IID margin reduced to 128

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 176006fcc1073ea837b04b27dcdcc8d3ace22e0e..7a8d3253048d2db2d7595493cb242692970f6d57 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"
@@ -67,8 +67,7 @@ namespace {
   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
-  constexpr int RazorMargin1 = 590;
-  constexpr int RazorMargin2 = 604;
+  constexpr int RazorMargin[] = {0, 590, 604};
   Value futility_margin(Depth d, bool improving) {
     return Value((175 - 50 * improving) * d / ONE_PLY);
   }
@@ -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)
@@ -800,7 +791,7 @@ namespace {
     // Step 11. Internal iterative deepening (skipped when in check)
     if (    depth >= 6 * ONE_PLY
         && !ttMove
-        && (PvNode || ss->staticEval + 256 >= beta))
+        && (PvNode || ss->staticEval + 128 >= beta))
     {
         Depth d = 3 * depth / 4 - 2 * ONE_PLY;
         search<NT>(pos, ss, alpha, beta, d, cutNode, true);
@@ -1157,7 +1148,6 @@ moves_loop: // When in check, search starts from here
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
 
     constexpr bool PvNode = NT == PV;
-    const bool inCheck = bool(pos.checkers());
 
     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