From: Marco Costalba <mcostalba@gmail.com>
Date: Sat, 7 Feb 2015 11:07:43 +0000 (+0100)
Subject: Micro-optimize SEE
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=47a076810291cb7e9b9333e106f2aa9cd4c30c58

Micro-optimize SEE

Results for 10 tests for each version (gcc 4.8.3 on mingw):

            Base      Test      Diff
    Mean    1502447   1507917   -5470
    StDev   3119      1364      4153

p-value: 0,906
speedup: 0,004

Results for 10 tests for each version (MSVC 2013):

            Base      Test      Diff
    Mean    1400899   1403713   -2814
    StDev   1273      2804      2700

p-value: 0,851
speedup: 0,002

No functional change.
---

diff --git a/src/position.cpp b/src/position.cpp
index cc320b4b..8d4b9f4f 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1098,21 +1098,11 @@ Value Position::see(Move m) const {
 
       // Locate and remove the next least valuable attacker
       captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
-
-      // Stop before processing a king capture
-      if (captured == KING)
-      {
-          if (stmAttackers == attackers)
-              ++slIndex;
-
-          break;
-      }
-
       stm = ~stm;
       stmAttackers = attackers & pieces(stm);
       ++slIndex;
 
-  } while (stmAttackers);
+  } while (stmAttackers && (captured != KING || (--slIndex, false))); // Stop before a king capture
 
   // Having built the swap list, we negamax through it to find the best
   // achievable score from the point of view of the side to move.