Updated to "Tweak late move reductions at root".

official-stockfish/Stockfish@baf184e
This is more or less SF 11, but I skipped one SMP patch.

src/endgame.c

@@ -162,10 +162,10 @@ static Value EvaluateKXK(const Pos *pos, unsigned strongSide)
   unsigned weakSide = strongSide ^ 1;
 
   assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
-  assert(!pos_checkers()); // Eval is never called when in check
+  assert(!checkers()); // Eval is never called when in check
 
   // Stalemate detection with lone king
-  if (pos_stm() == weakSide) {
+  if (stm() == weakSide) {
     ExtMove list[MAX_MOVES];
     if (generate_legal(pos, list) == list)
       return VALUE_DRAW;
@@ -186,7 +186,7 @@ static Value EvaluateKXK(const Pos *pos, unsigned strongSide)
           && (pieces_p(BISHOP) & bb & LightSquares)))
     result = min(result + VALUE_KNOWN_WIN, VALUE_MATE_IN_MAX_PLY - 1);
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -215,7 +215,7 @@ static Value EvaluateKBNK(const Pos *pos, unsigned strongSide)
                 + PushClose[distance(winnerKSq, loserKSq)]
                 + PushToCorners[loserKSq];
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -232,14 +232,14 @@ static Value EvaluateKPK(const Pos *pos, unsigned strongSide)
   Square bksq = normalize(pos, strongSide, square_of(weakSide, KING));
   Square psq  = normalize(pos, strongSide, lsb(pieces_p(PAWN)));
 
-  unsigned us = strongSide == pos_stm() ? WHITE : BLACK;
+  unsigned us = strongSide == stm() ? WHITE : BLACK;
 
   if (!bitbases_probe(wksq, psq, bksq, us))
     return VALUE_DRAW;
 
   Value result = VALUE_KNOWN_WIN + PawnValueEg + (Value)(rank_of(psq));
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -268,7 +268,7 @@ static Value EvaluateKRKP(const Pos *pos, unsigned strongSide)
 
   // If the weaker side's king is too far from the pawn and the rook,
   // it's a win.
-  else if (   distance(bksq, psq) >= 3 + (pos_stm() == weakSide)
+  else if (   distance(bksq, psq) >= 3 + (stm() == weakSide)
            && distance(bksq, rsq) >= 3)
     result = RookValueEg - distance(wksq, psq);
 
@@ -277,15 +277,15 @@ static Value EvaluateKRKP(const Pos *pos, unsigned strongSide)
   else if (   rank_of(bksq) <= RANK_3
            && distance(bksq, psq) == 1
            && rank_of(wksq) >= RANK_4
-           && distance(wksq, psq) > 2 + (pos_stm() == strongSide))
+           && distance(wksq, psq) > 2 + (stm() == strongSide))
     result = (Value)(80) - 8 * distance(wksq, psq);
 
   else
     result =  (Value)(200) - 8 * (  distance(wksq, psq + SOUTH)
                                   - distance(bksq, psq + SOUTH)
                                   - distance(psq, queeningSq));
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -299,7 +299,7 @@ static Value EvaluateKRKB(const Pos *pos, unsigned strongSide)
   assert(verify_material(pos, weakSide, BishopValueMg, 0));
 
   Value result = (Value)PushToEdges[square_of(weakSide, KING)];
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -315,7 +315,7 @@ static Value EvaluateKRKN(const Pos *pos, unsigned strongSide)
   Square bksq = square_of(weakSide, KING);
   Square bnsq = lsb(pieces_p(KNIGHT));
   Value result = (Value)PushToEdges[bksq] + PushAway[distance(bksq, bnsq)];
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -341,7 +341,7 @@ static Value EvaluateKQKP(const Pos *pos, unsigned strongSide)
       || !((FileABB | FileCBB | FileFBB | FileHBB) & sq_bb(pawnSq)))
     result += QueenValueEg - PawnValueEg;
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -365,7 +365,7 @@ static Value EvaluateKQKR(const Pos *pos, unsigned strongSide)
                 + PushToEdges[loserKSq]
                 + PushClose[distance(winnerKSq, loserKSq)];
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -381,7 +381,7 @@ static Value EvaluateKNNKP(const Pos *pos, unsigned strongSide)
                 - PawnValueEg
                 + PushToEdges[square_of(weakSide, KING)];
 
-  return strongSide == pos_stm() ? result : -result;
+  return strongSide == stm() ? result : -result;
 }
 
 
@@ -512,7 +512,7 @@ static int ScaleKRPKR(const Pos *pos, unsigned strongSide)
   File f = file_of(wpsq);
   Rank r = rank_of(wpsq);
   Square queeningSq = make_square(f, RANK_8);
-  signed tempo = (pos_stm() == strongSide);
+  signed tempo = (stm() == strongSide);
 
   // If the pawn is not too far advanced and the defending king defends
   // the queening square, use the third-rank defence.
@@ -878,7 +878,7 @@ static int ScaleKPKP(const Pos *pos, unsigned strongSide)
   Square bksq = normalize(pos, strongSide, square_of(weakSide, KING));
   Square psq  = normalize(pos, strongSide, square_of(strongSide, PAWN));
 
