Introduce MovePicker::isBadCapture() and use in probcut

Small functional change due to the fact that now we skip
probcut on evasions.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 4be0f69a6ba5eef513fc02cbfd888c9ffb9e6357..69d60bade0f5fc93abeb087f1c6463fe1a241abc 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -46,6 +46,7 @@ namespace {
   const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVES, PH_QCAPTURES, PH_STOP };
 }
 
+bool MovePicker::isBadCapture() const { return phase == PH_BAD_CAPTURES; }
 
 /// Constructor for the MovePicker class. Apart from the position for which
 /// it is asked to pick legal moves, MovePicker also wants some information

diff --git a/src/movepick.h b/src/movepick.h
index 765cae29033de7bb1080a29b6506f6b88925d282..fb3d4a62da030af55793b464da69c66c43dcf652 100644 (file)
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -43,6 +43,7 @@ public:
   MovePicker(const Position&, Move, Depth, const History&, SearchStack*, Value);
   MovePicker(const Position&, Move, Depth, const History&);
   Move get_next_move();
+  bool isBadCapture() const;
 
 private:
   void score_captures();

diff --git a/src/search.cpp b/src/search.cpp
index dcfb7d46aff3177d95fba2c1cfdc7e13f6ea922e..2fdd2840ea2b38915c453baf46783cc097909b35 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -681,7 +681,7 @@ namespace {
     ValueType vt;
     Value bestValue, value, oldAlpha;
     Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific
-    bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous, isBadCap;
+    bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
     int moveCount = 0, playedMoveCount = 0;
     int threadID = pos.thread();
     SplitPoint* sp = NULL;
@@ -1023,16 +1023,6 @@ split_point_start: // At split points actual search starts from here
           }
       }
 
-      // Bad capture detection. Will be used by prob-cut search
-      isBadCap =   depth >= 3 * ONE_PLY
-                && depth < 8 * ONE_PLY
-                && captureOrPromotion
-                && move != ttMove
-                && !dangerous
-                && !move_is_promotion(move)
-                &&  abs(alpha) < VALUE_MATE_IN_PLY_MAX
-                &&  pos.see_sign(move) < 0;
-
       // Step 13. Make the move
       pos.do_move(move, st, ci, givesCheck);
 
@@ -1076,7 +1066,13 @@ split_point_start: // At split points actual search starts from here
 
           // Probcut search for bad captures. If a reduced search returns a value
           // very below beta then we can (almost) safely prune the bad capture.
-          if (isBadCap)
+          if (   depth >= 3 * ONE_PLY
+              && depth < 8 * ONE_PLY
+              && mp.isBadCapture()
+              && move != ttMove
+              && !dangerous
+              && !move_is_promotion(move)
+              &&  abs(alpha) < VALUE_MATE_IN_PLY_MAX)
           {
               ss->reduction = 3 * ONE_PLY;
               Value rAlpha = alpha - 300;