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src/hotspot/share/classfile/fieldLayoutBuilder.cpp

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*** 23,45 ***
   */
  
  #include "precompiled.hpp"
  #include "classfile/classFileParser.hpp"
  #include "classfile/fieldLayoutBuilder.hpp"
  #include "jvm.h"
  #include "memory/resourceArea.hpp"
  #include "oops/array.hpp"
  #include "oops/fieldStreams.inline.hpp"
  #include "oops/instanceMirrorKlass.hpp"
  #include "oops/instanceKlass.inline.hpp"
  #include "oops/klass.inline.hpp"
  #include "runtime/fieldDescriptor.inline.hpp"
  
  
  LayoutRawBlock::LayoutRawBlock(Kind kind, int size) :
    _next_block(nullptr),
    _prev_block(nullptr),
!   _kind(kind),
    _offset(-1),
    _alignment(1),
    _size(size),
!   _field_index(-1),
!   _is_reference(false) {
-   assert(kind == EMPTY || kind == RESERVED || kind == PADDING || kind == INHERITED,
           "Otherwise, should use the constructor with a field index argument");
    assert(size > 0, "Sanity check");
  }
  
  
! LayoutRawBlock::LayoutRawBlock(int index, Kind kind, int size, int alignment, bool is_reference) :
   _next_block(nullptr),
   _prev_block(nullptr),
!  _kind(kind),
   _offset(-1),
   _alignment(alignment),
   _size(size),
!  _field_index(index),
!  _is_reference(is_reference) {
-   assert(kind == REGULAR || kind == FLATTENED || kind == INHERITED,
           "Other kind do not have a field index");
    assert(size > 0, "Sanity check");
    assert(alignment > 0, "Sanity check");
  }
  
--- 23,100 ---
   */
  
  #include "precompiled.hpp"
  #include "classfile/classFileParser.hpp"
  #include "classfile/fieldLayoutBuilder.hpp"
+ #include "classfile/systemDictionary.hpp"
+ #include "classfile/vmSymbols.hpp"
  #include "jvm.h"
  #include "memory/resourceArea.hpp"
  #include "oops/array.hpp"
  #include "oops/fieldStreams.inline.hpp"
  #include "oops/instanceMirrorKlass.hpp"
  #include "oops/instanceKlass.inline.hpp"
  #include "oops/klass.inline.hpp"
+ #include "oops/inlineKlass.inline.hpp"
  #include "runtime/fieldDescriptor.inline.hpp"
+ #include "utilities/powerOfTwo.hpp"
  
+ static LayoutKind field_layout_selection(FieldInfo field_info, Array<InlineLayoutInfo>* inline_layout_info_array,
+                                          bool use_atomic_flat) {
+ 
+   if (field_info.field_flags().is_injected()) {
+     // don't flatten injected fields
+     return LayoutKind::REFERENCE;
+   }
+ 
+   if (inline_layout_info_array == nullptr || inline_layout_info_array->adr_at(field_info.index())->klass() == nullptr) {
+     // field's type is not a known value class, using a reference
+     return LayoutKind::REFERENCE;
+   }
+ 
+   InlineLayoutInfo* inline_field_info = inline_layout_info_array->adr_at(field_info.index());
+   InlineKlass* vk = inline_field_info->klass();
+ 
+   if (field_info.field_flags().is_null_free_inline_type()) {
+     assert(vk->is_implicitly_constructible(), "null-free fields must be implicitly constructible");
+     if (vk->must_be_atomic() || field_info.access_flags().is_volatile() || AlwaysAtomicAccesses) {
+       if (vk->is_naturally_atomic() && vk->has_non_atomic_layout()) return LayoutKind::NON_ATOMIC_FLAT;
+       return (vk->has_atomic_layout() && use_atomic_flat) ? LayoutKind::ATOMIC_FLAT : LayoutKind::REFERENCE;
+     } else {
+       return vk->has_non_atomic_layout() ? LayoutKind::NON_ATOMIC_FLAT : LayoutKind::REFERENCE;
+     }
+   } else {
+     if (NullableFieldFlattening && vk->has_nullable_layout()) {
+       return use_atomic_flat ? LayoutKind::NULLABLE_ATOMIC_FLAT : LayoutKind::REFERENCE;
+     } else {
+       return LayoutKind::REFERENCE;
+     }
+   }
+ }
+ 
+ static void get_size_and_alignment(InlineKlass* vk, LayoutKind kind, int* size, int* alignment) {
+   switch(kind) {
+     case LayoutKind::NON_ATOMIC_FLAT:
+       *size = vk->non_atomic_size_in_bytes();
+       *alignment = vk->non_atomic_alignment();
+       break;
+     case LayoutKind::ATOMIC_FLAT:
+       *size = vk->atomic_size_in_bytes();
+       *alignment = *size;
+       break;
+     case LayoutKind::NULLABLE_ATOMIC_FLAT:
+       *size = vk->nullable_size_in_bytes();
+       *alignment = *size;
+     break;
+     default:
+       ShouldNotReachHere();
+   }
+ }
  
  LayoutRawBlock::LayoutRawBlock(Kind kind, int size) :
    _next_block(nullptr),
    _prev_block(nullptr),
!   _inline_klass(nullptr),
+   _block_kind(kind),
    _offset(-1),
    _alignment(1),
    _size(size),
!   _field_index(-1) {
!   assert(kind == EMPTY || kind == RESERVED || kind == PADDING || kind == INHERITED || kind == NULL_MARKER,
           "Otherwise, should use the constructor with a field index argument");
    assert(size > 0, "Sanity check");
  }
  
  
! LayoutRawBlock::LayoutRawBlock(int index, Kind kind, int size, int alignment) :
   _next_block(nullptr),
   _prev_block(nullptr),
!  _inline_klass(nullptr),
+  _block_kind(kind),
   _offset(-1),
   _alignment(alignment),
   _size(size),
!  _field_index(index) {
!   assert(kind == REGULAR || kind == FLAT || kind == INHERITED,
           "Other kind do not have a field index");
    assert(size > 0, "Sanity check");
    assert(alignment > 0, "Sanity check");
  }
  

*** 73,46 ***
    return _size >= size + adjustment;
  }
  
  FieldGroup::FieldGroup(int contended_group) :
    _next(nullptr),
!   _primitive_fields(nullptr),
    _oop_fields(nullptr),
    _contended_group(contended_group),  // -1 means no contended group, 0 means default contended group
    _oop_count(0) {}
  
  void FieldGroup::add_primitive_field(int idx, BasicType type) {
    int size = type2aelembytes(type);
!   LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */, false);
!   if (_primitive_fields == nullptr) {
!     _primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
    }
-   _primitive_fields->append(block);
  }
  
  void FieldGroup::add_oop_field(int idx) {
    int size = type2aelembytes(T_OBJECT);
!   LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */, true);
    if (_oop_fields == nullptr) {
      _oop_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
    }
    _oop_fields->append(block);
    _oop_count++;
  }
  
  void FieldGroup::sort_by_size() {
!   if (_primitive_fields != nullptr) {
!     _primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
    }
  }
  
! FieldLayout::FieldLayout(GrowableArray<FieldInfo>* field_info, ConstantPool* cp) :
    _field_info(field_info),
    _cp(cp),
    _blocks(nullptr),
    _start(_blocks),
!   _last(_blocks) {}
  
  void FieldLayout::initialize_static_layout() {
    _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
    _blocks->set_offset(0);
    _last = _blocks;
--- 128,84 ---
    return _size >= size + adjustment;
  }
  
  FieldGroup::FieldGroup(int contended_group) :
    _next(nullptr),
!   _small_primitive_fields(nullptr),
+   _big_primitive_fields(nullptr),
    _oop_fields(nullptr),
    _contended_group(contended_group),  // -1 means no contended group, 0 means default contended group
    _oop_count(0) {}
  
  void FieldGroup::add_primitive_field(int idx, BasicType type) {
    int size = type2aelembytes(type);
!   LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */);
!   if (size >= oopSize) {
!     add_to_big_primitive_list(block);
+   } else {
+     add_to_small_primitive_list(block);
    }
  }
  
  void FieldGroup::add_oop_field(int idx) {
    int size = type2aelembytes(T_OBJECT);
!   LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */);
    if (_oop_fields == nullptr) {
      _oop_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
    }
    _oop_fields->append(block);
    _oop_count++;
  }
  
+ void FieldGroup::add_flat_field(int idx, InlineKlass* vk, LayoutKind lk, int size, int alignment) {
+   LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::FLAT, size, alignment);
+   block->set_inline_klass(vk);
+   block->set_layout_kind(lk);
+   if (block->size() >= oopSize) {
+     add_to_big_primitive_list(block);
+   } else {
+     add_to_small_primitive_list(block);
+   }
+ }
+ 
  void FieldGroup::sort_by_size() {
!   if (_small_primitive_fields != nullptr) {
!     _small_primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
+   }
+   if (_big_primitive_fields != nullptr) {
+     _big_primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
    }
  }
  
