X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=264d941f602b45368c5871afa87e6a6d16691da0;hb=cad300c;hp=0b887c99d0afb31abc3c963e7645a4224d082d3a;hpb=595a90dfd0cd393a8805f4f51cf5c5d8b264c121;p=stockfish

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 0b887c99..c0809f28 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,14 +1,14 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2009 Marco Costalba
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
-
   Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ -18,351 +18,270 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-
-////
-//// Includes
-////
-
-#include <algorithm>
 #include <cassert>
 
-#include "history.h"
-#include "evaluate.h"
-#include "movegen.h"
 #include "movepick.h"
-#include "search.h"
-#include "value.h"
-
-
-////
-//// Local definitions
-////
 
 namespace {
 
-  /// Variables
+  enum Stages {
+    MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLER0, KILLER1, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES,
+    EVASION, EVASIONS_INIT, ALL_EVASIONS,
+    PROBCUT, PROBCUT_CAPTURES_INIT, PROBCUT_CAPTURES,
+    QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS
+  };
+
+  // partial_insertion_sort() sorts moves in descending order up to and including
+  // a given limit. The order of moves smaller than the limit is left unspecified.
+  void partial_insertion_sort(ExtMove* begin, ExtMove* end, int limit) {
+
+    for (ExtMove *sortedEnd = begin, *p = begin + 1; p < end; ++p)
+        if (p->value >= limit)
+        {
+            ExtMove tmp = *p, *q;
+            *p = *++sortedEnd;
+            for (q = sortedEnd; q != begin && *(q - 1) < tmp; --q)
+                *q = *(q - 1);
+            *q = tmp;
+        }
+  }
 
-  CACHE_LINE_ALIGNMENT
-  const MovegenPhaseT MainSearchPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_GOOD_CAPTURES, PH_KILLERS, PH_NONCAPTURES, PH_BAD_CAPTURES, PH_STOP};
-  const MovegenPhaseT EvasionsPhaseTable[] = { PH_STOP, PH_EVASIONS, PH_STOP};
-  const MovegenPhaseT QsearchWithChecksPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_QCAPTURES, PH_QCHECKS, PH_STOP};
-  const MovegenPhaseT QsearchWithoutChecksPhaseTable[] = { PH_STOP, PH_TT_MOVES, PH_QCAPTURES, PH_STOP};
-}
+  // pick_best() finds the best move in the range (begin, end) and moves it to
+  // the front. It's faster than sorting all the moves in advance when there
+  // are few moves, e.g., the possible captures.
+  Move pick_best(ExtMove* begin, ExtMove* end) {
 
+    std::swap(*begin, *std::max_element(begin, end));
+    return *begin;
+  }
 
-////
-//// Functions
-////
+} // namespace
 
 
-/// Constructor for the MovePicker class.  Apart from the position for which
-/// it is asked to pick legal moves, MovePicker also wants some information
-/// to help it to return the presumably good moves first, to decide which
+/// Constructors of the MovePicker class. As arguments we pass information
+/// to help it to return the (presumably) good moves first, to decide which
 /// moves to return (in the quiescence search, for instance, we only want to
-/// search captures, promotions and some checks) and about how important good
-/// move ordering is at the current node.
-
-MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
-                       const History& h, SearchStack* ss) : pos(p), H(h) {
-  ttMoves[0] = ttm;
-  if (ss)
-  {
-      ttMoves[1] = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
-      killers[0] = ss->killers[0];
-      killers[1] = ss->killers[1];
-  } else
-      ttMoves[1] = killers[0] = killers[1] = MOVE_NONE;
-
-  movesPicked = numOfMoves = numOfBadCaptures = 0;
-  finished = false;
-
-  if (p.is_check())
-      phasePtr = EvasionsPhaseTable;
-  else if (d > Depth(0))
-      phasePtr = MainSearchPhaseTable;
-  else if (d == Depth(0))
-      phasePtr = QsearchWithChecksPhaseTable;
-  else
-      phasePtr = QsearchWithoutChecksPhaseTable;
-
-  Color us = pos.side_to_move();
-
-  dc = p.discovered_check_candidates(us);
-  pinned = p.pinned_pieces(us);
-}
-
+/// search captures, promotions, and some checks) and how important good move
+/// ordering is at the current node.
 
