From 6f6b9fad662ca61e1b9f14fc65e9416aa8c7d3f7 Mon Sep 17 00:00:00 2001
From: Protobuf Team Bot <protobuf-github-bot@google.com>
Date: Tue, 16 Apr 2024 11:12:17 -0700
Subject: [PATCH] Do not prefetch nullptr. - On ARM, this change improved the
 performance BM_RepeatedPtrField_Add_Sso   by 3.x times.

PiperOrigin-RevId: 625392922
---
 src/google/protobuf/repeated_ptr_field.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/google/protobuf/repeated_ptr_field.cc b/src/google/protobuf/repeated_ptr_field.cc
index c716be5abd..010b7aabd9 100644
--- a/src/google/protobuf/repeated_ptr_field.cc
+++ b/src/google/protobuf/repeated_ptr_field.cc
@@ -96,12 +96,12 @@ void RepeatedPtrFieldBase::DestroyProtos() {
 template <typename F>
 void* RepeatedPtrFieldBase::AddInternal(F factory) {
   Arena* const arena = GetArena();
-  absl::PrefetchToLocalCache(tagged_rep_or_elem_);
   if (tagged_rep_or_elem_ == nullptr) {
     ExchangeCurrentSize(1);
     tagged_rep_or_elem_ = factory(arena);
     return tagged_rep_or_elem_;
   }
+  absl::PrefetchToLocalCache(tagged_rep_or_elem_);
   if (using_sso()) {
     if (current_size_ == 0) {
       ExchangeCurrentSize(1);