1 /*
2 * Copyright (c) 2020, 2026, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "classfile/classFileParser.hpp"
26 #include "classfile/fieldLayoutBuilder.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "jvm.h"
30 #include "memory/resourceArea.hpp"
31 #include "oops/array.hpp"
32 #include "oops/fieldStreams.inline.hpp"
33 #include "oops/inlineKlass.inline.hpp"
34 #include "oops/instanceKlass.inline.hpp"
35 #include "oops/instanceMirrorKlass.hpp"
36 #include "oops/klass.inline.hpp"
37 #include "runtime/fieldDescriptor.inline.hpp"
38 #include "utilities/align.hpp"
39 #include "utilities/powerOfTwo.hpp"
40
41 static LayoutKind field_layout_selection(FieldInfo field_info, Array<InlineLayoutInfo>* inline_layout_info_array,
42 bool can_use_atomic_flat) {
43
44 // The can_use_atomic_flat argument indicates if an atomic flat layout can be used for this field.
45 // This argument will be false if the container is a loosely consistent value class. Using an atomic layout
46 // in a container that has no atomicity guarantee creates a risk to see this field's value be subject to
47 // tearing even if the field's class was declared atomic (non loosely consistent).
48
49 if (!UseFieldFlattening) {
50 return LayoutKind::REFERENCE;
51 }
52
53 if (field_info.field_flags().is_injected()) {
54 // don't flatten injected fields
55 return LayoutKind::REFERENCE;
56 }
57
58 if (field_info.access_flags().is_volatile()) {
59 // volatile is used as a keyword to prevent flattening
60 return LayoutKind::REFERENCE;
61 }
62
63 if (field_info.access_flags().is_static()) {
64 // don't flatten static fields
65 return LayoutKind::REFERENCE;
66 }
67
68 if (inline_layout_info_array == nullptr || inline_layout_info_array->adr_at(field_info.index())->klass() == nullptr) {
69 // field's type is not a known value class, using a reference
70 return LayoutKind::REFERENCE;
71 }
72
73 InlineLayoutInfo* inline_field_info = inline_layout_info_array->adr_at(field_info.index());
74 InlineKlass* vk = inline_field_info->klass();
75
76 if (field_info.field_flags().is_null_free_inline_type()) {
77 assert(field_info.access_flags().is_strict(), "null-free fields must be strict");
78 if (vk->must_be_atomic()) {
79 if (vk->is_naturally_atomic(true /* null-free */) && vk->has_null_free_non_atomic_layout()) {
80 return LayoutKind::NULL_FREE_NON_ATOMIC_FLAT;
81 }
82 return (vk->has_null_free_atomic_layout() && can_use_atomic_flat) ? LayoutKind::NULL_FREE_ATOMIC_FLAT : LayoutKind::REFERENCE;
83 } else {
84 return vk->has_null_free_non_atomic_layout() ? LayoutKind::NULL_FREE_NON_ATOMIC_FLAT : LayoutKind::REFERENCE;
85 }
86 } else {
87 // To preserve the consistency between the null-marker and the field content, the NULLABLE_NON_ATOMIC_FLAT
88 // can only be used in containers that have atomicity guarantees (can_use_atomic_flat argument set to true)
89 if (field_info.access_flags().is_strict() && field_info.access_flags().is_final() && can_use_atomic_flat) {
90 if (vk->has_nullable_non_atomic_layout()) {
91 return LayoutKind::NULLABLE_NON_ATOMIC_FLAT;
92 }
93 }
94 // Another special case where NULLABLE_NON_ATOMIC_FLAT can be used: nullable empty values, because the
95 // payload of those values contains only the null-marker
96 if (vk->is_empty_inline_type() && vk->has_nullable_non_atomic_layout()) {
97 return LayoutKind::NULLABLE_NON_ATOMIC_FLAT;
98 }
99 if (UseNullableAtomicValueFlattening && vk->has_nullable_atomic_layout()) {
100 return can_use_atomic_flat ? LayoutKind::NULLABLE_ATOMIC_FLAT : LayoutKind::REFERENCE;
101 } else {
102 return LayoutKind::REFERENCE;
103 }
104 }
105 }
106
107 static LayoutKind adjust_with_budget(FieldInfo field_info, Array<InlineLayoutInfo>* inline_layout_info_array,
