Updated to "Retire KingDanger array".

official-stockfish/Stockfish@01f2466

Author: syzygy

src/bitboard.h

@@ -32,7 +32,7 @@ void bitboards_init();
 void print_pretty(Bitboard b);
 
 #define DarkSquares  0xAA55AA55AA55AA55ULL
-#define LightSquares 0x55AA55AA55AA55AAULL
+#define LightSquares (~DarkSquares)
 
 #define FileABB 0x0101010101010101ULL
 #define FileBBB (FileABB << 1)

src/evaluate.c

@@ -216,21 +216,15 @@ static const Score TrappedBishopA1H1 = S(50, 50);
 #undef S
 #undef V
 
-// King danger constants and variables. The king danger scores are looked-up
-// in KingDanger[]. Various little "meta-bonuses" measuring the strength
-// of the enemy attack are added up into an integer, which is used as an
-// index to KingDanger[].
-static Score KingDanger[400];
-
 // KingAttackWeights[PieceType] contains king attack weights by piece type
-static const int KingAttackWeights[8] = { 0, 0, 7, 5, 4, 1 };
+static const int KingAttackWeights[8] = { 0, 0, 78, 56, 45, 11 };
 
 // Penalties for enemy's safe checks
-#define QueenContactCheck 89
-#define QueenCheck        62
-#define RookCheck         57
-#define BishopCheck       48
-#define KnightCheck       78
+#define QueenContactCheck 997
+#define QueenCheck        695
+#define RookCheck         638
+#define BishopCheck       538
+#define KnightCheck       874
 
 
 // eval_init() initializes king and attack bitboards for a given color
@@ -410,7 +404,7 @@ INLINE Score evaluate_king(Pos *pos, EvalInfo *ei, int Us)
   const int Up = (Us == WHITE ? DELTA_N : DELTA_S);
 
   Bitboard undefended, b, b1, b2, safe, other;
-  int attackUnits;
+  int kingDanger;
   const Square ksq = square_of(Us, KING);
 
   // King shelter and enemy pawns storm
@@ -428,24 +422,24 @@ INLINE Score evaluate_king(Pos *pos, EvalInfo *ei, int Us)
     b =  ei->attackedBy[Them][0] & ~ei->attackedBy[Us][0]
        & ei->kingRing[Us] & ~pieces_c(Them);
 
-    // Initialize the 'attackUnits' variable, which is used later on as an
-    // index into the KingDanger[] array. The initial value is based on the
+    // Initialize the 'kingDanger' variable, which will be transformed
+    // later into a king danger score. The initial value is based on the
     // number and types of the enemy's attacking pieces, the number of
     // attacked and undefended squares around our king and the quality of
     // the pawn shelter (current 'score' value).
-    attackUnits =  min(72, ei->kingAttackersCount[Them] * ei->kingAttackersWeight[Them])
-                 +  9 * ei->kingAdjacentZoneAttacksCount[Them]
-                 + 21 * popcount(undefended)
-                 + 12 * (popcount(b) + !!ei->pinnedPieces[Us])
-                 - 64 * !pieces_cp(Them, QUEEN)
-                 - mg_value(score) / 8;
+    kingDanger =  min(807, ei->kingAttackersCount[Them] * ei->kingAttackersWeight[Them])
+                + 101 * ei->kingAdjacentZoneAttacksCount[Them]
+                + 235 * popcount(undefended)
+                + 134 * (popcount(b) + !!ei->pinnedPieces[Us])
+                - 717 * !pieces_cp(Them, QUEEN)
+                -   7 * mg_value(score) / 5 - 5;
 
     // Analyse the enemy's safe queen contact checks. Firstly, find the
     // undefended squares around the king reachable by the enemy queen...
     b = undefended & ei->attackedBy[Them][QUEEN] & ~pieces_c(Them);
 
     // ...and keep squares supported by another enemy piece
-    attackUnits += QueenContactCheck * popcount(b & ei->attackedBy2[Them]);
+    kingDanger += QueenContactCheck * popcount(b & ei->attackedBy2[Them]);
 
     // Analyse the safe enemy's checks which are possible on next move...
     safe  = ~(ei->attackedBy[Us][0] | pieces_c(Them));
@@ -460,7 +454,7 @@ INLINE Score evaluate_king(Pos *pos, EvalInfo *ei, int Us)
 
     // Enemy queen safe checks
     if ((b1 | b2) & ei->attackedBy[Them][QUEEN] & safe) {
-      attackUnits += QueenCheck;
+      kingDanger += QueenCheck;
       score -= SafeCheck;
     }
 
@@ -472,7 +466,7 @@ INLINE Score evaluate_king(Pos *pos, EvalInfo *ei, int Us)
 
     // Enemy rooks safe and other checks
     if (b1 & ei->attackedBy[Them][ROOK] & safe) {
-      attackUnits += RookCheck;
+      kingDanger += RookCheck;
       score -= SafeCheck;
     }
 
