Fix a few minor code style inconsistencies

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index bf34b77e5d8bd7f8ccbe0177fe4d2ae3da6e5038..7979fd5b549a349add8853c513ccd5da5388b745 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -31,8 +31,8 @@
 #include "movepick.h"
 #include "position.h"
 #include "search.h"
-#include "timeman.h"
 #include "thread.h"
+#include "timeman.h"
 #include "tt.h"
 #include "uci.h"
 #include "syzygy/tbprobe.h"
@@ -63,12 +63,11 @@ namespace {
   enum NodeType { NonPV, PV };
 
   // Sizes and phases of the skip-blocks, used for distributing search depths across the threads
-  const int SkipSize[]  = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
-  const int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
+  constexpr int SkipSize[]  = { 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
+  constexpr int SkipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
 
   // Razor and futility margins
-  const int RazorMargin1 = 590;
-  const int RazorMargin2 = 604;
+  constexpr int RazorMargin[] = {0, 590, 604};
   Value futility_margin(Depth d, bool improving) {
     return Value((175 - 50 * improving) * d / ONE_PLY);
   }
@@ -455,12 +454,12 @@ void Thread::search() {
                      timeReduction *= 1.25;
 
               // Use part of the gained time from a previous stable move for the current move
-              double unstablePvFactor = 1.0 + mainThread->bestMoveChanges;
-              unstablePvFactor *= std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
+              double bestMoveInstability = 1.0 + mainThread->bestMoveChanges;
+              bestMoveInstability *= std::pow(mainThread->previousTimeReduction, 0.528) / timeReduction;
 
               // Stop the search if we have only one legal move, or if available time elapsed
               if (   rootMoves.size() == 1
-                  || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 581)
+                  || Time.elapsed() > Time.optimum() * bestMoveInstability * improvingFactor / 581)
               {
                   // If we are allowed to ponder do not stop the search now but
                   // keep pondering until the GUI sends "ponderhit" or "stop".
@@ -495,7 +494,7 @@ namespace {
     if (depth < ONE_PLY)
         return qsearch<NT>(pos, ss, alpha, beta);
 
-    const bool PvNode = NT == PV;
+    constexpr bool PvNode = NT == PV;
     const bool rootNode = PvNode && ss->ply == 0;
 
     assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
@@ -690,21 +689,13 @@ namespace {
 
     // Step 7. Razoring (skipped when in check)
     if (  !PvNode
-        && depth <= 2 * ONE_PLY)
+        && depth < 3 * ONE_PLY
+        && eval <= alpha - RazorMargin[depth / ONE_PLY])
     {
-        if (   depth == ONE_PLY
-            && eval + RazorMargin1 <= alpha)
-            return qsearch<NonPV>(pos, ss, alpha, alpha+1);
-
-        else if (eval + RazorMargin2 <= alpha)
-        {
-            Value ralpha = alpha - RazorMargin2;
-
-            Value v = qsearch<NonPV>(pos, ss, ralpha, ralpha+1);
-
-            if (v <= ralpha)
-                return v;
-        }
+        Value ralpha = alpha - (depth >= 2 * ONE_PLY) * RazorMargin[depth / ONE_PLY];
+        Value v = qsearch<NonPV>(pos, ss, ralpha, ralpha+1);
+        if (depth < 2 * ONE_PLY || v <= ralpha)
+            return v;
     }
 
     // Step 8. Futility pruning: child node (skipped when in check)
@@ -1156,8 +1147,7 @@ moves_loop: // When in check, search starts from here
   template <NodeType NT>
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
 
-    const bool PvNode = NT == PV;
-    const bool inCheck = bool(pos.checkers());
+    constexpr bool PvNode = NT == PV;
 
     assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
     assert(PvNode || (alpha == beta - 1));
@@ -1171,7 +1161,7 @@ moves_loop: // When in check, search starts from here
     Move ttMove, move, bestMove;
     Depth ttDepth;
     Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
-    bool ttHit, givesCheck, evasionPrunable;
+    bool ttHit, inCheck, givesCheck, evasionPrunable;
     int moveCount;
 
     if (PvNode)
@@ -1183,6 +1173,7 @@ moves_loop: // When in check, search starts from here
 
     (ss+1)->ply = ss->ply + 1;
     ss->currentMove = bestMove = MOVE_NONE;
+    inCheck = pos.checkers();
     moveCount = 0;
 
     // Check for an immediate draw or maximum ply reached