-/// MovePicker::get_next_move() is the most important method of the MovePicker
-/// class.  It returns a new legal move every time it is called, until there
-/// are no more moves left of the types we are interested in.
+/// MovePicker constructor for the main search
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,
+                       const CapturePieceToHistory* cph, const PieceToHistory** ch, Move cm, Move* killers_p)
+           : pos(p), mainHistory(mh), captureHistory(cph), contHistory(ch), countermove(cm),
+             killers{killers_p[0], killers_p[1]}, depth(d){
 
-Move MovePicker::get_next_move() {
+  assert(d > DEPTH_ZERO);
 
-  Move move;
-
-  while (true)
-  {
-    // If we already have a list of generated moves, pick the best move from
-    // the list, and return it.
-    move = pick_move_from_list();
-    if (move != MOVE_NONE)
-    {
-        assert(move_is_ok(move));
-        return move;
-    }
-
-    // Next phase
-    phasePtr++;
-    switch (*phasePtr) {
-
-    case PH_TT_MOVES:
-        movesPicked = 0; // This is used as index to ttMoves[]
-        break;
-
-    case PH_GOOD_CAPTURES:
-        numOfMoves = generate_captures(pos, moves);
-        score_captures();
-        std::sort(moves, moves + numOfMoves);
-        movesPicked = 0;
-        break;
-
-    case PH_KILLERS:
-        movesPicked = 0; // This is used as index to killers[]
-        break;
-
-    case PH_NONCAPTURES:
-        numOfMoves = generate_noncaptures(pos, moves);
-        score_noncaptures();
-        std::sort(moves, moves + numOfMoves);
-        movesPicked = 0;
-        break;
-
-    case PH_BAD_CAPTURES:
-        // Bad captures SEE value is already calculated so just sort them
-        // to get SEE move ordering.
-        std::sort(badCaptures, badCaptures + numOfBadCaptures);
-        movesPicked = 0;
-        break;
-
-    case PH_EVASIONS:
-        assert(pos.is_check());
-        numOfMoves = generate_evasions(pos, moves, pinned);
-        score_evasions();
-        std::sort(moves, moves + numOfMoves);
-        movesPicked = 0;
-        break;
-
-    case PH_QCAPTURES:
-        numOfMoves = generate_captures(pos, moves);
-        score_captures();
-        std::sort(moves, moves + numOfMoves);
-        movesPicked = 0;
-        break;
-
-    case PH_QCHECKS:
-        // Perhaps we should order moves move here?  FIXME
-        numOfMoves = generate_non_capture_checks(pos, moves, dc);
-        movesPicked = 0;
-        break;
-
-    case PH_STOP:
-        return MOVE_NONE;
-
-    default:
-        assert(false);
-        return MOVE_NONE;
-    }
-  }
+  stage = pos.checkers() ? EVASION : MAIN_SEARCH;
+  ttMove = ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE;
+  stage += (ttMove == MOVE_NONE);
 }
 
+/// MovePicker constructor for quiescence search
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHistory* mh,  const CapturePieceToHistory* cph, Square s)
+           : pos(p), mainHistory(mh), captureHistory(cph), recaptureSquare(s), depth(d) {
 
-/// A variant of get_next_move() which takes a lock as a parameter, used to
-/// prevent multiple threads from picking the same move at a split point.
+  assert(d <= DEPTH_ZERO);
 
-Move MovePicker::get_next_move(Lock &lock) {
+  stage = pos.checkers() ? EVASION : QSEARCH;
+  ttMove =    ttm
+           && pos.pseudo_legal(ttm)
+           && (depth > DEPTH_QS_RECAPTURES || to_sq(ttm) == recaptureSquare) ? ttm : MOVE_NONE;
+  stage += (ttMove == MOVE_NONE);
+}
+
+/// MovePicker constructor for ProbCut: we generate captures with SEE higher
+/// than or equal to the given threshold.
+MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePieceToHistory* cph)
+           : pos(p), captureHistory(cph), threshold(th) {
 
