From: Marco Costalba <mcostalba@gmail.com>
Date: Sat, 1 Dec 2012 13:51:49 +0000 (+0100)
Subject: Don't read eval from TT anymore
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=a5ea3a202eacff75f97e866f51da3f703359eb89;ds=inline

Don't read eval from TT anymore

Rely fully on eval cache. Note that we still save eval
info to TT, this is not needed at this moment and will be
removed in future patches. We keep it so to have a "non
functional change" patch.

No functional change.
---

diff --git a/src/search.cpp b/src/search.cpp
index b5388979..79046ad2 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -574,31 +574,21 @@ namespace {
     // Step 5. Evaluate the position statically and update parent's gain statistics
     if (inCheck)
         ss->staticEval = ss->evalMargin = eval = VALUE_NONE;
-
-    else if (tte)
+    else
     {
-        // Following asserts are valid only in single thread condition because
-        // TT access is always racy and its contents cannot be trusted.
-        assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
-        assert(ttValue != VALUE_NONE || tte->type() == BOUND_NONE || Threads.size() > 1);
-
-        ss->staticEval = eval = tte->static_value();
-        ss->evalMargin = tte->static_value_margin();
-
-        if (eval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race
-            eval = ss->staticEval = evaluate(pos, ss->evalMargin);
+        eval = ss->staticEval = evaluate(pos, ss->evalMargin);
 
         // Can ttValue be used as a better position evaluation?
-        if (ttValue != VALUE_NONE)
+        if (tte && ttValue != VALUE_NONE)
+        {
             if (   ((tte->type() & BOUND_LOWER) && ttValue > eval)
                 || ((tte->type() & BOUND_UPPER) && ttValue < eval))
                 eval = ttValue;
-    }
-    else
-    {
-        eval = ss->staticEval = evaluate(pos, ss->evalMargin);
-        TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
-                 ss->staticEval, ss->evalMargin);
+        }
+
+        if (!tte)
+            TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE,
+                     ss->staticEval, ss->evalMargin);
     }
 
     // Update gain for the parent non-capture move given the static position
@@ -1151,18 +1141,7 @@ split_point_start: // At split points actual search starts from here
     }
     else
     {
-        if (tte)
-        {
-            assert(tte->static_value() != VALUE_NONE || Threads.size() > 1);
-
-            ss->staticEval = bestValue = tte->static_value();
-            ss->evalMargin = tte->static_value_margin();
-
-            if (ss->staticEval == VALUE_NONE || ss->evalMargin == VALUE_NONE) // Due to a race
-                ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
-        }
-        else
-            ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
+        ss->staticEval = bestValue = evaluate(pos, ss->evalMargin);
 
         // Stand pat. Return immediately if static value is at least beta
         if (bestValue >= beta)