Retire can_return_tt() and rewirte TT-hit code

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index cf98ca35af3878dbfd5043da2446970236c1157f..a3d8781889a690e15e0b91c4044c0243245f90d1 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -104,7 +104,6 @@ namespace {
   bool connected_moves(const Position& pos, Move m1, Move m2);
   Value value_to_tt(Value v, int ply);
   Value value_from_tt(Value v, int ply);
-  bool can_return_tt(const TTEntry* tte, Depth depth, Value ttValue, Value beta);
   bool connected_threat(const Position& pos, Move m, Move threat);
   Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval);
   Move do_skill_level();
@@ -175,8 +174,9 @@ void Search::think() {
   Position& pos = RootPosition;
   Chess960 = pos.is_chess960();
   Eval::RootColor = pos.side_to_move();
-  Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Eval::ContemptFactor;
-  Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Eval::ContemptFactor;
+  int scaledCF = Eval::ContemptFactor * MaterialTable::game_phase(pos) / PHASE_MIDGAME;
+  Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Value(scaledCF);
+  Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Value(scaledCF);
   TimeMgr.init(Limits, pos.startpos_ply_counter(), pos.side_to_move());
   TT.new_search();
   H.clear();
@@ -543,8 +543,11 @@ namespace {
     // a fail high/low. Biggest advantage at probing at PV nodes is to have a
     // smooth experience in analysis mode. We don't probe at Root nodes otherwise
     // we should also update RootMoveList to avoid bogus output.
-    if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == BOUND_EXACT
-                                    : can_return_tt(tte, depth, ttValue, beta)))
+    if (   !RootNode
+        && tte && tte->depth() >= depth
+        && (           PvNode ?  tte->type() == BOUND_EXACT
+            : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+                              : (tte->type() & BOUND_UPPER)))
     {
         TT.refresh(tte);
         ss->currentMove = ttMove; // Can be MOVE_NONE
@@ -1094,7 +1097,10 @@ split_point_start: // At split points actual search starts from here
     // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
     ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS;
 
-    if (!PvNode && tte && can_return_tt(tte, ttDepth, ttValue, beta))
+    if (   tte && tte->depth() >= ttDepth
+        && (           PvNode ?  tte->type() == BOUND_EXACT
+            : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+                              : (tte->type() & BOUND_UPPER)))
     {
         ss->currentMove = ttMove; // Can be MOVE_NONE
         return ttValue;
@@ -1418,20 +1424,6 @@ split_point_start: // At split points actual search starts from here
   }
 
 
-  // can_return_tt() returns true if a transposition table score can be used to
-  // cut-off at a given point in search.
-
-  bool can_return_tt(const TTEntry* tte, Depth depth, Value v, Value beta) {
-
-    return   (   tte->depth() >= depth
-              || v >= std::max(VALUE_MATE_IN_MAX_PLY, beta)
-              || v < std::min(VALUE_MATED_IN_MAX_PLY, beta))
-
-          && (   ((tte->type() & BOUND_LOWER) && v >= beta)
-              || ((tte->type() & BOUND_UPPER) && v < beta));
-  }
-
-
   // refine_eval() returns the transposition table score if possible, otherwise
   // falls back on static position evaluation.