8324286: Fix backsliding on use of nullptr instead of NULL

Reviewed-by: jsjolen, coleenp, jwaters

src/hotspot/cpu/aarch64/c2_MacroAssembler_aarch64.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, 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
@@ -111,10 +111,10 @@ void C2_MacroAssembler::fast_lock(Register objectReg, Register boxReg, Register
   // Handle existing monitor.
   bind(object_has_monitor);
 
-  // The object's monitor m is unlocked iff m->owner == NULL,
+  // The object's monitor m is unlocked iff m->owner == nullptr,
   // otherwise m->owner may contain a thread or a stack address.
   //
-  // Try to CAS m->owner from NULL to current thread.
+  // Try to CAS m->owner from null to current thread.
   add(tmp, disp_hdr, (in_bytes(ObjectMonitor::owner_offset())-markWord::monitor_value));
   cmpxchg(tmp, zr, rthread, Assembler::xword, /*acquire*/ true,
           /*release*/ true, /*weak*/ false, tmp3Reg); // Sets flags for result

src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020, 2022, Huawei Technologies Co., Ltd. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -121,10 +121,10 @@ void C2_MacroAssembler::fast_lock(Register objectReg, Register boxReg,
 
   // Handle existing monitor.
   bind(object_has_monitor);
-  // The object's monitor m is unlocked iff m->owner == NULL,
+  // The object's monitor m is unlocked iff m->owner == nullptr,
   // otherwise m->owner may contain a thread or a stack address.
   //
-  // Try to CAS m->owner from NULL to current thread.
+  // Try to CAS m->owner from null to current thread.
   add(tmp, disp_hdr, (in_bytes(ObjectMonitor::owner_offset()) - markWord::monitor_value));
   cmpxchg(/*memory address*/tmp, /*expected value*/zr, /*new value*/xthread, Assembler::int64, Assembler::aq,
           Assembler::rl, /*result*/flag); // cas succeeds if flag == zr(expected)

src/hotspot/cpu/s390/templateTable_s390.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2016, 2023 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -2868,7 +2868,7 @@ void TemplateTable::jvmti_post_field_mod(Register cache,
   __ z_lgr(fieldEntry, cache);
 
   if (is_static) {
-    // Life is simple. NULL the object pointer.
+    // Life is simple. Null the object pointer.
     __ clear_reg(obj, true, false); // Don't set CC.
   } else {
     // Life is harder. The stack holds the value on top, followed by

src/hotspot/os/aix/os_aix.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2023 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -1584,7 +1584,7 @@ static char* reserve_shmated_memory (size_t bytes, char* requested_addr) {
 
   // Now attach the shared segment.
   // Note that we deliberately *don't* pass SHM_RND. The contract of os::attempt_reserve_memory_at() -
-  // which invokes this function with a request address != NULL - is to map at the specified address
+  // which invokes this function with a request address != nullptr - is to map at the specified address
   // excactly, or to fail. If the caller passed us an address that is not usable (aka not a valid segment
   // boundary), shmat should not round down the address, or think up a completely new one.
   // (In places where this matters, e.g. when reserving the heap, we take care of passing segment-aligned

src/hotspot/os/linux/os_linux.cpp

@@ -4136,7 +4136,7 @@ char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, bool
 
 size_t os::vm_min_address() {
   // Determined by sysctl vm.mmap_min_addr. It exists as a safety zone to prevent
-  // NULL pointer dereferences.
+  // null pointer dereferences.
   // Most distros set this value to 64 KB. It *can* be zero, but rarely is. Here,
   // we impose a minimum value if vm.mmap_min_addr is too low, for increased protection.
   static size_t value = 0;

src/hotspot/share/cds/filemap.cpp

@@ -2156,7 +2156,7 @@ bool FileMapInfo::map_heap_region_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");
       dealloc_heap_region();
       unmap_region(MetaspaceShared::hp);

src/hotspot/share/prims/whitebox.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, 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
@@ -1890,7 +1890,7 @@ WB_END
 WB_ENTRY(jint, WB_getFieldCPIndex(JNIEnv* env, jobject wb, jclass klass, jint index))
   InstanceKlass* ik = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve(klass)));
   ConstantPool* cp = ik->constants();
-  if (cp->cache() == NULL) {
+  if (cp->cache() == nullptr) {
       return -1;
   }
   return cp->resolved_field_entry_at(index)->constant_pool_index();
@@ -1908,7 +1908,7 @@ WB_END
 WB_ENTRY(jint, WB_getMethodCPIndex(JNIEnv* env, jobject wb, jclass klass, jint index))
   InstanceKlass* ik = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve(klass)));
   ConstantPool* cp = ik->constants();
-  if (cp->cache() == NULL) {
+  if (cp->cache() == nullptr) {
       return -1;
   }
   return cp->resolved_method_entry_at(index)->constant_pool_index();

src/hotspot/share/runtime/os.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, 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
@@ -191,7 +191,7 @@ class os: AllStatic {
   static PageSizes          _page_sizes;
 
   // The default value for os::vm_min_address() unless the platform knows better. This value
-  // is chosen to give us reasonable protection against NULL pointer dereferences while being
+  // is chosen to give us reasonable protection against null pointer dereferences while being
   // low enough to leave most of the valuable low-4gb address space open.
   static constexpr size_t _vm_min_address_default = 16 * M;
 

src/hotspot/share/services/heapDumper.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2023, Alibaba Group Holding Limited. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -680,7 +680,7 @@ DumpWriter::~DumpWriter(){
   if (_tmp_buffer != nullptr) {
     os::free(_tmp_buffer);
   }
-  if (_writer != NULL) {
+  if (_writer != nullptr) {
     delete _writer;
   }
   _bytes_written = -1;