }
 
 // Explicit template instantiation

src/pawns.h

@@ -38,15 +38,7 @@ struct Entry {
   Bitboard passed_pawns(Color c) const { return passedPawns[c]; }
   Bitboard pawn_attacks_span(Color c) const { return pawnAttacksSpan[c]; }
   int weak_unopposed(Color c) const { return weakUnopposed[c]; }
-  int pawn_asymmetry() const { return asymmetry; }
+  int passed_count() const { return popcount(passedPawns[WHITE] | passedPawns[BLACK]); };
-
-  int semiopen_file(Color c, File f) const {
-    return semiopenFiles[c] & (1 << f);
-  }
-
-  int pawns_on_same_color_squares(Color c, Square s) const {
-    return pawnsOnSquares[c][bool(DarkSquares & s)];
-  }
 
   template<Color Us>
   Score king_safety(const Position& pos) {
@@ -69,14 +61,11 @@ struct Entry {
   Score kingSafety[COLOR_NB];
   int weakUnopposed[COLOR_NB];
   int castlingRights[COLOR_NB];
-  int semiopenFiles[COLOR_NB];
   int pawnsOnSquares[COLOR_NB][COLOR_NB]; // [color][light/dark squares]
-  int asymmetry;
 };
 
 typedef HashTable<Entry, 16384> Table;
 
-void init();
 Entry* probe(const Position& pos);
 
 } // namespace Pawns

src/position.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 #include <cstddef> // For offsetof()
 #include <cstring> // For std::memset, std::memcmp
@@ -341,13 +340,8 @@ void Position::set_castling_right(Color c, Square rfrom) {
   Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
   Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
 
-  for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
+  castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto)
-      if (s != kfrom && s != rfrom)
+                   & ~(square_bb(kfrom) | rfrom);
-          castlingPath[cr] |= s;
-
-  for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
-      if (s != kfrom && s != rfrom)
-          castlingPath[cr] |= s;
 }
 
 
@@ -629,7 +623,7 @@ bool Position::pseudo_legal(const Move m) const {
   {
       // We have already handled promotion moves, so destination
       // cannot be on the 8th/1st rank.
-      if (rank_of(to) == relative_rank(us, RANK_8))
+      if ((Rank8BB | Rank1BB) & to)
           return false;
 
       if (   !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture

src/position.h

@@ -95,6 +95,7 @@ public:
   template<PieceType Pt> int count() const;
   template<PieceType Pt> const Square* squares(Color c) const;
   template<PieceType Pt> Square square(Color c) const;
+  int semiopen_file(Color c, File f) const;
 
   // Castling
   int castling_rights(Color c) const;
@@ -128,6 +129,7 @@ public:
   // Piece specific
   bool pawn_passed(Color c, Square s) const;
   bool opposite_bishops() const;
+  int  pawns_on_same_color_squares(Color c, Square s) const;
 
   // Doing and undoing moves
   void do_move(Move m, StateInfo& newSt);
@@ -260,6 +262,10 @@ inline Square Position::ep_square() const {
   return st->epSquare;
 }
 
+inline int Position::semiopen_file(Color c, File f) const {
+  return !(pieces(c, PAWN) & file_bb(f));
+}
+
 inline bool Position::can_castle(CastlingRight cr) const {
   return st->castlingRights & cr;
 }
@@ -318,6 +324,10 @@ inline bool Position::advanced_pawn_push(Move m) const {
         && relative_rank(sideToMove, from_sq(m)) > RANK_4;
 }
 
+inline int Position::pawns_on_same_color_squares(Color c, Square s) const {
+  return popcount(pieces(c, PAWN) & ((DarkSquares & s) ? DarkSquares : ~DarkSquares));
+}
+
 inline Key Position::key() const {
   return st->key;
 }
@@ -413,7 +423,7 @@ inline void Position::move_piece(Piece pc, Square from, Square to) {
 
   // index[from] is not updated and becomes stale. This works as long as index[]
   // is accessed just by known occupied squares.
-  Bitboard fromTo = SquareBB[from] ^ SquareBB[to];
+  Bitboard fromTo = square_bb(from) | square_bb(to);
   byTypeBB[ALL_PIECES] ^= fromTo;
   byTypeBB[type_of(pc)] ^= fromTo;
   byColorBB[color_of(pc)] ^= fromTo;

src/search.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 #include <cmath>
 #include <cstring>   // For std::memset
@@ -69,10 +68,10 @@ namespace {
   }
 