-  unsigned us = strongSide == pos_stm() ? WHITE : BLACK;
+  unsigned us = strongSide == stm() ? WHITE : BLACK;
 
   // If the pawn has advanced to the fifth rank or further, and is not a
   // rook pawn, it is too dangerous to assume that it is at least a draw.

src/evaluate.c

@@ -277,19 +277,19 @@ INLINE Score evaluate_piece(const Pos *pos, EvalInfo *ei, Score *mobility,
         // squares
         if (more_than_one(attacks_bb_bishop(s, pieces_p(PAWN)) & Center))
           score += LongDiagonalBishop;
-      }
 
-      // An important Chess960 pattern: A cornered bishop blocked by a friendly
-      // pawn diagonally in front of it is a very serious problem, especially
-      // when that pawn is also blocked.
-      if (   Pt == BISHOP
-          && is_chess960()
-          && (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1))) {
-        Square d = pawn_push(Us) + (file_of(s) == FILE_A ? EAST : WEST);
-        if (piece_on(s + d) == make_piece(Us, PAWN))
-          score -=  piece_on(s + d + pawn_push(Us))             ? CorneredBishop * 4
-                  : piece_on(s + d + d) == make_piece(Us, PAWN) ? CorneredBishop * 2
-                                                                : CorneredBishop;
+        // An important Chess960 pattern: a cornered bishop blocked by a
+        // friendly pawn diagonally in front of it is a very serious problem,
+        // especially when that pawn is also blocked.
+        if (   is_chess960()
+            && (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
+        {
+          Square d = pawn_push(Us) + (file_of(s) == FILE_A ? EAST : WEST);
+          if (piece_on(s + d) == make_piece(Us, PAWN))
+            score -=  piece_on(s + d + pawn_push(Us))             ? CorneredBishop * 4
+                    : piece_on(s + d + d) == make_piece(Us, PAWN) ? CorneredBishop * 2
+                                                                  : CorneredBishop;
+        }
       }
     }
 
@@ -709,7 +709,7 @@ INLINE int evaluate_scale_factor(const Pos *pos, EvalInfo *ei, Value eg)
       sf = 22;
     else
       sf = min(sf, 36 + (opposite_bishops(pos) ? 2 : 7) * piece_count(strongSide, PAWN));
-    sf = max(0, sf - (pos_rule50_count() - 12) / 4);
+    sf = max(0, sf - (rule50_count() - 12) / 4);
   }
 
   return sf;
@@ -721,7 +721,7 @@ INLINE int evaluate_scale_factor(const Pos *pos, EvalInfo *ei, Value eg)
 
 Value evaluate(const Pos *pos)
 {
-  assert(!pos_checkers());
+  assert(!checkers());
 
   Score mobility[2] = { SCORE_ZERO, SCORE_ZERO };
   Value v;
@@ -739,7 +739,7 @@ Value evaluate(const Pos *pos)
   // in the position struct (material + piece square tables) and the
   // material imbalance. Score is computed internally from the white point
   // of view.
-  Score score = pos_psq_score() + material_imbalance(ei.me) + pos->contempt;
+  Score score = psq_score() + material_imbalance(ei.me) + pos->contempt;
 
   // Probe the pawn hash table
   ei.pe = pawn_probe(pos);
@@ -748,7 +748,7 @@ Value evaluate(const Pos *pos)
   // Early exit if score is high
   v = (mg_value(score) + eg_value(score)) / 2;
   if (abs(v) > LazyThreshold + non_pawn_material() / 64)
-    return pos_stm() == WHITE ? v : -v;
+    return stm() == WHITE ? v : -v;
 
   // Initialize attack and king safety bitboards.
   evalinfo_init(pos, &ei, WHITE);
@@ -789,5 +789,5 @@ Value evaluate(const Pos *pos)
 
   v /= PHASE_MIDGAME;
 
-  return (pos_stm() == WHITE ? v : -v) + Tempo; // Side to move point of view
+  return (stm() == WHITE ? v : -v) + Tempo; // Side to move point of view
 }

src/material.h

@@ -57,7 +57,7 @@ void material_entry_fill(const Pos *pos, MaterialEntry *e, Key key);
 
 INLINE MaterialEntry *material_probe(const Pos *pos)
 {
-  Key key = pos_material_key();
+  Key key = material_key();
   MaterialEntry *e = &pos->materialTable[key >> (64-13)];
 
   if (unlikely(e->key != key))

src/movegen.c

@@ -246,9 +246,9 @@ INLINE ExtMove *generate_all(const Pos *pos, ExtMove *list, Bitboard target,
 INLINE ExtMove *generate(const Pos *pos, ExtMove *list, const int Type)
 {
   assert(Type == CAPTURES || Type == QUIETS || Type == NON_EVASIONS);
-  assert(!pos_checkers());
+  assert(!checkers());
 
