X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=95b14021c4e51bc7f7d8ad3d89686fd4ee8739c2;hp=21b669c42ef53b1ae987caf5f85253d7da853666;hb=ca6ce6398b1bd21ff2ac29b2dc27d7c25abbb509;hpb=82ad9ce9cfb0eff33f1d781f329f7c5dc0b277eb

diff --git a/src/search.cpp b/src/search.cpp
index 21b669c4..95b14021 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -86,8 +86,8 @@ namespace {
 
   // Add a small random component to draw evaluations to avoid 3fold-blindness
   Value value_draw(Depth depth, Thread* thisThread) {
-    return depth < 4 ? VALUE_DRAW
-                     : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
+    return depth < 4 * ONE_PLY ? VALUE_DRAW
+                               : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
   }
 
   // Skill structure is used to implement strength limit
@@ -191,8 +191,11 @@ void MainThread::search() {
   else
   {
       for (Thread* th : Threads)
+      {
+          th->bestMoveChanges = 0;
           if (th != this)
               th->start_searching();
+      }
 
       Thread::search(); // Let's start searching!
   }
@@ -283,7 +286,7 @@ void Thread::search() {
   Move  lastBestMove = MOVE_NONE;
   Depth lastBestMoveDepth = DEPTH_ZERO;
   MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
-  double timeReduction = 1.0;
+  double timeReduction = 1, totBestMoveChanges = 0;
   Color us = rootPos.side_to_move();
 
   std::memset(ss-7, 0, 10 * sizeof(Stack));
@@ -294,9 +297,6 @@ void Thread::search() {
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
 
-  if (mainThread)
-      mainThread->bestMoveChanges = 0;
-
   size_t multiPV = Options["MultiPV"];
   Skill skill(Options["Skill Level"]);
 
@@ -328,7 +328,7 @@ void Thread::search() {
   {
       // Age out PV variability metric
       if (mainThread)
-          mainThread->bestMoveChanges *= 0.517;
+          totBestMoveChanges /= 2;
 
       // Save the last iteration's scores before first PV line is searched and
       // all the move scores except the (new) PV are set to -VALUE_INFINITE.
@@ -459,7 +459,7 @@ void Thread::search() {
           && !Threads.stop
           && !mainThread->stopOnPonderhit)
       {
-          double fallingEval = (306 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
+          double fallingEval = (314 + 9 * (mainThread->previousScore - bestValue)) / 581.0;
           fallingEval = clamp(fallingEval, 0.5, 1.5);
 
           // If the bestMove is stable over several iterations, reduce time accordingly
@@ -467,7 +467,12 @@ void Thread::search() {
           double reduction = std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
 
           // Use part of the gained time from a previous stable move for the current move
-          double bestMoveInstability = 1.0 + mainThread->bestMoveChanges;
+          for (Thread* th : Threads)
+          {
+              totBestMoveChanges += th->bestMoveChanges;
+              th->bestMoveChanges = 0;
+          }
+          double bestMoveInstability = 1 + totBestMoveChanges / Threads.size();
 
           // Stop the search if we have only one legal move, or if available time elapsed
           if (   rootMoves.size() == 1
@@ -533,7 +538,7 @@ namespace {
     Key posKey;
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
-    Value bestValue, value, ttValue, eval, maxValue, pureStaticEval;
+    Value bestValue, value, ttValue, eval, maxValue;
     bool ttHit, ttPv, inCheck, givesCheck, improving;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
     Piece movedPiece;
@@ -627,9 +632,8 @@ namespace {
                 if (!pos.capture_or_promotion(ttMove))
                     update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
 
-                // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
-                if (    ((ss-1)->moveCount == 1 || (ss-1)->currentMove == (ss-1)->killers[0])
-                     && !pos.captured_piece())
+                // Extra penalty for early quiet moves of the previous ply
+                if ((ss-1)->moveCount <= 2 && !pos.captured_piece())
                         update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
             }
             // Penalty for a quiet ttMove that fails low
@@ -697,16 +701,16 @@ namespace {
     // Step 6. Static evaluation of the position
     if (inCheck)
     {
-        ss->staticEval = eval = pureStaticEval = VALUE_NONE;
+        ss->staticEval = eval = VALUE_NONE;
         improving = false;
         goto moves_loop;  // Skip early pruning when in check
     }
     else if (ttHit)
     {
         // Never assume anything on values stored in TT
-        ss->staticEval = eval = pureStaticEval = tte->eval();
+        ss->staticEval = eval = tte->eval();
         if (eval == VALUE_NONE)
-            ss->staticEval = eval = pureStaticEval = evaluate(pos);
+            ss->staticEval = eval = evaluate(pos);
 
