diff --git a/src/hotspot/share/cds/archiveBuilder.cpp b/src/hotspot/share/cds/archiveBuilder.cpp
index 89d3fc68079..b13aa55da08 100644
--- a/src/hotspot/share/cds/archiveBuilder.cpp
+++ b/src/hotspot/share/cds/archiveBuilder.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2023, 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
@@ -51,7 +51,7 @@
 #include "utilities/bitMap.inline.hpp"
 #include "utilities/formatBuffer.hpp"
 
-ArchiveBuilder* ArchiveBuilder::_current = NULL;
+ArchiveBuilder* ArchiveBuilder::_current = nullptr;
 
 ArchiveBuilder::OtherROAllocMark::~OtherROAllocMark() {
   char* newtop = ArchiveBuilder::current()->_ro_region.top();
@@ -95,7 +95,7 @@ void ArchiveBuilder::SourceObjList::remember_embedded_pointer(SourceObjInfo* src
   address* field_addr = ref->addr();
   assert(src_info->ptrmap_start() < _total_bytes, "sanity");
   assert(src_info->ptrmap_end() <= _total_bytes, "sanity");
-  assert(*field_addr != NULL, "should have checked");
+  assert(*field_addr != nullptr, "should have checked");
 
   intx field_offset_in_bytes = ((address)field_addr) - src_obj;
   DEBUG_ONLY(int src_obj_size = src_info->size_in_bytes();)
@@ -141,17 +141,17 @@ void ArchiveBuilder::SourceObjList::relocate(int i, ArchiveBuilder* builder) {
 }
 
 ArchiveBuilder::ArchiveBuilder() :
-  _current_dump_space(NULL),
-  _buffer_bottom(NULL),
-  _last_verified_top(NULL),
+  _current_dump_space(nullptr),
+  _buffer_bottom(nullptr),
+  _last_verified_top(nullptr),
   _num_dump_regions_used(0),
   _other_region_used_bytes(0),
-  _requested_static_archive_bottom(NULL),
-  _requested_static_archive_top(NULL),
-  _requested_dynamic_archive_bottom(NULL),
-  _requested_dynamic_archive_top(NULL),
-  _mapped_static_archive_bottom(NULL),
-  _mapped_static_archive_top(NULL),
+  _requested_static_archive_bottom(nullptr),
+  _requested_static_archive_top(nullptr),
+  _requested_dynamic_archive_bottom(nullptr),
+  _requested_dynamic_archive_top(nullptr),
+  _mapped_static_archive_bottom(nullptr),
+  _mapped_static_archive_top(nullptr),
   _buffer_to_requested_delta(0),
   _rw_region("rw", MAX_SHARED_DELTA),
   _ro_region("ro", MAX_SHARED_DELTA),
@@ -169,13 +169,13 @@ ArchiveBuilder::ArchiveBuilder() :
   _symbols = new (mtClassShared) GrowableArray<Symbol*>(256 * K, mtClassShared);
   _special_refs = new (mtClassShared) GrowableArray<SpecialRefInfo>(24 * K, mtClassShared);
 
-  assert(_current == NULL, "must be");
+  assert(_current == nullptr, "must be");
   _current = this;
 }
 
 ArchiveBuilder::~ArchiveBuilder() {
   assert(_current == this, "must be");
-  _current = NULL;
+  _current = nullptr;
 
   clean_up_src_obj_table();
 
@@ -207,7 +207,7 @@ public:
 };
 
 bool ArchiveBuilder::gather_klass_and_symbol(MetaspaceClosure::Ref* ref, bool read_only) {
-  if (ref->obj() == NULL) {
+  if (ref->obj() == nullptr) {
     return false;
   }
   if (get_follow_mode(ref) != make_a_copy) {
@@ -430,7 +430,7 @@ public:
   };
 
   virtual void do_pending_ref(Ref* ref) {
-    if (ref->obj() != NULL) {
+    if (ref->obj() != nullptr) {
       _builder->remember_embedded_pointer_in_copied_obj(enclosing_ref(), ref);
     }
   }
@@ -439,7 +439,7 @@ public:
 bool ArchiveBuilder::gather_one_source_obj(MetaspaceClosure::Ref* enclosing_ref,
                                            MetaspaceClosure::Ref* ref, bool read_only) {
   address src_obj = ref->obj();
-  if (src_obj == NULL) {
+  if (src_obj == nullptr) {
     return false;
   }
   ref->set_keep_after_pushing();
@@ -476,11 +476,11 @@ void ArchiveBuilder::add_special_ref(MetaspaceClosure::SpecialRef type, address
 
 void ArchiveBuilder::remember_embedded_pointer_in_copied_obj(MetaspaceClosure::Ref* enclosing_ref,
                                                              MetaspaceClosure::Ref* ref) {
-  assert(ref->obj() != NULL, "should have checked");
+  assert(ref->obj() != nullptr, "should have checked");
 
-  if (enclosing_ref != NULL) {
+  if (enclosing_ref != nullptr) {
     SourceObjInfo* src_info = (SourceObjInfo*)enclosing_ref->user_data();
-    if (src_info == NULL) {
+    if (src_info == nullptr) {
       // source objects of point_to_it/set_to_null types are not copied
       // so we don't need to remember their pointers.
     } else {
@@ -641,7 +641,7 @@ void ArchiveBuilder::make_shallow_copy(DumpRegion *dump_region, SourceObjInfo* s
   }
 
   intptr_t* archived_vtable = CppVtables::get_archived_vtable(ref->msotype(), (address)dest);
-  if (archived_vtable != NULL) {
+  if (archived_vtable != nullptr) {
     *(address*)dest = (address)archived_vtable;
     ArchivePtrMarker::mark_pointer((address*)dest);
   }
@@ -654,7 +654,7 @@ void ArchiveBuilder::make_shallow_copy(DumpRegion *dump_region, SourceObjInfo* s
 
 address ArchiveBuilder::get_buffered_addr(address src_addr) const {
   SourceObjInfo* p = _src_obj_table.get(src_addr);
-  assert(p != NULL, "must be");
+  assert(p != nullptr, "must be");
 
   return p->buffered_addr();
 }
@@ -662,7 +662,7 @@ address ArchiveBuilder::get_buffered_addr(address src_addr) const {
 address ArchiveBuilder::get_source_addr(address buffered_addr) const {
   assert(is_in_buffer_space(buffered_addr), "must be");
   address* src_p = _buffered_to_src_table.get(buffered_addr);
-  assert(src_p != NULL && *src_p != NULL, "must be");
+  assert(src_p != nullptr && *src_p != nullptr, "must be");
   return *src_p;
 }
 
@@ -846,7 +846,7 @@ void ArchiveBuilder::relocate_klass_ptr_of_oop(oop o) {
 // - See ArchiveBuilder header for the definition of "buffer", "mapped" and "requested"
 // - ArchivePtrMarker::ptrmap() marks all the pointers in the rw/ro regions
 // - Every pointer must have one of the following values:
-//   [a] NULL:
+//   [a] nullptr:
 //       No relocation is needed. Remove this pointer from ptrmap so we don't need to
 //       consider it at runtime.
 //   [b] Points into an object X which is inside the buffer:
@@ -886,7 +886,7 @@ class RelocateBufferToRequested : public BitMapClosure {
     address* p = (address*)_buffer_bottom + offset;
     assert(_builder->is_in_buffer_space(p), "pointer must live in buffer space");
 
-    if (*p == NULL) {
+    if (*p == nullptr) {
       // todo -- clear bit, etc
       ArchivePtrMarker::ptrmap()->clear_bit(offset);
     } else {
@@ -1064,7 +1064,7 @@ class ArchiveBuilder::CDSMapLogger : AllStatic {
         size_t byte_size;
         oop archived_oop = cast_to_oop(start);
         oop original_oop = HeapShared::get_original_object(archived_oop);
-        if (original_oop != NULL) {
+        if (original_oop != nullptr) {
           ResourceMark rm;
           log_info(cds, map)(PTR_FORMAT ": @@ Object %s",
                              p2i(to_requested(start)), original_oop->klass()->external_name());
@@ -1143,10 +1143,10 @@ public:
     log_data((address)bitmap, bitmap_end, 0);
 
 #if INCLUDE_CDS_JAVA_HEAP
-    if (closed_heap_regions != NULL) {
+    if (closed_heap_regions != nullptr) {
       log_heap_regions("closed heap region", closed_heap_regions);
     }
-    if (open_heap_regions != NULL) {
+    if (open_heap_regions != nullptr) {
       log_heap_regions("open heap region", open_heap_regions);
     }
 #endif
@@ -1180,7 +1180,7 @@ void ArchiveBuilder::write_archive(FileMapInfo* mapinfo,
   char* bitmap = mapinfo->write_bitmap_region(ArchivePtrMarker::ptrmap(), closed_heap_bitmaps, open_heap_bitmaps,
                                               bitmap_size_in_bytes);
 
-  if (closed_heap_regions != NULL) {
+  if (closed_heap_regions != nullptr) {
     _total_closed_heap_region_size = mapinfo->write_heap_regions(
                                         closed_heap_regions,
                                         closed_heap_bitmaps,
@@ -1239,7 +1239,7 @@ void ArchiveBuilder::print_region_stats(FileMapInfo *mapinfo,
 
   print_bitmap_region_stats(bitmap_used, total_reserved);
 
-  if (closed_heap_regions != NULL) {
+  if (closed_heap_regions != nullptr) {
     print_heap_region_stats(closed_heap_regions, "ca", total_reserved);
     print_heap_region_stats(open_heap_regions, "oa", total_reserved);
   }
@@ -1255,7 +1255,7 @@ void ArchiveBuilder::print_bitmap_region_stats(size_t size, size_t total_size) {
 
 void ArchiveBuilder::print_heap_region_stats(GrowableArray<MemRegion>* regions,
                                              const char *name, size_t total_size) {
-  int arr_len = regions == NULL ? 0 : regions->length();
+  int arr_len = regions == nullptr ? 0 : regions->length();
   for (int i = 0; i < arr_len; i++) {
       char* start = (char*)regions->at(i).start();
       size_t size = regions->at(i).byte_size();
diff --git a/src/hotspot/share/cds/archiveBuilder.hpp b/src/hotspot/share/cds/archiveBuilder.hpp
index b16467be20e..21b130f494a 100644
--- a/src/hotspot/share/cds/archiveBuilder.hpp
+++ b/src/hotspot/share/cds/archiveBuilder.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2023, 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
@@ -159,7 +159,7 @@ private:
       if (follow_mode == point_to_it) {
         _buffered_addr = ref->obj();
       } else {
-        _buffered_addr = NULL;
+        _buffered_addr = nullptr;
       }
     }
 
@@ -167,8 +167,8 @@ private:
     MetaspaceClosure::Ref* ref() const { return  _ref; }
     void set_buffered_addr(address addr)  {
       assert(should_copy(), "must be");
-      assert(_buffered_addr == NULL, "cannot be copied twice");
-      assert(addr != NULL, "must be a valid copy");
+      assert(_buffered_addr == nullptr, "cannot be copied twice");
+      assert(addr != nullptr, "must be a valid copy");
       _buffered_addr = addr;
     }
     void set_ptrmap_start(uintx v) { _ptrmap_start = v;    }
@@ -422,12 +422,12 @@ public:
   GrowableArray<Symbol*>* symbols() const { return _symbols; }
 
   static bool is_active() {
-    return (_current != NULL);
+    return (_current != nullptr);
   }
 
   static ArchiveBuilder* current() {
     assert_is_vm_thread();
-    assert(_current != NULL, "ArchiveBuilder must be active");
+    assert(_current != nullptr, "ArchiveBuilder must be active");
     return _current;
   }
 
@@ -447,7 +447,7 @@ public:
 
   static Klass* get_buffered_klass(Klass* src_klass) {
     Klass* klass = (Klass*)current()->get_buffered_addr((address)src_klass);
-    assert(klass != NULL && klass->is_klass(), "must be");
+    assert(klass != nullptr && klass->is_klass(), "must be");
     return klass;
   }
 
diff --git a/src/hotspot/share/cds/archiveHeapLoader.cpp b/src/hotspot/share/cds/archiveHeapLoader.cpp
index ce5eb2b6e75..4854eaf4e6c 100644
--- a/src/hotspot/share/cds/archiveHeapLoader.cpp
+++ b/src/hotspot/share/cds/archiveHeapLoader.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2023, 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
@@ -449,7 +449,7 @@ class VerifyLoadedHeapEmbeddedPointers: public BasicOopIterateClosure {
 
   virtual void do_oop(narrowOop* p) {
     // This should be called before the loaded regions are modified, so all the embedded pointers
-    // must be NULL, or must point to a valid object in the loaded regions.
+    // must be null, or must point to a valid object in the loaded regions.
     narrowOop v = *p;
     if (!CompressedOops::is_null(v)) {
       oop o = CompressedOops::decode_not_null(v);
@@ -540,7 +540,7 @@ void ArchiveHeapLoader::patch_native_pointers() {
   for (int i = MetaspaceShared::first_archive_heap_region;
        i <= MetaspaceShared::last_archive_heap_region; i++) {
     FileMapRegion* r = FileMapInfo::current_info()->region_at(i);
-    if (r->mapped_base() != NULL && r->has_ptrmap()) {
+    if (r->mapped_base() != nullptr && r->has_ptrmap()) {
       log_info(cds, heap)("Patching native pointers in heap region %d", i);
       BitMapView bm = r->ptrmap_view();
       PatchNativePointers patcher((Metadata**)r->mapped_base());
diff --git a/src/hotspot/share/cds/archiveHeapLoader.hpp b/src/hotspot/share/cds/archiveHeapLoader.hpp
index 754893cb4fa..9701e684862 100644
--- a/src/hotspot/share/cds/archiveHeapLoader.hpp
+++ b/src/hotspot/share/cds/archiveHeapLoader.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2023, 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
@@ -103,10 +103,10 @@ public:
   // than CompressedOops::{base,shift} -- see FileMapInfo::map_heap_regions_impl.
   // To decode them, do not use CompressedOops::decode_not_null. Use this
   // function instead.
-  inline static oop decode_from_archive(narrowOop v) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
+  inline static oop decode_from_archive(narrowOop v) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
 
   // More efficient version, but works only when ArchiveHeap is mapped.
-  inline static oop decode_from_mapped_archive(narrowOop v) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
+  inline static oop decode_from_mapped_archive(narrowOop v) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
 
   static void patch_compressed_embedded_pointers(BitMapView bm,
                                                  FileMapInfo* info,
@@ -172,7 +172,7 @@ private:
   }
 
   template<bool IS_MAPPED>
-  inline static oop decode_from_archive_impl(narrowOop v) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
+  inline static oop decode_from_archive_impl(narrowOop v) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
 
 public:
 
diff --git a/src/hotspot/share/cds/archiveUtils.cpp b/src/hotspot/share/cds/archiveUtils.cpp
index 238331832aa..12901360b32 100644
--- a/src/hotspot/share/cds/archiveUtils.cpp
+++ b/src/hotspot/share/cds/archiveUtils.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, 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
@@ -44,13 +44,13 @@
 #include "utilities/formatBuffer.hpp"
 #include "utilities/globalDefinitions.hpp"
 
-CHeapBitMap* ArchivePtrMarker::_ptrmap = NULL;
+CHeapBitMap* ArchivePtrMarker::_ptrmap = nullptr;
 VirtualSpace* ArchivePtrMarker::_vs;
 
 bool ArchivePtrMarker::_compacted;
 
 void ArchivePtrMarker::initialize(CHeapBitMap* ptrmap, VirtualSpace* vs) {
-  assert(_ptrmap == NULL, "initialize only once");
+  assert(_ptrmap == nullptr, "initialize only once");
   _vs = vs;
   _compacted = false;
   _ptrmap = ptrmap;
@@ -67,18 +67,18 @@ void ArchivePtrMarker::initialize(CHeapBitMap* ptrmap, VirtualSpace* vs) {
 }
 
 void ArchivePtrMarker::mark_pointer(address* ptr_loc) {
-  assert(_ptrmap != NULL, "not initialized");
+  assert(_ptrmap != nullptr, "not initialized");
   assert(!_compacted, "cannot mark anymore");
 
   if (ptr_base() <= ptr_loc && ptr_loc < ptr_end()) {
     address value = *ptr_loc;
     // We don't want any pointer that points to very bottom of the archive, otherwise when
     // MetaspaceShared::default_base_address()==0, we can't distinguish between a pointer
-    // to nothing (NULL) vs a pointer to an objects that happens to be at the very bottom
+    // to nothing (null) vs a pointer to an objects that happens to be at the very bottom
     // of the archive.
     assert(value != (address)ptr_base(), "don't point to the bottom of the archive");
 
-    if (value != NULL) {
+    if (value != nullptr) {
       assert(uintx(ptr_loc) % sizeof(intptr_t) == 0, "pointers must be stored in aligned addresses");
       size_t idx = ptr_loc - ptr_base();
       if (_ptrmap->size() <= idx) {
@@ -92,7 +92,7 @@ void ArchivePtrMarker::mark_pointer(address* ptr_loc) {
 }
 
 void ArchivePtrMarker::clear_pointer(address* ptr_loc) {
-  assert(_ptrmap != NULL, "not initialized");
+  assert(_ptrmap != nullptr, "not initialized");
   assert(!_compacted, "cannot clear anymore");
 
   assert(ptr_base() <= ptr_loc && ptr_loc < ptr_end(), "must be");
@@ -118,14 +118,14 @@ public:
   bool do_bit(size_t offset) {
     address* ptr_loc = _ptr_base + offset;
     address  ptr_value = *ptr_loc;
-    if (ptr_value != NULL) {
+    if (ptr_value != nullptr) {
       assert(_relocatable_base <= ptr_value && ptr_value < _relocatable_end, "do not point to arbitrary locations!");
       if (_max_non_null_offset < offset) {
         _max_non_null_offset = offset;
       }
     } else {
       _ptrmap->clear_bit(offset);
-      DEBUG_ONLY(log_trace(cds, reloc)("Clearing pointer [" PTR_FORMAT  "] -> NULL @ " SIZE_FORMAT_W(9), p2i(ptr_loc), offset));
+      DEBUG_ONLY(log_trace(cds, reloc)("Clearing pointer [" PTR_FORMAT  "] -> null @ " SIZE_FORMAT_W(9), p2i(ptr_loc), offset));
     }
 
     return true;
@@ -253,7 +253,7 @@ void DumpRegion::pack(DumpRegion* next) {
   assert(!is_packed(), "sanity");
   _end = (char*)align_up(_top, MetaspaceShared::core_region_alignment());
   _is_packed = true;
-  if (next != NULL) {
+  if (next != nullptr) {
     next->_rs = _rs;
     next->_vs = _vs;
     next->_base = next->_top = this->_end;
@@ -262,7 +262,7 @@ void DumpRegion::pack(DumpRegion* next) {
 }
 
 void WriteClosure::do_oop(oop* o) {
-  if (*o == NULL) {
+  if (*o == nullptr) {
     _dump_region->append_intptr_t(0);
   } else {
     assert(HeapShared::can_write(), "sanity");
@@ -288,7 +288,7 @@ void WriteClosure::do_region(u_char* start, size_t size) {
 }
 
 void ReadClosure::do_ptr(void** p) {
-  assert(*p == NULL, "initializing previous initialized pointer.");
+  assert(*p == nullptr, "initializing previous initialized pointer.");
   intptr_t obj = nextPtr();
   assert((intptr_t)obj >= 0 || (intptr_t)obj < -100,
          "hit tag while initializing ptrs.");
@@ -317,7 +317,7 @@ void ReadClosure::do_oop(oop *p) {
   if (UseCompressedOops) {
     narrowOop o = CompressedOops::narrow_oop_cast(nextPtr());
     if (CompressedOops::is_null(o) || !ArchiveHeapLoader::is_fully_available()) {
-      *p = NULL;
+      *p = nullptr;
     } else {
       assert(ArchiveHeapLoader::can_use(), "sanity");
       assert(ArchiveHeapLoader::is_fully_available(), "must be");
@@ -326,7 +326,7 @@ void ReadClosure::do_oop(oop *p) {
   } else {
     intptr_t dumptime_oop = nextPtr();
     if (dumptime_oop == 0 || !ArchiveHeapLoader::is_fully_available()) {
-      *p = NULL;
+      *p = nullptr;
     } else {
       assert(!ArchiveHeapLoader::is_loaded(), "ArchiveHeapLoader::can_load() is not supported for uncompessed oops");
       intptr_t runtime_oop = dumptime_oop + ArchiveHeapLoader::mapped_heap_delta();
diff --git a/src/hotspot/share/cds/archiveUtils.hpp b/src/hotspot/share/cds/archiveUtils.hpp
index be8d8a0e84e..d5526dce4df 100644
--- a/src/hotspot/share/cds/archiveUtils.hpp
+++ b/src/hotspot/share/cds/archiveUtils.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, 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
@@ -142,7 +142,7 @@ private:
 
 public:
   DumpRegion(const char* name, uintx max_delta = 0)
-    : _name(name), _base(NULL), _top(NULL), _end(NULL),
+    : _name(name), _base(nullptr), _top(nullptr), _end(nullptr),
       _max_delta(max_delta), _is_packed(false) {}
 
   char* expand_top_to(char* newtop);
@@ -157,7 +157,7 @@ public:
   size_t used()     const { return _top - _base; }
   bool is_packed()  const { return _is_packed;   }
   bool is_allocatable() const {
-    return !is_packed() && _base != NULL;
+    return !is_packed() && _base != nullptr;
   }
 
   void print(size_t total_bytes) const;
@@ -165,7 +165,7 @@ public:
 
   void init(ReservedSpace* rs, VirtualSpace* vs);
 
