Refine improving-logic

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 24bcb9ad2af5baf1f9d15d49e05068fb552687f1..55e04ec363e90467665aa24c8c79dd578f96ea9e 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -65,9 +65,9 @@ namespace {
   constexpr uint64_t ttHitAverageResolution = 1024;
 
   // Razor and futility margins
-  constexpr int RazorMargin = 661;
+  constexpr int RazorMargin = 594;
   Value futility_margin(Depth d, bool improving) {
-    return Value(198 * (d - improving));
+    return Value(232 * (d - improving));
   }
 
   // Reductions lookup table, initialized at startup
@@ -335,6 +335,7 @@ void Thread::search() {
   MainThread* mainThread = (this == Threads.main() ? Threads.main() : nullptr);
   double timeReduction = 1, totBestMoveChanges = 0;
   Color us = rootPos.side_to_move();
+  int iterIdx = 0;
 
   std::memset(ss-7, 0, 10 * sizeof(Stack));
   for (int i = 7; i > 0; i--)
@@ -345,6 +346,16 @@ void Thread::search() {
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
 
+  if (mainThread)
+  {
+      if (mainThread->previousScore == VALUE_INFINITE)
+          for (int i=0; i<4; ++i)
+              mainThread->iterValue[i] = VALUE_ZERO;
+      else
+          for (int i=0; i<4; ++i)
+              mainThread->iterValue[i] = mainThread->previousScore;
+  }
+
   size_t multiPV = Options["MultiPV"];
 
   // Pick integer skill levels, but non-deterministically round up or down
@@ -520,7 +531,8 @@ void Thread::search() {
           && !Threads.stop
           && !mainThread->stopOnPonderhit)
       {
-          double fallingEval = (354 + 10 * (mainThread->previousScore - bestValue)) / 692.0;
+          double fallingEval = (354 +  6 * (mainThread->previousScore - bestValue)
+                                    +  6 * (mainThread->iterValue[iterIdx]  - bestValue)) / 692.0;
           fallingEval = clamp(fallingEval, 0.5, 1.5);
 
           // If the bestMove is stable over several iterations, reduce time accordingly
@@ -547,6 +559,9 @@ void Thread::search() {
                   Threads.stop = true;
           }
       }
+
+      mainThread->iterValue[iterIdx] = bestValue;
+      iterIdx = (iterIdx + 1) & 3;
   }
 
   if (!mainThread)
@@ -797,8 +812,8 @@ namespace {
         &&  eval <= alpha - RazorMargin)
         return qsearch<NT>(pos, ss, alpha, beta);
 
-    improving =   ss->staticEval >= (ss-2)->staticEval
-               || (ss-2)->staticEval == VALUE_NONE;
+    improving =  (ss-2)->staticEval == VALUE_NONE ? (ss->staticEval >= (ss-4)->staticEval
+              || (ss-4)->staticEval == VALUE_NONE) : ss->staticEval >= (ss-2)->staticEval;
 
     // Step 8. Futility pruning: child node (~30 Elo)
     if (   !PvNode
@@ -974,8 +989,7 @@ moves_loop: // When in check, search starts from here
           moveCountPruning = moveCount >= futility_move_count(improving, depth);
 
           if (   !captureOrPromotion
-              && !givesCheck
-              && (!PvNode || !pos.advanced_pawn_push(move) || pos.non_pawn_material(~us) > BishopValueMg))
+              && !givesCheck)
           {
               // Reduced depth of the next LMR search
               int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), 0);
@@ -1034,8 +1048,7 @@ moves_loop: // When in check, search starts from here
           // search without the ttMove. So we assume this expected Cut-node is not singular,
           // that multiple moves fail high, and we can prune the whole subtree by returning
           // a soft bound.
-          else if (   eval >= beta
-                   && singularBeta >= beta)
+          else if (singularBeta >= beta)
               return singularBeta;
       }
 
@@ -1050,6 +1063,11 @@ moves_loop: // When in check, search starts from here
                && pos.pawn_passed(us, to_sq(move)))
           extension = 1;
 
+      // Last captures extension
+      else if (   PieceValue[EG][pos.captured_piece()] > PawnValueEg
+               && pos.non_pawn_material() <= 2 * RookValueMg)
+          extension = 1;
+
       // Castling extension
       if (type_of(move) == CASTLING)
           extension = 1;
@@ -1085,7 +1103,8 @@ moves_loop: // When in check, search starts from here
           && (  !captureOrPromotion
               || moveCountPruning
               || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
-              || cutNode))
+              || cutNode
+              || thisThread->ttHitAverage < 384 * ttHitAverageResolution * ttHitAverageWindow / 1024))
       {
           Depth r = reduction(improving, depth, moveCount);
 
@@ -1458,9 +1477,7 @@ moves_loop: // When in check, search starts from here
                        && !pos.capture(move);
 
       // Don't search moves with negative SEE values
-      if (  (!inCheck || evasionPrunable)
-          && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move))
-          && !pos.see_ge(move))
+      if (  (!inCheck || evasionPrunable) && !pos.see_ge(move))
           continue;
 
       // Speculative prefetch as early as possible
@@ -1721,7 +1738,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
 
   for (size_t i = 0; i < multiPV; ++i)
   {
-      bool updated = (i <= pvIdx && rootMoves[i].score != -VALUE_INFINITE);
+      bool updated = rootMoves[i].score != -VALUE_INFINITE;
 
       if (depth == 1 && !updated)
           continue;