Revert "Retire null search verification"

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 6d900f7bb7ae673575f2d52b953ed63ca2c2d3ff..7188925c0e73c2f3e2fae8d5e2c1b77e5dea2374 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -154,10 +154,10 @@ void Search::init() {
 /// Search::perft() is our utility to verify move generation. All the leaf nodes
 /// up to the given depth are generated and counted and the sum returned.
 
-static size_t perft(Position& pos, Depth depth) {
+static uint64_t perft(Position& pos, Depth depth) {
 
   StateInfo st;
-  size_t cnt = 0;
+  uint64_t cnt = 0;
   CheckInfo ci(pos);
   const bool leaf = depth == 2 * ONE_PLY;
 
@@ -170,7 +170,7 @@ static size_t perft(Position& pos, Depth depth) {
   return cnt;
 }
 
-size_t Search::perft(Position& pos, Depth depth) {
+uint64_t Search::perft(Position& pos, Depth depth) {
   return depth > ONE_PLY ? ::perft(pos, depth) : MoveList<LEGAL>(pos).size();
 }
 
@@ -640,8 +640,24 @@ namespace {
         (ss+1)->skipNullMove = false;
         pos.undo_null_move();
 
-        if (nullValue >= beta) // Do not return unproven mate scores
-            return nullValue >= VALUE_MATE_IN_MAX_PLY ? beta : nullValue;
+        if (nullValue >= beta)
+        {
+            // Do not return unproven mate scores
+            if (nullValue >= VALUE_MATE_IN_MAX_PLY)
+                nullValue = beta;
+
+            if (depth < 12 * ONE_PLY)
+                return nullValue;
+
+            // Do verification search at high depths
+            ss->skipNullMove = true;
+            Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta, DEPTH_ZERO)
+                                        :  search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
+            ss->skipNullMove = false;
+
+            if (v >= beta)
+                return nullValue;
+        }
     }
 
     // Step 9. ProbCut (skipped when in check)
@@ -754,7 +770,11 @@ moves_loop: // When in check and at SpNode search starts from here
 
       ext = DEPTH_ZERO;
       captureOrPromotion = pos.capture_or_promotion(move);
-      givesCheck = pos.gives_check(move, ci);
+
+      givesCheck =  type_of(move) == NORMAL && !ci.dcCandidates
+                  ? ci.checkSq[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
+                  : pos.gives_check(move, ci);
+
       dangerous =   givesCheck
                  || type_of(move) != NORMAL
                  || pos.advanced_pawn_push(move);
@@ -1134,7 +1154,9 @@ moves_loop: // When in check and at SpNode search starts from here
     {
       assert(is_ok(move));
 
-      givesCheck = pos.gives_check(move, ci);
+      givesCheck =  type_of(move) == NORMAL && !ci.dcCandidates
+                  ? ci.checkSq[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
+                  : pos.gives_check(move, ci);
 
       // Futility pruning
       if (   !PvNode