Rename ProbCut to Multicut

[stockfish] / src / movepick.cpp

diff --git a/src/movepick.cpp b/src/movepick.cpp
index ba30a2bcded328e13288fc1422ced52193779d34..e0bd2a674025d0795955310c60758127509b4867 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -30,7 +30,7 @@ namespace {
     EVASION,     EVASIONS_S2,
     QSEARCH_0,   CAPTURES_S3, QUIET_CHECKS_S3,
     QSEARCH_1,   CAPTURES_S4,
-    PROBCUT,     CAPTURES_S5,
+    MULTICUT,    CAPTURES_S5,
     RECAPTURE,   CAPTURES_S6,
     STOP
   };
@@ -71,13 +71,14 @@ namespace {
 /// ordering is at the current node.
 
 MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h,
-                       Move* cm, Search::Stack* s) : pos(p), history(h), depth(d) {
+                       Move* cm, Move* fm, Search::Stack* s) : pos(p), history(h), depth(d) {
 
   assert(d > DEPTH_ZERO);
 
   cur = end = moves;
   endBadCaptures = moves + MAX_MOVES - 1;
   countermoves = cm;
+  followupmoves = fm;
   ss = s;
 
   if (p.checkers())
@@ -127,9 +128,9 @@ MovePicker::MovePicker(const Position& p, Move ttm, const HistoryStats& h, Piece
 
   assert(!pos.checkers());
 
-  stage = PROBCUT;
+  stage = MULTICUT;
 
-  // In ProbCut we generate only captures that are better than the parent's
+  // In MultiCut we generate only captures that are better than the parent's
   // captured piece.
   captureThreshold = PieceValue[MG][pt];
   ttMove = (ttm && pos.pseudo_legal(ttm) ? ttm : MOVE_NONE);
@@ -209,10 +210,10 @@ void MovePicker::score<EVASIONS>() {
 }
 
 
-/// generate_next() generates, scores and sorts the next bunch of moves, when
-/// there are no more moves to try for the current phase.
+/// generate_next_stage() generates, scores and sorts the next bunch of moves,
+/// when there are no more moves to try for the current stage.
 
-void MovePicker::generate_next() {
+void MovePicker::generate_next_stage() {
 
   cur = moves;
 
@@ -230,15 +231,24 @@ void MovePicker::generate_next() {
       killers[0].move = ss->killers[0];
       killers[1].move = ss->killers[1];
       killers[2].move = killers[3].move = MOVE_NONE;
+      killers[4].move = killers[5].move = MOVE_NONE;
+
+      // Please note that following code is racy and could yield to rare (less
+      // than 1 out of a million) duplicated entries in SMP case. This is harmless.
 
       // Be sure countermoves are different from killers
       for (int i = 0; i < 2; ++i)
-          if (countermoves[i] != cur->move && countermoves[i] != (cur+1)->move)
+          if (   countermoves[i] != (cur+0)->move
+              && countermoves[i] != (cur+1)->move)
               (end++)->move = countermoves[i];
 
-      if (countermoves[1] && countermoves[1] == countermoves[0]) // Due to SMP races
-          killers[3].move = MOVE_NONE;
-
+      // Be sure followupmoves are different from killers and countermoves
+      for (int i = 0; i < 2; ++i)
+          if (   followupmoves[i] != (cur+0)->move
+              && followupmoves[i] != (cur+1)->move
+              && followupmoves[i] != (cur+2)->move
+              && followupmoves[i] != (cur+3)->move)
+              (end++)->move = followupmoves[i];
       return;
 
   case QUIETS_1_S1:
@@ -271,7 +281,7 @@ void MovePicker::generate_next() {
       end = generate<QUIET_CHECKS>(pos, moves);
       return;
 
-  case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT: case RECAPTURE:
+  case EVASION: case QSEARCH_0: case QSEARCH_1: case MULTICUT: case RECAPTURE:
       stage = STOP;
   case STOP:
       end = cur + 1; // Avoid another next_phase() call
@@ -286,7 +296,7 @@ void MovePicker::generate_next() {
 /// 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 score from a list of generated moves
-/// taking care not returning the ttMove if it has already been searched previously.
+/// taking care not to return the ttMove if it has already been searched.
 template<>
 Move MovePicker::next_move<false>() {
 
@@ -295,11 +305,11 @@ Move MovePicker::next_move<false>() {
   while (true)
   {
       while (cur == end)
-          generate_next();
+          generate_next_stage();
 
       switch (stage) {
 
-      case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case PROBCUT:
+      case MAIN_SEARCH: case EVASION: case QSEARCH_0: case QSEARCH_1: case MULTICUT:
           ++cur;
           return ttMove;
 
@@ -330,7 +340,9 @@ Move MovePicker::next_move<false>() {
               && move != killers[0].move
               && move != killers[1].move
               && move != killers[2].move
-              && move != killers[3].move)
+              && move != killers[3].move
+              && move != killers[4].move
+              && move != killers[5].move)
               return move;
           break;