@@ -481,7 +475,7 @@ INLINE Score evaluate_king(Pos *pos, EvalInfo *ei, int Us)
 
     // Enemy bishops safe and other checks
     if (b2 & ei->attackedBy[Them][BISHOP] & safe) {
-      attackUnits += BishopCheck;
+      kingDanger += BishopCheck;
       score -= SafeCheck;
     }
 
@@ -491,16 +485,17 @@ INLINE Score evaluate_king(Pos *pos, EvalInfo *ei, int Us)
     // Enemy knights safe and other checks
     b = attacks_from_knight(ksq) & ei->attackedBy[Them][KNIGHT];
     if (b & safe) {
-      attackUnits += KnightCheck;
+      kingDanger += KnightCheck;
       score -= SafeCheck;
     }
 
     else if (b & other)
       score -= OtherCheck;
 
+    // Compute the king danger score and subtract it from the evaluation.
     // Finally, extract the king danger score from the KingDanger[]
-    // array and subtract the score from the evaluation.
-    score -= KingDanger[max(min(attackUnits, 399), 0)];
+    if (kingDanger > 0)
+      score -= make_score(min(kingDanger * kingDanger / 4096, 2 * BishopValueMg), 0);
   }
 
   // King tropism: firstly, find squares that we attack in the enemy king flank
@@ -930,17 +925,3 @@ void eval_trace(Pos *pos)
 }
 #endif
 
-
-// eval_init() computes evaluation weights, usually at startup.
-
-void eval_init() {
-  int MaxSlope = 322;
-  int Peak = 47410;
-  int t = 0;
-
-  for (int i = 0; i < 400; ++i) {
-    t = min(Peak, min(i * i - 16, t + MaxSlope));
-    KingDanger[i] = make_score(t * 268 / 7700, 0);
-  }
-}
-

src/evaluate.h

@@ -7,7 +7,6 @@ typedef struct Pos Pos;
 
 #define Tempo ((Value)20)
 
-void eval_init();
 void trace(Pos *pos);
 
 //template<bool DoTrace = false>

src/main.c

@@ -22,7 +22,6 @@
 
 #include "bitboard.h"
 #include "endgame.h"
-#include "evaluate.h"
 #include "pawns.h"
 #include "position.h"
 #include "search.h"
@@ -40,7 +39,6 @@ int main(int argc, char **argv)
   bitboards_init();
   bitbases_init();
   search_init();
-  eval_init();
   pawn_init();
   endgames_init();
   threads_init();

src/movegen2.c

@@ -142,7 +142,7 @@ INLINE ExtMove *generate_pawn_moves(Pos *pos, ExtMove *list, Bitboard target,
       // if the pawn is not on the same file as the enemy king, because we
       // don't generate captures. Note that a possible discovery check
       // promotion has been already generated amongst the captures.
-      Bitboard dcCandidates = discovered_check_candidates(pos);
+      Bitboard dcCandidates = blockers_for_king(pos, Them);
       if (pawnsNotOn7 & dcCandidates) {
         Bitboard dc1 = shift_bb(Up, pawnsNotOn7 & dcCandidates) & emptySquares & ~file_bb_s(st->ksq);
         Bitboard dc2 = shift_bb(Up, dc1 & TRank3BB) & emptySquares;
@@ -235,7 +235,7 @@ INLINE ExtMove *generate_moves(Pos *pos, ExtMove *list, int us,
           && !(PseudoAttacks[Pt][from] & target & pos->st->checkSquares[Pt]))
           continue;
 
-      if (discovered_check_candidates(pos) & sq_bb(from))
+      if (blockers_for_king(pos, us ^ 1) & sq_bb(from))
         continue;
     }
 

src/movepick.c

@@ -118,7 +118,7 @@ void mp_init_q(Pos *pos, Move ttm, Depth depth, Square s)
   else if (depth > DEPTH_QS_RECAPTURES)
     st->stage = ST_QSEARCH_WITHOUT_CHECKS;
   else {
-    st->stage = ST_RECAPTURES;
+    st->stage = ST_RECAPTURES_GEN;
     st->recaptureSquare = s;
     return;
   }
@@ -156,7 +156,7 @@ void mp_init_pc(Pos *pos, Move ttm, Value threshold)
 // score() assigns a numerical value to each move in a move list. The moves with
 // highest values will be picked first.
 