-   lock_grab(&lock);
-   if (finished)
-   {
-       lock_release(&lock);
-       return MOVE_NONE;
-   }
-   Move m = get_next_move();
-   if (m == MOVE_NONE)
-       finished = true;
+  assert(!pos.checkers());
 
-   lock_release(&lock);
-   return m;
+  stage = PROBCUT;
+  ttMove =   ttm
+          && pos.pseudo_legal(ttm)
+          && pos.capture(ttm)
+          && pos.see_ge(ttm, threshold) ? ttm : MOVE_NONE;
+  stage += (ttMove == MOVE_NONE);
 }
 
+/// score() assigns a numerical value to each move in a list, used for sorting.
+/// Captures are ordered by Most Valuable Victim (MVV), preferring captures
+/// with a good history. Quiets are ordered using the histories.
+template<GenType Type>
+void MovePicker::score() {
 
-/// MovePicker::score_captures(), MovePicker::score_noncaptures(),
-/// MovePicker::score_evasions() and MovePicker::score_qcaptures() assign a
-/// numerical move ordering score to each move in a move list.  The moves
-/// with highest scores will be picked first by pick_move_from_list().
-
-void MovePicker::score_captures() {
-  // Winning and equal captures in the main search are ordered by MVV/LVA.
-  // Suprisingly, this appears to perform slightly better than SEE based
-  // move ordering. The reason is probably that in a position with a winning
-  // capture, capturing a more valuable (but sufficiently defended) piece
-  // first usually doesn't hurt. The opponent will have to recapture, and
-  // the hanging piece will still be hanging (except in the unusual cases
-  // where it is possible to recapture with the hanging piece). Exchanging
-  // big pieces before capturing a hanging piece probably helps to reduce
-  // the subtree size.
-  // In main search we want to push captures with negative SEE values to
-  // badCaptures[] array, but instead of doing it now we delay till when
-  // the move has been picked up in pick_move_from_list(), this way we save
-  // some SEE calls in case we get a cutoff (idea from Pablo Vazquez).
-  Move m;
-
-  // Use MVV/LVA ordering
-  for (int i = 0; i < numOfMoves; i++)
-  {
-      m = moves[i].move;
-      if (move_is_promotion(m))
-          moves[i].score = QueenValueMidgame;
-      else
-          moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
-                          -int(pos.type_of_piece_on(move_from(m)));
-  }
-}
+  static_assert(Type == CAPTURES || Type == QUIETS || Type == EVASIONS, "Wrong type");
 
-void MovePicker::score_noncaptures() {
-  // First score by history, when no history is available then use
-  // piece/square tables values. This seems to be better then a
-  // random choice when we don't have an history for any move.
-  Piece piece;
-  Square from, to;
-  int hs;
-
-  for (int i = 0; i < numOfMoves; i++)
-  {
-      from = move_from(moves[i].move);
-      to = move_to(moves[i].move);
-      piece = pos.piece_on(from);
-      hs = H.move_ordering_score(piece, to);
-
-      // Ensure history is always preferred to pst
-      if (hs > 0)
-          hs += 1000;
-
-      // pst based scoring
-      moves[i].score = hs + pos.pst_delta<Position::MidGame>(piece, from, to);
-  }
-}
+  for (auto& m : *this)
+      if (Type == CAPTURES)
+          m.value =  PieceValue[MG][pos.piece_on(to_sq(m))]
+                   + (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))];
 
-void MovePicker::score_evasions() {
+      else if (Type == QUIETS)
+          m.value =  (*mainHistory)[pos.side_to_move()][from_to(m)]
+                   + (*contHistory[0])[pos.moved_piece(m)][to_sq(m)]
+                   + (*contHistory[1])[pos.moved_piece(m)][to_sq(m)]
+                   + (*contHistory[3])[pos.moved_piece(m)][to_sq(m)];
 
