8299974: Replace NULL with nullptr in share/adlc/

Reviewed-by: dlong, kvn

src/hotspot/share/adlc/adlArena.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 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
@@ -26,7 +26,7 @@
 
 void* AdlAllocateHeap(size_t size) {
   unsigned char* ptr = (unsigned char*) malloc(size);
-  if (ptr == NULL && size != 0) {
+  if (ptr == nullptr && size != 0) {
     fprintf(stderr, "Error: Out of memory in ADLC\n"); // logging can cause crash!
     fflush(stderr);
     exit(1);
@@ -36,7 +36,7 @@ void* AdlAllocateHeap(size_t size) {
 
 void* AdlReAllocateHeap(void* old_ptr, size_t size) {
   unsigned char* ptr = (unsigned char*) realloc(old_ptr, size);
-  if (ptr == NULL && size != 0) {
+  if (ptr == nullptr && size != 0) {
     fprintf(stderr, "Error: Out of memory in ADLC\n"); // logging can cause crash!
     fflush(stderr);
     exit(1);
@@ -53,7 +53,7 @@ void  AdlChunk::operator delete(void* p, size_t length) {
 }
 
 AdlChunk::AdlChunk(size_t length) {
-  _next = NULL;         // Chain on the linked list
+  _next = nullptr;      // Chain on the linked list
   _len  = length;       // Save actual size
 }
 
@@ -71,7 +71,7 @@ void AdlChunk::chop() {
 
 void AdlChunk::next_chop() {
   _next->chop();
-  _next = NULL;
+  _next = nullptr;
 }
 
 //------------------------------AdlArena------------------------------------------
@@ -164,8 +164,8 @@ void *AdlArena::Arealloc( void *old_ptr, size_t old_size, size_t new_size ) {
 // Reset this AdlArena to empty, and return this AdlArenas guts in a new AdlArena.
 AdlArena *AdlArena::reset(void) {
   AdlArena *a = new AdlArena(this);   // New empty arena
-  _first = _chunk = NULL;       // Normal, new-arena initialization
-  _hwm = _max = NULL;
+  _first = _chunk = nullptr;    // Normal, new-arena initialization
+  _hwm = _max = nullptr;
   return a;                     // Return AdlArena with guts
 }