-  void pack(DumpRegion* next = NULL);
+  void pack(DumpRegion* next = nullptr);
 
   bool contains(char* p) {
     return base() <= p && p < top();
diff --git a/src/hotspot/share/cds/archiveUtils.inline.hpp b/src/hotspot/share/cds/archiveUtils.inline.hpp
index ac9ac0edfc7..7df344e3701 100644
--- a/src/hotspot/share/cds/archiveUtils.inline.hpp
+++ b/src/hotspot/share/cds/archiveUtils.inline.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, 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
@@ -35,10 +35,10 @@ inline bool SharedDataRelocator::do_bit(size_t offset) {
 
   address old_ptr = *p;
   assert(_valid_old_base <= old_ptr && old_ptr < _valid_old_end, "must be");
-  assert(old_ptr != NULL, "bits for NULL pointers should have been cleaned at dump time");
+  assert(old_ptr != nullptr, "bits for null pointers should have been cleaned at dump time");
 
   address new_ptr = old_ptr + _delta;
-  assert(new_ptr != NULL, "don't point to the bottom of the archive"); // See ArchivePtrMarker::mark_pointer().
+  assert(new_ptr != nullptr, "don't point to the bottom of the archive"); // See ArchivePtrMarker::mark_pointer().
   assert(_valid_new_base <= new_ptr && new_ptr < _valid_new_end, "must be");
 
   DEBUG_ONLY(log_trace(cds, reloc)("Patch2: @%8d [" PTR_FORMAT "] " PTR_FORMAT " -> " PTR_FORMAT,
diff --git a/src/hotspot/share/cds/cdsHeapVerifier.cpp b/src/hotspot/share/cds/cdsHeapVerifier.cpp
index 28065f9e2a1..1b17536c63f 100644
--- a/src/hotspot/share/cds/cdsHeapVerifier.cpp
+++ b/src/hotspot/share/cds/cdsHeapVerifier.cpp
@@ -84,7 +84,7 @@
 
 CDSHeapVerifier::CDSHeapVerifier() : _archived_objs(0), _problems(0)
 {
-# define ADD_EXCL(...) { static const char* e[] = {__VA_ARGS__, NULL}; add_exclusion(e); }
+# define ADD_EXCL(...) { static const char* e[] = {__VA_ARGS__, nullptr}; add_exclusion(e); }
 
   // Unfortunately this needs to be manually maintained. If
   // test/hotspot/jtreg/runtime/cds/appcds/cacheObject/ArchivedEnumTest.java fails,
@@ -166,10 +166,10 @@ public:
     }
 
     oop static_obj_field = _ik->java_mirror()->obj_field(fd->offset());
-    if (static_obj_field != NULL) {
+    if (static_obj_field != nullptr) {
       Klass* klass = static_obj_field->klass();
-      if (_exclusions != NULL) {
-        for (const char** p = _exclusions; *p != NULL; p++) {
+      if (_exclusions != nullptr) {
+        for (const char** p = _exclusions; *p != nullptr; p++) {
           if (fd->name()->equals(*p)) {
             return;
           }
@@ -228,7 +228,7 @@ inline bool CDSHeapVerifier::do_entry(oop& orig_obj, HeapShared::CachedOopInfo&
   _archived_objs++;
 
   StaticFieldInfo* info = _table.get(orig_obj);
-  if (info != NULL) {
+  if (info != nullptr) {
     ResourceMark rm;
     LogStream ls(Log(cds, heap)::warning());
     ls.print_cr("Archive heap points to a static field that may be reinitialized at runtime:");
@@ -236,7 +236,7 @@ inline bool CDSHeapVerifier::do_entry(oop& orig_obj, HeapShared::CachedOopInfo&
     ls.print("Value: ");
     orig_obj->print_on(&ls);
     ls.print_cr("--- trace begin ---");
-    trace_to_root(&ls, orig_obj, NULL, &value);
+    trace_to_root(&ls, orig_obj, nullptr, &value);
     ls.print_cr("--- trace end ---");
     ls.cr();
     _problems ++;
@@ -267,8 +267,8 @@ public:
 // Call this function (from gdb, etc) if you want to know why an object is archived.
 void CDSHeapVerifier::trace_to_root(outputStream* st, oop orig_obj) {
   HeapShared::CachedOopInfo* info = HeapShared::archived_object_cache()->get(orig_obj);
-  if (info != NULL) {
-    trace_to_root(st, orig_obj, NULL, info);
+  if (info != nullptr) {
+    trace_to_root(st, orig_obj, nullptr, info);
   } else {
     st->print_cr("Not an archived object??");
   }
@@ -276,9 +276,9 @@ void CDSHeapVerifier::trace_to_root(outputStream* st, oop orig_obj) {
 
 int CDSHeapVerifier::trace_to_root(outputStream* st, oop orig_obj, oop orig_field, HeapShared::CachedOopInfo* info) {
   int level = 0;
-  if (info->_referrer != NULL) {
+  if (info->_referrer != nullptr) {
     HeapShared::CachedOopInfo* ref = HeapShared::archived_object_cache()->get(info->_referrer);
-    assert(ref != NULL, "sanity");
+    assert(ref != nullptr, "sanity");
     level = trace_to_root(st, info->_referrer, orig_obj, ref) + 1;
   } else if (java_lang_String::is_instance(orig_obj)) {
     st->print_cr("[%2d] (shared string table)", level++);
@@ -288,7 +288,7 @@ int CDSHeapVerifier::trace_to_root(outputStream* st, oop orig_obj, oop orig_fiel
   st->print("[%2d] ", level);
   orig_obj->print_address_on(st);
   st->print(" %s", k->internal_name());
-  if (orig_field != NULL) {
+  if (orig_field != nullptr) {
     if (k->is_instance_klass()) {
       TraceFields clo(orig_obj, orig_field, st);
       InstanceKlass::cast(k)->do_nonstatic_fields(&clo);
diff --git a/src/hotspot/share/cds/cdsHeapVerifier.hpp b/src/hotspot/share/cds/cdsHeapVerifier.hpp
index 648ef8dd7f3..2a68fccf038 100644
--- a/src/hotspot/share/cds/cdsHeapVerifier.hpp
+++ b/src/hotspot/share/cds/cdsHeapVerifier.hpp
@@ -67,7 +67,7 @@ class CDSHeapVerifier : public KlassClosure {
         return &excl[1];
       }
     }
-    return NULL;
+    return nullptr;
   }
   static int trace_to_root(outputStream* st, oop orig_obj, oop orig_field, HeapShared::CachedOopInfo* p);
 
diff --git a/src/hotspot/share/cds/cdsProtectionDomain.cpp b/src/hotspot/share/cds/cdsProtectionDomain.cpp
index 6992fd0d5dc..d1020b992e5 100644
--- a/src/hotspot/share/cds/cdsProtectionDomain.cpp
+++ b/src/hotspot/share/cds/cdsProtectionDomain.cpp
@@ -58,7 +58,7 @@ Handle CDSProtectionDomain::init_security_info(Handle class_loader, InstanceKlas
     //   for fast access by the VM.
     // all packages from module image are already created during VM bootstrap in
     // Modules::define_module().
-    assert(pkg_entry != NULL, "archived class in module image cannot be from unnamed package");
+    assert(pkg_entry != nullptr, "archived class in module image cannot be from unnamed package");
     ModuleEntry* mod_entry = pkg_entry->module();
     return get_shared_protection_domain(class_loader, mod_entry, THREAD);
   } else {
@@ -83,17 +83,17 @@ Handle CDSProtectionDomain::init_security_info(Handle class_loader, InstanceKlas
     //     url = _shared_jar_urls[index];
     //     define_shared_package(class_name, class_loader, manifest, url, CHECK_NH);
     //
-    //   Note that if an element of these 3 _shared_xxx arrays is NULL, it will be initialized by
+    //   Note that if an element of these 3 _shared_xxx arrays is null, it will be initialized by
     //   the corresponding SystemDictionaryShared::get_shared_xxx() function.
     Handle manifest = get_shared_jar_manifest(index, CHECK_NH);
     Handle url = get_shared_jar_url(index, CHECK_NH);
     int index_offset = index - ClassLoaderExt::app_class_paths_start_index();
     if (index_offset < PackageEntry::max_index_for_defined_in_class_path()) {
-      if (pkg_entry == NULL || !pkg_entry->is_defined_by_cds_in_class_path(index_offset)) {
+      if (pkg_entry == nullptr || !pkg_entry->is_defined_by_cds_in_class_path(index_offset)) {
         // define_shared_package only needs to be called once for each package in a jar specified
         // in the shared class path.
         define_shared_package(class_name, class_loader, manifest, url, CHECK_NH);
-        if (pkg_entry != NULL) {
+        if (pkg_entry != nullptr) {
           pkg_entry->set_defined_by_cds_in_class_path(index_offset);
         }
       }
@@ -108,7 +108,7 @@ Handle CDSProtectionDomain::get_package_name(Symbol* class_name, TRAPS) {
   ResourceMark rm(THREAD);
   Handle pkgname_string;
   TempNewSymbol pkg = ClassLoader::package_from_class_name(class_name);
-  if (pkg != NULL) { // Package prefix found
+  if (pkg != nullptr) { // Package prefix found
     const char* pkgname = pkg->as_klass_external_name();
     pkgname_string = java_lang_String::create_from_str(pkgname,
                                                        CHECK_(pkgname_string));
@@ -118,17 +118,17 @@ Handle CDSProtectionDomain::get_package_name(Symbol* class_name, TRAPS) {
 
 PackageEntry* CDSProtectionDomain::get_package_entry_from_class(InstanceKlass* ik, Handle class_loader) {
   PackageEntry* pkg_entry = ik->package();
-  if (MetaspaceShared::use_full_module_graph() && ik->is_shared() && pkg_entry != NULL) {
+  if (MetaspaceShared::use_full_module_graph() && ik->is_shared() && pkg_entry != nullptr) {
     assert(MetaspaceShared::is_in_shared_metaspace(pkg_entry), "must be");
     assert(!ik->is_shared_unregistered_class(), "unexpected archived package entry for an unregistered class");
     assert(ik->module()->is_named(), "unexpected archived package entry for a class in an unnamed module");
     return pkg_entry;
   }
   TempNewSymbol pkg_name = ClassLoader::package_from_class_name(ik->name());
-  if (pkg_name != NULL) {
+  if (pkg_name != nullptr) {
     pkg_entry = ClassLoaderData::class_loader_data(class_loader())->packages()->lookup_only(pkg_name);
   } else {
-    pkg_entry = NULL;
+    pkg_entry = nullptr;
   }
   return pkg_entry;
 }
@@ -142,7 +142,7 @@ void CDSProtectionDomain::define_shared_package(Symbol*  class_name,
                                                    Handle url,
                                                    TRAPS) {
   assert(SystemDictionary::is_system_class_loader(class_loader()), "unexpected class loader");
-  // get_package_name() returns a NULL handle if the class is in unnamed package
+  // get_package_name() returns a null handle if the class is in unnamed package
   Handle pkgname_string = get_package_name(class_name, CHECK);
   if (pkgname_string.not_null()) {
     Klass* app_classLoader_klass = vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass();
@@ -177,7 +177,7 @@ Handle CDSProtectionDomain::create_jar_manifest(const char* manifest_chars, size
 
 Handle CDSProtectionDomain::get_shared_jar_manifest(int shared_path_index, TRAPS) {
   Handle manifest;
-  if (shared_jar_manifest(shared_path_index) == NULL) {
+  if (shared_jar_manifest(shared_path_index) == nullptr) {
     SharedClassPathEntry* ent = FileMapInfo::shared_path(shared_path_index);
     size_t size = (size_t)ent->manifest_size();
     if (size == 0) {
@@ -186,7 +186,7 @@ Handle CDSProtectionDomain::get_shared_jar_manifest(int shared_path_index, TRAPS
 
     // ByteArrayInputStream bais = new ByteArrayInputStream(buf);
     const char* src = ent->manifest();
-    assert(src != NULL, "No Manifest data");
+    assert(src != nullptr, "No Manifest data");
     manifest = create_jar_manifest(src, size, CHECK_NH);
     atomic_set_shared_jar_manifest(shared_path_index, manifest());
   }
@@ -197,7 +197,7 @@ Handle CDSProtectionDomain::get_shared_jar_manifest(int shared_path_index, TRAPS
 
 Handle CDSProtectionDomain::get_shared_jar_url(int shared_path_index, TRAPS) {
   Handle url_h;
-  if (shared_jar_url(shared_path_index) == NULL) {
+  if (shared_jar_url(shared_path_index) == nullptr) {
     JavaValue result(T_OBJECT);
     const char* path = FileMapInfo::shared_path_name(shared_path_index);
     Handle path_string = java_lang_String::create_from_str(path, CHECK_(url_h));
@@ -240,7 +240,7 @@ Handle CDSProtectionDomain::get_shared_protection_domain(Handle class_loader,
                                                             Handle url,
                                                             TRAPS) {
   Handle protection_domain;
-  if (shared_protection_domain(shared_path_index) == NULL) {
+  if (shared_protection_domain(shared_path_index) == nullptr) {
     Handle pd = get_protection_domain_from_classloader(class_loader, url, THREAD);
     atomic_set_shared_protection_domain(shared_path_index, pd());
   }
@@ -257,9 +257,9 @@ Handle CDSProtectionDomain::get_shared_protection_domain(Handle class_loader,
 Handle CDSProtectionDomain::get_shared_protection_domain(Handle class_loader,
                                                          ModuleEntry* mod, TRAPS) {
   ClassLoaderData *loader_data = mod->loader_data();
-  if (mod->shared_protection_domain() == NULL) {
+  if (mod->shared_protection_domain() == nullptr) {
     Symbol* location = mod->location();
-    if (location != NULL) {
+    if (location != nullptr) {
       Handle location_string = java_lang_String::create_from_symbol(
                                      location, CHECK_NH);
       Handle url;
@@ -301,7 +301,7 @@ oop CDSProtectionDomain::shared_protection_domain(int index) {
 }
 
 void CDSProtectionDomain::allocate_shared_protection_domain_array(int size, TRAPS) {
-  if (_shared_protection_domains.resolve() == NULL) {
+  if (_shared_protection_domains.resolve() == nullptr) {
     oop spd = oopFactory::new_objArray(
         vmClasses::ProtectionDomain_klass(), size, CHECK);
     _shared_protection_domains = OopHandle(Universe::vm_global(), spd);
@@ -313,7 +313,7 @@ oop CDSProtectionDomain::shared_jar_url(int index) {
 }
 
 void CDSProtectionDomain::allocate_shared_jar_url_array(int size, TRAPS) {
-  if (_shared_jar_urls.resolve() == NULL) {
+  if (_shared_jar_urls.resolve() == nullptr) {
     oop sju = oopFactory::new_objArray(
         vmClasses::URL_klass(), size, CHECK);
     _shared_jar_urls = OopHandle(Universe::vm_global(), sju);
@@ -325,7 +325,7 @@ oop CDSProtectionDomain::shared_jar_manifest(int index) {
 }
 
 void CDSProtectionDomain::allocate_shared_jar_manifest_array(int size, TRAPS) {
-  if (_shared_jar_manifests.resolve() == NULL) {
+  if (_shared_jar_manifests.resolve() == nullptr) {
     oop sjm = oopFactory::new_objArray(
         vmClasses::Jar_Manifest_klass(), size, CHECK);
     _shared_jar_manifests = OopHandle(Universe::vm_global(), sjm);
diff --git a/src/hotspot/share/cds/cds_globals.hpp b/src/hotspot/share/cds/cds_globals.hpp
index aad48c5fac3..4f427d60876 100644
--- a/src/hotspot/share/cds/cds_globals.hpp
+++ b/src/hotspot/share/cds/cds_globals.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2023, 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
@@ -57,7 +57,7 @@
           "Address to allocate shared memory region for class data")        \
           range(0, SIZE_MAX)                                                \
                                                                             \
-  product(ccstr, SharedArchiveConfigFile, NULL,                             \
+  product(ccstr, SharedArchiveConfigFile, nullptr,                             \
           "Data to add to the CDS archive file")                            \
                                                                             \
   product(uint, SharedSymbolTableBucketSize, 4,                             \
@@ -67,25 +67,25 @@
   product(bool, AllowArchivingWithJavaAgent, false, DIAGNOSTIC,             \
           "Allow Java agent to be run with CDS dumping")                    \
                                                                             \
-  develop(ccstr, ArchiveHeapTestClass, NULL,                                \
+  develop(ccstr, ArchiveHeapTestClass, nullptr,                                \
           "For JVM internal testing only. The static field named "          \
           "\"archivedObjects\" of the specified class is stored in the "    \
           "CDS archive heap")                                               \
                                                                             \
-  product(ccstr, DumpLoadedClassList, NULL,                                 \
+  product(ccstr, DumpLoadedClassList, nullptr,                                 \
           "Dump the names all loaded classes, that could be stored into "   \
           "the CDS archive, in the specified file")                         \
                                                                             \
-  product(ccstr, SharedClassListFile, NULL,                                 \
+  product(ccstr, SharedClassListFile, nullptr,                                 \
           "Override the default CDS class list")                            \
                                                                             \
-  product(ccstr, SharedArchiveFile, NULL,                                   \
+  product(ccstr, SharedArchiveFile, nullptr,                                   \
           "Override the default location of the CDS archive file")          \
                                                                             \
-  product(ccstr, ArchiveClassesAtExit, NULL,                                \
+  product(ccstr, ArchiveClassesAtExit, nullptr,                                \
           "The path and name of the dynamic archive file")                  \
                                                                             \
-  product(ccstr, ExtraSharedClassListFile, NULL,                            \
+  product(ccstr, ExtraSharedClassListFile, nullptr,                            \
           "Extra classlist for building the CDS archive file")              \
                                                                             \
   product(int, ArchiveRelocationMode, 0, DIAGNOSTIC,                        \
diff --git a/src/hotspot/share/cds/classListParser.cpp b/src/hotspot/share/cds/classListParser.cpp
index 4243c9635a6..753fe7507ea 100644
--- a/src/hotspot/share/cds/classListParser.cpp
+++ b/src/hotspot/share/cds/classListParser.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2023, 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
@@ -51,14 +51,14 @@
 #include "utilities/defaultStream.hpp"
 #include "utilities/macros.hpp"
 
-volatile Thread* ClassListParser::_parsing_thread = NULL;
-ClassListParser* ClassListParser::_instance = NULL;
+volatile Thread* ClassListParser::_parsing_thread = nullptr;
+ClassListParser* ClassListParser::_instance = nullptr;
 
 ClassListParser::ClassListParser(const char* file, ParseMode parse_mode) : _id2klass_table(INITIAL_TABLE_SIZE, MAX_TABLE_SIZE) {
   log_info(cds)("Parsing %s%s", file,
                 (parse_mode == _parse_lambda_forms_invokers_only) ? " (lambda form invokers only)" : "");
   _classlist_file = file;
-  _file = NULL;
+  _file = nullptr;
   // Use os::open() because neither fopen() nor os::fopen()
   // can handle long path name on Windows.
   int fd = os::open(file, O_RDONLY, S_IREAD);
@@ -67,7 +67,7 @@ ClassListParser::ClassListParser(const char* file, ParseMode parse_mode) : _id2k
     // can be used in parse_one_line()
     _file = os::fdopen(fd, "r");
   }
-  if (_file == NULL) {
+  if (_file == nullptr) {
     char errmsg[JVM_MAXPATHLEN];
     os::lasterror(errmsg, JVM_MAXPATHLEN);
     vm_exit_during_initialization("Loading classlist failed", errmsg);
@@ -78,7 +78,7 @@ ClassListParser::ClassListParser(const char* file, ParseMode parse_mode) : _id2k
   _parse_mode = parse_mode;
 
   // _instance should only be accessed by the thread that created _instance.
-  assert(_instance == NULL, "must be singleton");
+  assert(_instance == nullptr, "must be singleton");
   _instance = this;
   Atomic::store(&_parsing_thread, Thread::current());
 }
@@ -88,13 +88,13 @@ bool ClassListParser::is_parsing_thread() {
 }
 
 ClassListParser::~ClassListParser() {
-  if (_file != NULL) {
+  if (_file != nullptr) {
     fclose(_file);
   }
-  Atomic::store(&_parsing_thread, (Thread*)NULL);
+  Atomic::store(&_parsing_thread, (Thread*)nullptr);
   delete _indy_items;
   delete _interfaces;
-  _instance = NULL;
+  _instance = nullptr;
 }
 
 int ClassListParser::parse(TRAPS) {
@@ -130,7 +130,7 @@ int ClassListParser::parse(TRAPS) {
       ResourceMark rm(THREAD);
       char* ex_msg = (char*)"";
       oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
-      if (message != NULL) {
+      if (message != nullptr) {
         ex_msg = java_lang_String::as_utf8_string(message);
       }
       log_warning(cds)("%s: %s", PENDING_EXCEPTION->klass()->external_name(), ex_msg);
@@ -141,7 +141,7 @@ int ClassListParser::parse(TRAPS) {
       continue;
     }
 
-    assert(klass != NULL, "sanity");
+    assert(klass != nullptr, "sanity");
     if (log_is_enabled(Trace, cds)) {
       ResourceMark rm(THREAD);
       log_trace(cds)("Shared spaces preloaded: %s", klass->external_name());
@@ -165,7 +165,7 @@ int ClassListParser::parse(TRAPS) {
 
 bool ClassListParser::parse_one_line() {
   for (;;) {
-    if (fgets(_line, sizeof(_line), _file) == NULL) {
+    if (fgets(_line, sizeof(_line), _file) == nullptr) {
       return false;
     }
     ++ _line_no;
@@ -207,7 +207,7 @@ bool ClassListParser::parse_one_line() {
   _id = _unspecified;
   _super = _unspecified;
   _interfaces->clear();
-  _source = NULL;
+  _source = nullptr;
   _interfaces_specified = false;
   _indy_items->clear();
   _lambda_form_line = false;
@@ -216,7 +216,7 @@ bool ClassListParser::parse_one_line() {
     return parse_at_tags();
   }
 
-  if ((_token = strchr(_line, ' ')) == NULL) {
+  if ((_token = strchr(_line, ' ')) == nullptr) {
     // No optional arguments are specified.
     return true;
   }
@@ -242,7 +242,7 @@ bool ClassListParser::parse_one_line() {
       skip_whitespaces();
       _source = _token;
       char* s = strchr(_token, ' ');
-      if (s == NULL) {
+      if (s == nullptr) {
         break; // end of input line
       } else {
         *s = '\0'; // mark the end of _source
@@ -284,7 +284,7 @@ void ClassListParser::split_tokens_by_whitespace(int offset) {
 int ClassListParser::split_at_tag_from_line() {
   _token = _line;
   char* ptr;
-  if ((ptr = strchr(_line, ' ')) == NULL) {
+  if ((ptr = strchr(_line, ' ')) == nullptr) {
     error("Too few items following the @ tag \"%s\" line #%d", _line, _line_no);
     return 0;
   }
@@ -445,7 +445,7 @@ void ClassListParser::error(const char* msg, ...) {
     jio_fprintf(defaultStream::error_stream(), "^\n");
   }
 
