Atomic contempt. Bench: 5072738

src/evaluate.cpp

@@ -23,6 +23,7 @@
 #include <cstring>   // For std::memset
 #include <iomanip>
 #include <sstream>
+#include <atomic>
 
 #include "bitboard.h"
 #include "evaluate.h"
@@ -905,7 +906,7 @@ namespace {
 
 } // namespace
 
-Score Eval::Contempt = SCORE_ZERO;
+std::atomic<Score> Eval::Contempt;
 
 /// evaluate() is the evaluator for the outer world. It returns a static evaluation
 /// of the position from the point of view of the side to move.

src/evaluate.h

@@ -22,6 +22,7 @@
 #define EVALUATE_H_INCLUDED
 
 #include <string>
+#include <atomic>
 
 #include "types.h"
 
@@ -31,7 +32,7 @@ namespace Eval {
 
 const Value Tempo = Value(20); // Must be visible to search
 
-extern Score Contempt;
+extern std::atomic<Score> Contempt;
 
 std::string trace(const Position& pos);