From 38cfbeeb50c7dde79450f1b44171d5655e555ae5 Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Sat, 18 May 2013 12:49:31 +0200
Subject: [PATCH] Delay killers[] initialization

Most of the time we cut-off earlier, at captures, so this
results in useless work.

There is a small functionality change becuase 'ss' can change
from MovePicker c'tor to when killers are tried due, for
instance, to singular search.

bench: 4603795
---
 src/movepick.cpp | 25 ++++++++++++-------------
 src/movepick.h   |  1 +
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 2e449945..cd8f5da6 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -78,6 +78,7 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats&
   captureThreshold = 0;
   cur = end = moves;
   endBadCaptures = moves + MAX_MOVES - 1;
+  countermoves = cm;
   ss = s;
 
   if (p.checkers())
@@ -87,17 +88,12 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats&
   {
       phase = MAIN_SEARCH;
 
-      killers[0].move = ss->killers[0];
-      killers[1].move = ss->killers[1];
-      killers[2].move = cm[0];
-      killers[3].move = cm[1];
-
       // Consider sligtly negative captures as good if at low depth and far from beta
-      if (ss && ss->staticEval < beta - PawnValueMg && d < 3 * ONE_PLY)
+      if (ss->staticEval < beta - PawnValueMg && d < 3 * ONE_PLY)
           captureThreshold = -PawnValueMg;
 
       // Consider negative captures as good if still enough to reach beta
-      else if (ss && ss->staticEval > beta)
+      else if (ss->staticEval > beta)
           captureThreshold = beta - ss->staticEval;
   }
 
@@ -241,15 +237,18 @@ void MovePicker::generate_next() {
       cur = killers;
       end = cur + 2;
 
-      if ((cur+3)->move && (cur+3)->move == (cur+2)->move) // Due to a SMP race
-          (cur+3)->move = MOVE_NONE;
+      killers[0].move = ss->killers[0];
+      killers[1].move = ss->killers[1];
+      killers[2].move = killers[3].move = MOVE_NONE;
 
       // Be sure countermoves are different from killers
-      if ((cur+2)->move != cur->move && (cur+2)->move != (cur+1)->move)
-          end++;
+      for (int i = 0; i < 2; i++)
+          if (countermoves[i] != cur->move && countermoves[i] != (cur+1)->move)
+              (end++)->move = countermoves[i];
+
+      if (countermoves[1] && countermoves[1] == countermoves[0]) // Due to SMP races
+          killers[3].move = MOVE_NONE;
 
-      if ((cur+3)->move != cur->move && (cur+3)->move != (cur+1)->move)
-          (end++)->move = (cur+3)->move;
       return;
 
   case QUIETS_1_S1:
diff --git a/src/movepick.h b/src/movepick.h
index 5fbaa688..57fe1c0e 100644
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -97,6 +97,7 @@ private:
   const Position& pos;
   const HistoryStats& history;
   Search::Stack* ss;
+  Move* countermoves;
   Depth depth;
   Move ttMove;
   MoveStack killers[4];
-- 
2.39.2