-  for (int i = 0; i < numOfMoves; i++)
-  {
-      Move m = moves[i].move;
-      if (m == ttMoves[0])
-          moves[i].score = 2*HistoryMax;
-      else if (!pos.square_is_empty(move_to(m)))
+      else // Type == EVASIONS
       {
-          int seeScore = pos.see(m);
-          moves[i].score = (seeScore >= 0)? seeScore + HistoryMax : seeScore;
-      } else
-          moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
-  }
+          if (pos.capture(m))
+              m.value =  PieceValue[MG][pos.piece_on(to_sq(m))]
+                       - Value(type_of(pos.moved_piece(m)));
+          else
+              m.value = (*mainHistory)[pos.side_to_move()][from_to(m)] - (1 << 28);
+      }
 }
 
+/// next_move() is the most important method of the MovePicker class. It returns
+/// a new pseudo legal move every time it is called, until there are no more moves
+/// left. It picks the move with the biggest value from a list of generated moves
+/// taking care not to return the ttMove if it has already been searched.
 
-/// MovePicker::pick_move_from_list() picks the move with the biggest score
-/// from a list of generated moves (moves[] or badCaptures[], depending on
-/// the current move generation phase).  It takes care not to return the
-/// transposition table move if that has already been serched previously.
+Move MovePicker::next_move(bool skipQuiets) {
 
-Move MovePicker::pick_move_from_list() {
+  Move move;
 
-  assert(movesPicked >= 0);
-  assert(!pos.is_check() || *phasePtr == PH_EVASIONS || *phasePtr == PH_STOP);
-  assert( pos.is_check() || *phasePtr != PH_EVASIONS);
+  switch (stage) {
 
-  switch (*phasePtr) {
+  case MAIN_SEARCH: case EVASION: case QSEARCH: case PROBCUT:
+      ++stage;
+      return ttMove;
 
-  case PH_TT_MOVES:
-        while (movesPicked < 2) {
-            Move move = ttMoves[movesPicked++];
-            if (   move != MOVE_NONE
-                && move_is_legal(pos, move, pinned))
-                return move;
-        }
-        break;
+  case CAPTURES_INIT:
+  case PROBCUT_CAPTURES_INIT:
+  case QCAPTURES_INIT:
+      endBadCaptures = cur = moves;
+      endMoves = generate<CAPTURES>(pos, cur);
+      score<CAPTURES>();
+      ++stage;
+
+      // Rebranch at the top of the switch via a recursive call
+      return next_move(skipQuiets);
 
-  case PH_GOOD_CAPTURES:
-      while (movesPicked < numOfMoves)
+  case GOOD_CAPTURES:
+      while (cur < endMoves)
       {
-          Move move = moves[movesPicked++].move;
-          if (   move != ttMoves[0]
-              && move != ttMoves[1]
-              && pos.pl_move_is_legal(move, pinned))
+          move = pick_best(cur++, endMoves);
+          if (move != ttMove)
           {
-              // Check for a non negative SEE now
-              int seeValue = pos.see_sign(move);
-              if (seeValue >= 0)
+              if (pos.see_ge(move, Value(-55 * (cur-1)->value / 1024)))
                   return move;
 