         // Can ttValue be used as a better position evaluation?
         if (    ttValue != VALUE_NONE
@@ -719,13 +723,12 @@ namespace {
         {
             int bonus = -(ss-1)->statScore / 512;
 
-            pureStaticEval = evaluate(pos);
-            ss->staticEval = eval = pureStaticEval + bonus;
+            ss->staticEval = eval = evaluate(pos) + bonus;
         }
         else
-            ss->staticEval = eval = pureStaticEval = -(ss-1)->staticEval + 2 * Eval::Tempo;
+            ss->staticEval = eval = -(ss-1)->staticEval + 2 * Eval::Tempo;
 
-        tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, pureStaticEval);
+        tte->save(posKey, VALUE_NONE, ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
     }
 
     // Step 7. Razoring (~2 Elo)
@@ -749,7 +752,7 @@ namespace {
         && (ss-1)->currentMove != MOVE_NULL
         && (ss-1)->statScore < 23200
         &&  eval >= beta
-        &&  pureStaticEval >= beta - 36 * depth / ONE_PLY + 225
+        &&  ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -781,7 +784,7 @@ namespace {
 
             // Do verification search at high depths, with null move pruning disabled
             // for us, until ply exceeds nmpMinPly.
-            thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4;
+            thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / (4 * ONE_PLY);
             thisThread->nmpColor = us;
 
             Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
@@ -908,8 +911,9 @@ moves_loop: // When in check, search starts from here
           &&  pos.legal(move))
       {
           Value singularBeta = ttValue - 2 * depth / ONE_PLY;
+          Depth halfDepth = depth / (2 * ONE_PLY) * ONE_PLY; // ONE_PLY invariant
           ss->excludedMove = move;
-          value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, depth / 2, cutNode);
+          value = search<NonPV>(pos, ss, singularBeta - 1, singularBeta, halfDepth, cutNode);
           ss->excludedMove = MOVE_NONE;
 
           if (value < singularBeta)
@@ -937,6 +941,12 @@ moves_loop: // When in check, search starts from here
       else if (type_of(move) == CASTLING)
           extension = ONE_PLY;
 
+      // Passed pawn extension
+      else if (   move == ss->killers[0]
+               && pos.advanced_pawn_push(move)
+               && pos.pawn_passed(us, to_sq(move)))
+          extension = ONE_PLY;
+
       // Calculate new depth for this move
       newDepth = depth - ONE_PLY + extension;
 
@@ -957,7 +967,8 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Reduced depth of the next LMR search
-              int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
+              int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
+              lmrDepth /= ONE_PLY;
 
               // Countermoves based pruning (~20 Elo)
               if (   lmrDepth < 3 + ((ss-1)->statScore > 0 || (ss-1)->moveCount == 1)
@@ -1102,8 +1113,8 @@ moves_loop: // When in check, search starts from here
               // We record how often the best move has been changed in each
               // iteration. This information is used for time management: When
               // the best move changes frequently, we allocate some more time.
-              if (moveCount > 1 && thisThread == Threads.main())
-                  ++static_cast<MainThread*>(thisThread)->bestMoveChanges;
+              if (moveCount > 1)
+                  ++thisThread->bestMoveChanges;
           }
           else
               // All other moves but the PV are set to the lowest value: this
@@ -1189,7 +1200,7 @@ moves_loop: // When in check, search starts from here
         tte->save(posKey, value_to_tt(bestValue, ss->ply), ttPv,
                   bestValue >= beta ? BOUND_LOWER :
                   PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
-                  depth, bestMove, pureStaticEval);
+                  depth, bestMove, ss->staticEval);
 
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
@@ -1228,8 +1239,7 @@ moves_loop: // When in check, search starts from here
 
     Thread* thisThread = pos.this_thread();
     (ss+1)->ply = ss->ply + 1;
-    ss->currentMove = bestMove = MOVE_NONE;
-    ss->continuationHistory = &thisThread->continuationHistory[NO_PIECE][0];
+    bestMove = MOVE_NONE;
     inCheck = pos.checkers();
     moveCount = 0;