From b1983e465ad2ef1c8d88013eb8ff9136f40e971f Mon Sep 17 00:00:00 2001
From: xu-shawn <50402888+xu-shawn@users.noreply.github.com>
Date: Tue, 24 Dec 2024 11:52:08 -0800
Subject: [PATCH] Speed up finny table refreshes (#500)

Elo | 3.35 +- 2.30 (95%)
SPRT | 4.0+0.04s Threads=1 Hash=16MB
LLR | 2.91 (-2.25, 2.89) [0.00, 3.00]
Games | N: 23658 W: 6190 L: 5962 D: 11506
Penta | [121, 2573, 6239, 2749, 147]

Bench: 8476323
---
 src/nnue.cpp | 13 ++++++++++++-
 src/types.h  |  2 +-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/nnue.cpp b/src/nnue.cpp
index c598fd85..07bdbb76 100644
--- a/src/nnue.cpp
+++ b/src/nnue.cpp
@@ -138,6 +138,18 @@ void NNUE::Pov_Accumulator::refresh(Position *pos) {
     // figure out a diff
     for (int piece = WP; piece <= BK; piece++) {
         auto added = pos->bitboards[piece] & ~cachedEntry->occupancies[piece];
+        auto removed = cachedEntry->occupancies[piece] & ~pos->bitboards[piece];
+        while (added && removed) {
+            auto added_square = popLsb(added);
+            auto added_index = GetIndex(piece, added_square, kingSq, flip);
+            const auto Add = &net.FTWeights[added_index * L1_SIZE];
+            auto removed_square = popLsb(removed);
+            auto removed_index = GetIndex(piece, removed_square, kingSq, flip);
+            const auto Sub = &net.FTWeights[removed_index * L1_SIZE];
+            for (int i = 0; i < L1_SIZE; i++) {
+              this->values[i] = this->values[i] + Add[i] - Sub[i];
+            }
+        }
         while (added) {
             auto square = popLsb(added);
             auto index = GetIndex(piece, square, kingSq, flip);
@@ -146,7 +158,6 @@ void NNUE::Pov_Accumulator::refresh(Position *pos) {
                 this->values[i] += Add[i];
             }
         }
-        auto removed = cachedEntry->occupancies[piece] & ~pos->bitboards[piece];
         while (removed) {
             auto square = popLsb(removed);
             auto index = GetIndex(piece, square, kingSq, flip);
diff --git a/src/types.h b/src/types.h
index e01f3179..fb40c4c2 100644
--- a/src/types.h
+++ b/src/types.h
@@ -4,7 +4,7 @@
 // include the tune stuff here to give it global visibility
 #include "tune.h"
 
-#define NAME "Alexandria-7.1.5"
+#define NAME "Alexandria-7.1.6"
 
 inline int reductions[2][64][64];
 inline int lmp_margin[64][2];