-              // Losing capture, move it to the badCaptures[] array, note
-              // that move has now been already checked for legality.
-              assert(numOfBadCaptures < 63);
-              badCaptures[numOfBadCaptures].move = move;
-              badCaptures[numOfBadCaptures++].score = seeValue;
+              // Losing capture, move it to the beginning of the array
+              *endBadCaptures++ = move;
           }
       }
+      ++stage;
+      /* fallthrough */
+
+  case KILLER0:
+  case KILLER1:
+      do
+      {
+          move = killers[++stage - KILLER1];
+          if (    move != MOVE_NONE
+              &&  move != ttMove
+              &&  pos.pseudo_legal(move)
+              && !pos.capture(move))
+              return move;
+      } while (stage <= KILLER1);
+      /* fallthrough */
+
+  case COUNTERMOVE:
+      ++stage;
+      move = countermove;
+      if (    move != MOVE_NONE
+          &&  move != ttMove
+          &&  move != killers[0]
+          &&  move != killers[1]
+          &&  pos.pseudo_legal(move)
+          && !pos.capture(move))
+          return move;
+      /* fallthrough */
+
+  case QUIET_INIT:
+      cur = endBadCaptures;
+      endMoves = generate<QUIETS>(pos, cur);
+      score<QUIETS>();
+      partial_insertion_sort(cur, endMoves, -4000 * depth / ONE_PLY);
+      ++stage;
+      /* fallthrough */
+
+  case QUIET:
+      if (!skipQuiets)
+          while (cur < endMoves)
+          {
+              move = *cur++;
+              if (   move != ttMove
+                  && move != killers[0]
+                  && move != killers[1]
+                  && move != countermove)
+                  return move;
+          }
+      ++stage;
+      cur = moves; // Point to beginning of bad captures
+      /* fallthrough */
+
+  case BAD_CAPTURES:
+      if (cur < endBadCaptures)
+          return *cur++;
       break;
 
-  case PH_KILLERS:
-        while (movesPicked < 2) {
-            Move move = killers[movesPicked++];
-            if (   move != MOVE_NONE
-                && move != ttMoves[0]
-                && move != ttMoves[1]
-                && move_is_legal(pos, move, pinned)
-                && !pos.move_is_capture(move))
-                return move;
-        }
-        break;
+  case EVASIONS_INIT:
+      cur = moves;
+      endMoves = generate<EVASIONS>(pos, cur);
+      score<EVASIONS>();
+      ++stage;
+      /* fallthrough */
 
-  case PH_NONCAPTURES:
-      while (movesPicked < numOfMoves)
+  case ALL_EVASIONS:
+      while (cur < endMoves)
       {
-          Move move = moves[movesPicked++].move;
-          if (   move != ttMoves[0]
-              && move != ttMoves[1]
-              && move != killers[0]
-              && move != killers[1]
-              && pos.pl_move_is_legal(move, pinned))
+          move = pick_best(cur++, endMoves);
+          if (move != ttMove)
               return move;
       }
       break;
 
-  case PH_EVASIONS:
-      if (movesPicked < numOfMoves)
-          return moves[movesPicked++].move;
-      break;
-
-  case PH_BAD_CAPTURES:
-      if (movesPicked < numOfBadCaptures)
-          return badCaptures[movesPicked++].move;
+  case PROBCUT_CAPTURES:
+      while (cur < endMoves)
+      {
+          move = pick_best(cur++, endMoves);
+          if (   move != ttMove
+              && pos.see_ge(move, threshold))
+              return move;
+      }
       break;
 
-  case PH_QCAPTURES:
-  case PH_QCHECKS:
-      while (movesPicked < numOfMoves)
+  case QCAPTURES:
+      while (cur < endMoves)
       {
-          Move move = moves[movesPicked++].move;
-          // Maybe postpone the legality check until after futility pruning?
-          if (   move != ttMoves[0]
-              && pos.pl_move_is_legal(move, pinned))
+          move = pick_best(cur++, endMoves);
+          if (   move != ttMove
+              && (depth > DEPTH_QS_RECAPTURES || to_sq(move) == recaptureSquare))
+              return move;
+      }
+      if (depth <= DEPTH_QS_NO_CHECKS)
+          break;
+      cur = moves;
+      endMoves = generate<QUIET_CHECKS>(pos, cur);
+      ++stage;
+      /* fallthrough */
+
+  case QCHECKS:
+      while (cur < endMoves)
+      {
+          move = *cur++;
+          if (move != ttMove)
               return move;
       }
       break;
 
   default:
-      break;
+      assert(false);
   }
+
   return MOVE_NONE;
 }