From: Marco Costalba <mcostalba@gmail.com>
Date: Tue, 20 Mar 2012 10:45:27 +0000 (+0100)
Subject: Use a local copy of tte->value()
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=e26d13bb318776bd0b156e55bb392d096a7dc37a

Use a local copy of tte->value()

This should avoid some aliasing issues
with TT table access.

After 3913 games at 10"+0.05
Mod vs Orig 662 - 651 - 2600  ELO +0 (+- 6.4)

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

diff --git a/src/search.cpp b/src/search.cpp
index b6fc0697..8d1b43b0 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -136,9 +136,9 @@ 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 beta, 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 defaultEval, int ply);
+  Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval);
   Move do_skill_level();
   string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE);
   void pv_info_to_log(Position& pos, int depth, Value score, int time, Move pv[]);
@@ -542,7 +542,7 @@ namespace {
     Move ttMove, move, excludedMove, bestMove, threatMove;
     Depth ext, newDepth;
     Bound bt;
-    Value bestValue, value, oldAlpha;
+    Value bestValue, value, oldAlpha, ttValue;
     Value refinedValue, nullValue, futilityBase, futilityValue;
     bool isPvMove, inCheck, singularExtensionNode, givesCheck;
     bool captureOrPromotion, dangerous, doFullDepthSearch;
@@ -613,19 +613,19 @@ namespace {
     posKey = excludedMove ? pos.exclusion_key() : pos.key();
     tte = TT.probe(posKey);
     ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
+    ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_ZERO;
 
     // At PV nodes we check for exact scores, while at non-PV nodes we check for
     // 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, beta, ss->ply)))
+                                    : can_return_tt(tte, depth, ttValue, beta)))
     {
         TT.refresh(tte);
         ss->currentMove = ttMove; // Can be MOVE_NONE
-        value = value_from_tt(tte->value(), ss->ply);
 
-        if (   value >= beta
+        if (   ttValue >= beta
             && ttMove
             && !pos.is_capture_or_promotion(ttMove)
             && ttMove != ss->killers[0])
@@ -633,7 +633,7 @@ namespace {
             ss->killers[1] = ss->killers[0];
             ss->killers[0] = ttMove;
         }
-        return value;
+        return ttValue;
     }
 
     // Step 5. Evaluate the position statically and update parent's gain statistics
@@ -645,7 +645,7 @@ namespace {
 
         ss->eval = tte->static_value();
         ss->evalMargin = tte->static_value_margin();
-        refinedValue = refine_eval(tte, ss->eval, ss->ply);
+        refinedValue = refine_eval(tte, ttValue, ss->eval);
     }
     else
     {
@@ -878,8 +878,6 @@ split_point_start: // At split points actual search starts from here
           && move == ttMove
           && pos.pl_move_is_legal(move, ci.pinned))
       {
-          Value ttValue = value_from_tt(tte->value(), ss->ply);
-
           if (abs(ttValue) < VALUE_KNOWN_WIN)
           {
               Value rBeta = ttValue - int(depth);
@@ -1139,7 +1137,7 @@ split_point_start: // At split points actual search starts from here
 
     StateInfo st;
     Move ttMove, move, bestMove;
-    Value bestValue, value, evalMargin, futilityValue, futilityBase;
+    Value ttValue, bestValue, value, evalMargin, futilityValue, futilityBase;
     bool inCheck, enoughMaterial, givesCheck, evasionPrunable;
     const TTEntry* tte;
     Depth ttDepth;
@@ -1163,11 +1161,12 @@ split_point_start: // At split points actual search starts from here
     // pruning, but only for move ordering.
     tte = TT.probe(pos.key());
     ttMove = (tte ? tte->move() : MOVE_NONE);
+    ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_ZERO;
 
-    if (!PvNode && tte && can_return_tt(tte, ttDepth, beta, ss->ply))
+    if (!PvNode && tte && can_return_tt(tte, ttDepth, ttValue, beta))
     {
         ss->currentMove = ttMove; // Can be MOVE_NONE
-        return value_from_tt(tte->value(), ss->ply);
+        return ttValue;
     }
 
     // Evaluate the position statically
@@ -1485,9 +1484,7 @@ 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 beta, int ply) {
-
-    Value v = value_from_tt(tte->value(), ply);
+  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)
@@ -1501,12 +1498,10 @@ split_point_start: // At split points actual search starts from here
   // refine_eval() returns the transposition table score if possible, otherwise
   // falls back on static position evaluation.
 
-  Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
+  Value refine_eval(const TTEntry* tte, Value v, Value defaultEval) {
 
       assert(tte);
 
-      Value v = value_from_tt(tte->value(), ply);
-
       if (   ((tte->type() & BOUND_LOWER) && v >= defaultEval)
           || ((tte->type() & BOUND_UPPER) && v < defaultEval))
           return v;