Simplify qsearch stages in MovePicker

[stockfish] / src / movepick.cpp

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 15188712e891f041d1c29fb86071191b42135724..9882960d9fda66475be430842ab847e801ad30d6 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -28,9 +28,7 @@ namespace {
     MAIN_SEARCH, CAPTURES_INIT, GOOD_CAPTURES, KILLERS, COUNTERMOVE, QUIET_INIT, QUIET, BAD_CAPTURES,
     EVASION, EVASIONS_INIT, ALL_EVASIONS,
     PROBCUT, PROBCUT_INIT, PROBCUT_CAPTURES,
-    QSEARCH_WITH_CHECKS, QCAPTURES_1_INIT, QCAPTURES_1, QCHECKS,
-    QSEARCH_NO_CHECKS, QCAPTURES_2_INIT, QCAPTURES_2,
-    QSEARCH_RECAPTURES, QRECAPTURES
+    QSEARCH, QCAPTURES_INIT, QCAPTURES, QCHECKS, QSEARCH_RECAPTURES, QRECAPTURES
   };
 
   // partial_insertion_sort() sorts moves in descending order up to and including
@@ -81,18 +79,15 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const ButterflyHist
 
 /// 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) {
+           : pos(p), mainHistory(mh), captureHistory(cph), depth(d) {
 
   assert(d <= DEPTH_ZERO);
 
   if (pos.checkers())
       stage = EVASION;
 
-  else if (d > DEPTH_QS_NO_CHECKS)
-      stage = QSEARCH_WITH_CHECKS;
-
   else if (d > DEPTH_QS_RECAPTURES)
-      stage = QSEARCH_NO_CHECKS;
+      stage = QSEARCH;
 
   else
   {
@@ -123,7 +118,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Value th, const CapturePiece
 
 /// score() assigns a numerical value to each move in a list, used for sorting.
 /// Captures are ordered by Most Valuable Victim (MVV), preferring captures
-/// near our home rank. Quiets are ordered using the histories.
+/// with a good history. Quiets are ordered using the histories.
 template<GenType Type>
 void MovePicker::score() {
 
@@ -161,8 +156,7 @@ Move MovePicker::next_move(bool skipQuiets) {
 
   switch (stage) {
 
-  case MAIN_SEARCH: case EVASION: case QSEARCH_WITH_CHECKS:
-  case QSEARCH_NO_CHECKS: case PROBCUT:
+  case MAIN_SEARCH: case EVASION: case QSEARCH: case PROBCUT:
       ++stage;
       return ttMove;
 
@@ -179,12 +173,7 @@ Move MovePicker::next_move(bool skipQuiets) {
           move = pick_best(cur++, endMoves);
           if (move != ttMove)
           {
-              if (pos.see_ge(move))
-                  return move;
-
-              if (   type_of(pos.piece_on(to_sq(move))) == KNIGHT
-                  && type_of(pos.moved_piece(move)) == BISHOP
-                  && (cur-1)->value > 1090)
+              if (pos.see_ge(move, Value(-55 * (cur-1)->value / 1024)))
                   return move;
 
               // Losing capture, move it to the beginning of the array
@@ -285,21 +274,21 @@ Move MovePicker::next_move(bool skipQuiets) {
       }
       break;
 
-  case QCAPTURES_1_INIT: case QCAPTURES_2_INIT:
+  case QCAPTURES_INIT:
       cur = moves;
       endMoves = generate<CAPTURES>(pos, cur);
       score<CAPTURES>();
       ++stage;
       /* fallthrough */
 
-  case QCAPTURES_1: case QCAPTURES_2:
+  case QCAPTURES:
       while (cur < endMoves)
       {
           move = pick_best(cur++, endMoves);
           if (move != ttMove)
               return move;
       }
-      if (stage == QCAPTURES_2)
+      if (depth <= DEPTH_QS_NO_CHECKS)
           break;
       cur = moves;
       endMoves = generate<QUIET_CHECKS>(pos, cur);