From: Gian-Carlo Pascutto <gcp@sjeng.org>
Date: Tue, 7 Nov 2017 08:26:13 +0000 (+0100)
Subject: Always do MaxCardinality checks.
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8cfcca12d1f31e69a1e00ef657743841a7ef18b9

Always do MaxCardinality checks.

Stockfish currently relies on the "filter_root_moves" function also
having the side effect of clamping Cardinality against MaxCardinality
(the actual piece count in the tablebases). So if we skip this function,
we will end up probing in the search even without tablebases installed.

We cannot bail out of this function before this check is done, so move
the MultiPV hack a few lines below.
---

diff --git a/src/search.cpp b/src/search.cpp
index cf380b31..f7efd41c 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1599,10 +1599,6 @@ void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves)
     ProbeDepth = Options["SyzygyProbeDepth"] * ONE_PLY;
     Cardinality = Options["SyzygyProbeLimit"];
 
-    // Don't filter any moves if the user requested analysis on multiple
-    if (Options["MultiPV"] != 1)
-        return;
-
     // Skip TB probing when no TB found: !TBLargest -> !TB::Cardinality
     if (Cardinality > MaxCardinality)
     {
@@ -1613,6 +1609,10 @@ void Tablebases::filter_root_moves(Position& pos, Search::RootMoves& rootMoves)
     if (Cardinality < popcount(pos.pieces()) || pos.can_castle(ANY_CASTLING))
         return;
 
+    // Don't filter any moves if the user requested analysis on multiple
+    if (Options["MultiPV"] != 1)
+        return;
+
     // If the current root position is in the tablebases, then RootMoves
     // contains only moves that preserve the draw or the win.
     RootInTB = root_probe(pos, rootMoves, TB::Score);