! void FieldGroup::add_to_small_primitive_list(LayoutRawBlock* block) {
+   if (_small_primitive_fields == nullptr) {
+     _small_primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
+   }
+   _small_primitive_fields->append(block);
+ }
+ 
+ void FieldGroup::add_to_big_primitive_list(LayoutRawBlock* block) {
+   if (_big_primitive_fields == nullptr) {
+     _big_primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
+   }
+   _big_primitive_fields->append(block);
+ }
+ 
+ FieldLayout::FieldLayout(GrowableArray<FieldInfo>* field_info, Array<InlineLayoutInfo>* inline_layout_info_array, ConstantPool* cp) :
    _field_info(field_info),
+   _inline_layout_info_array(inline_layout_info_array),
    _cp(cp),
    _blocks(nullptr),
    _start(_blocks),
!   _last(_blocks),
+   _super_first_field_offset(-1),
+   _super_alignment(-1),
+   _super_min_align_required(-1),
+   _default_value_offset(-1),
+   _null_reset_value_offset(-1),
+   _super_has_fields(false),
+   _has_inherited_fields(false) {}
  
  void FieldLayout::initialize_static_layout() {
    _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
    _blocks->set_offset(0);
    _last = _blocks;

*** 133,32 ***
      _blocks->set_offset(0);
      _last = _blocks;
      _start = _blocks;
      insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes()));
    } else {
!     bool has_fields = reconstruct_layout(super_klass);
      fill_holes(super_klass);
!     if (!super_klass->has_contended_annotations() || !has_fields) {
        _start = _blocks;  // start allocating fields from the first empty block
      } else {
        _start = _last;    // append fields at the end of the reconstructed layout
      }
    }
  }
  
  LayoutRawBlock* FieldLayout::first_field_block() {
!   LayoutRawBlock* block = _start;
!   while (block->kind() != LayoutRawBlock::INHERITED && block->kind() != LayoutRawBlock::REGULAR
!       && block->kind() != LayoutRawBlock::FLATTENED && block->kind() != LayoutRawBlock::PADDING) {
      block = block->next_block();
    }
    return block;
  }
  
! 
! // Insert a set of fields into a layout using a best-fit strategy.
- // For each field, search for the smallest empty slot able to fit the field
  // (satisfying both size and alignment requirements), if none is found,
  // add the field at the end of the layout.
  // Fields cannot be inserted before the block specified in the "start" argument
  void FieldLayout::add(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
    if (list == nullptr) return;
--- 226,34 ---
      _blocks->set_offset(0);
      _last = _blocks;
      _start = _blocks;
      insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes()));
    } else {
!     _super_has_fields = reconstruct_layout(super_klass);
      fill_holes(super_klass);
!     if ((!super_klass->has_contended_annotations()) || !_super_has_fields) {
        _start = _blocks;  // start allocating fields from the first empty block
      } else {
        _start = _last;    // append fields at the end of the reconstructed layout
      }
    }
  }
  
  LayoutRawBlock* FieldLayout::first_field_block() {
!   LayoutRawBlock* block = _blocks;
!   while (block != nullptr
!          && block->block_kind() != LayoutRawBlock::INHERITED
+          && block->block_kind() != LayoutRawBlock::REGULAR
+          && block->block_kind() != LayoutRawBlock::FLAT
+          && block->block_kind() != LayoutRawBlock::NULL_MARKER) {
      block = block->next_block();
    }
    return block;
  }
  
! // Insert a set of fields into a layout.
! // For each field, search for an empty slot able to fit the field
  // (satisfying both size and alignment requirements), if none is found,
  // add the field at the end of the layout.
  // Fields cannot be inserted before the block specified in the "start" argument
  void FieldLayout::add(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
    if (list == nullptr) return;

*** 168,11 ***
    int last_alignment = 0;
    for (int i = 0; i < list->length(); i ++) {
      LayoutRawBlock* b = list->at(i);
      LayoutRawBlock* cursor = nullptr;
      LayoutRawBlock* candidate = nullptr;
- 
      // if start is the last block, just append the field
      if (start == last_block()) {
        candidate = last_block();
      }
      // Before iterating over the layout to find an empty slot fitting the field's requirements,
--- 263,10 ---

*** 186,12 ***
        last_size = b->size();
        last_alignment = b->alignment();
        cursor = last_block()->prev_block();
        assert(cursor != nullptr, "Sanity check");
        last_search_success = true;
        while (cursor != start) {
!         if (cursor->kind() == LayoutRawBlock::EMPTY && cursor->fit(b->size(), b->alignment())) {
            if (candidate == nullptr || cursor->size() < candidate->size()) {
              candidate = cursor;
            }
          }
          cursor = cursor->prev_block();
--- 280,13 ---
        last_size = b->size();
        last_alignment = b->alignment();
        cursor = last_block()->prev_block();
        assert(cursor != nullptr, "Sanity check");
        last_search_success = true;
+ 
        while (cursor != start) {
!         if (cursor->block_kind() == LayoutRawBlock::EMPTY && cursor->fit(b->size(), b->alignment())) {
            if (candidate == nullptr || cursor->size() < candidate->size()) {
              candidate = cursor;
            }
          }
          cursor = cursor->prev_block();

*** 199,14 ***
        if (candidate == nullptr) {
          candidate = last_block();
          last_search_success = false;
        }
        assert(candidate != nullptr, "Candidate must not be null");
!       assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
        assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
      }
- 
      insert_field_block(candidate, b);
    }
  }
  
  // Used for classes with hard coded field offsets, insert a field at the specified offset */
--- 294,13 ---
        if (candidate == nullptr) {
          candidate = last_block();
          last_search_success = false;
        }
        assert(candidate != nullptr, "Candidate must not be null");
!       assert(candidate->block_kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
        assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
      }
      insert_field_block(candidate, b);
    }
  }
  
  // Used for classes with hard coded field offsets, insert a field at the specified offset */

*** 218,22 ***
    }
    LayoutRawBlock* slot = start;
    while (slot != nullptr) {
      if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
          slot == _last){
!       assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
!       assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
        if (slot->offset() < block->offset()) {
          int adjustment = block->offset() - slot->offset();
          LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
          insert(slot, adj);
        }
        insert(slot, block);
        if (slot->size() == 0) {
          remove(slot);
        }
!       _field_info->adr_at(block->field_index())->set_offset(block->offset());
        return;
      }
      slot = slot->next_block();
    }
    fatal("Should have found a matching slot above, corrupted layout or invalid offset");
--- 312,24 ---
    }
    LayoutRawBlock* slot = start;
    while (slot != nullptr) {
      if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
          slot == _last){
!       assert(slot->block_kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
!       assert(slot->size() >= block->offset() - slot->offset() + block->size() ,"Matching slot must be big enough");
        if (slot->offset() < block->offset()) {
          int adjustment = block->offset() - slot->offset();
          LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
          insert(slot, adj);
        }
        insert(slot, block);
        if (slot->size() == 0) {
          remove(slot);
        }
!       if (block->block_kind() == LayoutRawBlock::REGULAR || block->block_kind() == LayoutRawBlock::FLAT) {
+         _field_info->adr_at(block->field_index())->set_offset(block->offset());
+       }
        return;
      }
      slot = slot->next_block();
    }
    fatal("Should have found a matching slot above, corrupted layout or invalid offset");

*** 258,19 ***
    if (start == last_block()) {
      candidate = last_block();
    } else {
      LayoutRawBlock* first = list->at(0);
      candidate = last_block()->prev_block();
!     while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
        if (candidate == start) {
          candidate = last_block();
          break;
        }
        candidate = candidate->prev_block();
      }
      assert(candidate != nullptr, "Candidate must not be null");
!     assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
      assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
    }
  
    for (int i = 0; i < list->length(); i++) {
      LayoutRawBlock* b = list->at(i);
--- 354,19 ---
    if (start == last_block()) {
      candidate = last_block();
    } else {
      LayoutRawBlock* first = list->at(0);
      candidate = last_block()->prev_block();
!     while (candidate->block_kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
        if (candidate == start) {
          candidate = last_block();
          break;
        }
        candidate = candidate->prev_block();
      }
      assert(candidate != nullptr, "Candidate must not be null");
!     assert(candidate->block_kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
      assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
    }
  
    for (int i = 0; i < list->length(); i++) {
      LayoutRawBlock* b = list->at(i);

