Simplify threshold handling for probcut. (#936)

[stockfish] / src / movepick.cpp

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 95e60003f00b6eafc9d5f5592e0cdd22c64bedef..abb753baea75d118ae41cfecefdf38992050227d 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -111,11 +111,11 @@ MovePicker::MovePicker(const Position& p, Move ttm, Value th)
 
   stage = PROBCUT;
 
-  // In ProbCut we generate captures with SEE higher than the given threshold
+  // In ProbCut we generate captures with SEE higher than or equal to the given threshold
   ttMove =   ttm
           && pos.pseudo_legal(ttm)
           && pos.capture(ttm)
-          && pos.see_ge(ttm, threshold + 1)? ttm : MOVE_NONE;
+          && pos.see_ge(ttm, threshold)? ttm : MOVE_NONE;
 
   stage += (ttMove == MOVE_NONE);
 }
@@ -271,8 +271,7 @@ Move MovePicker::next_move() {
   case EVASIONS_INIT:
       cur = moves;
       endMoves = generate<EVASIONS>(pos, cur);
-      if (endMoves - cur - (ttMove != MOVE_NONE) > 1)
-          score<EVASIONS>();
+      score<EVASIONS>();
       ++stage;
 
   case ALL_EVASIONS:
@@ -295,7 +294,7 @@ Move MovePicker::next_move() {
       {
           move = pick_best(cur++, endMoves);
           if (   move != ttMove
-              && pos.see_ge(move, threshold + 1))
+              && pos.see_ge(move, threshold))
               return move;
       }
       break;