   // Reductions lookup table, initialized at startup
-  int Reductions[64]; // [depth or moveNumber]
+  int Reductions[MAX_MOVES]; // [depth or moveNumber]
 
   template <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
-    int r = Reductions[std::min(d / ONE_PLY, 63)] * Reductions[std::min(mn, 63)] / 1024;
+    int r = Reductions[d / ONE_PLY] * Reductions[mn] / 1024;
     return ((r + 512) / 1024 + (!i && r > 1024) - PvNode) * ONE_PLY;
   }
 
@@ -86,11 +85,10 @@ namespace {
     return d > 17 ? 0 : 29 * d * d + 138 * d - 134;
   }
 
-  // Add a small random component to draw evaluations to keep search dynamic
+  // Add a small random component to draw evaluations to avoid 3fold-blindness
-  // and to avoid 3fold-blindness.
   Value value_draw(Depth depth, Thread* thisThread) {
-    return depth < 4 ? VALUE_DRAW
+    return depth < 4 * ONE_PLY ? VALUE_DRAW
-                     : VALUE_DRAW + Value(2 * (thisThread->nodes.load(std::memory_order_relaxed) % 2) - 1);
+                               : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
   }
 
   // Skill structure is used to implement strength limit
@@ -117,13 +115,6 @@ namespace {
   void update_quiet_stats(const Position& pos, Stack* ss, Move move, Move* quiets, int quietCount, int bonus);
   void update_capture_stats(const Position& pos, Move move, Move* captures, int captureCount, int bonus);
 
-  inline bool gives_check(const Position& pos, Move move) {
-    Color us = pos.side_to_move();
-    return  type_of(move) == NORMAL && !(pos.blockers_for_king(~us) & pos.pieces(us))
-          ? pos.check_squares(type_of(pos.moved_piece(move))) & to_sq(move)
-          : pos.gives_check(move);
-  }
-
   // perft() is our utility to verify move generation. All the leaf nodes up
   // to the given depth are generated and counted, and the sum is returned.
   template<bool Root>
@@ -157,7 +148,7 @@ namespace {
 
 void Search::init() {
 
-  for (int i = 1; i < 64; ++i)
+  for (int i = 1; i < MAX_MOVES; ++i)
       Reductions[i] = int(1024 * std::log(i) / std::sqrt(1.95));
 }
 
@@ -171,12 +162,12 @@ void Search::clear() {
   Time.availableNodes = 0;
   TT.clear();
   Threads.clear();
-  Tablebases::init(Options["SyzygyPath"]); // Free up mapped files
+  Tablebases::init(Options["SyzygyPath"]); // Free mapped files
 }
 
 
-/// MainThread::search() is called by the main thread when the program receives
+/// MainThread::search() is started when the program receives the UCI 'go'
-/// the UCI 'go' command. It searches from the root position and outputs the "bestmove".
+/// command. It searches from the root position and outputs the "bestmove".
 
 void MainThread::search() {
 
@@ -203,8 +194,11 @@ void MainThread::search() {
   else
   {
       for (Thread* th : Threads)
+      {
+          th->bestMoveChanges = 0;
           if (th != this)
               th->start_searching();
+      }
 
       Thread::search(); // Let's start searching!
   }
@@ -235,8 +229,9 @@ void MainThread::search() {
   if (Limits.npmsec)
       Time.availableNodes += Limits.inc[us] - Cluster::nodes_searched();
 
