8374800: [lworld] Add a NULLABLE_NON_ATOMIC_FLAT layout

src/hotspot/share/cds/heapShared.cpp

@@ -823,7 +823,7 @@ void HeapShared::copy_java_mirror(oop orig_mirror, oop scratch_m) {
     if (ik->is_inline_klass() && ik->is_initialized()) {
       // Only concrete value classes need the null_reset field
       InlineKlass* ilk = InlineKlass::cast(k);
-      if (ilk->has_nullable_atomic_layout()) {
+      if (ilk->supports_nullable_layouts()) {
         scratch_m->obj_field_put(ilk->null_reset_value_offset(), ilk->null_reset_value());
       }
     }

src/hotspot/share/ci/ciInlineKlass.cpp

@@ -95,12 +95,12 @@ InlineKlass* ciInlineKlass::get_InlineKlass() const {
   GUARDED_VM_ENTRY(return to_InlineKlass();)
 }
 
-bool ciInlineKlass::has_non_atomic_layout() const {
-  GUARDED_VM_ENTRY(return get_InlineKlass()->has_non_atomic_layout();)
+bool ciInlineKlass::has_null_free_non_atomic_layout() const {
+  GUARDED_VM_ENTRY(return get_InlineKlass()->has_null_free_non_atomic_layout();)
 }
 
-bool ciInlineKlass::has_atomic_layout() const {
-  GUARDED_VM_ENTRY(return get_InlineKlass()->has_atomic_layout();)
+bool ciInlineKlass::has_null_free_atomic_layout() const {
+  GUARDED_VM_ENTRY(return get_InlineKlass()->has_null_free_atomic_layout();)
 }
 
 bool ciInlineKlass::has_nullable_atomic_layout() const {
@@ -115,9 +115,9 @@ int ciInlineKlass::null_marker_offset_in_payload() const {
 BasicType ciInlineKlass::atomic_size_to_basic_type(bool null_free) const {
   VM_ENTRY_MARK
   InlineKlass* vk = get_InlineKlass();
-  assert(!null_free || vk->has_atomic_layout(), "No null-free atomic layout available");
+  assert(!null_free || vk->has_null_free_atomic_layout(), "No null-free atomic layout available");
   assert( null_free || vk->has_nullable_atomic_layout(), "No nullable atomic layout available");
-  int size = null_free ? vk->atomic_size_in_bytes() : vk->nullable_atomic_size_in_bytes();
+  int size = null_free ? vk->null_free_atomic_size_in_bytes() : vk->nullable_atomic_size_in_bytes();
   BasicType bt = T_ILLEGAL;
   if (size == sizeof(jlong)) {
     bt = T_LONG;

src/hotspot/share/ci/ciInlineKlass.hpp

@@ -72,8 +72,8 @@ class ciInlineKlass : public ciInstanceKlass {
   address unpack_handler() const;
   InlineKlass* get_InlineKlass() const;
   int nullable_size_in_bytes() const;
-  bool has_non_atomic_layout() const;
-  bool has_atomic_layout() const;
+  bool has_null_free_non_atomic_layout() const;
+  bool has_null_free_atomic_layout() const;
   bool has_nullable_atomic_layout() const;
   int null_marker_offset_in_payload() const;
   BasicType atomic_size_to_basic_type(bool null_free) const;

src/hotspot/share/classfile/classFileParser.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -5514,10 +5514,11 @@ void ClassFileParser::fill_instance_klass(InstanceKlass* ik,
     vk->set_payload_alignment(_layout_info->_payload_alignment);
     vk->set_payload_offset(_layout_info->_payload_offset);
     vk->set_payload_size_in_bytes(_layout_info->_payload_size_in_bytes);
-    vk->set_non_atomic_size_in_bytes(_layout_info->_non_atomic_size_in_bytes);
-    vk->set_non_atomic_alignment(_layout_info->_non_atomic_alignment);
-    vk->set_atomic_size_in_bytes(_layout_info->_atomic_layout_size_in_bytes);
-    vk->set_nullable_size_in_bytes(_layout_info->_nullable_layout_size_in_bytes);
+    vk->set_null_free_non_atomic_size_in_bytes(_layout_info->_null_free_non_atomic_size_in_bytes);
+    vk->set_null_free_non_atomic_alignment(_layout_info->_null_free_non_atomic_alignment);
+    vk->set_null_free_atomic_size_in_bytes(_layout_info->_null_free_atomic_layout_size_in_bytes);
+    vk->set_nullable_atomic_size_in_bytes(_layout_info->_nullable_atomic_layout_size_in_bytes);
+    vk->set_nullable_non_atomic_size_in_bytes(_layout_info->_nullable_non_atomic_layout_size_in_bytes);
     vk->set_null_marker_offset(_layout_info->_null_marker_offset);
     vk->set_null_reset_value_offset(_layout_info->_null_reset_value_offset);
     if (_layout_info->_is_empty_inline_klass) vk->set_is_empty_inline_type();

src/hotspot/share/classfile/classFileParser.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -80,10 +80,11 @@ class FieldLayoutInfo : public ResourceObj {
   int _payload_alignment;
   int _payload_offset;
   int _payload_size_in_bytes;
-  int _non_atomic_size_in_bytes;
-  int _non_atomic_alignment;
-  int _atomic_layout_size_in_bytes;
-  int _nullable_layout_size_in_bytes;
+  int _null_free_non_atomic_size_in_bytes;
+  int _null_free_non_atomic_alignment;
+  int _null_free_atomic_layout_size_in_bytes;
+  int _nullable_atomic_layout_size_in_bytes;
+  int _nullable_non_atomic_layout_size_in_bytes;
   int _null_marker_offset;
   int _null_reset_value_offset;
   int _acmp_maps_offset;
@@ -95,8 +96,9 @@ class FieldLayoutInfo : public ResourceObj {
   FieldLayoutInfo() : oop_map_blocks(nullptr), _nonoop_acmp_map(nullptr), _oop_acmp_map(nullptr),
                       _instance_size(-1), _nonstatic_field_size(-1), _static_field_size(-1),
                       _payload_alignment(-1), _payload_offset(-1), _payload_size_in_bytes(-1),
-                      _non_atomic_size_in_bytes(-1), _non_atomic_alignment(-1),
-                      _atomic_layout_size_in_bytes(-1), _nullable_layout_size_in_bytes(-1),
+                      _null_free_non_atomic_size_in_bytes(-1), _null_free_non_atomic_alignment(-1),
+                      _null_free_atomic_layout_size_in_bytes(-1), _nullable_atomic_layout_size_in_bytes(-1),
+                      _nullable_non_atomic_layout_size_in_bytes(-1),
                       _null_marker_offset(-1), _null_reset_value_offset(-1), _acmp_maps_offset(-1),
                       _has_nonstatic_fields(false), _is_naturally_atomic(false), _must_be_atomic(false),
                       _has_inline_fields(false), _is_empty_inline_klass(false) { }