X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=0d290eec65dae9451fc7c96a2c4a38fda23d0870;hp=1b11092aa3d527a5561245e45660cb66da7898ac;hb=6b82a234d03bb70e538ace708c128238811f06e7;hpb=d10ae90dea62794de96a6bd756e3b73a51bb8909

diff --git a/src/search.cpp b/src/search.cpp
index 1b11092a..0d290eec 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -52,9 +52,6 @@ using namespace Search;
 
 namespace {
 
-  // Set to true to force running with one thread. Used for debugging
-  const bool FakeSplit = false;
-
   // Different node types, used as template parameter
   enum NodeType { Root, PV, NonPV };
 
@@ -76,7 +73,7 @@ namespace {
     return (Depth) Reductions[PvNode][i][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
   }
 
-  size_t MultiPV, PVIdx;
+  size_t PVIdx;
   TimeManager TimeMgr;
   double BestMoveChanges;
   Value DrawValue[COLOR_NB];
@@ -97,18 +94,21 @@ namespace {
   string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
 
   struct Skill {
-    Skill(int l) : level(l), best(MOVE_NONE) {}
+    Skill(int l, int rootSize) : level(l),
+                                 candidates(l < 20 ? std::min(4, rootSize) : 0),
+                                 best(MOVE_NONE) {}
    ~Skill() {
-      if (enabled()) // Swap best PV line with the sub-optimal one
+      if (candidates) // Swap best PV line with the sub-optimal one
           std::swap(RootMoves[0], *std::find(RootMoves.begin(),
                     RootMoves.end(), best ? best : pick_move()));
     }
 
-    bool enabled() const { return level < 20; }
+    size_t candidates_size() const { return candidates; }
     bool time_to_pick(int depth) const { return depth == 1 + level; }
     Move pick_move();
 
     int level;
+    size_t candidates;
     Move best;
   };
 
@@ -282,15 +282,12 @@ namespace {
     Countermoves.clear();
     Followupmoves.clear();
 
-    MultiPV = Options["MultiPV"];
-    Skill skill(Options["Skill Level"]);
+    size_t multiPV = Options["MultiPV"];
+    Skill skill(Options["Skill Level"], RootMoves.size());
 
     // Do we have to play with skill handicap? In this case enable MultiPV search
     // that we will use behind the scenes to retrieve a set of possible moves.
-    if (skill.enabled() && MultiPV < 4)
-        MultiPV = 4;
-
-    MultiPV = std::min(MultiPV, RootMoves.size());
+    multiPV = std::max(multiPV, skill.candidates_size());
 
     // Iterative deepening loop until requested to stop or target depth reached
     while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
@@ -304,7 +301,7 @@ namespace {
             RootMoves[i].prevScore = RootMoves[i].score;
 
         // MultiPV loop. We perform a full root search for each PV line
-        for (PVIdx = 0; PVIdx < MultiPV && !Signals.stop; ++PVIdx)
+        for (PVIdx = 0; PVIdx < multiPV && PVIdx < RootMoves.size() && !Signals.stop; ++PVIdx)
         {
             // Reset aspiration window starting size
             if (depth >= 5)
@@ -361,7 +358,7 @@ namespace {
                 else
                     break;
 
-                delta += delta / 2;
+                delta += 3 * delta / 8;
 
                 assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
             }
@@ -369,12 +366,12 @@ namespace {
             // Sort the PV lines searched so far and update the GUI
             std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1);
 
-            if (PVIdx + 1 == MultiPV || Time::now() - SearchTime > 3000)
+            if (PVIdx + 1 == multiPV || Time::now() - SearchTime > 3000)
                 sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
         }
 
         // If skill levels are enabled and time is up, pick a sub-optimal best move
-        if (skill.enabled() && skill.time_to_pick(depth))
+        if (skill.candidates_size() && skill.time_to_pick(depth))
             skill.pick_move();
 
         if (Options["Write Search Log"])
@@ -398,7 +395,7 @@ namespace {
         if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit)
         {
             // Take some extra time if the best move has changed
-            if (depth > 4 && depth < 50 &&  MultiPV == 1)
+            if (depth > 4 && multiPV == 1)
                 TimeMgr.pv_instability(BestMoveChanges);
 
             // Stop the search if only one legal move is available or all
@@ -469,7 +466,7 @@ namespace {
     bestValue = -VALUE_INFINITE;
     ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
     ss->ply = (ss-1)->ply + 1;
-    (ss+1)->skipNullMove = (ss+1)->nullChild = false; (ss+1)->reduction = DEPTH_ZERO;
+    (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
     (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
 
     // Used to send selDepth info to GUI
@@ -544,7 +541,9 @@ namespace {
     }
     else
     {
-        eval = ss->staticEval = ss->nullChild ? -(ss-1)->staticEval + 2 * Eval::Tempo : evaluate(pos);
+        eval = ss->staticEval =
+        (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Eval::Tempo;
+
         TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval);
     }
 
