Tuned Futility Equation

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 6d1a66e5f8688b24e6c5d9f96d7e8fd5c4b2c2c9..69488ad583fb81f1798487c5be2f6422a0db9a10 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -64,7 +64,7 @@ namespace {
   // Razor and futility margins
   constexpr int RazorMargin = 661;
   Value futility_margin(Depth d, bool improving) {
-    return Value((168 - 51 * improving) * d / ONE_PLY);
+    return Value(198 * (d / ONE_PLY) - 178 * improving);
   }
 
   // Reductions lookup table, initialized at startup
@@ -102,15 +102,16 @@ namespace {
     Move best = MOVE_NONE;
   };
 
-  // Breadcrumbs are used to mark nodes as being searched by a given thread.
+  // Breadcrumbs are used to mark nodes as being searched by a given thread
   struct Breadcrumb {
     std::atomic<Thread*> thread;
     std::atomic<Key> key;
   };
   std::array<Breadcrumb, 1024> breadcrumbs;
 
-  // ThreadHolding keeps track of which thread left breadcrumbs at the given node for potential reductions.
-  // A free node will be marked upon entering the moves loop, and unmarked upon leaving that loop, by the ctor/dtor of this struct.
+  // ThreadHolding structure keeps track of which thread left breadcrumbs at the given
+  // node for potential reductions. A free node will be marked upon entering the moves
+  // loop by the constructor, and unmarked upon leaving that loop by the destructor.
   struct ThreadHolding {
     explicit ThreadHolding(Thread* thisThread, Key posKey, int ply) {
        location = ply < 8 ? &breadcrumbs[posKey & (breadcrumbs.size() - 1)] : nullptr;
@@ -118,7 +119,7 @@ namespace {
        owning = false;
        if (location)
        {
-          // see if another already marked this location, if not, mark it ourselves.
+          // See if another already marked this location, if not, mark it ourselves
           Thread* tmp = (*location).thread.load(std::memory_order_relaxed);
           if (tmp == nullptr)
           {
@@ -133,7 +134,7 @@ namespace {
     }
 
     ~ThreadHolding() {
-       if (owning) // free the marked location.
+       if (owning) // Free the marked location
            (*location).thread.store(nullptr, std::memory_order_relaxed);
     }
 
@@ -341,7 +342,7 @@ void Thread::search() {
   bestValue = delta = alpha = -VALUE_INFINITE;
   beta = VALUE_INFINITE;
 
-  multiPV = Options["MultiPV"];
+  size_t multiPV = Options["MultiPV"];
 
   // Pick integer skill levels, but non-deterministically round up or down
   // such that the average integer skill corresponds to the input floating point one.
@@ -647,9 +648,9 @@ namespace {
     // statScore of the previous grandchild. This influences the reduction rules in
     // LMR which are based on the statScore of parent position.
     if (rootNode)
-        (ss + 4)->statScore = 0;
+        (ss+4)->statScore = 0;
     else
-        (ss + 2)->statScore = 0;
+        (ss+2)->statScore = 0;
 
     // Step 4. Transposition table lookup. We don't want the score of a partial
     // search to overwrite a previous full search TT value, so we use a different
@@ -680,7 +681,7 @@ namespace {
 
                 // Extra penalty for early quiet moves of the previous ply
                 if ((ss-1)->moveCount <= 2 && !pos.captured_piece())
-                        update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+                    update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
             }
             // Penalty for a quiet ttMove that fails low
             else if (!pos.capture_or_promotion(ttMove))
@@ -908,7 +909,7 @@ moves_loop: // When in check, search starts from here
     moveCountPruning = false;
     ttCapture = ttMove && pos.capture_or_promotion(ttMove);
 
-    // Mark this node as being searched.
+    // Mark this node as being searched
     ThreadHolding th(thisThread, posKey, ss->ply);
 
     // Step 12. Loop through all pseudo-legal moves until no moves remain
@@ -934,12 +935,6 @@ moves_loop: // When in check, search starts from here
           sync_cout << "info depth " << depth / ONE_PLY
                     << " currmove " << UCI::move(move, pos.is_chess960())
                     << " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl;
-
-      // In MultiPV mode also skip moves which will be searched later as PV moves
-      if (rootNode && std::count(thisThread->rootMoves.begin() + thisThread->pvIdx + 1,
-                                 thisThread->rootMoves.begin() + thisThread->multiPV, move))
-          continue;
-
       if (PvNode)
           (ss+1)->pv = nullptr;