8301178: Replace NULL with nullptr in share/gc/epsilon/

Reviewed-by: tschatzl, kbarrett

src/hotspot/share/gc/epsilon/epsilonBarrierSet.cpp

@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -39,8 +40,8 @@ EpsilonBarrierSet::EpsilonBarrierSet() : BarrierSet(
           make_barrier_set_assembler<BarrierSetAssembler>(),
           make_barrier_set_c1<BarrierSetC1>(),
           make_barrier_set_c2<BarrierSetC2>(),
-          NULL /* barrier_set_nmethod */,
-          NULL /* barrier_set_stack_chunk */,
+          nullptr /* barrier_set_nmethod */,
+          nullptr /* barrier_set_stack_chunk */,
           BarrierSet::FakeRtti(BarrierSet::EpsilonBarrierSet)) {}
 
 void EpsilonBarrierSet::on_thread_create(Thread *thread) {

src/hotspot/share/gc/epsilon/epsilonHeap.cpp

@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2017, 2022, Red Hat, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -104,11 +105,11 @@ EpsilonHeap* EpsilonHeap::heap() {
 HeapWord* EpsilonHeap::allocate_work(size_t size, bool verbose) {
   assert(is_object_aligned(size), "Allocation size should be aligned: " SIZE_FORMAT, size);
 
-  HeapWord* res = NULL;
+  HeapWord* res = nullptr;
   while (true) {
     // Try to allocate, assume space is available
     res = _space->par_allocate(size);
-    if (res != NULL) {
+    if (res != nullptr) {
       break;
     }
 
@@ -118,7 +119,7 @@ HeapWord* EpsilonHeap::allocate_work(size_t size, bool verbose) {
 
       // Try to allocate under the lock, assume another thread was able to expand
       res = _space->par_allocate(size);
-      if (res != NULL) {
+      if (res != nullptr) {
         break;
       }
 
@@ -137,7 +138,7 @@ HeapWord* EpsilonHeap::allocate_work(size_t size, bool verbose) {
         assert(expand, "Should be able to expand");
       } else {
         // No space left:
-        return NULL;
+        return nullptr;
       }
 
       _space->set_end((HeapWord *) _virtual_space.high());
@@ -235,7 +236,7 @@ HeapWord* EpsilonHeap::allocate_new_tlab(size_t min_size,
   // All prepared, let's do it!
   HeapWord* res = allocate_work(size);
 
-  if (res != NULL) {
+  if (res != nullptr) {
     // Allocation successful
     *actual_size = size;
     if (EpsilonElasticTLABDecay) {
@@ -297,7 +298,7 @@ void EpsilonHeap::print_on(outputStream *st) const {
 
   _virtual_space.print_on(st);
 
-  if (_space != NULL) {
+  if (_space != nullptr) {
     st->print_cr("Allocation space:");
     _space->print_on(st);
   }

src/hotspot/share/gc/epsilon/epsilonHeap.hpp

@@ -55,7 +55,7 @@ class EpsilonHeap : public CollectedHeap {
 
   EpsilonHeap() :
           _memory_manager("Epsilon Heap", ""),
-          _space(NULL) {};
+          _space(nullptr) {};
 
   Name kind() const override {
     return CollectedHeap::Epsilon;
@@ -114,7 +114,7 @@ class EpsilonHeap : public CollectedHeap {
   void unpin_object(JavaThread* thread, oop obj) override { }
 
   // No support for block parsing.
-  HeapWord* block_start(const void* addr) const { return NULL;  }
+  HeapWord* block_start(const void* addr) const { return nullptr;  }
   bool block_is_obj(const HeapWord* addr) const { return false; }
 
   // No GC threads