@@ -564,7 +563,6 @@ namespace {
         &&  depth < 4 * ONE_PLY
         &&  eval + razor_margin(depth) <= alpha
         &&  ttMove == MOVE_NONE
-        &&  abs(beta) < VALUE_MATE_IN_MAX_PLY
         && !pos.pawn_on_7th(pos.side_to_move()))
     {
         if (   depth <= ONE_PLY
@@ -592,7 +590,6 @@ namespace {
         && !ss->skipNullMove
         &&  depth >= 2 * ONE_PLY
         &&  eval >= beta
-        &&  abs(beta) < VALUE_MATE_IN_MAX_PLY
         &&  pos.non_pawn_material(pos.side_to_move()))
     {
         ss->currentMove = MOVE_NULL;
@@ -602,13 +599,14 @@ namespace {
         // Null move dynamic reduction based on depth and value
         Depth R =  3 * ONE_PLY
                  + depth / 4
-                 + int(eval - beta) / PawnValueMg * ONE_PLY;
+                 + (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY
+                                                : DEPTH_ZERO);
 
         pos.do_null_move(st);
-        (ss+1)->skipNullMove = (ss+1)->nullChild = true;
+        (ss+1)->skipNullMove = true;
         nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1, DEPTH_ZERO)
                                       : - search<NonPV, false>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
-        (ss+1)->skipNullMove = (ss+1)->nullChild = false;
+        (ss+1)->skipNullMove = false;
         pos.undo_null_move();
 
         if (nullValue >= beta)
@@ -617,7 +615,7 @@ namespace {
             if (nullValue >= VALUE_MATE_IN_MAX_PLY)
                 nullValue = beta;
 
-            if (depth < 12 * ONE_PLY)
+            if (depth < 12 * ONE_PLY && abs(beta) < VALUE_KNOWN_WIN)
                 return nullValue;
 
             // Do verification search at high depths
@@ -697,7 +695,10 @@ moves_loop: // When in check and at SpNode search starts from here
     singularExtensionNode =   !RootNode
                            && !SpNode
                            &&  depth >= 8 * ONE_PLY
+                           &&  abs(beta) < VALUE_KNOWN_WIN
                            &&  ttMove != MOVE_NONE
+                       /*  &&  ttValue != VALUE_NONE Already implicit in the next condition */
+                           &&  abs(ttValue) < VALUE_KNOWN_WIN
                            && !excludedMove // Recursive singular search is not allowed
                            && (tte->bound() & BOUND_LOWER)
                            &&  tte->depth() >= depth - 3 * ONE_PLY;
@@ -762,11 +763,8 @@ moves_loop: // When in check and at SpNode search starts from here
       if (    singularExtensionNode
           &&  move == ttMove
           && !ext
-          &&  pos.legal(move, ci.pinned)
-          &&  abs(ttValue) < VALUE_KNOWN_WIN)
+          &&  pos.legal(move, ci.pinned))
       {
-          assert(ttValue != VALUE_NONE);
-
           Value rBeta = ttValue - int(depth);
           ss->excludedMove = move;
           ss->skipNullMove = true;
@@ -986,8 +984,8 @@ moves_loop: // When in check and at SpNode search starts from here
       {
           assert(bestValue > -VALUE_INFINITE && bestValue < beta);
 
-          thisThread->split<FakeSplit>(pos, ss, alpha, beta, &bestValue, &bestMove,
-                                       depth, moveCount, &mp, NT, cutNode);
+          thisThread->split(pos, ss, alpha, beta, &bestValue, &bestMove,
+                            depth, moveCount, &mp, NT, cutNode);
 
           if (Signals.stop || thisThread->cutoff_occurred())
               return VALUE_ZERO;
@@ -1108,7 +1106,8 @@ moves_loop: // When in check and at SpNode search starts from here
                     bestValue = ttValue;
         }
         else
-            ss->staticEval = bestValue = ss->nullChild ? -(ss-1)->staticEval + 2 * Eval::Tempo : evaluate(pos);
+            ss->staticEval = bestValue =
+            (ss-1)->currentMove != MOVE_NULL ? evaluate(pos) : -(ss-1)->staticEval + 2 * Eval::Tempo;
 
         // Stand pat. Return immediately if static value is at least beta
         if (bestValue >= beta)
@@ -1293,8 +1292,8 @@ moves_loop: // When in check and at SpNode search starts from here
   }
 
 
-  // When playing with a strength handicap, choose best move among the MultiPV
-  // set using a statistical rule dependent on 'level'. Idea by Heinz van Saanen.
+  // When playing with a strength handicap, choose best move among the first 'candidates'
+  // RootMoves using a statistical rule dependent on 'level'. Idea by Heinz van Saanen.
 
   Move Skill::pick_move() {
 
@@ -1305,7 +1304,7 @@ moves_loop: // When in check and at SpNode search starts from here
         rk.rand<unsigned>();
 
     // RootMoves are already sorted by score in descending order
-    int variance = std::min(RootMoves[0].score - RootMoves[MultiPV - 1].score, PawnValueMg);
+    int variance = std::min(RootMoves[0].score - RootMoves[candidates - 1].score, PawnValueMg);
     int weakness = 120 - 2 * level;
     int max_s = -VALUE_INFINITE;
     best = MOVE_NONE;
@@ -1313,12 +1312,12 @@ moves_loop: // When in check and at SpNode search starts from here
     // Choose best move. For each move score we add two terms both dependent on
     // weakness. One deterministic and bigger for weaker moves, and one random,
     // then we choose the move with the resulting highest score.
-    for (size_t i = 0; i < MultiPV; ++i)
+    for (size_t i = 0; i < candidates; ++i)
     {
         int s = RootMoves[i].score;
 
         // Don't allow crazy blunders even at very low skills
-        if (i > 0 && RootMoves[i-1].score > s + 2 * PawnValueMg)
+        if (i > 0 && RootMoves[i - 1].score > s + 2 * PawnValueMg)
             break;
 
         // This is our magic formula