Retire pv[] from SearchStack

[stockfish] / src / movepick.cpp

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 6bb5c315554abab89fe17896af79e7427af2e980..63f77dbaebfc14570cb4ff56408348fa4b15adb0 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,7 +1,7 @@
 /*
   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) 2008-2010 Marco Costalba, Joona Kiiski, 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
@@ -70,17 +70,18 @@ namespace {
 /// 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) {
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const History& h,
+                       SearchStack* ss, Value beta) : pos(p), H(h) {
   int searchTT = ttm;
   ttMoves[0].move = ttm;
+  badCaptureThreshold = 0;
   lastBadCapture = badCaptures;
 
   pinned = p.pinned_pieces(pos.side_to_move());
 
   if (ss && !p.is_check())
   {
-      ttMoves[1].move = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
+      ttMoves[1].move = (ss->mateKiller == ttm) ? MOVE_NONE : ss->mateKiller;
       searchTT |= ttMoves[1].move;
       killers[0].move = ss->killers[0];
       killers[1].move = ss->killers[1];
@@ -90,7 +91,14 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
   if (p.is_check())
       phasePtr = EvasionsPhaseTable;
   else if (d > Depth(0))
+  {
+      // Consider sligtly negative captures as good if at low
+      // depth and far from beta.
+      if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * OnePly)
+          badCaptureThreshold = -PawnValueMidgame;
+
       phasePtr = MainSearchPhaseTable;
+  }
   else if (d == Depth(0))
       phasePtr = QsearchWithChecksPhaseTable;
   else
@@ -104,7 +112,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
           searchTT = ttMoves[0].move = MOVE_NONE;
   }
 
-  phasePtr += !searchTT - 1;
+  phasePtr += int(!searchTT) - 1;
   go_next_phase();
 }
 
@@ -290,7 +298,7 @@ Move MovePicker::get_next_move() {
               {
                   // Check for a non negative SEE now
                   int seeValue = pos.see_sign(move);
-                  if (seeValue >= 0)
+                  if (seeValue >= badCaptureThreshold)
                       return move;
 
                   // Losing capture, move it to the badCaptures[] array, note
@@ -305,9 +313,9 @@ Move MovePicker::get_next_move() {
           case PH_KILLERS:
               move = (curMove++)->move;
               if (   move != MOVE_NONE
+                  && move_is_legal(pos, move, pinned)
                   && move != ttMoves[0].move
                   && move != ttMoves[1].move
-                  && move_is_legal(pos, move, pinned)
                   && !pos.move_is_capture(move))
                   return move;
               break;