Lookup TT for eval also in PV nodes

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 37c3bd71bb40e2aab91f4e45751684b0e86d7ebb..aa577c79b7c4fdc2eab25bb2663170defb68e91f 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -179,8 +179,7 @@ namespace {
   // Step 9. Internal iterative deepening
 
   // Minimum depth for use of internal iterative deepening
-  const Depth IIDDepthAtPVNodes = 5 * OnePly;
-  const Depth IIDDepthAtNonPVNodes = 8 * OnePly;
+  const Depth IIDDepth[2] = { 8 * OnePly /* non-PV */, 5 * OnePly /* PV */};
 
   // At Non-PV nodes we do an internal iterative deepening search
   // when the static evaluation is at most IIDMargin below beta.
@@ -1023,11 +1022,11 @@ namespace {
   }
 
 
-  // search_pv() is the main search function for PV nodes.
+  // search<>() is the main search function for both PV and non-PV nodes
 
   template <NodeType PvNode>
-  Value search(Position& pos, SearchStack ss[], Value alpha, Value beta,
-               Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove) {
+  Value search(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth,
+               int ply, bool allowNullmove, int threadID, Move excludedMove) {
 
     assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
     assert(beta > alpha && beta <= VALUE_INFINITE);
@@ -1099,7 +1098,7 @@ namespace {
     isCheck = pos.is_check();
     if (!isCheck)
     {
-        if (!PvNode && tte && (tte->type() & VALUE_TYPE_EVAL))
+        if (tte && (tte->type() & VALUE_TYPE_EVAL))
             ss[ply].eval = value_from_tt(tte->value(), ply);
         else
             ss[ply].eval = evaluate(pos, ei, threadID);
@@ -1197,23 +1196,12 @@ namespace {
     }
 
     // Step 9. Internal iterative deepening
-    // We have different rules for PV nodes and non-pv nodes
-    if (   PvNode
-        && depth >= IIDDepthAtPVNodes
-        && ttMove == MOVE_NONE)
-    {
-        search<PV>(pos, ss, alpha, beta, depth-2*OnePly, ply, false, threadID);
-        ttMove = ss[ply].pv[ply];
-        tte = TT.retrieve(posKey);
-    }
-
-    if (   !PvNode
-        && depth >= IIDDepthAtNonPVNodes
+    if (   depth >= IIDDepth[PvNode]
         && ttMove == MOVE_NONE
-        && !isCheck
-        && ss[ply].eval >= beta - IIDMargin)
+        && (PvNode || (!isCheck && ss[ply].eval >= beta - IIDMargin)))
     {
-        search<NonPV>(pos, ss, alpha, beta, depth/2, ply, false, threadID);
+        Depth d = (PvNode ? depth - 2 * OnePly : depth / 2);
+        search<PvNode>(pos, ss, alpha, beta, d, ply, false, threadID);
         ttMove = ss[ply].pv[ply];
         tte = TT.retrieve(posKey);
     }