From: Marco Costalba <mcostalba@gmail.com>
Date: Sat, 8 Nov 2014 10:39:38 +0000 (+0100)
Subject: Retire pvMove in search()
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=1b0df1ae141be1461e3fbe809b5b27c3e360753f

Retire pvMove in search()

Now we can directly replace it with
the definition resulting in simpler
and possibly faster code because
PvNode is evaluated at compile time.

No functional change.
---

diff --git a/src/search.cpp b/src/search.cpp
index 5f43460a..8d713fb8 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -407,7 +407,7 @@ namespace {
     Move ttMove, move, excludedMove, bestMove;
     Depth ext, newDepth, predictedDepth;
     Value bestValue, value, ttValue, eval, nullValue, futilityValue;
-    bool inCheck, givesCheck, pvMove, singularExtensionNode, improving;
+    bool inCheck, givesCheck, singularExtensionNode, improving;
     bool captureOrPromotion, dangerous, doFullDepthSearch;
     int moveCount, quietCount;
 
@@ -802,7 +802,6 @@ moves_loop: // When in check and at SpNode search starts from here
           continue;
       }
 
-      pvMove = PvNode && moveCount == 1;
       ss->currentMove = move;
       if (!SpNode && !captureOrPromotion && quietCount < 64)
           quietsSearched[quietCount++] = move;
@@ -851,7 +850,7 @@ moves_loop: // When in check and at SpNode search starts from here
           ss->reduction = DEPTH_ZERO;
       }
       else
-          doFullDepthSearch = !pvMove;
+          doFullDepthSearch = !PvNode || moveCount > 1;
 
       // Step 16. Full depth search, when LMR is skipped or fails high
       if (doFullDepthSearch)
@@ -868,7 +867,7 @@ moves_loop: // When in check and at SpNode search starts from here
       // For PV nodes only, do a full PV search on the first move or after a fail
       // high (in the latter case search only if value < beta), otherwise let the
       // parent node fail low with value <= alpha and to try another move.
-      if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta))))
+      if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta))))
           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)
@@ -897,7 +896,7 @@ moves_loop: // When in check and at SpNode search starts from here
           RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move);
 
           // PV move or new best move ?
-          if (pvMove || value > alpha)
+          if (moveCount == 1 || value > alpha)
           {
               rm.score = value;
               rm.extract_pv_from_tt(pos);
@@ -905,7 +904,7 @@ moves_loop: // When in check and at SpNode search starts from here
               // We record how often the best move has been changed in each
               // iteration. This information is used for time management: When
               // the best move changes frequently, we allocate some more time.
-              if (!pvMove)
+              if (moveCount > 1)
                   ++BestMoveChanges;
           }
           else