From 4f87fb53ee5c6071fa57dfe9452eca9fe7b460ee Mon Sep 17 00:00:00 2001
From: Thomas Schatzl <tschatzl@openjdk.org>
Date: Wed, 21 Jan 2026 09:01:00 +0000
Subject: [PATCH] 8375622: G1: Convert G1CodeRootSet to use Atomic<T>

Reviewed-by: shade, sjohanss
---
 src/hotspot/share/gc/g1/g1CodeRootSet.cpp | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/hotspot/share/gc/g1/g1CodeRootSet.cpp b/src/hotspot/share/gc/g1/g1CodeRootSet.cpp
index 60ad3a2af32..ca4487876b9 100644
--- a/src/hotspot/share/gc/g1/g1CodeRootSet.cpp
+++ b/src/hotspot/share/gc/g1/g1CodeRootSet.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,7 +28,7 @@
 #include "gc/g1/g1HeapRegion.hpp"
 #include "memory/allocation.hpp"
 #include "oops/oop.inline.hpp"
-#include "runtime/atomicAccess.hpp"
+#include "runtime/atomic.hpp"
 #include "utilities/concurrentHashTable.inline.hpp"
 #include "utilities/concurrentHashTableTasks.inline.hpp"
 
@@ -60,7 +60,7 @@ class G1CodeRootSetHashTable : public CHeapObj<mtGC> {
   HashTable _table;
   HashTableScanTask _table_scanner;
 
-  size_t volatile _num_entries;
+  Atomic<size_t> _num_entries;
 
   bool is_empty() const { return number_of_entries() == 0; }
 
@@ -120,7 +120,7 @@ public:
     bool grow_hint = false;
     bool inserted = _table.insert(Thread::current(), lookup, method, &grow_hint);
     if (inserted) {
-      AtomicAccess::inc(&_num_entries);
+      _num_entries.add_then_fetch(1u);
     }
     if (grow_hint) {
       _table.grow(Thread::current());
@@ -131,7 +131,7 @@ public:
     HashTableLookUp lookup(method);
     bool removed = _table.remove(Thread::current(), lookup);
     if (removed) {
-      AtomicAccess::dec(&_num_entries);
+      _num_entries.sub_then_fetch(1u);
     }
     return removed;
   }
@@ -182,7 +182,7 @@ public:
     guarantee(succeeded, "unable to clean table");
 
     if (num_deleted != 0) {
-      size_t current_size = AtomicAccess::sub(&_num_entries, num_deleted);
+      size_t current_size = _num_entries.sub_then_fetch(num_deleted);
       shrink_to_match(current_size);
     }
   }
@@ -226,7 +226,7 @@ public:
 
   size_t mem_size() { return sizeof(*this) + _table.get_mem_size(Thread::current()); }
 
-  size_t number_of_entries() const { return AtomicAccess::load(&_num_entries); }
+  size_t number_of_entries() const { return _num_entries.load_relaxed(); }
 };
 
 uintx G1CodeRootSetHashTable::HashTableLookUp::get_hash() const {