From: Marco Costalba <mcostalba@gmail.com>
Date: Mon, 28 Feb 2011 19:17:57 +0000 (+0100)
Subject: Fix aspiration corner case
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=1f73a9ed639b6e55b96635c33b249f29ba726145

Fix aspiration corner case

Fix a corner case where we start aspiration window and
suddendly we get a VALUE_KNOWN_WIN / MATE score, this makes
aspiration to blow up in a series of researches loops.

Exit aspiration loop in that case.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/search.cpp b/src/search.cpp
index 5a0af8f8..3f367d83 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -643,8 +643,7 @@ namespace {
 
         // Start with a small aspiration window and, in case of fail high/low,
         // research with bigger window until not failing high/low anymore.
-        while (true)
-        {
+        do {
             // Search starting from ss+1 to allow calling update_gains()
             value = search<PV, false, true>(pos, ss+1, alpha, beta, depth * ONE_PLY, 0);
 
@@ -680,7 +679,8 @@ namespace {
             }
             else
                 break;
-        }
+
+        } while (abs(value) < VALUE_KNOWN_WIN);
 
         // Collect info about search result
         bestMove = Rml[0].pv[0];