-  vm_exit_during_initialization("class list format error.", NULL);
+  vm_exit_during_initialization("class list format error.", nullptr);
   va_end(ap);
 }
 
@@ -544,7 +544,7 @@ void ClassListParser::resolve_indy(JavaThread* current, Symbol* class_name_symbo
     ResourceMark rm(current);
     char* ex_msg = (char*)"";
     oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
-    if (message != NULL) {
+    if (message != nullptr) {
       ex_msg = java_lang_String::as_utf8_string(message);
     }
     log_warning(cds)("resolve_indy for class %s has encountered exception: %s %s",
@@ -640,7 +640,7 @@ Klass* ClassListParser::load_current_class(Symbol* class_name_symbol, TRAPS) {
 
     assert(result.get_type() == T_OBJECT, "just checking");
     oop obj = result.get_oop();
-    assert(obj != NULL, "jdk.internal.loader.BuiltinClassLoader::loadClass never returns null");
+    assert(obj != nullptr, "jdk.internal.loader.BuiltinClassLoader::loadClass never returns null");
     klass = java_lang_Class::as_Klass(obj);
   } else {
     // If "source:" tag is specified, all super class and super interfaces must be specified in the
@@ -648,7 +648,7 @@ Klass* ClassListParser::load_current_class(Symbol* class_name_symbol, TRAPS) {
     klass = load_class_from_source(class_name_symbol, CHECK_NULL);
   }
 
-  assert(klass != NULL, "exception should have been thrown");
+  assert(klass != nullptr, "exception should have been thrown");
   assert(klass->is_instance_klass(), "array classes should have been filtered out");
 
   if (is_id_specified()) {
@@ -669,22 +669,22 @@ Klass* ClassListParser::load_current_class(Symbol* class_name_symbol, TRAPS) {
 }
 
 bool ClassListParser::is_loading_from_source() {
-  return (_source != NULL);
+  return (_source != nullptr);
 }
 
 InstanceKlass* ClassListParser::lookup_class_by_id(int id) {
   InstanceKlass** klass_ptr = id2klass_table()->get(id);
-  if (klass_ptr == NULL) {
+  if (klass_ptr == nullptr) {
     error("Class ID %d has not been defined", id);
   }
-  assert(*klass_ptr != NULL, "must be");
+  assert(*klass_ptr != nullptr, "must be");
   return *klass_ptr;
 }
 
 
 InstanceKlass* ClassListParser::lookup_super_for_current_class(Symbol* super_name) {
   if (!is_loading_from_source()) {
-    return NULL;
+    return nullptr;
   }
 
   InstanceKlass* k = lookup_class_by_id(super());
@@ -698,7 +698,7 @@ InstanceKlass* ClassListParser::lookup_super_for_current_class(Symbol* super_nam
 
 InstanceKlass* ClassListParser::lookup_interface_for_current_class(Symbol* interface_name) {
   if (!is_loading_from_source()) {
-    return NULL;
+    return nullptr;
   }
 
   const int n = _interfaces->length();
@@ -721,5 +721,5 @@ InstanceKlass* ClassListParser::lookup_interface_for_current_class(Symbol* inter
   error("The interface %s implemented by class %s does not match any of the specified interface IDs",
         interface_name->as_klass_external_name(), _class_name);
   ShouldNotReachHere();
-  return NULL;
+  return nullptr;
 }
diff --git a/src/hotspot/share/cds/classListParser.hpp b/src/hotspot/share/cds/classListParser.hpp
index a13aaa34228..74a2ff10515 100644
--- a/src/hotspot/share/cds/classListParser.hpp
+++ b/src/hotspot/share/cds/classListParser.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2023, 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
@@ -39,12 +39,12 @@ class Thread;
 class CDSIndyInfo {
   GrowableArray<const char*>* _items;
 public:
-  CDSIndyInfo() : _items(NULL) {}
+  CDSIndyInfo() : _items(nullptr) {}
   void add_item(const char* item) {
-    if (_items == NULL) {
+    if (_items == nullptr) {
       _items = new GrowableArray<const char*>(9);
     }
-    assert(_items != NULL, "sanity");
+    assert(_items != nullptr, "sanity");
     _items->append(item);
   }
   void add_ref_kind(int ref_kind) {
@@ -144,7 +144,7 @@ public:
   static bool is_parsing_thread();
   static ClassListParser* instance() {
     assert(is_parsing_thread(), "call this only in the thread that created ClassListParsing::_instance");
-    assert(_instance != NULL, "must be");
+    assert(_instance != nullptr, "must be");
     return _instance;
   }
 
diff --git a/src/hotspot/share/cds/classListWriter.cpp b/src/hotspot/share/cds/classListWriter.cpp
index 2615bc8ae4b..bd178a029d7 100644
--- a/src/hotspot/share/cds/classListWriter.cpp
+++ b/src/hotspot/share/cds/classListWriter.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2023, 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
@@ -34,12 +34,12 @@
 #include "oops/instanceKlass.hpp"
 #include "runtime/mutexLocker.hpp"
 
-fileStream* ClassListWriter::_classlist_file = NULL;
+fileStream* ClassListWriter::_classlist_file = nullptr;
 
 void ClassListWriter::init() {
   // For -XX:DumpLoadedClassList=<file> option
-  if (DumpLoadedClassList != NULL) {
-    const char* list_name = make_log_name(DumpLoadedClassList, NULL);
+  if (DumpLoadedClassList != nullptr) {
+    const char* list_name = make_log_name(DumpLoadedClassList, nullptr);
     _classlist_file = new(mtInternal)
                          fileStream(list_name);
     _classlist_file->print_cr("# NOTE: Do not modify this file.");
@@ -56,7 +56,7 @@ void ClassListWriter::write(const InstanceKlass* k, const ClassFileStream* cfs)
 
   if (!ClassLoader::has_jrt_entry()) {
     warning("DumpLoadedClassList and CDS are not supported in exploded build");
-    DumpLoadedClassList = NULL;
+    DumpLoadedClassList = nullptr;
     return;
   }
 
@@ -69,12 +69,12 @@ class ClassListWriter::IDTable : public ResourceHashtable<
   15889, // prime number
   AnyObj::C_HEAP> {};
 
-ClassListWriter::IDTable* ClassListWriter::_id_table = NULL;
+ClassListWriter::IDTable* ClassListWriter::_id_table = nullptr;
 int ClassListWriter::_total_ids = 0;
 
 int ClassListWriter::get_id(const InstanceKlass* k) {
   assert_locked();
-  if (_id_table == NULL) {
+  if (_id_table == nullptr) {
     _id_table = new (mtClass)IDTable();
   }
   bool created;
@@ -87,8 +87,8 @@ int ClassListWriter::get_id(const InstanceKlass* k) {
 
 bool ClassListWriter::has_id(const InstanceKlass* k) {
   assert_locked();
-  if (_id_table != NULL) {
-    return _id_table->get(k) != NULL;
+  if (_id_table != nullptr) {
+    return _id_table->get(k) != nullptr;
   } else {
     return false;
   }
@@ -96,7 +96,7 @@ bool ClassListWriter::has_id(const InstanceKlass* k) {
 
 void ClassListWriter::handle_class_unloading(const InstanceKlass* klass) {
   assert_locked();
-  if (_id_table != NULL) {
+  if (_id_table != nullptr) {
     _id_table->remove(klass);
   }
 }
@@ -132,7 +132,7 @@ void ClassListWriter::write_to_stream(const InstanceKlass* k, outputStream* stre
 
   {
     InstanceKlass* super = k->java_super();
-    if (super != NULL && !has_id(super)) {
+    if (super != nullptr && !has_id(super)) {
       return;
     }
 
@@ -158,7 +158,7 @@ void ClassListWriter::write_to_stream(const InstanceKlass* k, outputStream* stre
   stream->print("%s id: %d", k->name()->as_C_string(), get_id(k));
   if (!is_builtin_loader) {
     InstanceKlass* super = k->java_super();
-    assert(super != NULL, "must be");
+    assert(super != nullptr, "must be");
     stream->print(" super: %d", get_id(super));
 
     Array<InstanceKlass*>* interfaces = k->local_interfaces();
@@ -185,7 +185,7 @@ void ClassListWriter::write_to_stream(const InstanceKlass* k, outputStream* stre
 }
 
 void ClassListWriter::delete_classlist() {
-  if (_classlist_file != NULL) {
+  if (_classlist_file != nullptr) {
     delete _classlist_file;
   }
 }
diff --git a/src/hotspot/share/cds/classListWriter.hpp b/src/hotspot/share/cds/classListWriter.hpp
index 1e42c5fcc74..a6c749fea7c 100644
--- a/src/hotspot/share/cds/classListWriter.hpp
+++ b/src/hotspot/share/cds/classListWriter.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2023, 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
@@ -52,7 +52,7 @@ public:
   void handle_class_unloading(const InstanceKlass* klass);
 
   static bool is_enabled() {
-    return _classlist_file != NULL && _classlist_file->is_open();
+    return _classlist_file != nullptr && _classlist_file->is_open();
   }
 
 #else
@@ -65,7 +65,7 @@ public:
 
   static void init() NOT_CDS_RETURN;
   static void write(const InstanceKlass* k, const ClassFileStream* cfs) NOT_CDS_RETURN;
-  static void write_to_stream(const InstanceKlass* k, outputStream* stream, const ClassFileStream* cfs = NULL) NOT_CDS_RETURN;
+  static void write_to_stream(const InstanceKlass* k, outputStream* stream, const ClassFileStream* cfs = nullptr) NOT_CDS_RETURN;
   static void delete_classlist() NOT_CDS_RETURN;
 };
 
diff --git a/src/hotspot/share/cds/classPrelinker.cpp b/src/hotspot/share/cds/classPrelinker.cpp
index 91a1bf9b2e5..fca04e7fe21 100644
--- a/src/hotspot/share/cds/classPrelinker.cpp
+++ b/src/hotspot/share/cds/classPrelinker.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2023, 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
@@ -33,11 +33,11 @@
 #include "oops/klass.inline.hpp"
 #include "runtime/handles.inline.hpp"
 
-ClassPrelinker::ClassesTable* ClassPrelinker::_processed_classes = NULL;
-ClassPrelinker::ClassesTable* ClassPrelinker::_vm_classes = NULL;
+ClassPrelinker::ClassesTable* ClassPrelinker::_processed_classes = nullptr;
+ClassPrelinker::ClassesTable* ClassPrelinker::_vm_classes = nullptr;
 
 bool ClassPrelinker::is_vm_class(InstanceKlass* ik) {
-  return (_vm_classes->get(ik) != NULL);
+  return (_vm_classes->get(ik) != nullptr);
 }
 
 void ClassPrelinker::add_one_vm_class(InstanceKlass* ik) {
@@ -45,7 +45,7 @@ void ClassPrelinker::add_one_vm_class(InstanceKlass* ik) {
   _vm_classes->put_if_absent(ik, &created);
   if (created) {
     InstanceKlass* super = ik->java_super();
-    if (super != NULL) {
+    if (super != nullptr) {
       add_one_vm_class(super);
     }
     Array<InstanceKlass*>* ifs = ik->local_interfaces();
@@ -56,7 +56,7 @@ void ClassPrelinker::add_one_vm_class(InstanceKlass* ik) {
 }
 
 void ClassPrelinker::initialize() {
-  assert(_vm_classes == NULL, "must be");
+  assert(_vm_classes == nullptr, "must be");
   _vm_classes = new (mtClass)ClassesTable();
   _processed_classes = new (mtClass)ClassesTable();
   for (auto id : EnumRange<vmClassID>{}) {
@@ -65,11 +65,11 @@ void ClassPrelinker::initialize() {
 }
 
 void ClassPrelinker::dispose() {
-  assert(_vm_classes != NULL, "must be");
+  assert(_vm_classes != nullptr, "must be");
   delete _vm_classes;
   delete _processed_classes;
-  _vm_classes = NULL;
-  _processed_classes = NULL;
+  _vm_classes = nullptr;
+  _processed_classes = nullptr;
 }
 
 bool ClassPrelinker::can_archive_resolved_klass(ConstantPool* cp, int cp_index) {
@@ -77,7 +77,7 @@ bool ClassPrelinker::can_archive_resolved_klass(ConstantPool* cp, int cp_index)
   assert(cp->tag_at(cp_index).is_klass(), "must be resolved");
 
   Klass* resolved_klass = cp->resolved_klass_at(cp_index);
-  assert(resolved_klass != NULL, "must be");
+  assert(resolved_klass != nullptr, "must be");
 
   return can_archive_resolved_klass(cp->pool_holder(), resolved_klass);
 }
@@ -115,8 +115,8 @@ bool ClassPrelinker::can_archive_resolved_klass(InstanceKlass* cp_holder, Klass*
 
 void ClassPrelinker::dumptime_resolve_constants(InstanceKlass* ik, TRAPS) {
   constantPoolHandle cp(THREAD, ik->constants());
-  if (cp->cache() == NULL || cp->reference_map() == NULL) {
-    // The cache may be NULL if the pool_holder klass fails verification
+  if (cp->cache() == nullptr || cp->reference_map() == nullptr) {
+    // The cache may be null if the pool_holder klass fails verification
     // at dump time due to missing dependencies.
     return;
   }
@@ -146,16 +146,16 @@ Klass* ClassPrelinker::find_loaded_class(JavaThread* THREAD, oop class_loader, S
   Klass* k = SystemDictionary::find_instance_or_array_klass(THREAD, name,
                                                             h_loader,
                                                             Handle());
-  if (k != NULL) {
+  if (k != nullptr) {
     return k;
   }
   if (class_loader == SystemDictionary::java_system_loader()) {
     return find_loaded_class(THREAD, SystemDictionary::java_platform_loader(), name);
   } else if (class_loader == SystemDictionary::java_platform_loader()) {
-    return find_loaded_class(THREAD, NULL, name);
+    return find_loaded_class(THREAD, nullptr, name);
   }
 
-  return NULL;
+  return nullptr;
 }
 
 Klass* ClassPrelinker::maybe_resolve_class(constantPoolHandle cp, int cp_index, TRAPS) {
@@ -166,12 +166,12 @@ Klass* ClassPrelinker::maybe_resolve_class(constantPoolHandle cp, int cp_index,
       !cp_holder->is_shared_app_class()) {
     // Don't trust custom loaders, as they may not be well-behaved
     // when resolving classes.
-    return NULL;
+    return nullptr;
   }
 
   Symbol* name = cp->klass_name_at(cp_index);
   Klass* resolved_klass = find_loaded_class(THREAD, cp_holder->class_loader(), name);
-  if (resolved_klass != NULL && can_archive_resolved_klass(cp_holder, resolved_klass)) {
+  if (resolved_klass != nullptr && can_archive_resolved_klass(cp_holder, resolved_klass)) {
     Klass* k = cp->klass_at(cp_index, CHECK_NULL); // Should fail only with OOM
     assert(k == resolved_klass, "must be");
   }
@@ -193,7 +193,7 @@ void ClassPrelinker::resolve_string(constantPoolHandle cp, int cp_index, TRAPS)
 
 #ifdef ASSERT
 bool ClassPrelinker::is_in_archivebuilder_buffer(address p) {
-  if (!Thread::current()->is_VM_thread() || ArchiveBuilder::current() == NULL) {
+  if (!Thread::current()->is_VM_thread() || ArchiveBuilder::current() == nullptr) {
     return false;
   } else {
     return ArchiveBuilder::current()->is_in_buffer_space(p);
diff --git a/src/hotspot/share/cds/cppVtables.cpp b/src/hotspot/share/cds/cppVtables.cpp
index cf8c4d13049..d91c930f17c 100644
--- a/src/hotspot/share/cds/cppVtables.cpp
+++ b/src/hotspot/share/cds/cppVtables.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2023, 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
@@ -126,7 +126,7 @@ void CppVtableCloner<T>::initialize(const char* name, CppVtableInfo* info) {
 // trick by declaring 2 subclasses:
 //
 //   class CppVtableTesterA: public InstanceKlass {virtual int   last_virtual_method() {return 1;}    };
-//   class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return NULL}; };
+//   class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return nullptr}; };
 //
 // CppVtableTesterA and CppVtableTesterB's vtables have the following properties:
 // - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N)
@@ -149,7 +149,7 @@ public:
   virtual void* last_virtual_method() {
     // Make this different than CppVtableTesterB::last_virtual_method so the C++
     // compiler/linker won't alias the two functions.
-    return NULL;
+    return nullptr;
   }
 };
 
@@ -212,7 +212,7 @@ void CppVtableCloner<T>::init_orig_cpp_vtptr(int kind) {
 // the following holds true:
 //     _index[ConstantPool_Kind]->cloned_vtable()  == ((intptr_t**)cp)[0]
 //     _index[InstanceKlass_Kind]->cloned_vtable() == ((intptr_t**)ik)[0]
-CppVtableInfo** CppVtables::_index = NULL;
+CppVtableInfo** CppVtables::_index = nullptr;
 
 char* CppVtables::dumptime_init(ArchiveBuilder* builder) {
   assert(DumpSharedSpaces, "must");
@@ -277,7 +277,7 @@ intptr_t* CppVtables::get_archived_vtable(MetaspaceObj::Type msotype, address ob
     assert(kind < _num_cloned_vtable_kinds, "must be");
     return _index[kind]->cloned_vtable();
   } else {
-    return NULL;
+    return nullptr;
   }
 }
 
diff --git a/src/hotspot/share/cds/dumpAllocStats.hpp b/src/hotspot/share/cds/dumpAllocStats.hpp
index 606074c0c1c..f6e170cdef2 100644
--- a/src/hotspot/share/cds/dumpAllocStats.hpp
+++ b/src/hotspot/share/cds/dumpAllocStats.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2023, 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
@@ -55,7 +55,7 @@ public:
     SHAREDSPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
     default:
       ShouldNotReachHere();
-      return NULL;
+      return nullptr;
     }
   }
 
diff --git a/src/hotspot/share/cds/dumpTimeClassInfo.cpp b/src/hotspot/share/cds/dumpTimeClassInfo.cpp
index fed09b4f94c..e7e3b5c7b56 100644
--- a/src/hotspot/share/cds/dumpTimeClassInfo.cpp
+++ b/src/hotspot/share/cds/dumpTimeClassInfo.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2023, 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
@@ -46,12 +46,12 @@ DumpTimeClassInfo::DumpTimeClassInfo(const DumpTimeClassInfo& src) {
   _clsfile_crc32 = src._clsfile_crc32;
   _excluded = src._excluded;
   _is_early_klass = src._is_early_klass;
-  _verifier_constraints = NULL;
-  _verifier_constraint_flags = NULL;
-  _loader_constraints = NULL;
+  _verifier_constraints = nullptr;
+  _verifier_constraint_flags = nullptr;
+  _loader_constraints = nullptr;
 
-  assert(src._enum_klass_static_fields == NULL, "This should not happen with dynamic dump.");
-  _enum_klass_static_fields = NULL;
+  assert(src._enum_klass_static_fields == nullptr, "This should not happen with dynamic dump.");
+  _enum_klass_static_fields = nullptr;
 
   {
     int n = src.num_verifier_constraints();
@@ -77,12 +77,12 @@ DumpTimeClassInfo::DumpTimeClassInfo(const DumpTimeClassInfo& src) {
 }
 
 DumpTimeClassInfo::~DumpTimeClassInfo() {
-  if (_verifier_constraints != NULL) {
-    assert(_verifier_constraint_flags != NULL, "must be");
+  if (_verifier_constraints != nullptr) {
+    assert(_verifier_constraint_flags != nullptr, "must be");
     delete _verifier_constraints;
     delete _verifier_constraint_flags;
   }
-  if (_loader_constraints != NULL) {
+  if (_loader_constraints != nullptr) {
     delete _loader_constraints;
   }
 }
@@ -95,10 +95,10 @@ size_t DumpTimeClassInfo::runtime_info_bytesize() const {
 
 void DumpTimeClassInfo::add_verification_constraint(InstanceKlass* k, Symbol* name,
          Symbol* from_name, bool from_field_is_protected, bool from_is_array, bool from_is_object) {
-  if (_verifier_constraints == NULL) {
+  if (_verifier_constraints == nullptr) {
     _verifier_constraints = new (mtClass) GrowableArray<DTVerifierConstraint>(4, mtClass);
   }
-  if (_verifier_constraint_flags == NULL) {
+  if (_verifier_constraint_flags == nullptr) {
     _verifier_constraint_flags = new (mtClass) GrowableArray<char>(4, mtClass);
   }
   GrowableArray<DTVerifierConstraint>* vc_array = _verifier_constraints;
@@ -140,7 +140,7 @@ static char get_loader_type_by(oop  loader) {
 void DumpTimeClassInfo::record_linking_constraint(Symbol* name, Handle loader1, Handle loader2) {
   assert(loader1 != loader2, "sanity");
   LogTarget(Info, class, loader, constraints) log;
-  if (_loader_constraints == NULL) {
+  if (_loader_constraints == nullptr) {
     _loader_constraints = new (mtClass) GrowableArray<DTLoaderConstraint>(4, mtClass);
   }
   char lt1 = get_loader_type_by(loader1());
@@ -172,14 +172,14 @@ void DumpTimeClassInfo::record_linking_constraint(Symbol* name, Handle loader1,
 }
 
 void DumpTimeClassInfo::add_enum_klass_static_field(int archived_heap_root_index) {
-  if (_enum_klass_static_fields == NULL) {
+  if (_enum_klass_static_fields == nullptr) {
     _enum_klass_static_fields = new (mtClass) GrowableArray<int>(20, mtClass);
   }
   _enum_klass_static_fields->append(archived_heap_root_index);
 }
 
 int DumpTimeClassInfo::enum_klass_static_field(int which_field) {
-  assert(_enum_klass_static_fields != NULL, "must be");
+  assert(_enum_klass_static_fields != nullptr, "must be");
   return _enum_klass_static_fields->at(which_field);
 }
 