-void score_captures(Pos *pos)
+static void score_captures(Pos *pos)
 {
   Stack *st = pos->st;
 
@@ -168,7 +168,7 @@ void score_captures(Pos *pos)
               - (Value)(200 * relative_rank_s(pos_stm(), to_sq(m->move)));
 }
 
-void score_quiets(Pos *pos)
+static void score_quiets(Pos *pos)
 {
   Stack *st = pos->st;
   HistoryStats *history = pos->history;
@@ -177,7 +177,7 @@ void score_quiets(Pos *pos)
   CounterMoveStats *cm = (st-1)->counterMoves;
   CounterMoveStats *fm = (st-2)->counterMoves;
   CounterMoveStats *f2 = (st-4)->counterMoves;
-
+//if(!cm || !fm || !f2)printf("st->ply = %d (%d,%d,%d)\n", st->ply, !!cm, !!fm, !!f2);
   int c = pos_stm();
 
   for (ExtMove *m = st->cur; m < st->endMoves; m++)
@@ -188,7 +188,7 @@ void score_quiets(Pos *pos)
               + ft_get(*fromTo, c, m->move);
 }
 
-void score_evasions(Pos *pos)
+static void score_evasions(Pos *pos)
 {
   Stack *st = pos->st;
   // Try winning and equal captures ordered by MVV/LVA, then non-captures
@@ -227,13 +227,13 @@ Move next_move(Pos *pos)
     st->stage++;
     return st->ttMove;
 
-  case ST_GOOD_CAPTURES:
+  case ST_CAPTURES_GEN:
     st->endBadCaptures = st->cur = (st-1)->endMoves;
     st->endMoves = generate_captures(pos, st->cur);
     score_captures(pos);
     st->stage++;
 
-  case ST_GOOD_CAPTURES_2:
+  case ST_GOOD_CAPTURES:
     while (st->cur < st->endMoves) {
       move = pick_best(st->cur++, st->endMoves);
       if (move != st->ttMove) {
@@ -267,7 +267,7 @@ Move next_move(Pos *pos)
              && !is_capture(pos, move))
       return move;
 
-  case ST_QUIET:
+  case ST_QUIET_GEN:
     st->cur = st->endBadCaptures;
     st->endMoves = generate_quiets(pos, st->cur);
     score_quiets(pos);
@@ -278,7 +278,7 @@ Move next_move(Pos *pos)
       insertion_sort(st->cur, st->endMoves);
     st->stage++;
 
-  case ST_QUIET_2:
+  case ST_QUIET:
     while (st->cur < st->endMoves) {
       move = (st->cur++)->move;
       if (   move != st->ttMove && move != st->killers[0]
@@ -291,33 +291,31 @@ Move next_move(Pos *pos)
   case ST_BAD_CAPTURES:
     if (st->cur < st->endBadCaptures)
       return (st->cur++)->move;
-    return 0;
+    break;
 
-  case ST_EVASIONS_1:
+  case ST_ALL_EVASIONS:
     st->cur = (st-1)->endMoves;
     st->endMoves = generate_evasions(pos, st->cur);
     if (st->endMoves - st->cur > 1)
       score_evasions(pos);
     st->stage = ST_REMAINING;
-    goto remaining;
 
-  case ST_QCAPTURES_CHECKS_1:
-  case ST_QCAPTURES_NO_CHECKS_1:
-    st->cur = (st-1)->endMoves;
-    st->endMoves = generate_captures(pos, st->cur);
-    score_captures(pos);
-    st->stage++;
+    if (st->stage != ST_REMAINING) {
+  case ST_QCAPTURES_CHECKS_GEN: case ST_QCAPTURES_NO_CHECKS_GEN:
+      st->cur = (st-1)->endMoves;
+      st->endMoves = generate_captures(pos, st->cur);
+      score_captures(pos);
+      st->stage++;
+    }
 
-remaining:
-  case ST_QCAPTURES_CHECKS_2:
-  case ST_REMAINING:
+  case ST_QCAPTURES_CHECKS: case ST_REMAINING:
     while (st->cur < st->endMoves) {
       move = pick_best(st->cur++, st->endMoves);
       if (move != st->ttMove)
         return move;
     }
-    if (st->stage != ST_QCAPTURES_CHECKS_2)
-      return 0;
+    if (st->stage != ST_QCAPTURES_CHECKS)
+      break;
     st->cur = (st-1)->endMoves;
     st->endMoves = generate_quiet_checks(pos, st->cur);
     st->stage++;
@@ -328,23 +326,23 @@ Move next_move(Pos *pos)
       if (move != st->ttMove)
         return move;
     }
-    return 0;
+    break;
 
-  case ST_RECAPTURES:
+  case ST_RECAPTURES_GEN:
     st->cur = (st-1)->endMoves;
     st->endMoves = generate_captures(pos, st->cur);
     score_captures(pos);
     st->stage++;
 
-  case ST_RECAPTURES_2:
+  case ST_RECAPTURES:
     while (st->cur < st->endMoves) {
       move = pick_best(st->cur++, st->endMoves);
       if (to_sq(move) == st->recaptureSquare)
         return move;
     }
-    return 0;
+    break;
 
-  case ST_PROBCUT_1:
+  case ST_PROBCUT_GEN:
     st->cur = (st-1)->endMoves;
     st->endMoves = generate_captures(pos, st->cur);
     score_captures(pos);
@@ -356,12 +354,13 @@ Move next_move(Pos *pos)
       if (move != st->ttMove && see_test(pos, move, st->threshold + 1))
         return move;
     }
-    return 0;
+    break;
 
   default:
     assume(0);
-    return 0;
 
   }
+
+  return 0;
 }