Make staticEval independent of the search path

Current master can yield different staticEvals depending on the path
used to reach the position. The reason for this is that the evaluation after a
null move is always computed subtracting 2 * Eval::Tempo, while this is not
the case for lazy or specialized evals. This patch always adds tempo to evals,
which doesn't affect playing strength:

LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 59911 W: 7616 L: 7545 D: 44750

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 104947 W: 18897 L: 18919 D: 67131

Fixes issue #1335

Bench: 5208264

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 47a65c592cdfb7ef3456f27e99cca109ebb5ae0d..d9c306e8891c8cf91e320aae85992829bce131b9 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -891,7 +891,7 @@ namespace {
         Trace::add(TOTAL, score);
     }
 
         Trace::add(TOTAL, score);
     }
 

-    return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
+    return pos.side_to_move() == WHITE ? v : -v; // Side to move point of view

   }
 
 } // namespace
   }
 
 } // namespace


@@ -903,7 +903,7 @@ Score Eval::Contempt = SCORE_ZERO;
 
 Value Eval::evaluate(const Position& pos)
 {
 
 Value Eval::evaluate(const Position& pos)
 {

-   return Evaluation<>(pos).value();
+   return Evaluation<>(pos).value() + Eval::Tempo;

 }
 
 /// trace() is like evaluate(), but instead of returning a value, it returns
 }
 
 /// trace() is like evaluate(), but instead of returning a value, it returns


@@ -914,7 +914,7 @@ std::string Eval::trace(const Position& pos) {
 
   std::memset(scores, 0, sizeof(scores));
 
 
   std::memset(scores, 0, sizeof(scores));
 

-  Value v = Evaluation<TRACE>(pos).value();
+  Value v = Evaluation<TRACE>(pos).value() + Eval::Tempo;

   v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
 
   std::stringstream ss;
   v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
 
   std::stringstream ss;