-  // Check if there are threads with a better score than main thread
   Thread* bestThread = this;
+
+  // Check if there are threads with a better score than main thread
   if (    Options["MultiPV"] == 1
       && !Limits.depth
       && !Skill(Options["Skill Level"]).enabled()
@@ -310,9 +305,9 @@ void MainThread::search() {
 
 void Thread::search() {
 
-  // To allow access to (ss-5) up to (ss+2), the stack must be oversized.
+  // To allow access to (ss-7) up to (ss+2), the stack must be oversized.
   // The former is needed to allow update_continuation_histories(ss-1, ...),
-  // which accesses its argument at ss-4, also near the root.
+  // which accesses its argument at ss-6, also near the root.
   // The latter is needed for statScores and killer initialization.
   Stack stack[MAX_PLY+10], *ss = stack+7;
   Move  pv[MAX_PLY+1];
@@ -320,7 +315,7 @@ void Thread::search() {
   Move  lastBestMove = MOVE_NONE;
   Depth lastBestMoveDepth = DEPTH_ZERO;
   MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
-  double timeReduction = 1.0;
+  double timeReduction = 1, totBestMoveChanges = 0;
   Color us = rootPos.side_to_move();
 
   std::memset(ss-7, 0, 10 * sizeof(Stack));
@@ -331,9 +326,6 @@ void Thread::search() {
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
 
-  if (mainThread)
-      mainThread->bestMoveChanges = 0;
-
   size_t multiPV = Options["MultiPV"];
   Skill skill(Options["Skill Level"]);
 
@@ -354,7 +346,7 @@ void Thread::search() {
           : Options["Analysis Contempt"] == "Black" && us == WHITE ? -ct
           : ct;
 
-  // In evaluate.cpp the evaluation is from the white point of view
+  // Evaluation score is from the white point of view
   contempt = (us == WHITE ?  make_score(ct, ct / 2)
                           : -make_score(ct, ct / 2));
 
@@ -365,7 +357,7 @@ void Thread::search() {
   {
       // Age out PV variability metric
       if (mainThread)
-          mainThread->bestMoveChanges *= 0.517;
+          totBestMoveChanges /= 2;
 
 
       // Save the last iteration's scores before first PV line is searched and
@@ -504,15 +496,20 @@ void Thread::search() {
           && !Threads.stop
           && !mainThread->stopOnPonderhit)
       {
-          double fallingEval = (306 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
+          double fallingEval = (314 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
-          fallingEval        = std::max(0.5, std::min(1.5, fallingEval));
+          fallingEval = clamp(fallingEval, 0.5, 1.5);
 
           // If the bestMove is stable over several iterations, reduce time accordingly
           timeReduction = lastBestMoveDepth + 10 * ONE_PLY < completedDepth ? 1.95 : 1.0;
           double reduction = std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
 
           // Use part of the gained time from a previous stable move for the current move
-          double bestMoveInstability = 1.0 + mainThread->bestMoveChanges;
+          for (Thread* th : Threads)
+          {
+              totBestMoveChanges += th->bestMoveChanges;
+              th->bestMoveChanges = 0;
+          }
+          double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
 
           // Stop the search if we have only one legal move, or if available time elapsed
           if (   rootMoves.size() == 1
@@ -578,7 +575,7 @@ namespace {
     Key posKey;
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
-    Value bestValue, value, ttValue, eval, maxValue, pureStaticEval;
+    Value bestValue, value, ttValue, eval, maxValue;
     bool ttHit, ttPv, inCheck, givesCheck, improving;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
     Piece movedPiece;
@@ -624,8 +621,7 @@ namespace {
     assert(0 <= ss->ply && ss->ply < MAX_PLY);
 
     (ss+1)->ply = ss->ply + 1;
-    ss->currentMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
+    (ss+1)->excludedMove = bestMove = MOVE_NONE;
-    ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0];
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
     Square prevSq = to_sq((ss-1)->currentMove);
 
@@ -647,6 +643,15 @@ namespace {
             : ttHit    ? tte->move() : MOVE_NONE;
     ttPv = (ttHit && tte->is_pv()) || (PvNode && depth > 4 * ONE_PLY);
 
+    // If position has been searched at higher depths and we are shuffling,
+    // return value_draw.
+    if (   pos.rule50_count() > 36 - 6 * (pos.count<ALL_PIECES>() > 14)
+        && ss->ply > 36 - 6 * (pos.count<ALL_PIECES>() > 14)
+        && ttHit
+        && tte->depth() > depth
+        && pos.count<PAWN>() > 0)
+           return VALUE_DRAW;
+
     // At non-PV nodes we check for an early TT cutoff
     if (  !PvNode
         && ttHit
@@ -663,9 +668,8 @@ namespace {
                 if (!pos.capture_or_promotion(ttMove))
                     update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
 
