Use DEPTH_ZERO initializer for depth in qsearch (#931)

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index ec594d20a202a1f4619605ccae86289f375b4d41..24c21c4e71057bbd92cb068a3b9b484207af1097 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -165,7 +165,7 @@ namespace {
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning);
 
   template <NodeType NT, bool InCheck>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode, bool skipEarlyPruning);
 
   template <NodeType NT, bool InCheck>

-  Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
+  Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth = DEPTH_ZERO);

 
   Value value_to_tt(Value v, int ply);
   Value value_from_tt(Value v, int ply);
 
   Value value_to_tt(Value v, int ply);
   Value value_from_tt(Value v, int ply);


@@ -721,10 +721,10 @@ namespace {
         &&  eval + razor_margin[depth / ONE_PLY] <= alpha)
     {
         if (depth <= ONE_PLY)
         &&  eval + razor_margin[depth / ONE_PLY] <= alpha)
     {
         if (depth <= ONE_PLY)

-            return qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO);
+            return qsearch<NonPV, false>(pos, ss, alpha, beta);

 
         Value ralpha = alpha - razor_margin[depth / ONE_PLY];
 
         Value ralpha = alpha - razor_margin[depth / ONE_PLY];

-        Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
+        Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);

         if (v <= ralpha)
             return v;
     }
         if (v <= ralpha)
             return v;
     }


@@ -752,7 +752,7 @@ namespace {
         Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
 
         pos.do_null_move(st);
         Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
 
         pos.do_null_move(st);

-        nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1, DEPTH_ZERO)
+        nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)

                                       : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true);
         pos.undo_null_move();
 
                                       : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true);
         pos.undo_null_move();
 


@@ -766,7 +766,7 @@ namespace {
                 return nullValue;
 
             // Do verification search at high depths
                 return nullValue;
 
             // Do verification search at high depths

-            Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta, DEPTH_ZERO)
+            Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta)

                                         :  search<NonPV>(pos, ss, beta-1, beta, depth-R, false, true);
 
             if (v >= beta)
                                         :  search<NonPV>(pos, ss, beta-1, beta, depth-R, false, true);
 
             if (v >= beta)


@@ -1009,8 +1009,8 @@ moves_loop: // When in check search starts from here
       // Step 16. Full depth search when LMR is skipped or fails high
       if (doFullDepthSearch)
           value = newDepth <   ONE_PLY ?
       // Step 16. Full depth search when LMR is skipped or fails high
       if (doFullDepthSearch)
           value = newDepth <   ONE_PLY ?

-                            givesCheck ? -qsearch<NonPV,  true>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
-                                       : -qsearch<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+                            givesCheck ? -qsearch<NonPV,  true>(pos, ss+1, -(alpha+1), -alpha)
+                                       : -qsearch<NonPV, false>(pos, ss+1, -(alpha+1), -alpha)

                                        : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false);
 
       // For PV nodes only, do a full PV search on the first move or after a fail
                                        : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode, false);
 
       // For PV nodes only, do a full PV search on the first move or after a fail


@@ -1022,8 +1022,8 @@ moves_loop: // When in check search starts from here
           (ss+1)->pv[0] = MOVE_NONE;
 
           value = newDepth <   ONE_PLY ?
           (ss+1)->pv[0] = MOVE_NONE;
 
           value = newDepth <   ONE_PLY ?

-                            givesCheck ? -qsearch<PV,  true>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
-                                       : -qsearch<PV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+                            givesCheck ? -qsearch<PV,  true>(pos, ss+1, -beta, -alpha)
+                                       : -qsearch<PV, false>(pos, ss+1, -beta, -alpha)

                                        : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, false);
       }
 
                                        : - search<PV>(pos, ss+1, -beta, -alpha, newDepth, false, false);
       }
 


@@ -1147,8 +1147,7 @@ moves_loop: // When in check search starts from here
 
 
   // qsearch() is the quiescence search function, which is called by the main
 
 
   // qsearch() is the quiescence search function, which is called by the main

-  // search function when the remaining depth is zero (or, to be more precise,
-  // less than ONE_PLY).
+  // search function with depth zero, or recursively with depth less than ONE_PLY.

 
   template <NodeType NT, bool InCheck>
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
 
   template <NodeType NT, bool InCheck>
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {