From ed604600042a4f2c0023ac9a189215e50fc7aa0f Mon Sep 17 00:00:00 2001
From: Michael Chaly <Vizvezdenec@gmail.com>
Date: Fri, 15 Mar 2024 18:55:40 +0300
Subject: [PATCH] Clamp history bonus to stats range

Before, one always had to keep track of the bonus one assigns to a history to stop
the stats from overflowing. This is a quality of life improvement. Since this would often go unnoticed during benching.

Passed non-regression bounds:
https://tests.stockfishchess.org/tests/view/65ef2af40ec64f0526c44cbc
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 179232 W: 46513 L: 46450 D: 86269
Ptnml(0-2): 716, 20323, 47452, 20432, 693

closes https://github.com/official-stockfish/Stockfish/pull/5116

No functional change
---
 src/movepick.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/movepick.h b/src/movepick.h
index 357918a9..a16fdcd2 100644
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -19,17 +19,17 @@
 #ifndef MOVEPICK_H_INCLUDED
 #define MOVEPICK_H_INCLUDED
 
+#include <algorithm>
 #include <array>
 #include <cassert>
-#include <cmath>
 #include <cstdint>
 #include <cstdlib>
 #include <limits>
 #include <type_traits>  // IWYU pragma: keep
 
 #include "movegen.h"
-#include "types.h"
 #include "position.h"
+#include "types.h"
 
 namespace Stockfish {
 
@@ -69,10 +69,11 @@ class StatsEntry {
     operator const T&() const { return entry; }
 
     void operator<<(int bonus) {
-        assert(std::abs(bonus) <= D);  // Ensure range is [-D, D]
         static_assert(D <= std::numeric_limits<T>::max(), "D overflows T");
 
-        entry += bonus - entry * std::abs(bonus) / D;
+        // Make sure that bonus is in range [-D, D]
+        int clampedBonus = std::clamp(bonus, -D, D);
+        entry += clampedBonus - entry * std::abs(clampedBonus) / D;
 
         assert(std::abs(entry) <= D);
     }