@@ -199,7 +199,7 @@ DumpTimeClassInfo* DumpTimeSharedClassTable::allocate_info(InstanceKlass* k) {
 DumpTimeClassInfo* DumpTimeSharedClassTable::get_info(InstanceKlass* k) {
   assert(!k->is_shared(), "Do not call with shared classes");
   DumpTimeClassInfo* p = get(k);
-  assert(p != NULL, "we must not see any non-shared InstanceKlass* that's "
+  assert(p != nullptr, "we must not see any non-shared InstanceKlass* that's "
          "not stored with SystemDictionaryShared::init_dumptime_info");
   assert(p->_klass == k, "Sanity");
   return p;
diff --git a/src/hotspot/share/cds/dumpTimeClassInfo.hpp b/src/hotspot/share/cds/dumpTimeClassInfo.hpp
index 81c584b433e..9a360d662b1 100644
--- a/src/hotspot/share/cds/dumpTimeClassInfo.hpp
+++ b/src/hotspot/share/cds/dumpTimeClassInfo.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2023, 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
@@ -46,7 +46,7 @@ class DumpTimeClassInfo: public CHeapObj<mtClass> {
     char _loader_type1;
     char _loader_type2;
   public:
-    DTLoaderConstraint() : _name(NULL), _loader_type1('0'), _loader_type2('0') {}
+    DTLoaderConstraint() : _name(nullptr), _loader_type1('0'), _loader_type2('0') {}
     DTLoaderConstraint(Symbol* name, char l1, char l2) : _name(name), _loader_type1(l1), _loader_type2(l2) {
       Symbol::maybe_increment_refcount(_name);
     }
@@ -84,7 +84,7 @@ class DumpTimeClassInfo: public CHeapObj<mtClass> {
     Symbol* _name;
     Symbol* _from_name;
   public:
-    DTVerifierConstraint() : _name(NULL), _from_name(NULL) {}
+    DTVerifierConstraint() : _name(nullptr), _from_name(nullptr) {}
     DTVerifierConstraint(Symbol* n, Symbol* fn) : _name(n), _from_name(fn) {
       Symbol::maybe_increment_refcount(_name);
       Symbol::maybe_increment_refcount(_from_name);
@@ -130,8 +130,8 @@ public:
   GrowableArray<int>*                  _enum_klass_static_fields;
 
   DumpTimeClassInfo() {
-    _klass = NULL;
-    _nest_host = NULL;
+    _klass = nullptr;
+    _nest_host = nullptr;
     _failed_verification = false;
     _is_archived_lambda_proxy = false;
     _has_checked_exclusion = false;
@@ -140,10 +140,10 @@ public:
     _clsfile_crc32 = -1;
     _excluded = false;
     _is_early_klass = JvmtiExport::is_early_phase();
-    _verifier_constraints = NULL;
-    _verifier_constraint_flags = NULL;
-    _loader_constraints = NULL;
-    _enum_klass_static_fields = NULL;
+    _verifier_constraints = nullptr;
+    _verifier_constraint_flags = nullptr;
+    _loader_constraints = nullptr;
+    _enum_klass_static_fields = nullptr;
   }
   DumpTimeClassInfo(const DumpTimeClassInfo& src);
   DumpTimeClassInfo& operator=(const DumpTimeClassInfo&) = delete;
@@ -159,7 +159,7 @@ public:
 private:
   template <typename T>
   static int array_length_or_zero(GrowableArray<T>* array) {
-    if (array == NULL) {
+    if (array == nullptr) {
       return 0;
     } else {
       return array->length();
@@ -183,12 +183,12 @@ public:
   void metaspace_pointers_do(MetaspaceClosure* it) {
     it->push(&_klass);
     it->push(&_nest_host);
-    if (_verifier_constraints != NULL) {
+    if (_verifier_constraints != nullptr) {
       for (int i = 0; i < _verifier_constraints->length(); i++) {
         _verifier_constraints->adr_at(i)->metaspace_pointers_do(it);
       }
     }
-    if (_loader_constraints != NULL) {
+    if (_loader_constraints != nullptr) {
       for (int i = 0; i < _loader_constraints->length(); i++) {
         _loader_constraints->adr_at(i)->metaspace_pointers_do(it);
       }
diff --git a/src/hotspot/share/cds/dynamicArchive.cpp b/src/hotspot/share/cds/dynamicArchive.cpp
index 013979d0312..9b2b3b3e39c 100644
--- a/src/hotspot/share/cds/dynamicArchive.cpp
+++ b/src/hotspot/share/cds/dynamicArchive.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, 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
@@ -201,10 +201,10 @@ void DynamicArchiveBuilder::release_header() {
   // bad will happen.
   assert(SafepointSynchronize::is_at_safepoint(), "must be");
   FileMapInfo *mapinfo = FileMapInfo::dynamic_info();
-  assert(mapinfo != NULL && _header == mapinfo->dynamic_header(), "must be");
+  assert(mapinfo != nullptr && _header == mapinfo->dynamic_header(), "must be");
   delete mapinfo;
   assert(!DynamicArchive::is_mapped(), "must be");
-  _header = NULL;
+  _header = nullptr;
 }
 
 void DynamicArchiveBuilder::post_dump() {
@@ -225,14 +225,14 @@ void DynamicArchiveBuilder::sort_methods() {
 // The address order of the copied Symbols may be different than when the original
 // klasses were created. Re-sort all the tables. See Method::sort_methods().
 void DynamicArchiveBuilder::sort_methods(InstanceKlass* ik) const {
-  assert(ik != NULL, "DynamicArchiveBuilder currently doesn't support dumping the base archive");
+  assert(ik != nullptr, "DynamicArchiveBuilder currently doesn't support dumping the base archive");
   if (MetaspaceShared::is_in_shared_metaspace(ik)) {
     // We have reached a supertype that's already in the base archive
     return;
   }
 
-  if (ik->java_mirror() == NULL) {
-    // NULL mirror means this class has already been visited and methods are already sorted
+  if (ik->java_mirror() == nullptr) {
+    // null mirror means this class has already been visited and methods are already sorted
     return;
   }
   ik->remove_java_mirror();
@@ -257,13 +257,13 @@ void DynamicArchiveBuilder::sort_methods(InstanceKlass* ik) const {
   }
 
 #ifdef ASSERT
-  if (ik->methods() != NULL) {
+  if (ik->methods() != nullptr) {
     for (int m = 0; m < ik->methods()->length(); m++) {
       Symbol* name = ik->methods()->at(m)->name();
       assert(MetaspaceShared::is_in_shared_metaspace(name) || is_in_buffer_space(name), "must be");
     }
   }
-  if (ik->default_methods() != NULL) {
+  if (ik->default_methods() != nullptr) {
     for (int m = 0; m < ik->default_methods()->length(); m++) {
       Symbol* name = ik->default_methods()->at(m)->name();
       assert(MetaspaceShared::is_in_shared_metaspace(name) || is_in_buffer_space(name), "must be");
@@ -272,7 +272,7 @@ void DynamicArchiveBuilder::sort_methods(InstanceKlass* ik) const {
 #endif
 
   Method::sort_methods(ik->methods(), /*set_idnums=*/true, dynamic_dump_method_comparator);
-  if (ik->default_methods() != NULL) {
+  if (ik->default_methods() != nullptr) {
     Method::sort_methods(ik->default_methods(), /*set_idnums=*/false, dynamic_dump_method_comparator);
   }
   if (ik->is_linked()) {
@@ -320,10 +320,10 @@ void DynamicArchiveBuilder::write_archive(char* serialized_data) {
   _header->set_serialized_data(serialized_data);
 
   FileMapInfo* dynamic_info = FileMapInfo::dynamic_info();
-  assert(dynamic_info != NULL, "Sanity");
+  assert(dynamic_info != nullptr, "Sanity");
 
   dynamic_info->open_for_write();
-  ArchiveBuilder::write_archive(dynamic_info, NULL, NULL, NULL, NULL);
+  ArchiveBuilder::write_archive(dynamic_info, nullptr, nullptr, nullptr, nullptr);
 
   address base = _requested_dynamic_archive_bottom;
   address top  = _requested_dynamic_archive_top;
@@ -367,7 +367,7 @@ void DynamicArchive::check_for_dynamic_dump() {
 
 #define __THEMSG " is unsupported when base CDS archive is not loaded. Run with -Xlog:cds for more info."
     if (RecordDynamicDumpInfo) {
-      vm_exit_during_initialization("-XX:+RecordDynamicDumpInfo" __THEMSG, NULL);
+      vm_exit_during_initialization("-XX:+RecordDynamicDumpInfo" __THEMSG, nullptr);
     } else {
       assert(ArchiveClassesAtExit != nullptr, "sanity");
       warning("-XX:ArchiveClassesAtExit" __THEMSG);
diff --git a/src/hotspot/share/cds/dynamicArchive.hpp b/src/hotspot/share/cds/dynamicArchive.hpp
index 125fed3ab88..a56b91af69a 100644
--- a/src/hotspot/share/cds/dynamicArchive.hpp
+++ b/src/hotspot/share/cds/dynamicArchive.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, 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
@@ -63,7 +63,7 @@ public:
   static void prepare_for_dump_at_exit();
   static void dump_for_jcmd(const char* archive_name, TRAPS);
   static void dump(const char* archive_name, TRAPS);
-  static bool is_mapped() { return FileMapInfo::dynamic_info() != NULL; }
+  static bool is_mapped() { return FileMapInfo::dynamic_info() != nullptr; }
   static bool validate(FileMapInfo* dynamic_info);
 };
 #endif // INCLUDE_CDS
diff --git a/src/hotspot/share/cds/filemap.cpp b/src/hotspot/share/cds/filemap.cpp
index 6c792c0fd2b..3c9bbc180e9 100644
--- a/src/hotspot/share/cds/filemap.cpp
+++ b/src/hotspot/share/cds/filemap.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2023, 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
@@ -91,7 +91,7 @@ static void fail_exit(const char *msg, va_list ap) {
   jio_vfprintf(defaultStream::error_stream(), msg, ap);
   jio_fprintf(defaultStream::error_stream(), "\n");
   // Do not change the text of the below message because some tests check for it.
-  vm_exit_during_initialization("Unable to use shared archive.", NULL);
+  vm_exit_during_initialization("Unable to use shared archive.", nullptr);
 }
 
 
@@ -180,10 +180,10 @@ FileMapInfo::FileMapInfo(const char* full_path, bool is_static) :
   _is_static(is_static), _file_open(false), _is_mapped(false), _fd(-1), _file_offset(0),
   _full_path(full_path), _base_archive_name(nullptr), _header(nullptr) {
   if (_is_static) {
-    assert(_current_info == NULL, "must be singleton"); // not thread safe
+    assert(_current_info == nullptr, "must be singleton"); // not thread safe
     _current_info = this;
   } else {
-    assert(_dynamic_archive_info == NULL, "must be singleton"); // not thread safe
+    assert(_dynamic_archive_info == nullptr, "must be singleton"); // not thread safe
     _dynamic_archive_info = this;
   }
 }
@@ -191,10 +191,10 @@ FileMapInfo::FileMapInfo(const char* full_path, bool is_static) :
 FileMapInfo::~FileMapInfo() {
   if (_is_static) {
     assert(_current_info == this, "must be singleton"); // not thread safe
-    _current_info = NULL;
+    _current_info = nullptr;
   } else {
     assert(_dynamic_archive_info == this, "must be singleton"); // not thread safe
-    _dynamic_archive_info = NULL;
+    _dynamic_archive_info = nullptr;
   }
 
   if (_header != nullptr) {
@@ -207,7 +207,7 @@ FileMapInfo::~FileMapInfo() {
 }
 
 void FileMapInfo::populate_header(size_t core_region_alignment) {
-  assert(_header == NULL, "Sanity check");
+  assert(_header == nullptr, "Sanity check");
   size_t c_header_size;
   size_t header_size;
   size_t base_archive_name_size = 0;
@@ -428,7 +428,7 @@ void SharedClassPathEntry::copy_from(SharedClassPathEntry* ent, ClassLoaderData*
   _from_class_path_attr = ent->_from_class_path_attr;
   set_name(ent->name(), CHECK);
 
-  if (ent->is_jar() && !ent->is_signed() && ent->manifest() != NULL) {
+  if (ent->is_jar() && !ent->is_signed() && ent->manifest() != nullptr) {
     Array<u1>* buf = MetadataFactory::new_array<u1>(loader_data,
                                                     ent->manifest_size(),
                                                     CHECK);
@@ -561,12 +561,12 @@ void FileMapInfo::clone_shared_path_table(TRAPS) {
   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
   ClassPathEntry* jrt = ClassLoader::get_jrt_entry();
 
-  assert(jrt != NULL,
+  assert(jrt != nullptr,
          "No modular java runtime image present when allocating the CDS classpath entry table");
 
-  if (_saved_shared_path_table_array != NULL) {
+  if (_saved_shared_path_table_array != nullptr) {
     MetadataFactory::free_array<u8>(loader_data, _saved_shared_path_table_array);
-    _saved_shared_path_table_array = NULL;
+    _saved_shared_path_table_array = nullptr;
   }
 
   copy_shared_path_table(loader_data, CHECK);
@@ -578,7 +578,7 @@ void FileMapInfo::allocate_shared_path_table(TRAPS) {
   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
   ClassPathEntry* jrt = ClassLoader::get_jrt_entry();
 
-  assert(jrt != NULL,
+  assert(jrt != nullptr,
          "No modular java runtime image present when allocating the CDS classpath entry table");
 
   _shared_path_table.dumptime_init(loader_data, CHECK);
@@ -599,7 +599,7 @@ void FileMapInfo::allocate_shared_path_table(TRAPS) {
 }
 
 int FileMapInfo::add_shared_classpaths(int i, const char* which, ClassPathEntry *cpe, TRAPS) {
-  while (cpe != NULL) {
+  while (cpe != nullptr) {
     bool is_jrt = (cpe == ClassLoader::get_jrt_entry());
     bool is_module_path = i >= ClassLoaderExt::app_module_paths_start_index();
     const char* type = (is_jrt ? "jrt" : (cpe->is_jar_file() ? "jar" : "dir"));
@@ -643,14 +643,14 @@ void FileMapInfo::check_nonempty_dir_in_shared_path_table() {
   }
 
   if (has_nonempty_dir) {
-    ClassLoader::exit_with_path_failure("Cannot have non-empty directory in paths", NULL);
+    ClassLoader::exit_with_path_failure("Cannot have non-empty directory in paths", nullptr);
   }
 }
 
 void FileMapInfo::record_non_existent_class_path_entry(const char* path) {
   Arguments::assert_is_dumping_archive();
   log_info(class, path)("non-existent Class-Path entry %s", path);
-  if (_non_existent_class_paths == NULL) {
+  if (_non_existent_class_paths == nullptr) {
     _non_existent_class_paths = new (mtClass) GrowableArray<const char*>(10, mtClass);
   }
   _non_existent_class_paths->append(os::strdup(path));
@@ -658,7 +658,7 @@ void FileMapInfo::record_non_existent_class_path_entry(const char* path) {
 
 int FileMapInfo::num_non_existent_class_paths() {
   Arguments::assert_is_dumping_archive();
-  if (_non_existent_class_paths != NULL) {
+  if (_non_existent_class_paths != nullptr) {
     return _non_existent_class_paths->length();
   } else {
     return 0;
@@ -729,9 +729,9 @@ class ManifestStream: public ResourceObj {
       if (*_current == '\n') {
         *_current = '\0';
         u1* value = (u1*)strchr((char*)attr, ':');
-        if (value != NULL) {
+        if (value != nullptr) {
           assert(*(value+1) == ' ', "Unrecognized format" );
-          if (strstr((char*)attr, "-Digest") != NULL) {
+          if (strstr((char*)attr, "-Digest") != nullptr) {
             isSigned = true;
             break;
           }
@@ -752,7 +752,7 @@ void FileMapInfo::update_jar_manifest(ClassPathEntry *cpe, SharedClassPathEntry*
 
   assert(cpe->is_jar_file() && ent->is_jar(), "the shared class path entry is not a JAR file");
   char* manifest = ClassLoaderExt::read_manifest(THREAD, cpe, &manifest_size);
-  if (manifest != NULL) {
+  if (manifest != nullptr) {
     ManifestStream* stream = new ManifestStream((u1*)manifest,
                                                 manifest_size);
     if (stream->check_is_signed()) {
@@ -773,7 +773,7 @@ void FileMapInfo::update_jar_manifest(ClassPathEntry *cpe, SharedClassPathEntry*
 char* FileMapInfo::skip_first_path_entry(const char* path) {
   size_t path_sep_len = strlen(os::path_separator());
   char* p = strstr((char*)path, os::path_separator());
-  if (p != NULL) {
+  if (p != nullptr) {
     debug_only( {
       size_t image_name_len = strlen(MODULES_IMAGE_NAME);
       assert(strncmp(p - image_name_len, MODULES_IMAGE_NAME, image_name_len) == 0,
@@ -790,15 +790,15 @@ char* FileMapInfo::skip_first_path_entry(const char* path) {
 }
 
 int FileMapInfo::num_paths(const char* path) {
-  if (path == NULL) {
+  if (path == nullptr) {
     return 0;
   }
   int npaths = 1;
   char* p = (char*)path;
-  while (p != NULL) {
+  while (p != nullptr) {
     char* prev = p;
     p = strstr((char*)p, os::path_separator());
-    if (p != NULL) {
+    if (p != nullptr) {
       p++;
       // don't count empty path
       if ((p - prev) > 1) {
@@ -828,7 +828,7 @@ GrowableArray<const char*>* FileMapInfo::create_dumptime_app_classpath_array() {
   Arguments::assert_is_dumping_archive();
   GrowableArray<const char*>* path_array = new GrowableArray<const char*>(10);
   ClassPathEntry* cpe = ClassLoader::app_classpath_entries();
-  while (cpe != NULL) {
+  while (cpe != nullptr) {
     path_array->append(cpe->name());
     cpe = cpe->next();
   }
@@ -849,10 +849,10 @@ GrowableArray<const char*>* FileMapInfo::create_path_array(const char* paths) {
       }
     } else {
       const char* canonical_path = ClassLoader::get_canonical_path(path, current);
-      if (canonical_path != NULL) {
-        char* error_msg = NULL;
+      if (canonical_path != nullptr) {
+        char* error_msg = nullptr;
         jzfile* zip = ClassLoader::open_zip_file(canonical_path, &error_msg, current);
-        if (zip != NULL && error_msg == NULL) {
+        if (zip != nullptr && error_msg == nullptr) {
           path_array->append(path);
         }
       }
@@ -939,9 +939,9 @@ bool FileMapInfo::validate_boot_class_paths() {
   bool mismatch = false;
 
   bool relaxed_check = !header()->has_platform_or_app_classes();
-  if (dp_len == 0 && rp == NULL) {
+  if (dp_len == 0 && rp == nullptr) {
     return true;   // ok, both runtime and dump time boot paths have modules_images only
-  } else if (dp_len == 0 && rp != NULL) {
+  } else if (dp_len == 0 && rp != nullptr) {
     if (relaxed_check) {
       return true;   // ok, relaxed check, runtime has extra boot append path entries
     } else {
@@ -952,7 +952,7 @@ bool FileMapInfo::validate_boot_class_paths() {
         mismatch = true;
       }
     }
-  } else if (dp_len > 0 && rp != NULL) {
+  } else if (dp_len > 0 && rp != nullptr) {
     int num;
     ResourceMark rm;
     GrowableArray<const char*>* rp_array = create_path_array(rp);
@@ -984,7 +984,7 @@ bool FileMapInfo::validate_boot_class_paths() {
 
 bool FileMapInfo::validate_app_class_paths(int shared_app_paths_len) {
   const char *appcp = Arguments::get_appclasspath();
-  assert(appcp != NULL, "NULL app classpath");
+  assert(appcp != nullptr, "null app classpath");
   int rp_len = num_paths(appcp);
   bool mismatch = false;
   if (rp_len < shared_app_paths_len) {
@@ -1109,7 +1109,7 @@ bool FileMapInfo::validate_shared_path_table() {
         }
         log_info(class, path)("ok");
       } else {
-        if (_dynamic_archive_info != NULL && _dynamic_archive_info->_is_static) {
+        if (_dynamic_archive_info != nullptr && _dynamic_archive_info->_is_static) {
           assert(!UseSharedSpaces, "UseSharedSpaces should be disabled");
         }
         return false;
@@ -1118,7 +1118,7 @@ bool FileMapInfo::validate_shared_path_table() {
       if (shared_path(i)->validate(false /* not a class path entry */)) {
         log_info(class, path)("ok");
       } else {
-        if (_dynamic_archive_info != NULL && _dynamic_archive_info->_is_static) {
+        if (_dynamic_archive_info != nullptr && _dynamic_archive_info->_is_static) {
           assert(!UseSharedSpaces, "UseSharedSpaces should be disabled");
         }
         return false;
@@ -1144,7 +1144,7 @@ bool FileMapInfo::validate_shared_path_table() {
   _validating_shared_path_table = false;
 
 #if INCLUDE_JVMTI
-  if (_classpath_entries_for_jvmti != NULL) {
+  if (_classpath_entries_for_jvmti != nullptr) {
     os::free(_classpath_entries_for_jvmti);
   }
   size_t sz = sizeof(ClassPathEntry*) * get_number_of_shared_paths();
@@ -1209,7 +1209,7 @@ public:
   }
 
   bool initialize() {
-    assert(_archive_name != nullptr, "Archive name is NULL");
+    assert(_archive_name != nullptr, "Archive name is null");
     _fd = os::open(_archive_name, O_RDONLY | O_BINARY, 0);
     if (_fd < 0) {
       FileMapInfo::fail_continue("Specified shared archive not found (%s)", _archive_name);
@@ -1220,7 +1220,7 @@ public:
 