*** 278,47 ***
      assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
    }
  }
  
  LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
!   assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
    if (slot->offset() % block->alignment() != 0) {
      int adjustment = block->alignment() - (slot->offset() % block->alignment());
      LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
      insert(slot, adj);
    }
    insert(slot, block);
    if (slot->size() == 0) {
      remove(slot);
    }
!   _field_info->adr_at(block->field_index())->set_offset(block->offset());
    return block;
  }
  
  bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
    bool has_instance_fields = false;
    GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
    while (ik != nullptr) {
      for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
        BasicType type = Signature::basic_type(fs.signature());
        // distinction between static and non-static fields is missing
        if (fs.access_flags().is_static()) continue;
        has_instance_fields = true;
!       int size = type2aelembytes(type);
!       // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
!       LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
        block->set_offset(fs.offset());
        all_fields->append(block);
      }
      ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
    }
- 
    all_fields->sort(LayoutRawBlock::compare_offset);
    _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
    _blocks->set_offset(0);
    _last = _blocks;
- 
    for(int i = 0; i < all_fields->length(); i++) {
      LayoutRawBlock* b = all_fields->at(i);
      _last->set_next_block(b);
      b->set_prev_block(_last);
      _last = b;
--- 374,80 ---
      assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
    }
  }
  
  LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
!   assert(slot->block_kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
    if (slot->offset() % block->alignment() != 0) {
      int adjustment = block->alignment() - (slot->offset() % block->alignment());
      LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
      insert(slot, adj);
    }
+   assert(block->size() >= block->size(), "Enough space must remain after adjustment");
    insert(slot, block);
    if (slot->size() == 0) {
      remove(slot);
    }
!   // NULL_MARKER blocks are not real fields, so they don't have an entry in the FieldInfo array
+   if (block->block_kind() != LayoutRawBlock::NULL_MARKER) {
+     _field_info->adr_at(block->field_index())->set_offset(block->offset());
+     if (_field_info->adr_at(block->field_index())->name(_cp) == vmSymbols::default_value_name()) {
+       _default_value_offset = block->offset();
+     }
+     if (_field_info->adr_at(block->field_index())->name(_cp) == vmSymbols::null_reset_value_name()) {
+       _null_reset_value_offset = block->offset();
+     }
+   }
+   if (block->block_kind() == LayoutRawBlock::FLAT && block->layout_kind() == LayoutKind::NULLABLE_ATOMIC_FLAT) {
+     int nm_offset = block->inline_klass()->null_marker_offset() - block->inline_klass()->first_field_offset() + block->offset();
+     _field_info->adr_at(block->field_index())->set_null_marker_offset(nm_offset);
+     _inline_layout_info_array->adr_at(block->field_index())->set_null_marker_offset(nm_offset);
+   }
+ 
    return block;
  }
  
  bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
    bool has_instance_fields = false;
+   if (ik->is_abstract() && !ik->is_identity_class()) {
+     _super_alignment = type2aelembytes(BasicType::T_LONG);
+   }
    GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
    while (ik != nullptr) {
      for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
        BasicType type = Signature::basic_type(fs.signature());
        // distinction between static and non-static fields is missing
        if (fs.access_flags().is_static()) continue;
        has_instance_fields = true;
!       _has_inherited_fields = true;
!       if (_super_first_field_offset == -1 || fs.offset() < _super_first_field_offset) _super_first_field_offset = fs.offset();
!       LayoutRawBlock* block;
+       if (fs.is_flat()) {
+         InlineLayoutInfo layout_info = ik->inline_layout_info(fs.index());
+         InlineKlass* vk = layout_info.klass();
+         block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED,
+                                    vk->layout_size_in_bytes(layout_info.kind()),
+                                    vk->layout_alignment(layout_info.kind()));
+         assert(_super_alignment == -1 || _super_alignment >=  vk->payload_alignment(), "Invalid value alignment");
+         _super_min_align_required = _super_min_align_required > vk->payload_alignment() ? _super_min_align_required : vk->payload_alignment();
+       } else {
+         int size = type2aelembytes(type);
+         // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
+         block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size);
+         // For primitive types, the alignment is equal to the size
+         assert(_super_alignment == -1 || _super_alignment >=  size, "Invalid value alignment");
+         _super_min_align_required = _super_min_align_required > size ? _super_min_align_required : size;
+       }
        block->set_offset(fs.offset());
        all_fields->append(block);
      }
      ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
    }
    all_fields->sort(LayoutRawBlock::compare_offset);
    _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
    _blocks->set_offset(0);
    _last = _blocks;
    for(int i = 0; i < all_fields->length(); i++) {
      LayoutRawBlock* b = all_fields->at(i);
      _last->set_next_block(b);
      b->set_prev_block(_last);
      _last = b;

*** 339,22 ***
    LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
    LayoutRawBlock* b = _blocks;
    while (b->next_block() != nullptr) {
      if (b->next_block()->offset() > (b->offset() + b->size())) {
        int size = b->next_block()->offset() - (b->offset() + b->size());
        LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
        empty->set_offset(b->offset() + b->size());
        empty->set_next_block(b->next_block());
        b->next_block()->set_prev_block(empty);
        b->set_next_block(empty);
        empty->set_prev_block(b);
      }
      b = b->next_block();
    }
    assert(b->next_block() == nullptr, "Invariant at this point");
!   assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
- 
    // If the super class has @Contended annotation, a padding block is
    // inserted at the end to ensure that fields from the subclasses won't share
    // the cache line of the last field of the contended class
    if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
      LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
--- 468,22 ---
    LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
    LayoutRawBlock* b = _blocks;
    while (b->next_block() != nullptr) {
      if (b->next_block()->offset() > (b->offset() + b->size())) {
        int size = b->next_block()->offset() - (b->offset() + b->size());
+       // FIXME it would be better if initial empty block where tagged as PADDING for value classes
        LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
        empty->set_offset(b->offset() + b->size());
        empty->set_next_block(b->next_block());
        b->next_block()->set_prev_block(empty);
        b->set_next_block(empty);
        empty->set_prev_block(b);
      }
      b = b->next_block();
    }
    assert(b->next_block() == nullptr, "Invariant at this point");
!   assert(b->block_kind() != LayoutRawBlock::EMPTY, "Sanity check");
    // If the super class has @Contended annotation, a padding block is
    // inserted at the end to ensure that fields from the subclasses won't share
    // the cache line of the last field of the contended class
    if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
      LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);

*** 371,11 ***
    last->set_prev_block(b);
    _last = last;
  }
  
  LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
!   assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
    assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
    block->set_offset(slot->offset());
    slot->set_offset(slot->offset() + block->size());
    assert((slot->size() - block->size()) < slot->size(), "underflow checking");
    assert(slot->size() - block->size() >= 0, "no negative size allowed");
--- 500,11 ---
    last->set_prev_block(b);
    _last = last;
  }
  
  LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
!   assert(slot->block_kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
    assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
    block->set_offset(slot->offset());
    slot->set_offset(slot->offset() + block->size());
    assert((slot->size() - block->size()) < slot->size(), "underflow checking");
    assert(slot->size() - block->size() >= 0, "no negative size allowed");

*** 387,10 ***
--- 516,13 ---
      block->prev_block()->set_next_block(block);
    }
    if (_blocks == slot) {
      _blocks = block;
    }
+   if (_start == slot) {
+     _start = block;
+   }
    return block;
  }
  
  void FieldLayout::remove(LayoutRawBlock* block) {
    assert(block != nullptr, "Sanity check");

*** 408,101 ***
    if (block == _start) {
      _start = block->prev_block();
    }
  }
  
! void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
    ResourceMark rm;
    LayoutRawBlock* b = _blocks;
    while(b != _last) {
!     switch(b->kind()) {
        case LayoutRawBlock::REGULAR: {
          FieldInfo* fi = _field_info->adr_at(b->field_index());
!         output->print_cr(" @%d \"%s\" %s %d/%d %s",
                           b->offset(),
!                          fi->name(_cp)->as_C_string(),
-                          fi->signature(_cp)->as_C_string(),
                           b->size(),
                           b->alignment(),
!                          "REGULAR");
          break;
        }
!       case LayoutRawBlock::FLATTENED: {
          FieldInfo* fi = _field_info->adr_at(b->field_index());
!         output->print_cr(" @%d \"%s\" %s %d/%d %s",
                           b->offset(),
!                          fi->name(_cp)->as_C_string(),
-                          fi->signature(_cp)->as_C_string(),
                           b->size(),
                           b->alignment(),
!                          "FLATTENED");
          break;
        }
        case LayoutRawBlock::RESERVED: {
!         output->print_cr(" @%d %d/- %s",
                           b->offset(),
!                          b->size(),
!                          "RESERVED");
          break;
        }
        case LayoutRawBlock::INHERITED: {
          assert(!is_static, "Static fields are not inherited in layouts");
          assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
          bool found = false;
          const InstanceKlass* ik = super;
          while (!found && ik != nullptr) {
            for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
!             if (fs.offset() == b->offset()) {
!               output->print_cr(" @%d \"%s\" %s %d/%d %s",
                    b->offset(),
!                   fs.name()->as_C_string(),
-                   fs.signature()->as_C_string(),
                    b->size(),
!                   b->size(), // so far, alignment constraint == size, will change with Valhalla
!                   "INHERITED");
                found = true;
                break;
              }
-           }
-           ik = ik->java_super();
          }
!         break;
        }
!       case LayoutRawBlock::EMPTY:
!         output->print_cr(" @%d %d/1 %s",
!                          b->offset(),
!                          b->size(),
!                         "EMPTY");
!         break;
!       case LayoutRawBlock::PADDING:
!         output->print_cr(" @%d %d/1 %s",
!                          b->offset(),
!                          b->size(),
!                         "PADDING");
!         break;
      }
      b = b->next_block();
    }
  }
  
! FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
!       GrowableArray<FieldInfo>* field_info, bool is_contended, FieldLayoutInfo* info) :
    _classname(classname),
    _super_klass(super_klass),
    _constant_pool(constant_pool),
    _field_info(field_info),
    _info(info),
    _root_group(nullptr),
    _contended_groups(GrowableArray<FieldGroup*>(8)),
    _static_fields(nullptr),
    _layout(nullptr),
    _static_layout(nullptr),
    _nonstatic_oopmap_count(0),
!   _alignment(-1),
    _has_nonstatic_fields(false),
!   _is_contended(is_contended) {}
! 
  
  FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
    assert(g > 0, "must only be called for named contended groups");
    FieldGroup* fg = nullptr;
    for (int i = 0; i < _contended_groups.length(); i++) {
--- 540,210 ---
    if (block == _start) {
      _start = block->prev_block();
    }
  }
  
! void FieldLayout::shift_fields(int shift) {
+   LayoutRawBlock* b = first_field_block();
+   LayoutRawBlock* previous = b->prev_block();
+   if (previous->block_kind() == LayoutRawBlock::EMPTY) {
+     previous->set_size(previous->size() + shift);
+   } else {
+     LayoutRawBlock* nb = new LayoutRawBlock(LayoutRawBlock::PADDING, shift);
+     nb->set_offset(b->offset());
+     previous->set_next_block(nb);
+     nb->set_prev_block(previous);
+     b->set_prev_block(nb);
+     nb->set_next_block(b);
+   }
+   while (b != nullptr) {
+     b->set_offset(b->offset() + shift);
+     if (b->block_kind() == LayoutRawBlock::REGULAR || b->block_kind() == LayoutRawBlock::FLAT) {
+       _field_info->adr_at(b->field_index())->set_offset(b->offset());
+       if (b->layout_kind() == LayoutKind::NULLABLE_ATOMIC_FLAT) {
+         int new_nm_offset = _field_info->adr_at(b->field_index())->null_marker_offset() + shift;
+         _field_info->adr_at(b->field_index())->set_null_marker_offset(new_nm_offset);
+         _inline_layout_info_array->adr_at(b->field_index())->set_null_marker_offset(new_nm_offset);
+ 
+       }
+     }
+     assert(b->block_kind() == LayoutRawBlock::EMPTY || b->offset() % b->alignment() == 0, "Must still be correctly aligned");
+     b = b->next_block();
+   }
+ }
+ 
+ LayoutRawBlock* FieldLayout::find_null_marker() {
+   LayoutRawBlock* b = _blocks;
+   while (b != nullptr) {
+     if (b->block_kind() == LayoutRawBlock::NULL_MARKER) {
+       return b;
+     }
+     b = b->next_block();
+   }
+   ShouldNotReachHere();
+ }
+ 
+ void FieldLayout::remove_null_marker() {
+   LayoutRawBlock* b = first_field_block();
+   while (b != nullptr) {
+     if (b->block_kind() == LayoutRawBlock::NULL_MARKER) {
+       if (b->next_block()->block_kind() == LayoutRawBlock::EMPTY) {
+         LayoutRawBlock* n = b->next_block();
+         remove(b);
+         n->set_offset(b->offset());
+         n->set_size(n->size() + b->size());
+       } else {
+         b->set_block_kind(LayoutRawBlock::EMPTY);
+       }
+       return;
+     }
+     b = b->next_block();
+   }
+   ShouldNotReachHere(); // if we reach this point, the null marker was not found!
+ }
+ 
+ static const char* layout_kind_to_string(LayoutKind lk) {
+   switch(lk) {
+     case LayoutKind::REFERENCE:
+       return "REFERENCE";
+     case LayoutKind::NON_ATOMIC_FLAT:
+       return "NON_ATOMIC_FLAT";
+     case LayoutKind::ATOMIC_FLAT:
+       return "ATOMIC_FLAT";
+     case LayoutKind::NULLABLE_ATOMIC_FLAT:
+       return "NULLABLE_ATOMIC_FLAT";
+     case LayoutKind::UNKNOWN:
+       return "UNKNOWN";
+     default:
+       ShouldNotReachHere();
+   }
+ }
+ 
+ void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super, Array<InlineLayoutInfo>* inline_fields) {
    ResourceMark rm;
    LayoutRawBlock* b = _blocks;
    while(b != _last) {
!     switch(b->block_kind()) {
        case LayoutRawBlock::REGULAR: {
          FieldInfo* fi = _field_info->adr_at(b->field_index());
!         output->print_cr(" @%d %s %d/%d \"%s\" %s",
                           b->offset(),
!                          "REGULAR",
                           b->size(),
                           b->alignment(),
!                          fi->name(_cp)->as_C_string(),
+                          fi->signature(_cp)->as_C_string());
          break;
        }
!       case LayoutRawBlock::FLAT: {
          FieldInfo* fi = _field_info->adr_at(b->field_index());
!         InlineKlass* ik = inline_fields->adr_at(fi->index())->klass();
+         assert(ik != nullptr, "");
+         output->print_cr(" @%d %s %d/%d \"%s\" %s %s@%p %s",
                           b->offset(),
!                          "FLAT",
                           b->size(),
                           b->alignment(),
!                          fi->name(_cp)->as_C_string(),
+                          fi->signature(_cp)->as_C_string(),
+                          ik->name()->as_C_string(),
+                          ik->class_loader_data(), layout_kind_to_string(b->layout_kind()));
          break;
        }
        case LayoutRawBlock::RESERVED: {
!         output->print_cr(" @%d %s %d/-",
                           b->offset(),
!                          "RESERVED",
!                          b->size());
          break;
        }
        case LayoutRawBlock::INHERITED: {
          assert(!is_static, "Static fields are not inherited in layouts");
          assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
          bool found = false;
          const InstanceKlass* ik = super;
          while (!found && ik != nullptr) {
            for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
!             if (fs.offset() == b->offset() && fs.access_flags().is_static() == is_static) {
!               output->print_cr(" @%d %s %d/%d \"%s\" %s",
                    b->offset(),
!                   "INHERITED",
                    b->size(),
!                   b->size(), // so far, alignment constraint == size, will change with Valhalla => FIXME
!                   fs.name()->as_C_string(),
+                   fs.signature()->as_C_string());
                found = true;
                break;
              }
          }
!         ik = ik->java_super();
        }
!       break;
!     }
!     case LayoutRawBlock::EMPTY:
!       output->print_cr(" @%d %s %d/1",
!                        b->offset(),
!                       "EMPTY",
!                        b->size());
!       break;
!     case LayoutRawBlock::PADDING:
!       output->print_cr(" @%d %s %d/1",
!                       b->offset(),
!                       "PADDING",
+                       b->size());
+       break;
+     case LayoutRawBlock::NULL_MARKER:
+     {
+       output->print_cr(" @%d %s %d/1 ",
+                       b->offset(),
+                       "NULL_MARKER",
+                       b->size());
+       break;
+     }
+     default:
+       fatal("Unknown block type");
      }
      b = b->next_block();
    }
  }
  
! FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, ClassLoaderData* loader_data, const InstanceKlass* super_klass, ConstantPool* constant_pool,
!                                        GrowableArray<FieldInfo>* field_info, bool is_contended, bool is_inline_type,bool is_abstract_value,
+                                        bool must_be_atomic, FieldLayoutInfo* info, Array<InlineLayoutInfo>* inline_layout_info_array) :
    _classname(classname),
+   _loader_data(loader_data),
    _super_klass(super_klass),
    _constant_pool(constant_pool),
    _field_info(field_info),
    _info(info),
+   _inline_layout_info_array(inline_layout_info_array),
    _root_group(nullptr),
    _contended_groups(GrowableArray<FieldGroup*>(8)),
    _static_fields(nullptr),
    _layout(nullptr),
    _static_layout(nullptr),
    _nonstatic_oopmap_count(0),
!   _payload_alignment(-1),
+   _first_field_offset(-1),
+   _null_marker_offset(-1),
+   _payload_size_in_bytes(-1),
+   _non_atomic_layout_size_in_bytes(-1),
+   _non_atomic_layout_alignment(-1),
+   _atomic_layout_size_in_bytes(-1),
+   _nullable_layout_size_in_bytes(-1),
+   _fields_size_sum(0),
+   _declared_non_static_fields_count(0),
+   _has_non_naturally_atomic_fields(false),
+   _is_naturally_atomic(false),
+   _must_be_atomic(must_be_atomic),
    _has_nonstatic_fields(false),
!   _has_inline_type_fields(false),
!   _is_contended(is_contended),
+   _is_inline_type(is_inline_type),
+   _is_abstract_value(is_abstract_value),
+   _has_flattening_information(is_inline_type),
+   _is_empty_inline_class(false) {}
  
  FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
    assert(g > 0, "must only be called for named contended groups");
    FieldGroup* fg = nullptr;
    for (int i = 0; i < _contended_groups.length(); i++) {

*** 513,31 ***
    _contended_groups.append(fg);
    return fg;
  }
  
  void FieldLayoutBuilder::prologue() {
!   _layout = new FieldLayout(_field_info, _constant_pool);
    const InstanceKlass* super_klass = _super_klass;
    _layout->initialize_instance_layout(super_klass);
    if (super_klass != nullptr) {
      _has_nonstatic_fields = super_klass->has_nonstatic_fields();
    }
!   _static_layout = new FieldLayout(_field_info, _constant_pool);
    _static_layout->initialize_static_layout();
    _static_fields = new FieldGroup();
    _root_group = new FieldGroup();
  }
  
! // Field sorting for regular classes:
  //   - fields are sorted in static and non-static fields
  //   - non-static fields are also sorted according to their contention group
  //     (support of the @Contended annotation)
  //   - @Contended annotation is ignored for static fields
  void FieldLayoutBuilder::regular_field_sorting() {
    int idx = 0;
    for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
-     FieldInfo ctrl = _field_info->at(0);
      FieldGroup* group = nullptr;
      FieldInfo fieldinfo = *it;
      if (fieldinfo.access_flags().is_static()) {
        group = _static_fields;
      } else {
--- 754,32 ---
    _contended_groups.append(fg);
    return fg;
  }
  
  void FieldLayoutBuilder::prologue() {
!   _layout = new FieldLayout(_field_info, _inline_layout_info_array, _constant_pool);
    const InstanceKlass* super_klass = _super_klass;
    _layout->initialize_instance_layout(super_klass);
+   _nonstatic_oopmap_count = super_klass == nullptr ? 0 : super_klass->nonstatic_oop_map_count();
    if (super_klass != nullptr) {
      _has_nonstatic_fields = super_klass->has_nonstatic_fields();
    }
!   _static_layout = new FieldLayout(_field_info, _inline_layout_info_array, _constant_pool);
    _static_layout->initialize_static_layout();
    _static_fields = new FieldGroup();
    _root_group = new FieldGroup();
  }
  
! // Field sorting for regular (non-inline) classes:
  //   - fields are sorted in static and non-static fields
  //   - non-static fields are also sorted according to their contention group
  //     (support of the @Contended annotation)
  //   - @Contended annotation is ignored for static fields
+ //   - field flattening decisions are taken in this method
  void FieldLayoutBuilder::regular_field_sorting() {
    int idx = 0;
    for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
      FieldGroup* group = nullptr;
      FieldInfo fieldinfo = *it;
      if (fieldinfo.access_flags().is_static()) {
        group = _static_fields;
      } else {

*** 555,27 ***
        }
      }
      assert(group != nullptr, "invariant");
      BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
      switch(type) {
!       case T_BYTE:
!       case T_CHAR:
!       case T_DOUBLE:
!       case T_FLOAT:
!       case T_INT:
!       case T_LONG:
!       case T_SHORT:
!       case T_BOOLEAN:
!         group->add_primitive_field(idx, type);
!         break;
!       case T_OBJECT:
!       case T_ARRAY:
          if (group != _static_fields) _nonstatic_oopmap_count++;
          group->add_oop_field(idx);
!         break;
!       default:
!         fatal("Something wrong?");
      }
    }
    _root_group->sort_by_size();
    _static_fields->sort_by_size();
    if (!_contended_groups.is_empty()) {
--- 797,50 ---
        }
      }
      assert(group != nullptr, "invariant");
      BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
      switch(type) {
!     case T_BYTE:
!     case T_CHAR:
!     case T_DOUBLE:
!     case T_FLOAT:
!     case T_INT:
!     case T_LONG:
!     case T_SHORT:
!     case T_BOOLEAN:
!       group->add_primitive_field(idx, type);
!       break;
!     case T_OBJECT:
!     case T_ARRAY:
+     {
+       LayoutKind lk = field_layout_selection(fieldinfo, _inline_layout_info_array, true);
+       if (fieldinfo.field_flags().is_null_free_inline_type() || lk != LayoutKind::REFERENCE
+           || (!fieldinfo.field_flags().is_injected()
+               && _inline_layout_info_array != nullptr && _inline_layout_info_array->adr_at(fieldinfo.index())->klass() != nullptr
+               && !_inline_layout_info_array->adr_at(fieldinfo.index())->klass()->is_identity_class())) {
+         _has_inline_type_fields = true;
+         _has_flattening_information = true;
+       }
+       if (lk == LayoutKind::REFERENCE) {
          if (group != _static_fields) _nonstatic_oopmap_count++;
          group->add_oop_field(idx);
!       } else {
!         _has_flattening_information = true;
!         InlineKlass* vk = _inline_layout_info_array->adr_at(fieldinfo.index())->klass();
+         int size, alignment;
+         get_size_and_alignment(vk, lk, &size, &alignment);
+         group->add_flat_field(idx, vk, lk, size, alignment);
+         _inline_layout_info_array->adr_at(fieldinfo.index())->set_kind(lk);
+         _nonstatic_oopmap_count += vk->nonstatic_oop_map_count();
+         _field_info->adr_at(idx)->field_flags_addr()->update_flat(true);
+         _field_info->adr_at(idx)->set_layout_kind(lk);
+         // no need to update _must_be_atomic if vk->must_be_atomic() is true because current class is not an inline class
+       }
+       break;
+     }
+     default:
+       fatal("Something wrong?");
      }
    }
    _root_group->sort_by_size();
    _static_fields->sort_by_size();
    if (!_contended_groups.is_empty()) {

*** 583,87 ***
        _contended_groups.at(i)->sort_by_size();
      }
    }
  }
  
  void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
    if (ContendedPaddingWidth > 0) {
      LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
      _layout->insert(slot, padding);
    }
  }
  
! // Computation of regular classes layout is an evolution of the previous default layout
! // (FieldAllocationStyle 1):
! //   - primitive fields are allocated first (from the biggest to the smallest)
! //   - then oop fields are allocated, either in existing gaps or at the end of
! //     the layout
  void FieldLayoutBuilder::compute_regular_layout() {
    bool need_tail_padding = false;
    prologue();
    regular_field_sorting();
- 
    if (_is_contended) {
      _layout->set_start(_layout->last_block());
      // insertion is currently easy because the current strategy doesn't try to fill holes
      // in super classes layouts => the _start block is by consequence the _last_block
      insert_contended_padding(_layout->start());
      need_tail_padding = true;
    }
!   _layout->add(_root_group->primitive_fields());
    _layout->add(_root_group->oop_fields());
  
    if (!_contended_groups.is_empty()) {
      for (int i = 0; i < _contended_groups.length(); i++) {
        FieldGroup* cg = _contended_groups.at(i);
        LayoutRawBlock* start = _layout->last_block();
        insert_contended_padding(start);
!       _layout->add(cg->primitive_fields(), start);
        _layout->add(cg->oop_fields(), start);
        need_tail_padding = true;
      }
    }
  
    if (need_tail_padding) {
      insert_contended_padding(_layout->last_block());
    }
  
!   _static_layout->add_contiguously(this->_static_fields->oop_fields());
!   _static_layout->add(this->_static_fields->primitive_fields());
  
    epilogue();
  }
  
! void FieldLayoutBuilder::epilogue() {
!   // Computing oopmaps
!   int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
!   int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
  
!   OopMapBlocksBuilder* nonstatic_oop_maps =
!       new OopMapBlocksBuilder(max_oop_map_count);
!   if (super_oop_map_count > 0) {
!     nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
!     _super_klass->nonstatic_oop_map_count());
    }
  
!   if (_root_group->oop_fields() != nullptr) {
!     for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
!       LayoutRawBlock* b = _root_group->oop_fields()->at(i);
        nonstatic_oop_maps->add(b->offset(), 1);
      }
    }
  
    if (!_contended_groups.is_empty()) {
      for (int i = 0; i < _contended_groups.length(); i++) {
        FieldGroup* cg = _contended_groups.at(i);
        if (cg->oop_count() > 0) {
          assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
!         nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
        }
      }
    }
- 
    nonstatic_oop_maps->compact();
  
    int instance_end = align_up(_layout->last_block()->offset(), wordSize);
    int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
    int static_fields_size = (static_fields_end -
--- 848,434 ---
        _contended_groups.at(i)->sort_by_size();
      }
    }
  }
  
