From: VoyagerOne <excelgeek@gmail.com>
Date: Mon, 3 Oct 2016 13:36:40 +0000 (-0400)
Subject: Allow inCheck pruning
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=ab26c61971c2f73d312b003e6d024373fbacf8e6;ds=sidebyside

Allow inCheck pruning

This is a bit tricky because we don't want
to prune the only legal evasions, even if
with negative SEE. So add an assert to avoid
this subtle bug to slip in later.

STC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 14140 W: 2625 L: 2421 D: 9094

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 11558 W: 1555 L: 1379 D: 8624

bench: 5256717
---

diff --git a/src/search.cpp b/src/search.cpp
index 1d8139c4..64cdb325 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -919,7 +919,6 @@ moves_loop: // When in check search starts from here
 
       // Step 13. Pruning at shallow depth
       if (  !rootNode
-          && !inCheck
           &&  bestValue > VALUE_MATED_IN_MAX_PLY)
       {
           if (   !captureOrPromotion
@@ -1121,6 +1120,9 @@ moves_loop: // When in check search starts from here
     // All legal moves have been searched and if there are no legal moves, it
     // must be a mate or a stalemate. If we are in a singular extension search then
     // return a fail low score.
+
+    assert(moveCount || !inCheck || excludedMove || !MoveList<LEGAL>(pos).size());
+
     if (!moveCount)
         bestValue = excludedMove ? alpha
                    :     inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];