   // for an already opened file, do not set _fd
   bool initialize(int fd) {
-    assert(_archive_name != nullptr, "Archive name is NULL");
+    assert(_archive_name != nullptr, "Archive name is null");
     assert(fd != -1, "Archive must be opened already");
     // First read the generic header so we know the exact size of the actual header.
     GenericCDSFileMapHeader gen_header;
@@ -1358,14 +1358,14 @@ public:
 // Return value:
 // false:
 //      <archive_name> is not a valid archive. *base_archive_name is set to null.
-// true && (*base_archive_name) == NULL:
+// true && (*base_archive_name) == nullptr:
 //      <archive_name> is a valid static archive.
-// true && (*base_archive_name) != NULL:
+// true && (*base_archive_name) != nullptr:
 //      <archive_name> is a valid dynamic archive.
 bool FileMapInfo::get_base_archive_name_from_header(const char* archive_name,
                                                     char** base_archive_name) {
   FileHeaderHelper file_helper(archive_name, false);
-  *base_archive_name = NULL;
+  *base_archive_name = nullptr;
 
   if (!file_helper.initialize()) {
     return false;
@@ -1565,7 +1565,7 @@ void FileMapRegion::init(int region_index, size_t mapping_offset, size_t size, b
   _allow_exec = allow_exec;
   _crc = crc;
   _mapped_from_file = false;
-  _mapped_base = NULL;
+  _mapped_base = nullptr;
 }
 
 void FileMapRegion::init_bitmaps(ArchiveHeapBitmapInfo oopmap, ArchiveHeapBitmapInfo ptrmap) {
@@ -1627,10 +1627,10 @@ void FileMapInfo::write_region(int region, char* base, size_t size,
   size_t mapping_offset = 0;
 
   if (region == MetaspaceShared::bm) {
-    requested_base = NULL; // always NULL for bm region
+    requested_base = nullptr; // always null for bm region
   } else if (size == 0) {
     // This is an unused region (e.g., a heap region when !INCLUDE_CDS_JAVA_HEAP)
-    requested_base = NULL;
+    requested_base = nullptr;
   } else if (HeapShared::is_heap_region(region)) {
     assert(!DynamicDumpSharedSpaces, "must be");
     requested_base = base;
@@ -1660,7 +1660,7 @@ void FileMapInfo::write_region(int region, char* base, size_t size,
 
   r->init(region, mapping_offset, size, read_only, allow_exec, crc);
 
-  if (base != NULL) {
+  if (base != nullptr) {
     write_bytes_aligned(base, size);
   }
 }
@@ -1688,7 +1688,7 @@ char* FileMapInfo::write_bitmap_region(const CHeapBitMap* ptrmap,
   size_t size_in_bits = ptrmap->size();
   size_in_bytes = ptrmap->size_in_bytes();
 
-  if (closed_bitmaps != NULL && open_bitmaps != NULL) {
+  if (closed_bitmaps != nullptr && open_bitmaps != nullptr) {
     size_in_bytes = set_bitmaps_offset(closed_bitmaps, size_in_bytes);
     size_in_bytes = set_bitmaps_offset(open_bitmaps, size_in_bytes);
   }
@@ -1697,7 +1697,7 @@ char* FileMapInfo::write_bitmap_region(const CHeapBitMap* ptrmap,
   ptrmap->write_to((BitMap::bm_word_t*)buffer, ptrmap->size_in_bytes());
   header()->set_ptrmap_size_in_bits(size_in_bits);
 
-  if (closed_bitmaps != NULL && open_bitmaps != NULL) {
+  if (closed_bitmaps != nullptr && open_bitmaps != nullptr) {
     size_t curr_offset = write_bitmaps(closed_bitmaps, ptrmap->size_in_bytes(), buffer);
     write_bitmaps(open_bitmaps, curr_offset, buffer);
   }
@@ -1742,7 +1742,7 @@ size_t FileMapInfo::write_heap_regions(GrowableArray<MemRegion>* regions,
                                        int first_region_id, int max_num_regions) {
   assert(max_num_regions <= 2, "Only support maximum 2 memory regions");
 
-  int arr_len = regions == NULL ? 0 : regions->length();
+  int arr_len = regions == nullptr ? 0 : regions->length();
   if (arr_len > max_num_regions) {
     fail_stop("Unable to write archive heap memory regions: "
               "number of memory regions exceeds maximum due to fragmentation. "
@@ -1753,7 +1753,7 @@ size_t FileMapInfo::write_heap_regions(GrowableArray<MemRegion>* regions,
 
   size_t total_size = 0;
   for (int i = 0; i < max_num_regions; i++) {
-    char* start = NULL;
+    char* start = nullptr;
     size_t size = 0;
     if (i < arr_len) {
       start = (char*)regions->at(i).start();
@@ -1850,7 +1850,7 @@ bool FileMapInfo::remap_shared_readonly_as_readwrite() {
                                 r->allow_exec());
   close();
   // These have to be errors because the shared region is now unmapped.
-  if (base == NULL) {
+  if (base == nullptr) {
     log_error(cds)("Unable to remap shared readonly space (errno=%d).", errno);
     vm_exit(1);
   }
@@ -1867,7 +1867,7 @@ static const char* shared_region_name[] = { "ReadWrite", "ReadOnly", "Bitmap",
                                             "String1", "String2", "OpenArchive1", "OpenArchive2" };
 
 MapArchiveResult FileMapInfo::map_regions(int regions[], int num_regions, char* mapped_base_address, ReservedSpace rs) {
-  DEBUG_ONLY(FileMapRegion* last_region = NULL);
+  DEBUG_ONLY(FileMapRegion* last_region = nullptr);
   intx addr_delta = mapped_base_address - header()->requested_base_address();
 
   // Make sure we don't attempt to use header()->mapped_base_address() unless
@@ -1881,7 +1881,7 @@ MapArchiveResult FileMapInfo::map_regions(int regions[], int num_regions, char*
       return result;
     }
     FileMapRegion* r = region_at(idx);
-    DEBUG_ONLY(if (last_region != NULL) {
+    DEBUG_ONLY(if (last_region != nullptr) {
         // Ensure that the OS won't be able to allocate new memory spaces between any mapped
         // regions, or else it would mess up the simple comparison in MetaspaceObj::is_shared().
         assert(r->mapped_base() == last_region->mapped_end(), "must have no gaps");
@@ -1930,8 +1930,8 @@ MapArchiveResult FileMapInfo::map_region(int i, intx addr_delta, char* mapped_ba
   FileMapRegion* r = region_at(i);
   size_t size = r->used_aligned();
   char *requested_addr = mapped_base_address + r->mapping_offset();
-  assert(r->mapped_base() == NULL, "must be not mapped yet");
-  assert(requested_addr != NULL, "must be specified");
+  assert(r->mapped_base() == nullptr, "must be not mapped yet");
+  assert(requested_addr != nullptr, "must be specified");
 
   r->set_mapped_from_file(false);
 
@@ -1984,16 +1984,16 @@ MapArchiveResult FileMapInfo::map_region(int i, intx addr_delta, char* mapped_ba
 // The return value is the location of the archive relocation bitmap.
 char* FileMapInfo::map_bitmap_region() {
   FileMapRegion* r = region_at(MetaspaceShared::bm);
-  if (r->mapped_base() != NULL) {
+  if (r->mapped_base() != nullptr) {
     return r->mapped_base();
   }
   bool read_only = true, allow_exec = false;
-  char* requested_addr = NULL; // allow OS to pick any location
+  char* requested_addr = nullptr; // allow OS to pick any location
   char* bitmap_base = os::map_memory(_fd, _full_path, r->file_offset(),
                                      requested_addr, r->used_aligned(), read_only, allow_exec, mtClassShared);
-  if (bitmap_base == NULL) {
+  if (bitmap_base == nullptr) {
     log_info(cds)("failed to map relocation bitmap");
-    return NULL;
+    return nullptr;
   }
 
   if (VerifySharedSpaces && !region_crc_check(bitmap_base, r->used(), r->crc())) {
@@ -2001,7 +2001,7 @@ char* FileMapInfo::map_bitmap_region() {
     if (!os::unmap_memory(bitmap_base, r->used_aligned())) {
       fatal("os::unmap_memory of relocation bitmap failed");
     }
-    return NULL;
+    return nullptr;
   }
 
   r->set_mapped_base(bitmap_base);
@@ -2019,7 +2019,7 @@ bool FileMapInfo::relocate_pointers_in_core_regions(intx addr_delta) {
   log_debug(cds, reloc)("runtime archive relocation start");
   char* bitmap_base = map_bitmap_region();
 
-  if (bitmap_base == NULL) {
+  if (bitmap_base == nullptr) {
     return false; // OOM, or CRC check failure
   } else {
     size_t ptrmap_size_in_bits = header()->ptrmap_size_in_bits();
@@ -2080,8 +2080,8 @@ size_t FileMapInfo::readonly_total() {
   return total;
 }
 
-static MemRegion *closed_heap_regions = NULL;
-static MemRegion *open_heap_regions = NULL;
+static MemRegion *closed_heap_regions = nullptr;
+static MemRegion *open_heap_regions = nullptr;
 static int num_closed_heap_regions = 0;
 static int num_open_heap_regions = 0;
 
@@ -2096,7 +2096,7 @@ bool FileMapInfo::has_heap_regions() {
 // if/how these regions should be relocated at run time.
 MemRegion FileMapInfo::get_heap_regions_requested_range() {
   address start = (address) max_uintx;
-  address end   = NULL;
+  address end   = nullptr;
 
   for (int i = MetaspaceShared::first_closed_heap_region;
            i <= MetaspaceShared::last_valid_region;
@@ -2116,7 +2116,7 @@ MemRegion FileMapInfo::get_heap_regions_requested_range() {
       }
     }
   }
-  assert(end != NULL, "must have at least one used heap region");
+  assert(end != nullptr, "must have at least one used heap region");
 
   start = align_down(start, HeapRegion::GrainBytes);
   end = align_up(end, HeapRegion::GrainBytes);
@@ -2319,7 +2319,7 @@ void FileMapInfo::map_heap_regions_impl() {
 
   if (_heap_pointers_need_patching) {
     char* bitmap_base = map_bitmap_region();
-    if (bitmap_base == NULL) {
+    if (bitmap_base == nullptr) {
       log_info(cds)("CDS heap cannot be used because bitmap region cannot be mapped");
       _heap_pointers_need_patching = false;
       return;
@@ -2347,12 +2347,12 @@ bool FileMapInfo::map_heap_regions() {
   map_heap_regions_impl();
 
   if (!ArchiveHeapLoader::closed_regions_mapped()) {
-    assert(closed_heap_regions == NULL &&
+    assert(closed_heap_regions == nullptr &&
            num_closed_heap_regions == 0, "sanity");
   }
 
   if (!ArchiveHeapLoader::open_regions_mapped()) {
-    assert(open_heap_regions == NULL && num_open_heap_regions == 0, "sanity");
+    assert(open_heap_regions == nullptr && num_open_heap_regions == 0, "sanity");
     return false;
   } else {
     return true;
@@ -2413,7 +2413,7 @@ bool FileMapInfo::map_heap_regions(int first, int max,  bool is_open_archive,
     char* base = os::map_memory(_fd, _full_path, r->file_offset(),
                                 addr, regions[i].byte_size(), r->read_only(),
                                 r->allow_exec());
-    if (base == NULL || base != addr) {
+    if (base == nullptr || base != addr) {
       // dealloc the regions from java heap
       dealloc_heap_regions(regions, num_regions);
       log_info(cds)("UseSharedSpaces: Unable to map at required address in java heap. "
@@ -2463,7 +2463,7 @@ narrowOop FileMapInfo::encoded_heap_region_dumptime_address(FileMapRegion* r) {
 void FileMapInfo::patch_heap_embedded_pointers(MemRegion* regions, int num_regions,
                                                int first_region_idx) {
   char* bitmap_base = map_bitmap_region();
-  assert(bitmap_base != NULL, "must have already been mapped");
+  assert(bitmap_base != nullptr, "must have already been mapped");
   for (int i=0; i<num_regions; i++) {
     int region_idx = i + first_region_idx;
     FileMapRegion* r = region_at(region_idx);
@@ -2480,9 +2480,9 @@ void FileMapInfo::patch_heap_embedded_pointers(MemRegion* regions, int num_regio
 void FileMapInfo::fixup_mapped_heap_regions() {
   assert(vmClasses::Object_klass_loaded(), "must be");
   // If any closed regions were found, call the fill routine to make them parseable.
-  // Note that closed_heap_regions may be non-NULL even if no regions were found.
+  // Note that closed_heap_regions may be non-null even if no regions were found.
   if (num_closed_heap_regions != 0) {
-    assert(closed_heap_regions != NULL,
+    assert(closed_heap_regions != nullptr,
            "Null closed_heap_regions array with non-zero count");
     G1CollectedHeap::heap()->fill_archive_regions(closed_heap_regions,
                                                   num_closed_heap_regions);
@@ -2495,7 +2495,7 @@ void FileMapInfo::fixup_mapped_heap_regions() {
 
   // do the same for mapped open archive heap regions
   if (num_open_heap_regions != 0) {
-    assert(open_heap_regions != NULL, "NULL open_heap_regions array with non-zero count");
+    assert(open_heap_regions != nullptr, "Null open_heap_regions array with non-zero count");
     G1CollectedHeap::heap()->fill_archive_regions(open_heap_regions,
                                                   num_open_heap_regions);
 
@@ -2511,7 +2511,7 @@ void FileMapInfo::fixup_mapped_heap_regions() {
 // dealloc the archive regions from java heap
 void FileMapInfo::dealloc_heap_regions(MemRegion* regions, int num) {
   if (num > 0) {
-    assert(regions != NULL, "Null archive regions array with non-zero count");
+    assert(regions != nullptr, "Null archive regions array with non-zero count");
     G1CollectedHeap::heap()->dealloc_archive_regions(regions, num);
   }
 }
@@ -2552,7 +2552,7 @@ void FileMapInfo::unmap_region(int i) {
   char* mapped_base = r->mapped_base();
   size_t size = r->used_aligned();
 
-  if (mapped_base != NULL) {
+  if (mapped_base != nullptr) {
     if (size > 0 && r->mapped_from_file()) {
       log_info(cds)("Unmapping region #%d at base " INTPTR_FORMAT " (%s)", i, p2i(mapped_base),
                     shared_region_name[i]);
@@ -2560,7 +2560,7 @@ void FileMapInfo::unmap_region(int i) {
         fatal("os::unmap_memory failed");
       }
     }
-    r->set_mapped_base(NULL);
+    r->set_mapped_base(nullptr);
   }
 }
 
@@ -2578,15 +2578,15 @@ void FileMapInfo::metaspace_pointers_do(MetaspaceClosure* it, bool use_copy) {
   }
 }
 
-FileMapInfo* FileMapInfo::_current_info = NULL;
-FileMapInfo* FileMapInfo::_dynamic_archive_info = NULL;
+FileMapInfo* FileMapInfo::_current_info = nullptr;
+FileMapInfo* FileMapInfo::_dynamic_archive_info = nullptr;
 bool FileMapInfo::_heap_pointers_need_patching = false;
 SharedPathTable FileMapInfo::_shared_path_table;
 SharedPathTable FileMapInfo::_saved_shared_path_table;
-Array<u8>*      FileMapInfo::_saved_shared_path_table_array = NULL;
+Array<u8>*      FileMapInfo::_saved_shared_path_table_array = nullptr;
 bool FileMapInfo::_validating_shared_path_table = false;
 bool FileMapInfo::_memory_mapping_failed = false;
-GrowableArray<const char*>* FileMapInfo::_non_existent_class_paths = NULL;
+GrowableArray<const char*>* FileMapInfo::_non_existent_class_paths = nullptr;
 
 // Open the shared archive file, read and validate the header
 // information (version, boot classpath, etc.).  If initialization
@@ -2679,7 +2679,7 @@ bool FileMapHeader::validate() {
   // This must be done after header validation because it might change the
   // header data
   const char* prop = Arguments::get_property("java.system.class.loader");
-  if (prop != NULL) {
+  if (prop != nullptr) {
     warning("Archived non-system classes are disabled because the "
             "java.system.class.loader property is specified (value = \"%s\"). "
             "To use archived non-system classes, this property must not be set", prop);
@@ -2757,7 +2757,7 @@ bool FileMapInfo::validate_header() {
 
 // Unmap mapped regions of shared space.
 void FileMapInfo::stop_sharing_and_unmap(const char* msg) {
-  MetaspaceShared::set_shared_metaspace_range(NULL, NULL, NULL);
+  MetaspaceShared::set_shared_metaspace_range(nullptr, nullptr, nullptr);
 
   FileMapInfo *map_info = FileMapInfo::current_info();
   if (map_info) {
@@ -2779,7 +2779,7 @@ void FileMapInfo::stop_sharing_and_unmap(const char* msg) {
 }
 
 #if INCLUDE_JVMTI
-ClassPathEntry** FileMapInfo::_classpath_entries_for_jvmti = NULL;
+ClassPathEntry** FileMapInfo::_classpath_entries_for_jvmti = nullptr;
 
 ClassPathEntry* FileMapInfo::get_classpath_entry_for_jvmti(int i, TRAPS) {
   if (i == 0) {
@@ -2788,7 +2788,7 @@ ClassPathEntry* FileMapInfo::get_classpath_entry_for_jvmti(int i, TRAPS) {
     return ClassLoader::get_jrt_entry();
   }
   ClassPathEntry* ent = _classpath_entries_for_jvmti[i];
-  if (ent == NULL) {
+  if (ent == nullptr) {
     SharedClassPathEntry* scpe = shared_path(i);
     assert(scpe->is_jar(), "must be"); // other types of scpe will not produce archived classes
 
@@ -2797,18 +2797,18 @@ ClassPathEntry* FileMapInfo::get_classpath_entry_for_jvmti(int i, TRAPS) {
     if (os::stat(path, &st) != 0) {
       char *msg = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, strlen(path) + 128);
       jio_snprintf(msg, strlen(path) + 127, "error in finding JAR file %s", path);
-      THROW_MSG_(vmSymbols::java_io_IOException(), msg, NULL);
+      THROW_MSG_(vmSymbols::java_io_IOException(), msg, nullptr);
     } else {
       ent = ClassLoader::create_class_path_entry(THREAD, path, &st, false, false);
-      if (ent == NULL) {
+      if (ent == nullptr) {
         char *msg = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, strlen(path) + 128);
         jio_snprintf(msg, strlen(path) + 127, "error in opening JAR file %s", path);
-        THROW_MSG_(vmSymbols::java_io_IOException(), msg, NULL);
+        THROW_MSG_(vmSymbols::java_io_IOException(), msg, nullptr);
       }
     }
 
     MutexLocker mu(THREAD, CDSClassFileStream_lock);
-    if (_classpath_entries_for_jvmti[i] == NULL) {
+    if (_classpath_entries_for_jvmti[i] == nullptr) {
       _classpath_entries_for_jvmti[i] = ent;
     } else {
       // Another thread has beat me to creating this entry
@@ -2826,7 +2826,7 @@ ClassFileStream* FileMapInfo::open_stream_for_jvmti(InstanceKlass* ik, Handle cl
   assert(path_index < (int)get_number_of_shared_paths(), "sanity");
 
   ClassPathEntry* cpe = get_classpath_entry_for_jvmti(path_index, CHECK_NULL);
-  assert(cpe != NULL, "must be");
+  assert(cpe != nullptr, "must be");
 
   Symbol* name = ik->name();
   const char* const class_name = name->as_C_string();
@@ -2834,7 +2834,7 @@ ClassFileStream* FileMapInfo::open_stream_for_jvmti(InstanceKlass* ik, Handle cl
                                                                       name->utf8_length());
   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
   ClassFileStream* cfs = cpe->open_stream_for_loader(THREAD, file_name, loader_data);
-  assert(cfs != NULL, "must be able to read the classfile data of shared classes for built-in loaders.");
+  assert(cfs != nullptr, "must be able to read the classfile data of shared classes for built-in loaders.");
   log_debug(cds, jvmti)("classfile data for %s [%d: %s] = %d bytes", class_name, path_index,
                         cfs->source(), cfs->length());
   return cfs;
diff --git a/src/hotspot/share/cds/filemap.hpp b/src/hotspot/share/cds/filemap.hpp
index 541b8fd603a..bfe2f4c10d3 100644
--- a/src/hotspot/share/cds/filemap.hpp
+++ b/src/hotspot/share/cds/filemap.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2023, 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
@@ -88,10 +88,10 @@ public:
   time_t timestamp() const { return _timestamp; }
   const char* name() const;
   const char* manifest() const {
-    return (_manifest == NULL) ? NULL : (const char*)_manifest->data();
+    return (_manifest == nullptr) ? nullptr : (const char*)_manifest->data();
   }
   int manifest_size() const {
-    return (_manifest == NULL) ? 0 : _manifest->length();
+    return (_manifest == nullptr) ? 0 : _manifest->length();
   }
   void set_manifest(Array<u1>* manifest) {
     _manifest = manifest;
@@ -115,7 +115,7 @@ class SharedPathTable {
   Array<u8>* _table;
   int _size;
 public:
-  SharedPathTable() : _table(NULL), _size(0) {}
+  SharedPathTable() : _table(nullptr), _size(0) {}
   SharedPathTable(Array<u8>* table, int size) : _table(table), _size(size) {}
 
   void dumptime_init(ClassLoaderData* loader_data, TRAPS);
@@ -126,7 +126,7 @@ public:
   }
   SharedClassPathEntry* path_at(int index) {
     if (index < 0) {
-      return NULL;
+      return nullptr;
     }
     assert(index < _size, "sanity");
     char* p = (char*)_table->data();
@@ -429,7 +429,7 @@ public:
 
   static FileMapInfo* current_info() {
     CDS_ONLY(return _current_info;)
-    NOT_CDS(return NULL;)
+    NOT_CDS(return nullptr;)
   }
 
   static void set_current_info(FileMapInfo* info) {
@@ -438,7 +438,7 @@ public:
 
   static FileMapInfo* dynamic_info() {
     CDS_ONLY(return _dynamic_archive_info;)
-    NOT_CDS(return NULL;)
+    NOT_CDS(return nullptr;)
   }
 
   static void assert_mark(bool check);
@@ -561,11 +561,11 @@ public:
 
  private:
   void  seek_to_position(size_t pos);
-  char* skip_first_path_entry(const char* path) NOT_CDS_RETURN_(NULL);
+  char* skip_first_path_entry(const char* path) NOT_CDS_RETURN_(nullptr);
   int   num_paths(const char* path) NOT_CDS_RETURN_(0);
   bool  check_paths_existence(const char* paths) NOT_CDS_RETURN_(false);
-  GrowableArray<const char*>* create_dumptime_app_classpath_array() NOT_CDS_RETURN_(NULL);
-  GrowableArray<const char*>* create_path_array(const char* path) NOT_CDS_RETURN_(NULL);
+  GrowableArray<const char*>* create_dumptime_app_classpath_array() NOT_CDS_RETURN_(nullptr);
+  GrowableArray<const char*>* create_path_array(const char* path) NOT_CDS_RETURN_(nullptr);
   bool  classpath_failure(const char* msg, const char* name) NOT_CDS_RETURN_(false);
   unsigned int longest_common_app_classpath_prefix_len(int num_paths,
                                                        GrowableArray<const char*>* rp_array)
@@ -590,9 +590,9 @@ public:
   static size_t write_bitmaps(GrowableArray<ArchiveHeapBitmapInfo> *bitmaps, size_t curr_offset, char* buffer);
 
 public:
-  address heap_region_dumptime_address(FileMapRegion* r) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
-  address heap_region_requested_address(FileMapRegion* r) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
-  address heap_region_mapped_address(FileMapRegion* r) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
+  address heap_region_dumptime_address(FileMapRegion* r) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
+  address heap_region_requested_address(FileMapRegion* r) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
+  address heap_region_mapped_address(FileMapRegion* r) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
   narrowOop encoded_heap_region_dumptime_address(FileMapRegion* r);
 
 private:
diff --git a/src/hotspot/share/cds/heapShared.cpp b/src/hotspot/share/cds/heapShared.cpp
index 36947f7244b..b39c9c750a0 100644
--- a/src/hotspot/share/cds/heapShared.cpp
+++ b/src/hotspot/share/cds/heapShared.cpp
@@ -73,16 +73,16 @@ struct ArchivableStaticFieldInfo {
   BasicType type;
 