+ /* Field sorting for inline classes:
+  *   - because inline classes are immutable, the @Contended annotation is ignored
+  *     when computing their layout (with only read operation, there's no false
+  *     sharing issue)
+  *   - this method also records the alignment of the field with the most
+  *     constraining alignment, this value is then used as the alignment
+  *     constraint when flattening this inline type into another container
+  *   - field flattening decisions are taken in this method (those decisions are
+  *     currently only based in the size of the fields to be flattened, the size
+  *     of the resulting instance is not considered)
+  */
+ void FieldLayoutBuilder::inline_class_field_sorting() {
+   assert(_is_inline_type || _is_abstract_value, "Should only be used for inline classes");
+   int alignment = -1;
+   int idx = 0;
+   for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
+     FieldGroup* group = nullptr;
+     FieldInfo fieldinfo = *it;
+     int field_alignment = 1;
+     if (fieldinfo.access_flags().is_static()) {
+       group = _static_fields;
+     } else {
+       _has_nonstatic_fields = true;
+       _declared_non_static_fields_count++;
+       group = _root_group;
+     }
+     assert(group != nullptr, "invariant");
+     BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
+     switch(type) {
+     case T_BYTE:
+     case T_CHAR:
+     case T_DOUBLE:
+     case T_FLOAT:
+     case T_INT:
+     case T_LONG:
+     case T_SHORT:
+     case T_BOOLEAN:
+       if (group != _static_fields) {
+         field_alignment = type2aelembytes(type); // alignment == size for primitive types
+       }
+       group->add_primitive_field(fieldinfo.index(), type);
+       break;
+     case T_OBJECT:
+     case T_ARRAY:
+     {
+       bool use_atomic_flat = _must_be_atomic; // flatten atomic fields only if the container is itself atomic
+       LayoutKind lk = field_layout_selection(fieldinfo, _inline_layout_info_array, use_atomic_flat);
+       if (fieldinfo.field_flags().is_null_free_inline_type() || lk != LayoutKind::REFERENCE
+           || (!fieldinfo.field_flags().is_injected()
+               && _inline_layout_info_array != nullptr && _inline_layout_info_array->adr_at(fieldinfo.index())->klass() != nullptr
+               && !_inline_layout_info_array->adr_at(fieldinfo.index())->klass()->is_identity_class())) {
+         _has_inline_type_fields = true;
+         _has_flattening_information = true;
+       }
+       if (lk == LayoutKind::REFERENCE) {
+         if (group != _static_fields) {
+           _nonstatic_oopmap_count++;
+           field_alignment = type2aelembytes(type); // alignment == size for oops
+         }
+         group->add_oop_field(idx);
+       } else {
+         _has_flattening_information = true;
+         InlineKlass* vk = _inline_layout_info_array->adr_at(fieldinfo.index())->klass();
+         if (!vk->is_naturally_atomic()) _has_non_naturally_atomic_fields = true;
+         int size, alignment;
+         get_size_and_alignment(vk, lk, &size, &alignment);
+         group->add_flat_field(idx, vk, lk, size, alignment);
+         _inline_layout_info_array->adr_at(fieldinfo.index())->set_kind(lk);
+         _nonstatic_oopmap_count += vk->nonstatic_oop_map_count();
+         field_alignment = alignment;
+         _field_info->adr_at(idx)->field_flags_addr()->update_flat(true);
+         _field_info->adr_at(idx)->set_layout_kind(lk);
+       }
+       break;
+     }
+     default:
+       fatal("Unexpected BasicType");
+     }
+     if (!fieldinfo.access_flags().is_static() && field_alignment > alignment) alignment = field_alignment;
+   }
+   _payload_alignment = alignment;
+   assert(_has_nonstatic_fields || _is_abstract_value, "Concrete value types do not support zero instance size yet");
+ }
+ 
  void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
    if (ContendedPaddingWidth > 0) {
      LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
      _layout->insert(slot, padding);
    }
  }
  
! /* Computation of regular classes layout is an evolution of the previous default layout
!  * (FieldAllocationStyle 1):
!  *   - primitive fields (both primitive types and flat inline types) are allocated
!  *     first, from the biggest to the smallest
!  *   - then oop fields are allocated (to increase chances to have contiguous oops and
+  *     a simpler oopmap).
+  */
  void FieldLayoutBuilder::compute_regular_layout() {
    bool need_tail_padding = false;
    prologue();
    regular_field_sorting();
    if (_is_contended) {
      _layout->set_start(_layout->last_block());
      // insertion is currently easy because the current strategy doesn't try to fill holes
      // in super classes layouts => the _start block is by consequence the _last_block
      insert_contended_padding(_layout->start());
      need_tail_padding = true;
    }
!   _layout->add(_root_group->big_primitive_fields());
+   _layout->add(_root_group->small_primitive_fields());
    _layout->add(_root_group->oop_fields());
  
    if (!_contended_groups.is_empty()) {
      for (int i = 0; i < _contended_groups.length(); i++) {
        FieldGroup* cg = _contended_groups.at(i);
        LayoutRawBlock* start = _layout->last_block();
        insert_contended_padding(start);
!       _layout->add(cg->big_primitive_fields());
+       _layout->add(cg->small_primitive_fields(), start);
        _layout->add(cg->oop_fields(), start);
        need_tail_padding = true;
      }
    }
  
    if (need_tail_padding) {
      insert_contended_padding(_layout->last_block());
    }
  
!   // Warning: IntanceMirrorKlass expects static oops to be allocated first
!   _static_layout->add_contiguously(_static_fields->oop_fields());
+   _static_layout->add(_static_fields->big_primitive_fields());
+   _static_layout->add(_static_fields->small_primitive_fields());
  
    epilogue();
  }
  
! /* Computation of inline classes has a slightly different strategy than for
!  * regular classes. Regular classes have their oop fields allocated at the end
!  * of the layout to increase GC performances. Unfortunately, this strategy
!  * increases the number of empty slots inside an instance. Because the purpose
+  * of inline classes is to be embedded into other containers, it is critical
+  * to keep their size as small as possible. For this reason, the allocation
+  * strategy is:
+  *   - big primitive fields (primitive types and flat inline type smaller
+  *     than an oop) are allocated first (from the biggest to the smallest)
+  *   - then oop fields
+  *   - then small primitive fields (from the biggest to the smallest)
+  */
+ void FieldLayoutBuilder::compute_inline_class_layout() {
  
