X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=8f157b7ea54e8e05e2df1b0cf20530f22d75fb13;hb=602687801b73552fb8364bcc82191f932ddca8b7;hp=ff8764d8a808313da7d5650845c13496f45556f7;hpb=83eac08e7562d93787f75eccd4b7781c4bd45dd3;p=stockfish

diff --git a/src/search.cpp b/src/search.cpp
index ff8764d8..8f157b7e 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -165,7 +165,7 @@ namespace {
   uint64_t perft(Position& pos, Depth depth) {
 
     StateInfo st;
-    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+    ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
 
     uint64_t cnt, nodes = 0;
     const bool leaf = (depth == 2);
@@ -597,7 +597,7 @@ namespace {
 
     Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64];
     StateInfo st;
-    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+    ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
 
     TTEntry* tte;
     Key posKey;
@@ -618,7 +618,6 @@ namespace {
     moveCount          = captureCount = quietCount = ss->moveCount = 0;
     bestValue          = -VALUE_INFINITE;
     maxValue           = VALUE_INFINITE;
-    ss->distanceFromPv = (PvNode ? 0 : ss->distanceFromPv);
 
     // Check for the available remaining time
     if (thisThread == Threads.main())
@@ -1007,6 +1006,13 @@ moves_loop: // When in check, search starts from here
     value = bestValue;
     singularQuietLMR = moveCountPruning = false;
 
+    // Indicate PvNodes that will probably fail low if the node was searched
+    // at a depth equal or greater than the current depth, and the result of this search was a fail low.
+    bool likelyFailLow =    PvNode
+                         && ttMove
+                         && (tte->bound() & BOUND_UPPER)
+                         && tte->depth() >= depth;
+
     // Mark this node as being searched
     ThreadHolding th(thisThread, posKey, ss->ply);
 
@@ -1045,14 +1051,6 @@ moves_loop: // When in check, search starts from here
       movedPiece = pos.moved_piece(move);
       givesCheck = pos.gives_check(move);
 
-      // Indicate PvNodes that will probably fail low if node was searched with non-PV search
-      // at depth equal or greater to current depth and result of this search was far below alpha
-      bool likelyFailLow =    PvNode
-                           && ttMove
-                           && (tte->bound() & BOUND_UPPER)
-                           && ttValue < alpha + 200 + 100 * depth
-                           && tte->depth() >= depth;
-
       // Calculate new depth for this move
       newDepth = depth - 1;
 
@@ -1131,6 +1129,8 @@ moves_loop: // When in check, search starts from here
           {
               extension = 1;
               singularQuietLMR = !ttCapture;
+              if (!PvNode && value < singularBeta - 140)
+                  extension = 2;
           }
 
           // Multi-cut pruning
@@ -1154,16 +1154,6 @@ moves_loop: // When in check, search starts from here
           }
       }
 
-      // Check extension (~2 Elo)
-      else if (    givesCheck
-               && (pos.is_discovered_check_on_king(~us, move) || pos.see_ge(move)))
-          extension = 1;
-
-      // Last captures extension
-      else if (   PieceValue[EG][pos.captured_piece()] > PawnValueEg
-               && pos.non_pawn_material() <= 2 * RookValueMg)
-          extension = 1;
-
       // Add extension to new depth
       newDepth += extension;
 
@@ -1180,8 +1170,6 @@ moves_loop: // When in check, search starts from here
       // Step 15. Make the move
       pos.do_move(move, st, givesCheck);
 
-      (ss+1)->distanceFromPv = ss->distanceFromPv + moveCount - 1;
-
       // Step 16. Late moves reduction / extension (LMR, ~200 Elo)
       // We use various heuristics for the sons of a node after the first son has
       // been searched. In general we would like to reduce them, but there are many
@@ -1193,7 +1181,8 @@ moves_loop: // When in check, search starts from here
               || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
               || cutNode
               || (!PvNode && !formerPv && captureHistory[movedPiece][to_sq(move)][type_of(pos.captured_piece())] < 3678)
-              || thisThread->ttHitAverage < 432 * TtHitAverageResolution * TtHitAverageWindow / 1024))
+              || thisThread->ttHitAverage < 432 * TtHitAverageResolution * TtHitAverageWindow / 1024)
+          && (!PvNode || ss->ply > 1 || thisThread->id() % 4 != 3))
       {
           Depth r = reduction(improving, depth, moveCount);
 
@@ -1217,16 +1206,11 @@ moves_loop: // When in check, search starts from here
               && thisThread->bestMoveChanges <= 2)
               r++;
 
-          // More reductions for late moves if position was not in previous PV
-          if (   moveCountPruning
-              && !formerPv)
-              r++;
-
           // Decrease reduction if opponent's move count is high (~5 Elo)
           if ((ss-1)->moveCount > 13)
               r--;
 
-          // Decrease reduction if ttMove has been singularly extended (~3 Elo)
+          // Decrease reduction if ttMove has been singularly extended (~1 Elo)
           if (singularQuietLMR)
               r--;
 
@@ -1239,7 +1223,7 @@ moves_loop: // When in check, search starts from here
           }
           else
           {
-              // Increase reduction if ttMove is a capture (~5 Elo)
+              // Increase reduction if ttMove is a capture (~3 Elo)
               if (ttCapture)
                   r++;
 
@@ -1250,13 +1234,6 @@ moves_loop: // When in check, search starts from here
               if (cutNode)
                   r += 2;
 
-              // Decrease reduction for moves that escape a capture. Filter out
-              // castling moves, because they are coded as "king captures rook" and
-              // hence break reverse_move() (~2 Elo)
-              else if (    type_of(move) == NORMAL
-                       && !pos.see_ge(reverse_move(move)))
-                  r -= 2 + ss->ttPv - (type_of(movedPiece) == PAWN);
-
               ss->statScore =  thisThread->mainHistory[us][from_to(move)]
                              + (*contHist[0])[movedPiece][to_sq(move)]
                              + (*contHist[1])[movedPiece][to_sq(move)]
@@ -1280,10 +1257,10 @@ moves_loop: // When in check, search starts from here
                   r -= ss->statScore / 14790;
           }
 
-          // In general we want to cap the LMR depth search at newDepth. But for nodes
-          // close to the principal variation the cap is at (newDepth + 1), which will
-          // allow these nodes to be searched deeper than the pv (up to 4 plies deeper).
-          Depth d = std::clamp(newDepth - r, 1, newDepth + ((ss+1)->distanceFromPv <= 4));
+          // In general we want to cap the LMR depth search at newDepth. But if
+          // reductions are really negative and movecount is low, we allow this move
+          // to be searched deeper than the first move.
+          Depth d = std::clamp(newDepth - r, 1, newDepth + (r < -1 && moveCount <= 5));
 
           value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d, true);
 
@@ -1466,7 +1443,7 @@ moves_loop: // When in check, search starts from here
 
     Move pv[MAX_PLY+1];
     StateInfo st;
-    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+    ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
 
     TTEntry* tte;
     Key posKey;
@@ -1972,7 +1949,7 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
 bool RootMove::extract_ponder_from_tt(Position& pos) {
 
     StateInfo st;
-    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+    ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
 
     bool ttHit;