   ArchivableStaticFieldInfo(const char* k, const char* f)
-  : klass_name(k), field_name(f), klass(NULL), offset(0), type(T_ILLEGAL) {}
+  : klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
 
   bool valid() {
-    return klass_name != NULL;
+    return klass_name != nullptr;
   }
 };
 
 bool HeapShared::_disable_writing = false;
-DumpedInternedStrings *HeapShared::_dumped_interned_strings = NULL;
-GrowableArrayCHeap<Metadata**, mtClassShared>* HeapShared::_native_pointers = NULL;
+DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
+GrowableArrayCHeap<Metadata**, mtClassShared>* HeapShared::_native_pointers = nullptr;
 
 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
@@ -91,10 +91,10 @@ size_t HeapShared::_total_obj_size;
 
 #ifndef PRODUCT
 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
-static Array<char>* _archived_ArchiveHeapTestClass = NULL;
-static const char* _test_class_name = NULL;
-static const Klass* _test_class = NULL;
-static const ArchivedKlassSubGraphInfoRecord* _test_class_record = NULL;
+static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
+static const char* _test_class_name = nullptr;
+static const Klass* _test_class = nullptr;
+static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
 #endif
 
 
@@ -113,7 +113,7 @@ static ArchivableStaticFieldInfo closed_archive_subgraph_entry_fields[] = {
   {"java/lang/Character$CharacterCache",          "archivedCache"},
   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
-  {NULL, NULL},
+  {nullptr, nullptr},
 };
 // Entry fields for subgraphs archived in the open archive heap region.
 static ArchivableStaticFieldInfo open_archive_subgraph_entry_fields[] = {
@@ -123,9 +123,9 @@ static ArchivableStaticFieldInfo open_archive_subgraph_entry_fields[] = {
   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
 #ifndef PRODUCT
-  {NULL, NULL}, // Extra slot for -XX:ArchiveHeapTestClass
+  {nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
 #endif
-  {NULL, NULL},
+  {nullptr, nullptr},
 };
 
 // Entry fields for subgraphs archived in the open archive heap region (full module graph).
@@ -133,14 +133,14 @@ static ArchivableStaticFieldInfo fmg_open_archive_subgraph_entry_fields[] = {
   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
   {"jdk/internal/module/ArchivedBootLayer",       "archivedBootLayer"},
   {"java/lang/Module$ArchivedData",               "archivedData"},
-  {NULL, NULL},
+  {nullptr, nullptr},
 };
 
 KlassSubGraphInfo* HeapShared::_default_subgraph_info;
-GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = NULL;
+GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
 OopHandle HeapShared::_roots;
 OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
-KlassToOopHandleTable* HeapShared::_scratch_java_mirror_table = NULL;
+KlassToOopHandleTable* HeapShared::_scratch_java_mirror_table = nullptr;
 
 #ifdef ASSERT
 bool HeapShared::is_archived_object_during_dumptime(oop p) {
@@ -177,9 +177,9 @@ static void reset_states(oop obj, TRAPS) {
   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
   Symbol* method_sig = vmSymbols::void_method_signature();
 
-  while (klass != NULL) {
+  while (klass != nullptr) {
     Method* method = klass->find_method(method_name, method_sig);
-    if (method != NULL) {
+    if (method != nullptr) {
       assert(method->is_private(), "must be");
       if (log_is_enabled(Debug, cds)) {
         ResourceMark rm(THREAD);
@@ -218,16 +218,16 @@ void HeapShared::reset_archived_object_states(TRAPS) {
   reset_states(boot_loader(), CHECK);
 }
 
-HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = NULL;
-HeapShared::OriginalObjectTable* HeapShared::_original_object_table = NULL;
+HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
+HeapShared::OriginalObjectTable* HeapShared::_original_object_table = nullptr;
 oop HeapShared::find_archived_heap_object(oop obj) {
   assert(DumpSharedSpaces, "dump-time only");
   ArchivedObjectCache* cache = archived_object_cache();
   CachedOopInfo* p = cache->get(obj);
-  if (p != NULL) {
+  if (p != nullptr) {
     return p->_obj;
   } else {
-    return NULL;
+    return nullptr;
   }
 }
 
@@ -237,7 +237,7 @@ int HeapShared::append_root(oop obj) {
   // No GC should happen since we aren't scanning _pending_roots.
   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 
-  if (_pending_roots == NULL) {
+  if (_pending_roots == nullptr) {
     _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
   }
 
@@ -248,14 +248,14 @@ objArrayOop HeapShared::roots() {
   if (DumpSharedSpaces) {
     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
     if (!HeapShared::can_write()) {
-      return NULL;
+      return nullptr;
     }
   } else {
     assert(UseSharedSpaces, "must be");
   }
 
   objArrayOop roots = (objArrayOop)_roots.resolve();
-  assert(roots != NULL, "should have been initialized");
+  assert(roots != nullptr, "should have been initialized");
   return roots;
 }
 
@@ -264,7 +264,7 @@ oop HeapShared::get_root(int index, bool clear) {
   assert(index >= 0, "sanity");
   if (DumpSharedSpaces) {
     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
-    assert(_pending_roots != NULL, "sanity");
+    assert(_pending_roots != nullptr, "sanity");
     return _pending_roots->at(index);
   } else {
     assert(UseSharedSpaces, "must be");
@@ -285,7 +285,7 @@ void HeapShared::clear_root(int index) {
       oop old = roots()->obj_at(index);
       log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
     }
-    roots()->obj_at_put(index, NULL);
+    roots()->obj_at_put(index, nullptr);
   }
 }
 
@@ -295,7 +295,7 @@ oop HeapShared::archive_object(oop obj) {
   assert(!obj->is_stackChunk(), "do not archive stack chunks");
 
   oop ao = find_archived_heap_object(obj);
-  if (ao != NULL) {
+  if (ao != nullptr) {
     // already archived
     return ao;
   }
@@ -304,11 +304,11 @@ oop HeapShared::archive_object(oop obj) {
   if (G1CollectedHeap::heap()->is_archive_alloc_too_large(len)) {
     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
                          p2i(obj), (size_t)obj->size());
-    return NULL;
+    return nullptr;
   }
 
   oop archived_oop = cast_to_oop(G1CollectedHeap::heap()->archive_mem_allocate(len));
-  if (archived_oop != NULL) {
+  if (archived_oop != nullptr) {
     count_allocation(len);
     Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), cast_from_oop<HeapWord*>(archived_oop), len);
     // Reinitialize markword to remove age/marking/locking/etc.
@@ -327,7 +327,7 @@ oop HeapShared::archive_object(oop obj) {
     ArchivedObjectCache* cache = archived_object_cache();
     CachedOopInfo info = make_cached_oop_info(archived_oop);
     cache->put(obj, info);
-    if (_original_object_table != NULL) {
+    if (_original_object_table != nullptr) {
       _original_object_table->put(archived_oop, obj);
     }
     mark_native_pointers(obj, archived_oop);
@@ -355,10 +355,10 @@ public:
   oop get_oop(Klass* k) {
     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
     OopHandle* handle = get(k);
-    if (handle != NULL) {
+    if (handle != nullptr) {
       return handle->resolve();
     } else {
-      return NULL;
+      return nullptr;
     }
   }
   void set_oop(Klass* k, oop o) {
@@ -370,7 +370,7 @@ public:
   void remove_oop(Klass* k) {
     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
     OopHandle* handle = get(k);
-    if (handle != NULL) {
+    if (handle != nullptr) {
       handle->release(Universe::vm_global());
       remove(k);
     }
@@ -413,9 +413,9 @@ void HeapShared::archive_java_mirrors() {
     BasicType bt = (BasicType)i;
     if (!is_reference_type(bt)) {
       oop m = _scratch_basic_type_mirrors[i].resolve();
-      assert(m != NULL, "sanity");
+      assert(m != nullptr, "sanity");
       oop archived_m = archive_reachable_objects_from(1, _default_subgraph_info, m, /*is_closed_archive=*/ false);
-      assert(archived_m != NULL, "sanity");
+      assert(archived_m != nullptr, "sanity");
 
       log_trace(cds, heap, mirror)(
         "Archived %s mirror object from " PTR_FORMAT " ==> " PTR_FORMAT,
@@ -426,14 +426,14 @@ void HeapShared::archive_java_mirrors() {
   }
 
   GrowableArray<Klass*>* klasses = ArchiveBuilder::current()->klasses();
-  assert(klasses != NULL, "sanity");
+  assert(klasses != nullptr, "sanity");
   for (int i = 0; i < klasses->length(); i++) {
     Klass* orig_k = klasses->at(i);
     oop m = scratch_java_mirror(orig_k);
-    if (m != NULL) {
+    if (m != nullptr) {
       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
       oop archived_m = archive_reachable_objects_from(1, _default_subgraph_info, m, /*is_closed_archive=*/ false);
-      guarantee(archived_m != NULL, "scratch mirrors should not point to any unachivable objects");
+      guarantee(archived_m != nullptr, "scratch mirrors should not point to any unachivable objects");
       buffered_k->set_archived_java_mirror(append_root(archived_m));
       ResourceMark rm;
       log_trace(cds, heap, mirror)(
@@ -460,7 +460,7 @@ void HeapShared::mark_native_pointers(oop orig_obj, oop archived_obj) {
 
 void HeapShared::mark_one_native_pointer(oop archived_obj, int offset) {
   Metadata* ptr = archived_obj->metadata_field_acquire(offset);
-  if (ptr != NULL) {
+  if (ptr != nullptr) {
     // Set the native pointer to the requested address (at runtime, if the metadata
     // is mapped at the default location, it will be at this address).
     address buffer_addr = ArchiveBuilder::current()->get_buffered_addr((address)ptr);
@@ -520,7 +520,7 @@ void HeapShared::check_enum_obj(int level,
                     ik->external_name(), fd.name()->as_C_string());
         }
         oop oop_field = mirror->obj_field(fd.offset());
-        if (oop_field == NULL) {
+        if (oop_field == nullptr) {
           guarantee(false, "static field %s::%s must not be null",
                     ik->external_name(), fd.name()->as_C_string());
         } else if (oop_field->klass() != ik && oop_field->klass() != ik->array_klass_or_null()) {
@@ -545,7 +545,7 @@ bool HeapShared::initialize_enum_klass(InstanceKlass* k, TRAPS) {
   }
 
   RunTimeClassInfo* info = RunTimeClassInfo::get_for(k);
-  assert(info != NULL, "sanity");
+  assert(info != nullptr, "sanity");
 
   if (log_is_enabled(Info, cds, heap)) {
     ResourceMark rm;
@@ -662,7 +662,7 @@ void HeapShared::copy_roots() {
   // However, HeapShared::archive_objects() happens inside a safepoint, so we can't
   // allocate a "regular" ObjArray and pass the result to HeapShared::archive_object().
   // Instead, we have to roll our own alloc/copy routine here.
-  int length = _pending_roots != NULL ? _pending_roots->length() : 0;
+  int length = _pending_roots != nullptr ? _pending_roots->length() : 0;
   size_t size = objArrayOopDesc::object_size(length);
   Klass* k = Universe::objectArrayKlassObj(); // already relocated to point to archived klass
   HeapWord* mem = G1CollectedHeap::heap()->archive_mem_allocate(size);
@@ -689,7 +689,7 @@ void HeapShared::copy_roots() {
 //
 // Subgraph archiving support
 //
-HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = NULL;
+HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 
 // Get the subgraph_info for Klass k. A new subgraph_info is created if
@@ -709,7 +709,7 @@ KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_
 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
   assert(DumpSharedSpaces, "dump time only");
   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
-  assert(info != NULL, "must have been initialized");
+  assert(info != nullptr, "must have been initialized");
   return info;
 }
 
@@ -717,7 +717,7 @@ KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 void KlassSubGraphInfo::add_subgraph_entry_field(
       int static_field_offset, oop v, bool is_closed_archive) {
   assert(DumpSharedSpaces, "dump time only");
-  if (_subgraph_entry_fields == NULL) {
+  if (_subgraph_entry_fields == nullptr) {
     _subgraph_entry_fields =
       new (mtClass) GrowableArray<int>(10, mtClass);
   }
@@ -731,7 +731,7 @@ void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
   assert(DumpSharedSpaces, "dump time only");
   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
 
-  if (_subgraph_object_klasses == NULL) {
+  if (_subgraph_object_klasses == nullptr) {
     _subgraph_object_klasses =
       new (mtClass) GrowableArray<Klass*>(50, mtClass);
   }
@@ -787,12 +787,12 @@ void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
 
 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
   if (ik->module()->name() == vmSymbols::java_base()) {
-    assert(ik->package() != NULL, "classes in java.base cannot be in unnamed package");
+    assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
     return;
   }
 
 #ifndef PRODUCT
-  if (!ik->module()->is_named() && ik->package() == NULL) {
+  if (!ik->module()->is_named() && ik->package() == nullptr) {
     // This class is loaded by ArchiveHeapTestClass
     return;
   }
@@ -827,8 +827,8 @@ bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
   _k = info->klass();
-  _entry_field_records = NULL;
-  _subgraph_object_klasses = NULL;
+  _entry_field_records = nullptr;
+  _subgraph_object_klasses = nullptr;
   _is_full_module_graph = info->is_full_module_graph();
 
   if (_is_full_module_graph) {
@@ -849,7 +849,7 @@ void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 
   // populate the entry fields
   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
-  if (entry_fields != NULL) {
+  if (entry_fields != nullptr) {
     int num_entry_fields = entry_fields->length();
     assert(num_entry_fields % 2 == 0, "sanity");
     _entry_field_records =
@@ -861,7 +861,7 @@ void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 
   // the Klasses of the objects in the sub-graphs
   GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
-  if (subgraph_object_klasses != NULL) {
+  if (subgraph_object_klasses != nullptr) {
     int num_subgraphs_klasses = subgraph_object_klasses->length();
     _subgraph_object_klasses =
       ArchiveBuilder::new_ro_array<Klass*>(num_subgraphs_klasses);
@@ -888,7 +888,7 @@ struct CopyKlassSubGraphInfoToArchive : StackObj {
   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 
   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
-    if (info.subgraph_object_klasses() != NULL || info.subgraph_entry_fields() != NULL) {
+    if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
       ArchivedKlassSubGraphInfoRecord* record =
         (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
       record->init(&info);
@@ -922,7 +922,7 @@ void HeapShared::write_subgraph_info_table() {
   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 
 #ifndef PRODUCT
-  if (ArchiveHeapTestClass != NULL) {
+  if (ArchiveHeapTestClass != nullptr) {
     size_t len = strlen(ArchiveHeapTestClass) + 1;
     Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
     strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
@@ -935,13 +935,13 @@ void HeapShared::write_subgraph_info_table() {
 }
 
 void HeapShared::serialize_root(SerializeClosure* soc) {
-  oop roots_oop = NULL;
+  oop roots_oop = nullptr;
 
   if (soc->reading()) {
     soc->do_oop(&roots_oop); // read from archive
     assert(oopDesc::is_oop_or_null(roots_oop), "is oop");
     // Create an OopHandle only if we have actually mapped or loaded the roots
-    if (roots_oop != NULL) {
+    if (roots_oop != nullptr) {
       assert(ArchiveHeapLoader::is_fully_available(), "must be");
       _roots = OopHandle(Universe::vm_global(), roots_oop);
     }
@@ -956,7 +956,7 @@ void HeapShared::serialize_tables(SerializeClosure* soc) {
 
 #ifndef PRODUCT
   soc->do_ptr((void**)&_archived_ArchiveHeapTestClass);
-  if (soc->reading() && _archived_ArchiveHeapTestClass != NULL) {
+  if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
     _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
     setup_test_class(_test_class_name);
   }
@@ -1013,7 +1013,7 @@ void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableSt
     ArchivableStaticFieldInfo* info = &fields[i];
     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
-    assert(k != NULL && k->is_shared_boot_class(), "sanity");
+    assert(k != nullptr && k->is_shared_boot_class(), "sanity");
     resolve_classes_for_subgraph_of(current, k);
   }
 }
@@ -1026,7 +1026,7 @@ void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k)
   if (HAS_PENDING_EXCEPTION) {
    CLEAR_PENDING_EXCEPTION;
   }
-  if (record == NULL) {
+  if (record == nullptr) {
    clear_archived_roots_of(k);
   }
 }
@@ -1049,7 +1049,7 @@ void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k
     return;
   }
 
-  if (record != NULL) {
+  if (record != nullptr) {
     init_archived_fields_for(k, record);
   }
 }
@@ -1059,13 +1059,13 @@ HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAP
   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
 
   if (!k->is_shared()) {
-    return NULL;
+    return nullptr;
   }
   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 
 #ifndef PRODUCT
-  if (_test_class_name != NULL && k->name()->equals(_test_class_name) && record != NULL) {
+  if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
     _test_class = k;
     _test_class_record = record;
   }
@@ -1073,14 +1073,14 @@ HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAP
 
   // Initialize from archived data. Currently this is done only
   // during VM initialization time. No lock is needed.
-  if (record != NULL) {
+  if (record != nullptr) {
     if (record->is_full_module_graph() && !MetaspaceShared::use_full_module_graph()) {
       if (log_is_enabled(Info, cds, heap)) {
         ResourceMark rm(THREAD);
         log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
                             k->external_name());
       }
-      return NULL;
+      return nullptr;
     }
 
     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
@@ -1089,7 +1089,7 @@ HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAP
         log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
                             k->external_name());
       }
-      return NULL;
+      return nullptr;
     }
 
     if (log_is_enabled(Info, cds, heap)) {
@@ -1100,13 +1100,13 @@ HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAP
     resolve_or_init(k, do_init, CHECK_NULL);
 
     // Load/link/initialize the klasses of the objects in the subgraph.
-    // NULL class loader is used.
+    // nullptr class loader is used.
     Array<Klass*>* klasses = record->subgraph_object_klasses();
-    if (klasses != NULL) {
+    if (klasses != nullptr) {
       for (int i = 0; i < klasses->length(); i++) {
         Klass* klass = klasses->at(i);
         if (!klass->is_shared()) {
-          return NULL;
+          return nullptr;
         }
         resolve_or_init(klass, do_init, CHECK_NULL);
       }
@@ -1118,12 +1118,12 @@ HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAP
 
 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
   if (!do_init) {
-    if (k->class_loader_data() == NULL) {
+    if (k->class_loader_data() == nullptr) {
       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
     }
   } else {
-    assert(k->class_loader_data() != NULL, "must have been resolved by HeapShared::resolve_classes");
+    assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
     if (k->is_instance_klass()) {
       InstanceKlass* ik = InstanceKlass::cast(k);
       ik->initialize(CHECK);
@@ -1141,7 +1141,7 @@ void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphI
   // the corresponding fields within the mirror.
   oop m = k->java_mirror();
   Array<int>* entry_field_records = record->entry_field_records();
-  if (entry_field_records != NULL) {
+  if (entry_field_records != nullptr) {
     int efr_len = entry_field_records->length();
     assert(efr_len % 2 == 0, "sanity");
     for (int i = 0; i < efr_len; i += 2) {
@@ -1167,9 +1167,9 @@ void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphI
 void HeapShared::clear_archived_roots_of(Klass* k) {
   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
-  if (record != NULL) {
+  if (record != nullptr) {
     Array<int>* entry_field_records = record->entry_field_records();
-    if (entry_field_records != NULL) {
+    if (entry_field_records != nullptr) {
       int efr_len = entry_field_records->length();
       assert(efr_len % 2 == 0, "sanity");
       for (int i = 0; i < efr_len; i += 2) {
@@ -1235,7 +1235,7 @@ class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
 
       oop archived = HeapShared::archive_reachable_objects_from(
           _level + 1, _subgraph_info, obj, _is_closed_archive);
-      assert(archived != NULL, "VM should have exited with unarchivable objects for _level > 1");
+      assert(archived != nullptr, "VM should have exited with unarchivable objects for _level > 1");
       assert(HeapShared::is_archived_object_during_dumptime(archived), "must be");
 
       if (!_record_klasses_only) {
@@ -1253,14 +1253,14 @@ class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
   KlassSubGraphInfo* subgraph_info()          { return _subgraph_info;        }
 };
 
-WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = NULL;
+WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = nullptr;
 
 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop orig_obj) {
   CachedOopInfo info;
   WalkOopAndArchiveClosure* walker = WalkOopAndArchiveClosure::current();
 