!   // Test if the concrete inline class is an empty class (no instance fields)
!   // and insert a dummy field if needed
!   if (!_is_abstract_value) {
!     bool declares_non_static_fields = false;
!     for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it) {
+       FieldInfo fieldinfo = *it;
+       if (!fieldinfo.access_flags().is_static()) {
+         declares_non_static_fields = true;
+         break;
+       }
+     }
+     if (!declares_non_static_fields) {
+       bool has_inherited_fields = false;
+       const InstanceKlass* super = _super_klass;
+       while(super != nullptr) {
+         if (super->has_nonstatic_fields()) {
+           has_inherited_fields = true;
+           break;
+         }
+         super = super->super() == nullptr ? nullptr : InstanceKlass::cast(super->super());
+       }
+ 
+       if (!has_inherited_fields) {
+         // Inject ".empty" dummy field
+         _is_empty_inline_class = true;
+         FieldInfo::FieldFlags fflags(0);
+         fflags.update_injected(true);
+         AccessFlags aflags;
+         FieldInfo fi(aflags,
+                     (u2)vmSymbols::as_int(VM_SYMBOL_ENUM_NAME(empty_marker_name)),
+                     (u2)vmSymbols::as_int(VM_SYMBOL_ENUM_NAME(byte_signature)),
+                     0,
+                     fflags);
+         int idx = _field_info->append(fi);
+         _field_info->adr_at(idx)->set_index(idx);
+       }
+     }
+   }
+ 
+   prologue();
+   inline_class_field_sorting();
+ 
+   assert(_layout->start()->block_kind() == LayoutRawBlock::RESERVED, "Unexpected");
+ 
+   if (_layout->super_has_fields() && !_is_abstract_value) {  // non-static field layout
+     if (!_has_nonstatic_fields) {
+       assert(_is_abstract_value, "Concrete value types have at least one field");
+       // Nothing to do
+     } else {
+       // decide which alignment to use, then set first allowed field offset
+ 
+       assert(_layout->super_alignment() >= _payload_alignment, "Incompatible alignment");
+       assert(_layout->super_alignment() % _payload_alignment == 0, "Incompatible alignment");
+ 
+       if (_payload_alignment < _layout->super_alignment()) {
+         int new_alignment = _payload_alignment > _layout->super_min_align_required() ? _payload_alignment : _layout->super_min_align_required();
+         assert(new_alignment % _payload_alignment == 0, "Must be");
+         assert(new_alignment % _layout->super_min_align_required() == 0, "Must be");
+         _payload_alignment = new_alignment;
+       }
+       _layout->set_start(_layout->first_field_block());
+     }
+   } else {
+     if (_is_abstract_value && _has_nonstatic_fields) {
+       _payload_alignment = type2aelembytes(BasicType::T_LONG);
+     }
+     assert(_layout->start()->next_block()->block_kind() == LayoutRawBlock::EMPTY || !UseCompressedClassPointers, "Unexpected");
+     LayoutRawBlock* first_empty = _layout->start()->next_block();
+     if (first_empty->offset() % _payload_alignment != 0) {
+       LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, _payload_alignment - (first_empty->offset() % _payload_alignment));
+       _layout->insert(first_empty, padding);
+       if (first_empty->size() == 0) {
+         _layout->remove(first_empty);
+       }
+       _layout->set_start(padding);
+     }
+   }
+ 
+   _layout->add(_root_group->big_primitive_fields());
+   _layout->add(_root_group->oop_fields());
+   _layout->add(_root_group->small_primitive_fields());
+ 
+   LayoutRawBlock* first_field = _layout->first_field_block();
+   if (first_field != nullptr) {
+     _first_field_offset = _layout->first_field_block()->offset();
+     _payload_size_in_bytes = _layout->last_block()->offset() - _layout->first_field_block()->offset();
+   } else {
+     assert(_is_abstract_value, "Concrete inline types must have at least one field");
+     _first_field_offset = _layout->blocks()->size();
+     _payload_size_in_bytes = 0;
+   }
+ 
+   // Determining if the value class is naturally atomic:
+   if ((!_layout->super_has_fields() && _declared_non_static_fields_count <= 1 && !_has_non_naturally_atomic_fields)
+       || (_layout->super_has_fields() && _super_klass->is_naturally_atomic() && _declared_non_static_fields_count == 0)) {
+         _is_naturally_atomic = true;
+   }
+ 
+   // At this point, the characteristics of the raw layout (used in standalone instances) are known.
+   // From this, additional layouts will be computed: atomic and nullable layouts
+   // Once those additional layouts are computed, the raw layout might need some adjustments
+ 
+   if (!_is_abstract_value) { // Flat layouts are only for concrete value classes
+     // Validation of the non atomic layout
+     if ((InlineFieldMaxFlatSize < 0 || _payload_size_in_bytes * BitsPerByte <= InlineFieldMaxFlatSize)
+          && (!_must_be_atomic || _is_naturally_atomic)) {
+       _non_atomic_layout_size_in_bytes = _payload_size_in_bytes;
+       _non_atomic_layout_alignment = _payload_alignment;
+     }
+ 
+     // Next step is to compute the characteristics for a layout enabling atomic updates
+     if (AtomicFieldFlattening) {
+       int atomic_size = _payload_size_in_bytes == 0 ? 0 : round_up_power_of_2(_payload_size_in_bytes);
+       if (  atomic_size <= (int)MAX_ATOMIC_OP_SIZE
+           && (InlineFieldMaxFlatSize < 0 || atomic_size * BitsPerByte <= InlineFieldMaxFlatSize)) {
+         _atomic_layout_size_in_bytes = atomic_size;
+       }
+     }
+ 
+     // Next step is the nullable layout: the layout must include a null marker and must also be atomic
+     if (NullableFieldFlattening) {
+       // Looking if there's an empty slot inside the layout that could be used to store a null marker
+       // FIXME: could it be possible to re-use the .empty field as a null marker for empty values?
+       LayoutRawBlock* b = _layout->first_field_block();
+       assert(b != nullptr, "A concrete value class must have at least one (possible dummy) field");
+       int null_marker_offset = -1;
+       if (_is_empty_inline_class) {
+         // Reusing the dummy field as a field marker
+         assert(_field_info->adr_at(b->field_index())->name(_constant_pool) == vmSymbols::empty_marker_name(), "b must be the dummy field");
+         null_marker_offset = b->offset();
+       } else {
+         while (b != _layout->last_block()) {
+           if (b->block_kind() == LayoutRawBlock::EMPTY) {
+             break;
+           }
+           b = b->next_block();
+         }
+         if (b != _layout->last_block()) {
+           // found an empty slot, register its offset from the beginning of the payload
+           null_marker_offset = b->offset();
+           LayoutRawBlock* marker = new LayoutRawBlock(LayoutRawBlock::NULL_MARKER, 1);
+           _layout->add_field_at_offset(marker, b->offset());
+         }
+         if (null_marker_offset == -1) { // no empty slot available to store the null marker, need to inject one
+           int last_offset = _layout->last_block()->offset();
+           LayoutRawBlock* marker = new LayoutRawBlock(LayoutRawBlock::NULL_MARKER, 1);
+           _layout->insert_field_block(_layout->last_block(), marker);
+           assert(marker->offset() == last_offset, "Null marker should have been inserted at the end");
+           null_marker_offset = marker->offset();
+         }
+       }
+ 
+       // Now that the null marker is there, the size of the nullable layout must computed (remember, must be atomic too)
+       int new_raw_size = _layout->last_block()->offset() - _layout->first_field_block()->offset();
+       int nullable_size = round_up_power_of_2(new_raw_size);
+       if (nullable_size <= (int)MAX_ATOMIC_OP_SIZE
+         && (InlineFieldMaxFlatSize < 0 || nullable_size * BitsPerByte <= InlineFieldMaxFlatSize)) {
+         _nullable_layout_size_in_bytes = nullable_size;
+         _null_marker_offset = null_marker_offset;
+       } else {
+         // If the nullable layout is rejected, the NULL_MARKER block should be removed
+         // from the layout, otherwise it will appear anyway if the layout is printer
+         _layout->remove_null_marker();
+         _null_marker_offset = -1;
+       }
+     }
+     // If the inline class has an atomic or nullable (which is also atomic) layout,
+     // we want the raw layout to have the same alignment as those atomic layouts so access codes
+     // could remain  simple (single instruction without intermediate copy). This might required
+     // to shift all fields in the raw layout, but this operation is possible only if the class
+     // doesn't have inherited fields (offsets of inherited fields cannot be changed). If a
+     // field shift is needed but not possible, all atomic layouts are disabled and only reference
+     // and loosely consistent are supported.
+     int required_alignment = _payload_alignment;
+     if (has_atomic_layout() && _payload_alignment < atomic_layout_size_in_bytes()) {
+       required_alignment = atomic_layout_size_in_bytes();
+     }
+     if (has_nullable_layout() && _payload_alignment < nullable_layout_size_in_bytes()) {
+       required_alignment = nullable_layout_size_in_bytes();
+     }
+     int shift = first_field->offset() % required_alignment;
+     if (shift != 0) {
+       if (required_alignment > _payload_alignment && !_layout->has_inherited_fields()) {
+         assert(_layout->first_field_block() != nullptr, "A concrete value class must have at least one (possible dummy) field");
+         _layout->shift_fields(shift);
+         _first_field_offset = _layout->first_field_block()->offset();
+         if (has_nullable_layout()) {
+           assert(!_is_empty_inline_class, "Should not get here with empty values");
+           _null_marker_offset = _layout->find_null_marker()->offset();
+         }
+         _payload_alignment = required_alignment;
+       } else {
+         _atomic_layout_size_in_bytes = -1;
+         if (has_nullable_layout() && !_is_empty_inline_class) {  // empty values don't have a dedicated NULL_MARKER block
+           _layout->remove_null_marker();
+         }
+         _nullable_layout_size_in_bytes = -1;
+         _null_marker_offset = -1;
+       }
+     } else {
+       _payload_alignment = required_alignment;
+     }
+ 
+     // If the inline class has a nullable layout, the layout used in heap allocated standalone
+     // instances must also be the nullable layout, in order to be able to set the null marker to
+     // non-null before copying the payload to other containers.
+     if (has_nullable_layout() && payload_layout_size_in_bytes() < nullable_layout_size_in_bytes()) {
+       _payload_size_in_bytes = nullable_layout_size_in_bytes();
+     }
+   }
+   // Warning:: InstanceMirrorKlass expects static oops to be allocated first
+   _static_layout->add_contiguously(_static_fields->oop_fields());
+   _static_layout->add(_static_fields->big_primitive_fields());
+   _static_layout->add(_static_fields->small_primitive_fields());
+ 
+   epilogue();
+ }
+ 
+ void FieldLayoutBuilder::add_flat_field_oopmap(OopMapBlocksBuilder* nonstatic_oop_maps,
+                 InlineKlass* vklass, int offset) {
+   int diff = offset - vklass->first_field_offset();
+   const OopMapBlock* map = vklass->start_of_nonstatic_oop_maps();
+   const OopMapBlock* last_map = map + vklass->nonstatic_oop_map_count();
+   while (map < last_map) {
+     nonstatic_oop_maps->add(map->offset() + diff, map->count());
+     map++;
    }
+ }
  
