From: Lucas Braesch <lucas.braesch@gmail.com>
Date: Sat, 7 Sep 2013 07:20:22 +0000 (+0200)
Subject: Union of 2 changes
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=c86eee391830c9c74bc11be9c537ccbbf6cb412e;ds=sidebyside

Union of 2 changes

Union of

- LMR >= 3 plies from Gary tests.stockfishchess.org/tests/view/522522960ebc595d328fcafd

- allows() tweak from Reuven tests.stockfishchess.org/tests/view/5225fa1c0ebc595d328fcb53

Both passed Step I and failed Step II.

Instead this union passed both short TC:
LLR: 2.95 (-2.94,2.94)
Total: 14525 W: 3063 L: 2874 D: 8588

And long TC
LLR: 2.94 (-2.94,2.94)
Total: 31075 W: 5566 L: 5308 D: 20201

bench: 4238160
---

diff --git a/src/search.cpp b/src/search.cpp
index c9f1aee0..17d52cae 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -937,7 +937,7 @@ moves_loop: // When in check and at SpNode search starts from here
 
       // Step 15. Reduced depth search (LMR). If the move fails high will be
       // re-searched at full depth.
-      if (    depth > 3 * ONE_PLY
+      if (    depth >= 3 * ONE_PLY
           && !pvMove
           && !captureOrPromotion
           &&  move != ttMove
@@ -1361,7 +1361,10 @@ moves_loop: // When in check and at SpNode search starts from here
     Square m2to = to_sq(second);
 
     // The piece is the same or second's destination was vacated by the first move
-    if (m1to == m2from || m2to == m1from)
+    // We exclude the trivial case where a sliding piece does in two moves what
+    // it could do in one move: eg. Ra1a2, Ra2a3.
+    if (    m2to == m1from
+        || (m1to == m2from && !squares_aligned(m1from, m2from, m2to)))
         return true;
 
     // Second one moves through the square vacated by first one