-  info._subgraph_info = (walker == NULL) ? NULL : walker->subgraph_info();
-  info._referrer = (walker == NULL) ? NULL : walker->orig_referencing_obj();
+  info._subgraph_info = (walker == nullptr) ? nullptr : walker->subgraph_info();
+  info._referrer = (walker == nullptr) ? nullptr : walker->orig_referencing_obj();
   info._obj = orig_obj;
 
   return info;
@@ -1290,7 +1290,7 @@ oop HeapShared::archive_reachable_objects_from(int level,
                                                KlassSubGraphInfo* subgraph_info,
                                                oop orig_obj,
                                                bool is_closed_archive) {
-  assert(orig_obj != NULL, "must be");
+  assert(orig_obj != nullptr, "must be");
   assert(!is_archived_object_during_dumptime(orig_obj), "sanity");
 
   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
@@ -1313,7 +1313,7 @@ oop HeapShared::archive_reachable_objects_from(int level,
   }
 
   oop archived_obj = find_archived_heap_object(orig_obj);
-  if (java_lang_String::is_instance(orig_obj) && archived_obj != NULL) {
+  if (java_lang_String::is_instance(orig_obj) && archived_obj != nullptr) {
     // To save time, don't walk strings that are already archived. They just contain
     // pointers to a type array, whose klass doesn't need to be recorded.
     return archived_obj;
@@ -1326,11 +1326,11 @@ oop HeapShared::archive_reachable_objects_from(int level,
     set_has_been_seen_during_subgraph_recording(orig_obj);
   }
 
-  bool record_klasses_only = (archived_obj != NULL);
-  if (archived_obj == NULL) {
+  bool record_klasses_only = (archived_obj != nullptr);
+  if (archived_obj == nullptr) {
     ++_num_new_archived_objs;
     archived_obj = archive_object(orig_obj);
-    if (archived_obj == NULL) {
+    if (archived_obj == nullptr) {
       // Skip archiving the sub-graph referenced from the current entry field.
       ResourceMark rm;
       log_error(cds, heap)(
@@ -1340,7 +1340,7 @@ oop HeapShared::archive_reachable_objects_from(int level,
       if (level == 1) {
         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
         // as the Java code will take care of initializing this field dynamically.
-        return NULL;
+        return nullptr;
       } else {
         // We don't know how to handle an object that has been archived, but some of its reachable
         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
@@ -1353,17 +1353,17 @@ oop HeapShared::archive_reachable_objects_from(int level,
       if (Modules::check_module_oop(orig_obj)) {
         Modules::update_oops_in_archived_module(orig_obj, append_root(archived_obj));
       }
-      java_lang_Module::set_module_entry(archived_obj, NULL);
+      java_lang_Module::set_module_entry(archived_obj, nullptr);
     } else if (java_lang_ClassLoader::is_instance(orig_obj)) {
       // class_data will be restored explicitly at run time.
       guarantee(orig_obj == SystemDictionary::java_platform_loader() ||
                 orig_obj == SystemDictionary::java_system_loader() ||
-                java_lang_ClassLoader::loader_data(orig_obj) == NULL, "must be");
-      java_lang_ClassLoader::release_set_loader_data(archived_obj, NULL);
+                java_lang_ClassLoader::loader_data(orig_obj) == nullptr, "must be");
+      java_lang_ClassLoader::release_set_loader_data(archived_obj, nullptr);
     }
   }
 
-  assert(archived_obj != NULL, "must be");
+  assert(archived_obj != nullptr, "must be");
   Klass *orig_k = orig_obj->klass();
   subgraph_info->add_subgraph_object_klass(orig_k);
 
@@ -1436,7 +1436,7 @@ void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
 
     oop af = archive_reachable_objects_from(1, subgraph_info, f, is_closed_archive);
 
-    if (af == NULL) {
+    if (af == nullptr) {
       log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
                            klass_name, field_name);
     } else {
@@ -1449,7 +1449,7 @@ void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
   } else {
     // The field contains null, we still need to record the entry point,
     // so it can be restored at runtime.
-    subgraph_info->add_subgraph_entry_field(field_offset, NULL, false);
+    subgraph_info->add_subgraph_entry_field(field_offset, nullptr, false);
   }
 }
 
@@ -1486,7 +1486,7 @@ void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_o
 
 void HeapShared::verify_subgraph_from(oop orig_obj) {
   oop archived_obj = find_archived_heap_object(orig_obj);
-  if (archived_obj == NULL) {
+  if (archived_obj == nullptr) {
     // It's OK for the root of a subgraph to be not archived. See comments in
     // archive_reachable_objects_from().
     return;
@@ -1513,10 +1513,10 @@ void HeapShared::verify_reachable_objects_from(oop obj, bool is_archived) {
 
     if (is_archived) {
       assert(is_archived_object_during_dumptime(obj), "must be");
-      assert(find_archived_heap_object(obj) == NULL, "must be");
+      assert(find_archived_heap_object(obj) == nullptr, "must be");
     } else {
       assert(!is_archived_object_during_dumptime(obj), "must be");
-      assert(find_archived_heap_object(obj) != NULL, "must be");
+      assert(find_archived_heap_object(obj) != nullptr, "must be");
     }
 
     VerifySharedOopClosure walker(is_archived);
@@ -1550,7 +1550,7 @@ void HeapShared::check_default_subgraph_classes() {
   }
 }
 
-HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = NULL;
+HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
 int HeapShared::_num_new_walked_objs;
 int HeapShared::_num_new_archived_objs;
 int HeapShared::_num_old_recorded_klasses;
@@ -1562,7 +1562,7 @@ int HeapShared::_num_total_recorded_klasses = 0;
 int HeapShared::_num_total_verifications = 0;
 
 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
-  return _seen_objects_table->get(obj) != NULL;
+  return _seen_objects_table->get(obj) != nullptr;
 }
 
 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
@@ -1627,7 +1627,7 @@ void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
     ResourceMark rm; // for stringStream::as_string() etc.
 
 #ifndef PRODUCT
-    bool is_test_class = (ArchiveHeapTestClass != NULL) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
+    bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
 #else
     bool is_test_class = false;
 #endif
@@ -1663,7 +1663,7 @@ void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
       }
 
-      if (ik->package() != NULL) {
+      if (ik->package() != nullptr) {
         // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
         stringStream st;
         st.print("ArchiveHeapTestClass %s is not in unnamed package", ArchiveHeapTestClass);
@@ -1712,10 +1712,10 @@ void HeapShared::init_subgraph_entry_fields(TRAPS) {
 void HeapShared::setup_test_class(const char* test_class_name) {
   ArchivableStaticFieldInfo* p = open_archive_subgraph_entry_fields;
   int num_slots = sizeof(open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
-  assert(p[num_slots - 2].klass_name == NULL, "must have empty slot that's patched below");
-  assert(p[num_slots - 1].klass_name == NULL, "must have empty slot that marks the end of the list");
+  assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
+  assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
 
-  if (test_class_name != NULL) {
+  if (test_class_name != nullptr) {
     p[num_slots - 2].klass_name = test_class_name;
     p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
   }
@@ -1725,12 +1725,12 @@ void HeapShared::setup_test_class(const char* test_class_name) {
 // during runtime. This may be called before the module system is initialized so
 // we cannot rely on InstanceKlass::module(), etc.
 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
-  if (_test_class != NULL) {
+  if (_test_class != nullptr) {
     if (ik == _test_class) {
       return true;
     }
     Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
-    if (klasses == NULL) {
+    if (klasses == nullptr) {
       return false;
     }
 
@@ -1871,7 +1871,7 @@ class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
   virtual void do_oop(oop* p) {
     assert(!UseCompressedOops, "sanity");
     _num_total_oops ++;
-    if ((*p) != NULL) {
+    if ((*p) != nullptr) {
       size_t idx = p - (oop*)_start;
       _oopmap->set_bit(idx);
       if (DumpSharedSpaces) {
@@ -1889,7 +1889,7 @@ class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
 
 address HeapShared::to_requested_address(address dumptime_addr) {
   assert(DumpSharedSpaces, "static dump time only");
-  if (dumptime_addr == NULL || UseCompressedOops) {
+  if (dumptime_addr == nullptr || UseCompressedOops) {
     return dumptime_addr;
   }
 
@@ -1910,7 +1910,7 @@ address HeapShared::to_requested_address(address dumptime_addr) {
   intx delta = REQUESTED_BASE - actual_base;
 
   address requested_addr = dumptime_addr + delta;
-  assert(REQUESTED_BASE != 0 && requested_addr != NULL, "sanity");
+  assert(REQUESTED_BASE != 0 && requested_addr != nullptr, "sanity");
   return requested_addr;
 }
 
@@ -1921,7 +1921,7 @@ ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
   HeapWord* p   = region.start();
   HeapWord* end = region.end();
   FindEmbeddedNonNullPointers finder((void*)p, &oopmap);
-  ArchiveBuilder* builder = DumpSharedSpaces ? ArchiveBuilder::current() : NULL;
+  ArchiveBuilder* builder = DumpSharedSpaces ? ArchiveBuilder::current() : nullptr;
 
   int num_objs = 0;
   while (p < end) {
@@ -1952,7 +1952,7 @@ ResourceBitMap HeapShared::calculate_ptrmap(MemRegion region) {
   for (int i = 0; i < len; i++) {
     Metadata** p = _native_pointers->at(i);
     if (start <= p && p < end) {
-      assert(*p != NULL, "must be non-null");
+      assert(*p != nullptr, "must be non-null");
       num_non_null_ptrs ++;
       size_t idx = p - start;
       oopmap.set_bit(idx);
diff --git a/src/hotspot/share/cds/heapShared.hpp b/src/hotspot/share/cds/heapShared.hpp
index 6cef34d8ba3..6db5a5a306e 100644
--- a/src/hotspot/share/cds/heapShared.hpp
+++ b/src/hotspot/share/cds/heapShared.hpp
@@ -76,16 +76,16 @@ class KlassSubGraphInfo: public CHeapObj<mtClass> {
   static void check_allowed_klass(InstanceKlass* ik);
  public:
   KlassSubGraphInfo(Klass* k, bool is_full_module_graph) :
-    _k(k),  _subgraph_object_klasses(NULL),
-    _subgraph_entry_fields(NULL),
+    _k(k),  _subgraph_object_klasses(nullptr),
+    _subgraph_entry_fields(nullptr),
     _is_full_module_graph(is_full_module_graph),
     _has_non_early_klasses(false) {}
 
   ~KlassSubGraphInfo() {
-    if (_subgraph_object_klasses != NULL) {
+    if (_subgraph_object_klasses != nullptr) {
       delete _subgraph_object_klasses;
     }
-    if (_subgraph_entry_fields != NULL) {
+    if (_subgraph_entry_fields != nullptr) {
       delete _subgraph_entry_fields;
     }
   };
@@ -101,7 +101,7 @@ class KlassSubGraphInfo: public CHeapObj<mtClass> {
                                 bool is_closed_archive);
   void add_subgraph_object_klass(Klass *orig_k);
   int num_subgraph_object_klasses() {
-    return _subgraph_object_klasses == NULL ? 0 :
+    return _subgraph_object_klasses == nullptr ? 0 :
            _subgraph_object_klasses->length();
   }
   bool is_full_module_graph() const { return _is_full_module_graph; }
@@ -125,7 +125,7 @@ class ArchivedKlassSubGraphInfoRecord {
   Array<Klass*>* _subgraph_object_klasses;
  public:
   ArchivedKlassSubGraphInfoRecord() :
-    _k(NULL), _entry_field_records(NULL), _subgraph_object_klasses(NULL) {}
+    _k(nullptr), _entry_field_records(nullptr), _subgraph_object_klasses(nullptr) {}
   void init(KlassSubGraphInfo* info);
   Klass* klass() const { return _k; }
   Array<int>* entry_field_records() const { return _entry_field_records; }
@@ -159,8 +159,8 @@ public:
   static bool is_subgraph_root_class(InstanceKlass* ik);
 
   // Scratch objects for archiving Klass::java_mirror()
-  static oop scratch_java_mirror(BasicType t) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
-  static oop scratch_java_mirror(Klass* k)    NOT_CDS_JAVA_HEAP_RETURN_(NULL);
+  static oop scratch_java_mirror(BasicType t) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
+  static oop scratch_java_mirror(Klass* k)    NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
 
 private:
 #if INCLUDE_CDS_JAVA_HEAP
@@ -289,13 +289,13 @@ private:
   static KlassToOopHandleTable* _scratch_java_mirror_table;
 
   static void init_seen_objects_table() {
-    assert(_seen_objects_table == NULL, "must be");
+    assert(_seen_objects_table == nullptr, "must be");
     _seen_objects_table = new (mtClass)SeenObjectsTable();
   }
   static void delete_seen_objects_table() {
-    assert(_seen_objects_table != NULL, "must be");
+    assert(_seen_objects_table != nullptr, "must be");
     delete _seen_objects_table;
-    _seen_objects_table = NULL;
+    _seen_objects_table = nullptr;
   }
 
   // Statistics (for one round of start_recording_subgraph ... done_recording_subgraph)
@@ -347,25 +347,25 @@ private:
       _original_object_table =
         new (mtClass)OriginalObjectTable();
     } else {
-      _original_object_table = NULL;
+      _original_object_table = nullptr;
     }
   }
   static void destroy_archived_object_cache() {
     delete _archived_object_cache;
-    _archived_object_cache = NULL;
-    if (_original_object_table != NULL) {
+    _archived_object_cache = nullptr;
+    if (_original_object_table != nullptr) {
       delete _original_object_table;
-      _original_object_table = NULL;
+      _original_object_table = nullptr;
     }
   }
   static ArchivedObjectCache* archived_object_cache() {
     return _archived_object_cache;
   }
   static oop get_original_object(oop archived_object) {
-    assert(_original_object_table != NULL, "sanity");
+    assert(_original_object_table != nullptr, "sanity");
     oop* r = _original_object_table->get(archived_object);
-    if (r == NULL) {
-      return NULL;
+    if (r == nullptr) {
+      return nullptr;
     } else {
       return *r;
     }
@@ -445,7 +445,7 @@ private:
 
   // Returns the address of a heap object when it's mapped at the
   // runtime requested address. See comments in archiveBuilder.hpp.
-  static address to_requested_address(address dumptime_addr) NOT_CDS_JAVA_HEAP_RETURN_(NULL);
+  static address to_requested_address(address dumptime_addr) NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
   static oop to_requested_address(oop dumptime_oop) {
     return cast_to_oop(to_requested_address(cast_from_oop<address>(dumptime_oop)));
   }
diff --git a/src/hotspot/share/cds/lambdaFormInvokers.cpp b/src/hotspot/share/cds/lambdaFormInvokers.cpp
index 89d5e312903..e841fbb891e 100644
--- a/src/hotspot/share/cds/lambdaFormInvokers.cpp
+++ b/src/hotspot/share/cds/lambdaFormInvokers.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2023, 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
@@ -71,7 +71,7 @@ static bool should_be_archived(char* line) {
 
 void LambdaFormInvokers::append(char* line) {
   MutexLocker ml(Thread::current(), LambdaFormInvokers_lock);
-  if (_lambdaform_lines == NULL) {
+  if (_lambdaform_lines == nullptr) {
     _lambdaform_lines = new GrowableArrayCHeap<char*, mtClassShared>(150);
   }
   _lambdaform_lines->append(line);
@@ -118,7 +118,7 @@ void LambdaFormInvokers::regenerate_holder_classes(TRAPS) {
 
   Symbol* cds_name  = vmSymbols::jdk_internal_misc_CDS();
   Klass*  cds_klass = SystemDictionary::resolve_or_null(cds_name, THREAD);
-  guarantee(cds_klass != NULL, "jdk/internal/misc/CDS must exist!");
+  guarantee(cds_klass != nullptr, "jdk/internal/misc/CDS must exist!");
 
   HandleMark hm(THREAD);
   int len = _lambdaform_lines->length();
@@ -161,8 +161,8 @@ void LambdaFormInvokers::regenerate_holder_classes(TRAPS) {
   for (int i = 0; i < sz; i+= 2) {
     Handle h_name(THREAD, h_array->obj_at(i));
     typeArrayHandle h_bytes(THREAD, (typeArrayOop)h_array->obj_at(i+1));
-    assert(h_name != NULL, "Class name is NULL");
-    assert(h_bytes != NULL, "Class bytes is NULL");
+    assert(h_name != nullptr, "Class name is null");
+    assert(h_bytes != nullptr, "Class bytes is null");
 
     char *class_name = java_lang_String::as_utf8_string(h_name());
     if (strstr(class_name, "java/lang/invoke/BoundMethodHandle$Species_") != nullptr) {
@@ -171,7 +171,7 @@ void LambdaFormInvokers::regenerate_holder_classes(TRAPS) {
       // need to regenerate.
       TempNewSymbol class_name_sym = SymbolTable::new_symbol(class_name);
       Klass* klass = SystemDictionary::resolve_or_null(class_name_sym, THREAD);
-      assert(klass != NULL, "must already be loaded");
+      assert(klass != nullptr, "must already be loaded");
       if (!klass->is_shared() && klass->shared_classpath_index() < 0) {
         // Fake it, so that it will be included into the archive.
         klass->set_shared_classpath_index(0);
@@ -184,7 +184,7 @@ void LambdaFormInvokers::regenerate_holder_classes(TRAPS) {
       // make a copy of class bytes so GC will not affect us.
       char *buf = NEW_RESOURCE_ARRAY(char, len);
       memcpy(buf, (char*)h_bytes->byte_at_addr(0), len);
-      ClassFileStream st((u1*)buf, len, NULL, ClassFileStream::verify);
+      ClassFileStream st((u1*)buf, len, nullptr, ClassFileStream::verify);
       regenerate_class(class_name, st, CHECK);
     }
   }
@@ -193,7 +193,7 @@ void LambdaFormInvokers::regenerate_holder_classes(TRAPS) {
 void LambdaFormInvokers::regenerate_class(char* class_name, ClassFileStream& st, TRAPS) {
   TempNewSymbol class_name_sym = SymbolTable::new_symbol(class_name);
   Klass* klass = SystemDictionary::resolve_or_null(class_name_sym, THREAD);
-  assert(klass != NULL, "must exist");
+  assert(klass != nullptr, "must exist");
   assert(klass->is_instance_klass(), "Should be");
 
   ClassLoaderData* cld = ClassLoaderData::the_null_class_loader_data();
diff --git a/src/hotspot/share/cds/lambdaProxyClassDictionary.cpp b/src/hotspot/share/cds/lambdaProxyClassDictionary.cpp
index ded2e1e489c..f3defd6bf39 100644
--- a/src/hotspot/share/cds/lambdaProxyClassDictionary.cpp
+++ b/src/hotspot/share/cds/lambdaProxyClassDictionary.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2023, 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
@@ -30,8 +30,8 @@
 // This constructor is used only by SystemDictionaryShared::clone_dumptime_tables().
 // See comments there about the need for making a deep copy.
 DumpTimeLambdaProxyClassInfo::DumpTimeLambdaProxyClassInfo(const DumpTimeLambdaProxyClassInfo& src) {
-  _proxy_klasses = NULL;
-  if (src._proxy_klasses != NULL && src._proxy_klasses->length() > 0) {
+  _proxy_klasses = nullptr;
+  if (src._proxy_klasses != nullptr && src._proxy_klasses->length() > 0) {
     int n = src._proxy_klasses->length();
     _proxy_klasses = new (mtClassShared) GrowableArray<InstanceKlass*>(n, mtClassShared);
     for (int i = 0; i < n; i++) {
@@ -41,7 +41,7 @@ DumpTimeLambdaProxyClassInfo::DumpTimeLambdaProxyClassInfo(const DumpTimeLambdaP
 }
 
 DumpTimeLambdaProxyClassInfo::~DumpTimeLambdaProxyClassInfo() {
-  if (_proxy_klasses != NULL) {
+  if (_proxy_klasses != nullptr) {
     delete _proxy_klasses;
   }
 }
diff --git a/src/hotspot/share/cds/lambdaProxyClassDictionary.hpp b/src/hotspot/share/cds/lambdaProxyClassDictionary.hpp
index 5dc5398847b..0f1e855aeea 100644
--- a/src/hotspot/share/cds/lambdaProxyClassDictionary.hpp
+++ b/src/hotspot/share/cds/lambdaProxyClassDictionary.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2023, 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
@@ -77,8 +77,8 @@ public:
   unsigned int hash() const;
 
   static unsigned int dumptime_hash(Symbol* sym)  {
-    if (sym == NULL) {
-      // _invoked_name maybe NULL
+    if (sym == nullptr) {
+      // _invoked_name maybe null
       return 0;
     }
     return java_lang_String::hash_code((const jbyte*)sym->bytes(), sym->utf8_length());
@@ -107,16 +107,16 @@ public:
 class DumpTimeLambdaProxyClassInfo {
 public:
   GrowableArray<InstanceKlass*>* _proxy_klasses;
-  DumpTimeLambdaProxyClassInfo() : _proxy_klasses(NULL) {}
+  DumpTimeLambdaProxyClassInfo() : _proxy_klasses(nullptr) {}
   DumpTimeLambdaProxyClassInfo(const DumpTimeLambdaProxyClassInfo& src);
   DumpTimeLambdaProxyClassInfo& operator=(const DumpTimeLambdaProxyClassInfo&) = delete;
   ~DumpTimeLambdaProxyClassInfo();
 
   void add_proxy_klass(InstanceKlass* proxy_klass) {
-    if (_proxy_klasses == NULL) {
+    if (_proxy_klasses == nullptr) {
       _proxy_klasses = new (mtClassShared) GrowableArray<InstanceKlass*>(5, mtClassShared);
     }
-    assert(_proxy_klasses != NULL, "sanity");
+    assert(_proxy_klasses != nullptr, "sanity");
     _proxy_klasses->append(proxy_klass);
   }
 
diff --git a/src/hotspot/share/cds/metaspaceShared.cpp b/src/hotspot/share/cds/metaspaceShared.cpp
index 95cb57c74e4..7afa8fb947c 100644
--- a/src/hotspot/share/cds/metaspaceShared.cpp
+++ b/src/hotspot/share/cds/metaspaceShared.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2023, 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
@@ -90,7 +90,7 @@ VirtualSpace MetaspaceShared::_symbol_vs;
 bool MetaspaceShared::_has_error_classes;
 bool MetaspaceShared::_archive_loading_failed = false;
 bool MetaspaceShared::_remapped_readwrite = false;
-void* MetaspaceShared::_shared_metaspace_static_top = NULL;
+void* MetaspaceShared::_shared_metaspace_static_top = nullptr;
 intx MetaspaceShared::_relocation_delta;
 char* MetaspaceShared::_requested_base_address;
 bool MetaspaceShared::_use_optimized_module_handling = true;
@@ -185,7 +185,7 @@ public:
   }
 
   void do_cld(ClassLoaderData* cld) {
-    for (Klass* klass = cld->klasses(); klass != NULL; klass = klass->next_link()) {
+    for (Klass* klass = cld->klasses(); klass != nullptr; klass = klass->next_link()) {
       if (klass->is_instance_klass()) {
         dump(InstanceKlass::cast(klass));
       }
@@ -206,7 +206,7 @@ void MetaspaceShared::dump_loaded_classes(const char* file_name, TRAPS) {
 }
 
 static bool shared_base_too_high(char* specified_base, char* aligned_base, size_t cds_max) {
-  if (specified_base != NULL && aligned_base < specified_base) {
+  if (specified_base != nullptr && aligned_base < specified_base) {
     // SharedBaseAddress is very high (e.g., 0xffffffffffffff00) so
     // align_up(SharedBaseAddress, MetaspaceShared::core_region_alignment()) has wrapped around.
     return true;
@@ -223,7 +223,7 @@ static char* compute_shared_base(size_t cds_max) {
   char* specified_base = (char*)SharedBaseAddress;
   char* aligned_base = align_up(specified_base, MetaspaceShared::core_region_alignment());
 