! void FieldLayoutBuilder::register_embedded_oops_from_list(OopMapBlocksBuilder* nonstatic_oop_maps, GrowableArray<LayoutRawBlock*>* list) {
!   if (list == nullptr) return;
!   for (int i = 0; i < list->length(); i++) {
+     LayoutRawBlock* f = list->at(i);
+     if (f->block_kind() == LayoutRawBlock::FLAT) {
+       InlineKlass* vk = f->inline_klass();
+       assert(vk != nullptr, "Should have been initialized");
+       if (vk->contains_oops()) {
+         add_flat_field_oopmap(nonstatic_oop_maps, vk, f->offset());
+       }
+     }
+   }
+ }
+ 
+ void FieldLayoutBuilder::register_embedded_oops(OopMapBlocksBuilder* nonstatic_oop_maps, FieldGroup* group) {
+   if (group->oop_fields() != nullptr) {
+     for (int i = 0; i < group->oop_fields()->length(); i++) {
+       LayoutRawBlock* b = group->oop_fields()->at(i);
        nonstatic_oop_maps->add(b->offset(), 1);
      }
    }
+   register_embedded_oops_from_list(nonstatic_oop_maps, group->big_primitive_fields());
+   register_embedded_oops_from_list(nonstatic_oop_maps, group->small_primitive_fields());
+ }
  
+ void FieldLayoutBuilder::epilogue() {
+   // Computing oopmaps
+   OopMapBlocksBuilder* nonstatic_oop_maps =
+       new OopMapBlocksBuilder(_nonstatic_oopmap_count);
+   int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
+   if (super_oop_map_count > 0) {
+     nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
+     _super_klass->nonstatic_oop_map_count());
+   }
+   register_embedded_oops(nonstatic_oop_maps, _root_group);
    if (!_contended_groups.is_empty()) {
      for (int i = 0; i < _contended_groups.length(); i++) {
        FieldGroup* cg = _contended_groups.at(i);
        if (cg->oop_count() > 0) {
          assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
!         register_embedded_oops(nonstatic_oop_maps, cg);
        }
      }
    }
    nonstatic_oop_maps->compact();
  
    int instance_end = align_up(_layout->last_block()->offset(), wordSize);
    int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
    int static_fields_size = (static_fields_end -

*** 675,21 ***
    _info->oop_map_blocks = nonstatic_oop_maps;
    _info->_instance_size = align_object_size(instance_end / wordSize);
    _info->_static_field_size = static_fields_size;
    _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
    _info->_has_nonstatic_fields = _has_nonstatic_fields;
  
!   if (PrintFieldLayout) {
      ResourceMark rm;
!     tty->print_cr("Layout of class %s", _classname->as_C_string());
!     tty->print_cr("Instance fields:");
!     _layout->print(tty, false, _super_klass);
!     tty->print_cr("Static fields:");
!     _static_layout->print(tty, true, nullptr);
!     tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
!     tty->print_cr("---");
    }
  }
  
  void FieldLayoutBuilder::build_layout() {
!   compute_regular_layout();
  }
--- 1287,109 ---
    _info->oop_map_blocks = nonstatic_oop_maps;
    _info->_instance_size = align_object_size(instance_end / wordSize);
    _info->_static_field_size = static_fields_size;
    _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
    _info->_has_nonstatic_fields = _has_nonstatic_fields;
+   _info->_has_inline_fields = _has_inline_type_fields;
+   _info->_is_naturally_atomic = _is_naturally_atomic;
+   if (_is_inline_type) {
+     _info->_must_be_atomic = _must_be_atomic;
+     _info->_payload_alignment = _payload_alignment;
+     _info->_first_field_offset = _first_field_offset;
+     _info->_payload_size_in_bytes = _payload_size_in_bytes;
+     _info->_non_atomic_size_in_bytes = _non_atomic_layout_size_in_bytes;
+     _info->_non_atomic_alignment = _non_atomic_layout_alignment;
+     _info->_atomic_layout_size_in_bytes = _atomic_layout_size_in_bytes;
+     _info->_nullable_layout_size_in_bytes = _nullable_layout_size_in_bytes;
+     _info->_null_marker_offset = _null_marker_offset;
+     _info->_default_value_offset = _static_layout->default_value_offset();
+     _info->_null_reset_value_offset = _static_layout->null_reset_value_offset();
+     _info->_is_empty_inline_klass = _is_empty_inline_class;
+   }
+ 
+   // This may be too restrictive, since if all the fields fit in 64
+   // bits we could make the decision to align instances of this class
+   // to 64-bit boundaries, and load and store them as single words.
+   // And on machines which supported larger atomics we could similarly
+   // allow larger values to be atomic, if properly aligned.
+ 
+ #ifdef ASSERT
+   // Tests verifying integrity of field layouts are using the output of -XX:+PrintFieldLayout
+   // which prints the details of LayoutRawBlocks used to compute the layout.
+   // The code below checks that offsets in the _field_info meta-data match offsets
+   // in the LayoutRawBlocks
+   LayoutRawBlock* b = _layout->blocks();
+   while(b != _layout->last_block()) {
+     if (b->block_kind() == LayoutRawBlock::REGULAR || b->block_kind() == LayoutRawBlock::FLAT) {
+       if (_field_info->adr_at(b->field_index())->offset() != (u4)b->offset()) {
+         tty->print_cr("Offset from field info = %d, offset from block = %d", (int)_field_info->adr_at(b->field_index())->offset(), b->offset());
+       }
+       assert(_field_info->adr_at(b->field_index())->offset() == (u4)b->offset()," Must match");
+     }
+     b = b->next_block();
+   }
+   b = _static_layout->blocks();
+   while(b != _static_layout->last_block()) {
+     if (b->block_kind() == LayoutRawBlock::REGULAR || b->block_kind() == LayoutRawBlock::FLAT) {
+       assert(_field_info->adr_at(b->field_index())->offset() == (u4)b->offset()," Must match");
+     }
+     b = b->next_block();
+   }
+ #endif // ASSERT
+ 
+   static bool first_layout_print = true;
  
! 
+   if (PrintFieldLayout || (PrintInlineLayout && _has_flattening_information)) {
      ResourceMark rm;
!     stringStream st;
!     if (first_layout_print) {
!       st.print_cr("Field layout log format: @offset size/alignment [name] [signature] [comment]");
!       st.print_cr("Heap oop size = %d", heapOopSize);
!       first_layout_print = false;
!     }
!     if (_super_klass != nullptr) {
+       st.print_cr("Layout of class %s@%p extends %s@%p", _classname->as_C_string(),
+                     _loader_data, _super_klass->name()->as_C_string(), _super_klass->class_loader_data());
+     } else {
+       st.print_cr("Layout of class %s@%p", _classname->as_C_string(), _loader_data);
+     }
+     st.print_cr("Instance fields:");
+     _layout->print(&st, false, _super_klass, _inline_layout_info_array);
+     st.print_cr("Static fields:");
+     _static_layout->print(&st, true, nullptr, _inline_layout_info_array);
+     st.print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
+     if (_is_inline_type) {
+       st.print_cr("First field offset = %d", _first_field_offset);
+       st.print_cr("Payload layout: %d/%d", _payload_size_in_bytes, _payload_alignment);
+       if (has_non_atomic_flat_layout()) {
+         st.print_cr("Non atomic flat layout: %d/%d", _non_atomic_layout_size_in_bytes, _non_atomic_layout_alignment);
+       } else {
+         st.print_cr("Non atomic flat layout: -/-");
+       }
+       if (has_atomic_layout()) {
+         st.print_cr("Atomic flat layout: %d/%d", _atomic_layout_size_in_bytes, _atomic_layout_size_in_bytes);
+       } else {
+         st.print_cr("Atomic flat layout: -/-");
+       }
+       if (has_nullable_layout()) {
+         st.print_cr("Nullable flat layout: %d/%d", _nullable_layout_size_in_bytes, _nullable_layout_size_in_bytes);
+       } else {
+         st.print_cr("Nullable flat layout: -/-");
+       }
+       if (_null_marker_offset != -1) {
+         st.print_cr("Null marker offset = %d", _null_marker_offset);
+       }
+     }
+     st.print_cr("---");
+     // Print output all together.
+     tty->print_raw(st.as_string());
    }
  }
  
  void FieldLayoutBuilder::build_layout() {
!   if (_is_inline_type || _is_abstract_value) {
+     compute_inline_class_layout();
+   } else {
+     compute_regular_layout();
+   }
  }
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