-                // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
+                // Extra penalty for early quiet moves of the previous ply
-                if (    ((ss-1)->moveCount == 1 || (ss-1)->currentMove == (ss-1)->killers[0])
+                if ((ss-1)->moveCount <= 2 && !pos.captured_piece())
-                     && !pos.captured_piece())
                         update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
             }
             // Penalty for a quiet ttMove that fails low
@@ -734,16 +738,16 @@ namespace {
     // Step 6. Static evaluation of the position
     if (inCheck)
     {
-        ss->staticEval = eval = pureStaticEval = VALUE_NONE;
+        ss->staticEval = eval = VALUE_NONE;
         improving = false;
         goto moves_loop;  // Skip early pruning when in check
     }
     else if (ttHit)
     {
         // Never assume anything on values stored in TT
-        ss->staticEval = eval = pureStaticEval = tte->eval();
+        ss->staticEval = eval = tte->eval();
         if (eval == VALUE_NONE)
-            ss->staticEval = eval = pureStaticEval = evaluate(pos);
+            ss->staticEval = eval = evaluate(pos);
 
         // Can ttValue be used as a better position evaluation?
         if (    ttValue != VALUE_NONE
@@ -756,15 +760,14 @@ namespace {
         {
             int bonus = -(ss-1)->statScore / 512;
 
-            pureStaticEval = evaluate(pos);
+            ss->staticEval = eval = evaluate(pos) + bonus;
-            ss->staticEval = eval = pureStaticEval + bonus;
         }
         else
-            ss->staticEval = eval = pureStaticEval = -(ss-1)->staticEval + 2 * Eval::Tempo;
+            ss->staticEval = eval = -(ss-1)->staticEval + 2 * Eval::Tempo;
 
         Cluster::save(thisThread, tte,
                       posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
-                      pureStaticEval);
+                      eval);
     }
 
     // Step 7. Razoring (~2 Elo)
@@ -788,7 +791,7 @@ namespace {
         && (ss-1)->currentMove != MOVE_NULL
         && (ss-1)->statScore < 23200
         &&  eval >= beta
-        &&  pureStaticEval >= beta - 36 * depth / ONE_PLY + 225
+        &&  ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -820,7 +823,7 @@ namespace {
 
             // Do verification search at high depths, with null move pruning disabled
             // for us, until ply exceeds nmpMinPly.
-            thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4;
+            thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / (4 * ONE_PLY);
             thisThread->nmpColor = us;
 
             Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
@@ -871,8 +874,7 @@ namespace {
     }
 
     // Step 11. Internal iterative deepening (~2 Elo)
-    if (    depth >= 8 * ONE_PLY
+    if (depth >= 8 * ONE_PLY && !ttMove)
-        && !ttMove)
     {
         search<NT>(pos, ss, alpha, beta, depth - 7 * ONE_PLY, cutNode);
 
@@ -886,6 +888,7 @@ moves_loop: // When in check, search starts from here
     const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
                                           nullptr, (ss-4)->continuationHistory,
                                           nullptr, (ss-6)->continuationHistory };
+
     Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
 
     MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
@@ -893,8 +896,8 @@ moves_loop: // When in check, search starts from here
                                       contHist,
                                       countermove,
                                       ss->killers);
-    value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
 
+    value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
     moveCountPruning = false;
     ttCapture = ttMove && pos.capture_or_promotion(ttMove);
 
@@ -927,7 +930,7 @@ moves_loop: // When in check, search starts from here
       extension = DEPTH_ZERO;
       captureOrPromotion = pos.capture_or_promotion(move);
       movedPiece = pos.moved_piece(move);
-      givesCheck = gives_check(pos, move);
+      givesCheck = pos.gives_check(move);
 
       // Step 13. Extensions (~70 Elo)
 
@@ -947,8 +950,9 @@ moves_loop: // When in check, search starts from here
           &&  pos.legal(move))
       {
           Value singularBeta = ttValue - 2 * depth / ONE_PLY;
+          Depth halfDepth = depth / (2 * ONE_PLY) * ONE_PLY; // ONE_PLY invariant
           ss->excludedMove = move;
-          value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode);
+          value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
           ss->excludedMove = MOVE_NONE;
 
           if (value < singularBeta)
@@ -972,6 +976,20 @@ moves_loop: // When in check, search starts from here
       else if (type_of(move) == CASTLING)
           extension = ONE_PLY;
 