-  const char* err = NULL;
+  const char* err = nullptr;
   if (shared_base_too_high(specified_base, aligned_base, cds_max)) {
     err = "too high";
   } else if (!shared_base_valid(aligned_base)) {
@@ -282,7 +282,7 @@ void MetaspaceShared::post_initialize(TRAPS) {
       CDSProtectionDomain::allocate_shared_data_arrays(size, CHECK);
       if (!DynamicDumpSharedSpaces) {
         FileMapInfo* info;
-        if (FileMapInfo::dynamic_info() == NULL) {
+        if (FileMapInfo::dynamic_info() == nullptr) {
           info = FileMapInfo::current_info();
         } else {
           info = FileMapInfo::dynamic_info();
@@ -294,8 +294,8 @@ void MetaspaceShared::post_initialize(TRAPS) {
   }
 }
 
-static GrowableArrayCHeap<OopHandle, mtClassShared>* _extra_interned_strings = NULL;
-static GrowableArrayCHeap<Symbol*, mtClassShared>* _extra_symbols = NULL;
+static GrowableArrayCHeap<OopHandle, mtClassShared>* _extra_interned_strings = nullptr;
+static GrowableArrayCHeap<Symbol*, mtClassShared>* _extra_symbols = nullptr;
 
 void MetaspaceShared::read_extra_data(JavaThread* current, const char* filename) {
   _extra_interned_strings = new GrowableArrayCHeap<OopHandle, mtClassShared>(10000);
@@ -344,7 +344,7 @@ void MetaspaceShared::read_extra_data(JavaThread* current, const char* filename)
         }
 #endif
         // Make sure this string is included in the dumped interned string table.
-        assert(str != NULL, "must succeed");
+        assert(str != nullptr, "must succeed");
         _extra_interned_strings->append(OopHandle(Universe::vm_global(), str));
       }
     }
@@ -459,10 +459,10 @@ public:
 
   VM_PopulateDumpSharedSpace() :
     VM_GC_Operation(0 /* total collections, ignored */, GCCause::_archive_time_gc),
-    _closed_heap_regions(NULL),
-    _open_heap_regions(NULL),
-    _closed_heap_bitmaps(NULL),
-    _open_heap_bitmaps(NULL) {}
+    _closed_heap_regions(nullptr),
+    _open_heap_regions(nullptr),
+    _closed_heap_bitmaps(nullptr),
+    _open_heap_bitmaps(nullptr) {}
 
   bool skip_operation() const { return false; }
 
@@ -486,7 +486,7 @@ public:
     // may not be used by any of the archived classes -- these are usually
     // symbols that we anticipate to be used at run time, so we can store
     // them in the RO region, to be shared across multiple processes.
-    if (_extra_symbols != NULL) {
+    if (_extra_symbols != nullptr) {
       for (int i = 0; i < _extra_symbols->length(); i++) {
         it->push(_extra_symbols->adr_at(i));
       }
@@ -624,7 +624,7 @@ bool MetaspaceShared::may_be_eagerly_linked(InstanceKlass* ik) {
     // that may not be expected by custom class loaders.
     //
     // It's OK to do this for the built-in loaders as we know they can
-    // tolerate this. (Note that unregistered classes are loaded by the NULL
+    // tolerate this. (Note that unregistered classes are loaded by the null
     // loader during DumpSharedSpaces).
     return false;
   }
@@ -662,7 +662,7 @@ void MetaspaceShared::link_shared_classes(bool jcmd_request, TRAPS) {
     bool has_linked = false;
     for (int i = 0; i < collect_cld.nof_cld(); i++) {
       ClassLoaderData* cld = collect_cld.cld_at(i);
-      for (Klass* klass = cld->klasses(); klass != NULL; klass = klass->next_link()) {
+      for (Klass* klass = cld->klasses(); klass != nullptr; klass = klass->next_link()) {
         if (klass->is_instance_klass()) {
           InstanceKlass* ik = InstanceKlass::cast(klass);
           if (may_be_eagerly_linked(ik)) {
@@ -740,7 +740,7 @@ void MetaspaceShared::get_default_classlist(char* default_classlist, const size_
   os::jvm_path(default_classlist, (jint)(buf_size));
   for (int i = 0; i < 3; i++) {
     char *end = strrchr(default_classlist, *os::file_separator());
-    if (end != NULL) *end = '\0';
+    if (end != nullptr) *end = '\0';
   }
   size_t classlist_path_len = strlen(default_classlist);
   if (classlist_path_len >= 3) {
@@ -765,7 +765,7 @@ void MetaspaceShared::preload_classes(TRAPS) {
   const char* classlist_path;
 
   get_default_classlist(default_classlist, sizeof(default_classlist));
-  if (SharedClassListFile == NULL) {
+  if (SharedClassListFile == nullptr) {
     classlist_path = default_classlist;
   } else {
     classlist_path = SharedClassListFile;
@@ -836,9 +836,9 @@ bool MetaspaceShared::try_link_class(JavaThread* current, InstanceKlass* ik) {
   if (ik->is_loaded() && !ik->is_linked() && ik->can_be_verified_at_dumptime() &&
       !SystemDictionaryShared::has_class_failed_verification(ik)) {
     bool saved = BytecodeVerificationLocal;
-    if (ik->is_shared_unregistered_class() && ik->class_loader() == NULL) {
+    if (ik->is_shared_unregistered_class() && ik->class_loader() == nullptr) {
       // The verification decision is based on BytecodeVerificationRemote
-      // for non-system classes. Since we are using the NULL classloader
+      // for non-system classes. Since we are using the null classloader
       // to load non-system classes for customized class loaders during dumping,
       // we need to temporarily change BytecodeVerificationLocal to be the same as
       // BytecodeVerificationRemote. Note this can cause the parent system
@@ -883,7 +883,7 @@ void VM_PopulateDumpSharedSpace::dump_java_heap_objects(GrowableArray<Klass*>* k
       }
     }
   }
-  if (_extra_interned_strings != NULL) {
+  if (_extra_interned_strings != nullptr) {
     for (i = 0; i < _extra_interned_strings->length(); i ++) {
       OopHandle string = _extra_interned_strings->at(i);
       HeapShared::add_to_dumped_interned_strings(string.resolve());
@@ -933,7 +933,7 @@ void VM_PopulateDumpSharedSpace::dump_one_heap_bitmap(MemRegion region,
     bitmap.write_to(buffer, size_in_bytes);
   } else {
     size_in_bytes = 0;
-    buffer = NULL;
+    buffer = nullptr;
   }
 
   log_info(cds, heap)("%s = " INTPTR_FORMAT " (" SIZE_FORMAT_W(6) " bytes) for heap region "
@@ -970,9 +970,9 @@ void MetaspaceShared::initialize_runtime_shared_and_meta_spaces() {
   MapArchiveResult result = MAP_ARCHIVE_OTHER_FAILURE;
 
   FileMapInfo* static_mapinfo = open_static_archive();
-  FileMapInfo* dynamic_mapinfo = NULL;
+  FileMapInfo* dynamic_mapinfo = nullptr;
 
-  if (static_mapinfo != NULL) {
+  if (static_mapinfo != nullptr) {
     log_info(cds)("Core region alignment: " SIZE_FORMAT, static_mapinfo->core_region_alignment());
     dynamic_mapinfo = open_dynamic_archive();
 
@@ -987,7 +987,7 @@ void MetaspaceShared::initialize_runtime_shared_and_meta_spaces() {
   }
 
   if (result == MAP_ARCHIVE_SUCCESS) {
-    bool dynamic_mapped = (dynamic_mapinfo != NULL && dynamic_mapinfo->is_mapped());
+    bool dynamic_mapped = (dynamic_mapinfo != nullptr && dynamic_mapinfo->is_mapped());
     char* cds_base = static_mapinfo->mapped_base();
     char* cds_end =  dynamic_mapped ? dynamic_mapinfo->mapped_end() : static_mapinfo->mapped_end();
     set_shared_metaspace_range(cds_base, static_mapinfo->mapped_end(), cds_end);
@@ -1001,7 +1001,7 @@ void MetaspaceShared::initialize_runtime_shared_and_meta_spaces() {
       FileMapInfo::set_shared_path_table(static_mapinfo);
     }
   } else {
-    set_shared_metaspace_range(NULL, NULL, NULL);
+    set_shared_metaspace_range(nullptr, nullptr, nullptr);
     if (DynamicDumpSharedSpaces) {
       warning("-XX:ArchiveClassesAtExit is unsupported when base CDS archive is not loaded. Run with -Xlog:cds for more info.");
     }
@@ -1015,38 +1015,38 @@ void MetaspaceShared::initialize_runtime_shared_and_meta_spaces() {
     }
   }
 
-  if (static_mapinfo != NULL && !static_mapinfo->is_mapped()) {
+  if (static_mapinfo != nullptr && !static_mapinfo->is_mapped()) {
     delete static_mapinfo;
   }
-  if (dynamic_mapinfo != NULL && !dynamic_mapinfo->is_mapped()) {
+  if (dynamic_mapinfo != nullptr && !dynamic_mapinfo->is_mapped()) {
     delete dynamic_mapinfo;
   }
 }
 
 FileMapInfo* MetaspaceShared::open_static_archive() {
   const char* static_archive = Arguments::GetSharedArchivePath();
-  assert(static_archive != nullptr, "SharedArchivePath is NULL");
+  assert(static_archive != nullptr, "SharedArchivePath is nullptr");
   FileMapInfo* mapinfo = new FileMapInfo(static_archive, true);
   if (!mapinfo->initialize()) {
     delete(mapinfo);
-    return NULL;
+    return nullptr;
   }
   return mapinfo;
 }
 
 FileMapInfo* MetaspaceShared::open_dynamic_archive() {
   if (DynamicDumpSharedSpaces) {
-    return NULL;
+    return nullptr;
   }
   const char* dynamic_archive = Arguments::GetSharedDynamicArchivePath();
   if (dynamic_archive == nullptr) {
-    return NULL;
+    return nullptr;
   }
 
   FileMapInfo* mapinfo = new FileMapInfo(dynamic_archive, false);
   if (!mapinfo->initialize()) {
     delete(mapinfo);
-    return NULL;
+    return nullptr;
   }
   return mapinfo;
 }
@@ -1056,7 +1056,7 @@ FileMapInfo* MetaspaceShared::open_dynamic_archive() {
 //  false = map at an alternative address picked by OS.
 MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, FileMapInfo* dynamic_mapinfo,
                                                bool use_requested_addr) {
-  if (use_requested_addr && static_mapinfo->requested_base_address() == NULL) {
+  if (use_requested_addr && static_mapinfo->requested_base_address() == nullptr) {
     log_info(cds)("Archive(s) were created with -XX:SharedBaseAddress=0. Always map at os-selected address.");
     return MAP_ARCHIVE_MMAP_FAILURE;
   }
@@ -1074,7 +1074,7 @@ MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, File
     return MAP_ARCHIVE_MMAP_FAILURE;
   };
 
-  if (dynamic_mapinfo != NULL) {
+  if (dynamic_mapinfo != nullptr) {
     // Ensure that the OS won't be able to allocate new memory spaces between the two
     // archives, or else it would mess up the simple comparison in MetaspaceObj::is_shared().
     assert(static_mapinfo->mapping_end_offset() == dynamic_mapinfo->mapping_base_offset(), "no gap");
@@ -1088,7 +1088,7 @@ MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, File
                                                                  total_space_rs,
                                                                  archive_space_rs,
                                                                  class_space_rs);
-  if (mapped_base_address == NULL) {
+  if (mapped_base_address == nullptr) {
     result = MAP_ARCHIVE_MMAP_FAILURE;
     log_debug(cds)("Failed to reserve spaces (use_requested_addr=%u)", (unsigned)use_requested_addr);
   } else {
@@ -1163,7 +1163,7 @@ MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, File
       if (dynamic_result == MAP_ARCHIVE_SUCCESS) {
         result = MAP_ARCHIVE_SUCCESS;
       } else if (dynamic_result == MAP_ARCHIVE_OTHER_FAILURE) {
-        assert(dynamic_mapinfo != NULL && !dynamic_mapinfo->is_mapped(), "must have failed");
+        assert(dynamic_mapinfo != nullptr && !dynamic_mapinfo->is_mapped(), "must have failed");
         // No need to retry mapping the dynamic archive again, as it will never succeed
         // (bad file, etc) -- just keep the base archive.
         log_warning(cds, dynamic)("Unable to use shared archive. The top archive failed to load: %s",
@@ -1268,7 +1268,7 @@ MapArchiveResult MetaspaceShared::map_archives(FileMapInfo* static_mapinfo, File
 //      archive space, close enough such that narrow class pointer encoding
 //      covers both spaces.
 //      If UseCompressedClassPointers=0, class_space_rs remains unreserved.
-// - On error: NULL is returned and the spaces remain unreserved.
+// - On error: null is returned and the spaces remain unreserved.
 char* MetaspaceShared::reserve_address_space_for_archives(FileMapInfo* static_mapinfo,
                                                           FileMapInfo* dynamic_mapinfo,
                                                           bool use_archive_base_addr,
@@ -1276,16 +1276,16 @@ char* MetaspaceShared::reserve_address_space_for_archives(FileMapInfo* static_ma
                                                           ReservedSpace& archive_space_rs,
                                                           ReservedSpace& class_space_rs) {
 
-  address const base_address = (address) (use_archive_base_addr ? static_mapinfo->requested_base_address() : NULL);
+  address const base_address = (address) (use_archive_base_addr ? static_mapinfo->requested_base_address() : nullptr);
   const size_t archive_space_alignment = core_region_alignment();
 
   // Size and requested location of the archive_space_rs (for both static and dynamic archives)
   assert(static_mapinfo->mapping_base_offset() == 0, "Must be");
-  size_t archive_end_offset  = (dynamic_mapinfo == NULL) ? static_mapinfo->mapping_end_offset() : dynamic_mapinfo->mapping_end_offset();
+  size_t archive_end_offset  = (dynamic_mapinfo == nullptr) ? static_mapinfo->mapping_end_offset() : dynamic_mapinfo->mapping_end_offset();
   size_t archive_space_size = align_up(archive_end_offset, archive_space_alignment);
 
   // If a base address is given, it must have valid alignment and be suitable as encoding base.
-  if (base_address != NULL) {
+  if (base_address != nullptr) {
     assert(is_aligned(base_address, archive_space_alignment),
            "Archive base address invalid: " PTR_FORMAT ".", p2i(base_address));
     if (Metaspace::using_class_space()) {
@@ -1300,13 +1300,13 @@ char* MetaspaceShared::reserve_address_space_for_archives(FileMapInfo* static_ma
     archive_space_rs = ReservedSpace(archive_space_size, archive_space_alignment,
                                      os::vm_page_size(), (char*)base_address);
     if (archive_space_rs.is_reserved()) {
-      assert(base_address == NULL ||
+      assert(base_address == nullptr ||
              (address)archive_space_rs.base() == base_address, "Sanity");
       // Register archive space with NMT.
       MemTracker::record_virtual_memory_type(archive_space_rs.base(), mtClassShared);
       return archive_space_rs.base();
     }
-    return NULL;
+    return nullptr;
   }
 
 #ifdef _LP64
@@ -1353,7 +1353,7 @@ char* MetaspaceShared::reserve_address_space_for_archives(FileMapInfo* static_ma
     }
     if (!archive_space_rs.is_reserved() || !class_space_rs.is_reserved()) {
       release_reserved_spaces(total_space_rs, archive_space_rs, class_space_rs);
-      return NULL;
+      return nullptr;
     }
   } else {
     if (use_archive_base_addr && base_address != nullptr) {
@@ -1365,11 +1365,11 @@ char* MetaspaceShared::reserve_address_space_for_archives(FileMapInfo* static_ma
     }
 
     if (!total_space_rs.is_reserved()) {
-      return NULL;
+      return nullptr;
     }
 
     // Paranoid checks:
-    assert(base_address == NULL || (address)total_space_rs.base() == base_address,
+    assert(base_address == nullptr || (address)total_space_rs.base() == base_address,
            "Sanity (" PTR_FORMAT " vs " PTR_FORMAT ")", p2i(base_address), p2i(total_space_rs.base()));
     assert(is_aligned(total_space_rs.base(), archive_space_alignment), "Sanity");
     assert(total_space_rs.size() == total_range_size, "Sanity");
@@ -1396,7 +1396,7 @@ char* MetaspaceShared::reserve_address_space_for_archives(FileMapInfo* static_ma
 
 #else
   ShouldNotReachHere();
-  return NULL;
+  return nullptr;
 #endif
 
 }
@@ -1424,7 +1424,7 @@ static int archive_regions_count = 2;
 
 MapArchiveResult MetaspaceShared::map_archive(FileMapInfo* mapinfo, char* mapped_base_address, ReservedSpace rs) {
   assert(UseSharedSpaces, "must be runtime");
-  if (mapinfo == NULL) {
+  if (mapinfo == nullptr) {
     return MAP_ARCHIVE_SUCCESS; // The dynamic archive has not been specified. No error has happened -- trivially succeeded.
   }
 
@@ -1454,7 +1454,7 @@ MapArchiveResult MetaspaceShared::map_archive(FileMapInfo* mapinfo, char* mapped
 
 void MetaspaceShared::unmap_archive(FileMapInfo* mapinfo) {
   assert(UseSharedSpaces, "must be runtime");
-  if (mapinfo != NULL) {
+  if (mapinfo != nullptr) {
     mapinfo->unmap_regions(archive_regions, archive_regions_count);
     mapinfo->unmap_region(MetaspaceShared::bm);
     mapinfo->set_is_mapped(false);
@@ -1503,7 +1503,7 @@ void MetaspaceShared::initialize_shared_spaces() {
   static_mapinfo->unmap_region(MetaspaceShared::bm);
 
   FileMapInfo *dynamic_mapinfo = FileMapInfo::dynamic_info();
-  if (dynamic_mapinfo != NULL) {
+  if (dynamic_mapinfo != nullptr) {
     intptr_t* buffer = (intptr_t*)dynamic_mapinfo->serialized_data();
     ReadClosure rc(&buffer);
     SymbolTable::serialize_shared_table_header(&rc, false);
@@ -1541,7 +1541,7 @@ void MetaspaceShared::initialize_shared_spaces() {
     tty->print_cr("Number of shared symbols: %d", cl.total());
     tty->print_cr("Number of shared strings: %zu", StringTable::shared_entry_count());
     tty->print_cr("VM version: %s\r\n", static_mapinfo->vm_version());
-    if (FileMapInfo::current_info() == NULL || _archive_loading_failed) {
+    if (FileMapInfo::current_info() == nullptr || _archive_loading_failed) {
       tty->print_cr("archive is invalid");
       vm_exit(1);
     } else {
@@ -1561,7 +1561,7 @@ bool MetaspaceShared::remap_shared_readonly_as_readwrite() {
     if (!mapinfo->remap_shared_readonly_as_readwrite()) {
       return false;
     }
-    if (FileMapInfo::dynamic_info() != NULL) {
+    if (FileMapInfo::dynamic_info() != nullptr) {
       mapinfo = FileMapInfo::dynamic_info();
       if (!mapinfo->remap_shared_readonly_as_readwrite()) {
         return false;
diff --git a/src/hotspot/share/cds/unregisteredClasses.cpp b/src/hotspot/share/cds/unregisteredClasses.cpp
index c9c99f9fe0e..53b9debcd62 100644
--- a/src/hotspot/share/cds/unregisteredClasses.cpp
+++ b/src/hotspot/share/cds/unregisteredClasses.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2023, 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
@@ -43,7 +43,7 @@
 // the "source:" in the class list file (see classListParser.cpp), and can be a directory or
 // a JAR file.
 InstanceKlass* UnregisteredClasses::load_class(Symbol* name, const char* path, TRAPS) {
-  assert(name != NULL, "invariant");
+  assert(name != nullptr, "invariant");
   assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
 
   {
@@ -77,7 +77,7 @@ class URLClassLoaderTable : public ResourceHashtable<
   137, // prime number
   AnyObj::C_HEAP> {};
 
-static URLClassLoaderTable* _url_classloader_table = NULL;
+static URLClassLoaderTable* _url_classloader_table = nullptr;
 
 Handle UnregisteredClasses::create_url_classloader(Symbol* path, TRAPS) {
   ResourceMark rm(THREAD);
@@ -101,11 +101,11 @@ Handle UnregisteredClasses::create_url_classloader(Symbol* path, TRAPS) {
 }
 
 Handle UnregisteredClasses::get_url_classloader(Symbol* path, TRAPS) {
-  if (_url_classloader_table == NULL) {
+  if (_url_classloader_table == nullptr) {
     _url_classloader_table = new (mtClass)URLClassLoaderTable();
   }
   OopHandle* url_classloader_ptr = _url_classloader_table->get(path);
-  if (url_classloader_ptr != NULL) {
+  if (url_classloader_ptr != nullptr) {
     return Handle(THREAD, (*url_classloader_ptr).resolve());
   } else {
     Handle url_classloader = create_url_classloader(path, CHECK_NH);