Revert "Check for easy move just once"

This reverts commit a24da071f0d6128c633febab7df55f14475217c3

Seems a regression when tested against 2.3.1

With this patch, have after 20000 games at 60+0.05, we have

ELO: 13.42 +-4.8 (95%) LOS: 100.0%
Total: 20000 W: 3746 L: 2974 D: 13280

Instead with the patch reverted:

ELO: 16.62 +-4.8 (95%) LOS: 100.0%
Total: 20000 W: 3816 L: 2860 D: 13324

Although we are within error bounds here we take the conservative
approach of not introducing changes that are not proved stronger
It doesn't mean that the change shall be weaker, simply that we
don't want to take any risk.

No functional change.

diff --git a/src/search.cpp b/src/search.cpp
index 7970a393d003848a537f9e4c18650266fd12580d..0416c16cb3c89a9f7606d2ea6b4dd51173f53274 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -293,7 +293,6 @@ namespace {
     Stack ss[MAX_PLY_PLUS_2];
     int depth, prevBestMoveChanges;
     Value bestValue, alpha, beta, delta;
     Stack ss[MAX_PLY_PLUS_2];
     int depth, prevBestMoveChanges;
     Value bestValue, alpha, beta, delta;

-    bool triedEasyMove = false;

 
     memset(ss, 0, 4 * sizeof(Stack));
     depth = BestMoveChanges = 0;
 
     memset(ss, 0, 4 * sizeof(Stack));
     depth = BestMoveChanges = 0;


@@ -440,12 +439,10 @@ namespace {
             // Stop search early if one move seems to be much better than others
             if (    depth >= 12
                 && !stop
             // Stop search early if one move seems to be much better than others
             if (    depth >= 12
                 && !stop

-                && !triedEasyMove

                 &&  PVSize == 1
                 && (   RootMoves.size() == 1
                     || Time::now() - SearchTime > (TimeMgr.available_time() * 20) / 100))
             {
                 &&  PVSize == 1
                 && (   RootMoves.size() == 1
                     || Time::now() - SearchTime > (TimeMgr.available_time() * 20) / 100))
             {

-                triedEasyMove = true;

                 Value rBeta = bestValue - 2 * PawnValueMg;
                 (ss+1)->excludedMove = RootMoves[0].pv[0];
                 (ss+1)->skipNullMove = true;
                 Value rBeta = bestValue - 2 * PawnValueMg;
                 (ss+1)->excludedMove = RootMoves[0].pv[0];
                 (ss+1)->skipNullMove = true;