-  Color us = pos_stm();
+  Color us = stm();
 
   Bitboard target =  Type == CAPTURES     ?  pieces_c(us ^ 1)
                    : Type == QUIETS       ? ~pieces()
@@ -280,9 +280,9 @@ ExtMove *generate_non_evasions(const Pos *pos, ExtMove *list)
 // knight underpromotions that give check.
 ExtMove *generate_quiet_checks(const Pos *pos, ExtMove *list)
 {
-  assert(!pos_checkers());
+  assert(!checkers());
 
-  Color us = pos_stm();
+  Color us = stm();
   Bitboard dc = blockers_for_king(pos, us ^ 1) & pieces_c(us);
 
   while (dc) {
@@ -310,12 +310,12 @@ ExtMove *generate_quiet_checks(const Pos *pos, ExtMove *list)
 // side to move is in check.
 ExtMove *generate_evasions(const Pos *pos, ExtMove *list)
 {
-  assert(pos_checkers());
+  assert(checkers());
 
-  Color us = pos_stm();
+  Color us = stm();
   Square ksq = square_of(us, KING);
   Bitboard sliderAttacks = 0;
-  Bitboard sliders = pos_checkers() & ~pieces_pp(KNIGHT, PAWN);
+  Bitboard sliders = checkers() & ~pieces_pp(KNIGHT, PAWN);
 
   // Find all the squares attacked by slider checkers. We will remove them
   // from the king evasions in order to skip known illegal moves, which
@@ -330,11 +330,11 @@ ExtMove *generate_evasions(const Pos *pos, ExtMove *list)
   while (b)
       (list++)->move = make_move(ksq, pop_lsb(&b));
 
-  if (more_than_one(pos_checkers()))
+  if (more_than_one(checkers()))
       return list; // Double check, only a king move can save the day
 
   // Generate blocking evasions or captures of the checking piece
-  Square checksq = lsb(pos_checkers());
+  Square checksq = lsb(checkers());
   Bitboard target = between_bb(ksq, checksq) | sq_bb(checksq);
 
   return us == WHITE ? generate_all(pos, list, target, WHITE, EVASIONS)
@@ -346,12 +346,12 @@ ExtMove *generate_evasions(const Pos *pos, ExtMove *list)
 SMALL
 ExtMove *generate_legal(const Pos *pos, ExtMove *list)
 {
-  Color us = pos_stm();
+  Color us = stm();
   Bitboard pinned = blockers_for_king(pos, us) & pieces_c(us);
   Square ksq = square_of(us, KING);
   ExtMove *cur = list;
 
-  list = pos_checkers() ? generate_evasions(pos, list)
+  list = checkers() ? generate_evasions(pos, list)
                         : generate_non_evasions(pos, list);
   while (cur != list)
     if (   (pinned || from_sq(cur->move) == ksq

src/movepick.c

@@ -85,7 +85,7 @@ static void score_quiets(const Pos *pos)
   PieceToHistory *fmh2 = (st-4)->history;
   PieceToHistory *fmh3 = (st-6)->history;
 
-  Color c = pos_stm();
+  Color c = stm();
 
   for (ExtMove *m = st->cur; m < st->endMoves; m++) {
     uint32_t move = m->move & 4095;
@@ -107,7 +107,7 @@ static void score_evasions(const Pos *pos)
 
   ButterflyHistory *history = pos->history;
   PieceToHistory *cmh = (st-1)->history;
-  Color c = pos_stm();
+  Color c = stm();
 
   for (ExtMove *m = st->cur; m < st->endMoves; m++)
     if (is_capture(pos, m->move))

src/movepick.h

@@ -77,7 +77,7 @@ INLINE void mp_init(const Pos *pos, Move ttm, Depth d)
   st->mpKillers[0] = st->killers[0];
   st->mpKillers[1] = st->killers[1];
 
-  st->stage = pos_checkers() ? ST_EVASION : ST_MAIN_SEARCH;
+  st->stage = checkers() ? ST_EVASION : ST_MAIN_SEARCH;
   st->ttMove = ttm;
   if (!ttm || !is_pseudo_legal(pos, ttm)) {
     st->stage++;
@@ -91,7 +91,7 @@ INLINE void mp_init_q(const Pos *pos, Move ttm, Depth d, Square s)
 
   Stack *st = pos->st;
 
-  st->stage = pos_checkers() ? ST_EVASION : ST_QSEARCH;
+  st->stage = checkers() ? ST_EVASION : ST_QSEARCH;
   st->ttMove =   ttm
               && is_pseudo_legal(pos, ttm)
               && (d > DEPTH_QS_RECAPTURES || to_sq(ttm) == s) ? ttm : 0;
@@ -103,7 +103,7 @@ INLINE void mp_init_q(const Pos *pos, Move ttm, Depth d, Square s)
 
 INLINE void mp_init_pc(const Pos *pos, Move ttm, Value th)
 {
-  assert(!pos_checkers());
+  assert(!checkers());
 
   Stack *st = pos->st;