Assorted trivial cleanups 2/2019

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 98c8e9cb64941d6a35df34341e4d89d8dcbd0ee4..23402939a67bcea1ed663b821dd9fcecb742ec58 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -301,7 +301,7 @@ void Thread::search() {
   // The former is needed to allow update_continuation_histories(ss-1, ...),
   // which accesses its argument at ss-4, also near the root.
   // The latter is needed for statScores and killer initialization.
-  Stack stack[MAX_PLY+8], *ss = stack+5;
+  Stack stack[MAX_PLY+10], *ss = stack+7;
   Move  pv[MAX_PLY+1];
   Value bestValue, alpha, beta, delta;
   Move  lastBestMove = MOVE_NONE;
@@ -311,8 +311,8 @@ void Thread::search() {
   Color us = rootPos.side_to_move();
   bool failedLow;
 
-  std::memset(ss-5, 0, 8 * sizeof(Stack));
-  for (int i = 5; i > 0; i--)
+  std::memset(ss-7, 0, 10 * sizeof(Stack));
+  for (int i = 7; i > 0; i--)
      (ss-i)->continuationHistory = &this->continuationHistory[NO_PIECE][0]; // Use as sentinel
   ss->pv = pv;
 
@@ -569,7 +569,7 @@ namespace {
     Depth extension, newDepth;
     Value bestValue, value, ttValue, eval, maxValue, pureStaticEval;
     bool ttHit, ttPv, inCheck, givesCheck, improving;
-    bool captureOrPromotion, doFullDepthSearch, moveCountPruning, skipQuiets, ttCapture;
+    bool captureOrPromotion, doFullDepthSearch, moveCountPruning, ttCapture;
     Piece movedPiece;
     int moveCount, captureCount, quietCount;
 
@@ -845,7 +845,7 @@ namespace {
                 // Perform a preliminary qsearch to verify that the move holds
                 value = -qsearch<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1);
 
-                // If the qsearch held perform the regular search
+                // If the qsearch held, perform the regular search
                 if (value >= raisedBeta)
                     value = -search<NonPV>(pos, ss+1, -raisedBeta, -raisedBeta+1, depth - 4 * ONE_PLY, !cutNode);
 
@@ -869,7 +869,9 @@ namespace {
 
 moves_loop: // When in check, search starts from here
 
-    const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, nullptr, (ss-4)->continuationHistory };
+    const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
+                                          nullptr, (ss-4)->continuationHistory,
+                                          nullptr, (ss-6)->continuationHistory };
     Move countermove = thisThread->counterMoves[pos.piece_on(prevSq)][prevSq];
 
     MovePicker mp(pos, ttMove, depth, &thisThread->mainHistory,
@@ -879,12 +881,12 @@ moves_loop: // When in check, search starts from here
                                       ss->killers);
     value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
 
-    skipQuiets = false;
+    moveCountPruning = false;
     ttCapture = ttMove && pos.capture_or_promotion(ttMove);
 
     // Step 12. Loop through all pseudo-legal moves until no moves remain
     // or a beta cutoff occurs.
-    while ((move = mp.next_move(skipQuiets)) != MOVE_NONE)
+    while ((move = mp.next_move(moveCountPruning)) != MOVE_NONE)
     {
       assert(is_ok(move));
 
@@ -913,9 +915,6 @@ moves_loop: // When in check, search starts from here
       movedPiece = pos.moved_piece(move);
       givesCheck = gives_check(pos, move);
 
-      moveCountPruning =   depth < 16 * ONE_PLY
-                        && moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
-
       // Step 13. Extensions (~70 Elo)
 
       // Singular extension search (~60 Elo). If all moves but one fail low on a
@@ -966,16 +965,17 @@ moves_loop: // When in check, search starts from here
           && pos.non_pawn_material(us)
           && bestValue > VALUE_MATED_IN_MAX_PLY)
       {
+          // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold
+          moveCountPruning = depth < 16 * ONE_PLY
+                          && moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
+
           if (   !captureOrPromotion
               && !givesCheck
               && !pos.advanced_pawn_push(move))
           {
               // Move count based pruning (~30 Elo)
               if (moveCountPruning)
-              {
-                  skipQuiets = true;
                   continue;
-              }
 
               // Reduced depth of the next LMR search
               int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO) / ONE_PLY;
@@ -1322,7 +1322,9 @@ moves_loop: // When in check, search starts from here
         futilityBase = bestValue + 128;
     }
 
-    const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory, nullptr, (ss-4)->continuationHistory };
+    const PieceToHistory* contHist[] = { (ss-1)->continuationHistory, (ss-2)->continuationHistory,
+                                          nullptr, (ss-4)->continuationHistory,
+                                          nullptr, (ss-6)->continuationHistory };
 
     // Initialize a MovePicker object for the current position, and prepare
     // to search the moves. Because the depth is <= 0 here, only captures,
@@ -1472,7 +1474,7 @@ moves_loop: // When in check, search starts from here
 
   void update_continuation_histories(Stack* ss, Piece pc, Square to, int bonus) {
 
-    for (int i : {1, 2, 4})
+    for (int i : {1, 2, 4, 6})
         if (is_ok((ss-i)->currentMove))
             (*(ss-i)->continuationHistory)[pc][to] << bonus;
   }