+      // Shuffle extension
+      else if (   PvNode
+               && pos.rule50_count() > 18
+               && ss->ply > 18
+               && depth < 3 * ONE_PLY
+               && ss->ply < 3 * thisThread->rootDepth / ONE_PLY) // To avoid infinite loops
+          extension = ONE_PLY;
+
+      // Passed pawn extension
+      else if (   move == ss->killers[0]
+               && pos.advanced_pawn_push(move)
+               && pos.pawn_passed(us, to_sq(move)))
+          extension = ONE_PLY;
+
       // Calculate new depth for this move
       newDepth = depth - ONE_PLY + extension;
 
@@ -981,7 +999,7 @@ moves_loop: // When in check, search starts from here
           && bestValue > VALUE_MATED_IN_MAX_PLY)
       {
           // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
-          moveCountPruning = moveCount >= futility_move_count(improving,depth / ONE_PLY);
+          moveCountPruning = moveCount >= futility_move_count(improving, depth / ONE_PLY);
 
           if (   !captureOrPromotion
               && !givesCheck
@@ -992,7 +1010,8 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Reduced depth of the next LMR search
-              int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
+              int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
+              lmrDepth /= ONE_PLY;
 
               // Countermoves based pruning (~20 Elo)
               if (   lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
@@ -1137,8 +1156,8 @@ moves_loop: // When in check, search starts from here
               // We record how often the best move has been changed in each
               // iteration. This information is used for time management: When
               // the best move changes frequently, we allocate some more time.
-              if (moveCount > 1 && thisThread == Threads.main())
+              if (moveCount > 1)
-                  ++static_cast<MainThread*>(thisThread)->bestMoveChanges;
+                  ++thisThread->bestMoveChanges;
           }
           else
               // All other moves but the PV are set to the lowest value: this
@@ -1225,7 +1244,7 @@ moves_loop: // When in check, search starts from here
                       posKey, value_to_tt(bestValue, ss->ply), ttPv,
                       bestValue >= beta ? BOUND_LOWER :
                       PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
-                      depth, bestMove, pureStaticEval);
+                      depth, bestMove, ss->staticEval);
 
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
@@ -1264,8 +1283,7 @@ moves_loop: // When in check, search starts from here
 
     Thread* thisThread = pos.this_thread();
     (ss+1)->ply = ss->ply + 1;
-    ss->currentMove = bestMove = MOVE_NONE;
+    bestMove = MOVE_NONE;
-    ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0];
     inCheck = pos.checkers();
     moveCount = 0;
 
@@ -1355,7 +1373,7 @@ moves_loop: // When in check, search starts from here
     {
       assert(is_ok(move));
 
-      givesCheck = gives_check(pos, move);
+      givesCheck = pos.gives_check(move);
 
       moveCount++;
 

src/thread.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm> // For std::count
 #include <cassert>
 
 #include "movegen.h"
@@ -32,7 +31,7 @@ ThreadPool Threads; // Global object
 
 
 /// Thread constructor launches the thread and waits until it goes to sleep
-/// in idle_loop(). Note that 'searching' and 'exit' should be alredy set.
+/// in idle_loop(). Note that 'searching' and 'exit' should be already set.
 
 Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
 

src/thread.h

@@ -64,7 +64,7 @@ public:
   size_t pvIdx, pvLast;
   int selDepth, nmpMinPly;
   Color nmpColor;
-  std::atomic<uint64_t> nodes, tbHits, TTsaves;
+  std::atomic<uint64_t> nodes, tbHits, TTsaves, bestMoveChanges;
 
   Position rootPos;
   Search::RootMoves rootMoves;
@@ -93,7 +93,7 @@ struct MainThread : public Thread {
   void search() override;
   void check_time();
 
-  double bestMoveChanges, previousTimeReduction;
+  double previousTimeReduction;
   Value previousScore;
   int callsCnt;
   bool stopOnPonderhit;

src/timeman.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cfloat>
 #include <cmath>
 

src/ucioption.cpp

@@ -18,7 +18,6 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <algorithm>
 #include <cassert>
 #include <ostream>
 #include <sstream>