108 LayoutKind lk, int& budget) {
109 if (lk == LayoutKind::REFERENCE) return lk;
110 assert(LayoutKindHelper::is_flat((lk)), "Must be");
111 InlineLayoutInfo* inline_field_info = inline_layout_info_array->adr_at(field_info.index());
112 InlineKlass* vk = inline_field_info->klass();
113 int size = vk->layout_size_in_bytes(lk);
114 if (size > budget) {
115 return LayoutKind::REFERENCE;
116 } else {
117 budget -= size;
118 return lk;
119 }
120 }
121
122 static bool field_is_inlineable(FieldInfo fieldinfo, LayoutKind lk, Array<InlineLayoutInfo>* ili) {
123 if (fieldinfo.field_flags().is_null_free_inline_type()) {
124 // A null-free inline type is always inlineable
125 return true;
126 }
127
128 if (lk != LayoutKind::REFERENCE) {
129 assert(lk != LayoutKind::BUFFERED, "Sanity check");
130 assert(lk != LayoutKind::UNKNOWN, "Sanity check");
131 // We've chosen a layout that isn't a normal reference
132 return true;
133 }
134
135 const int field_index = (int)fieldinfo.index();
136 if (!fieldinfo.field_flags().is_injected() &&
137 ili != nullptr &&
138 ili->adr_at(field_index)->klass() != nullptr &&
139 !ili->adr_at(field_index)->klass()->is_identity_class() &&
140 !ili->adr_at(field_index)->klass()->is_abstract()) {
141 // The field's klass is not an identity class or abstract
142 return true;
143 }
144
145 return false;
146 }
147
148 LayoutRawBlock::LayoutRawBlock(Kind kind, int size) :
149 _next_block(nullptr),
150 _prev_block(nullptr),
151 _inline_klass(nullptr),
152 _block_kind(kind),
153 _layout_kind(LayoutKind::UNKNOWN),
154 _offset(-1),
155 _alignment(1),
156 _size(size),
157 _field_index(-1) {
158 assert(kind == EMPTY || kind == RESERVED || kind == PADDING || kind == INHERITED || kind == NULL_MARKER,
159 "Otherwise, should use the constructor with a field index argument");
160 assert(size > 0, "Sanity check");
161 }
162
163
164 LayoutRawBlock::LayoutRawBlock(int index, Kind kind, int size, int alignment) :
165 _next_block(nullptr),
166 _prev_block(nullptr),
167 _inline_klass(nullptr),
168 _block_kind(kind),
169 _layout_kind(LayoutKind::UNKNOWN),
170 _offset(-1),
171 _alignment(alignment),
172 _size(size),
173 _field_index(index) {
174 assert(kind == REGULAR || kind == FLAT || kind == INHERITED,
175 "Other kind do not have a field index");
176 assert(size > 0, "Sanity check");
177 assert(alignment > 0, "Sanity check");
178 }
179
180 bool LayoutRawBlock::fit(int size, int alignment) {
181 int adjustment = 0;
182 if ((_offset % alignment) != 0) {
183 adjustment = alignment - (_offset % alignment);
184 }
185 return _size >= size + adjustment;
186 }
187
188 FieldGroup::FieldGroup(int contended_group) :
189 _next(nullptr),
190 _small_primitive_fields(nullptr),
191 _big_primitive_fields(nullptr),
192 _oop_fields(nullptr),
193 _contended_group(contended_group) {} // -1 means no contended group, 0 means default contended group
194
195 void FieldGroup::add_primitive_field(int idx, BasicType type) {
196 int size = type2aelembytes(type);
197 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */);
198 if (size >= heapOopSize) {
199 add_to_big_primitive_list(block);
200 } else {
201 add_to_small_primitive_list(block);
202 }
203 }
204
205 void FieldGroup::add_oop_field(int idx) {
206 int size = type2aelembytes(T_OBJECT);
207 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */);
208 if (_oop_fields == nullptr) {
209 _oop_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
210 }
211 _oop_fields->append(block);
212 }
213
214 void FieldGroup::add_flat_field(int idx, InlineKlass* vk, LayoutKind lk) {
215 const int size = vk->layout_size_in_bytes(lk);
216 const int alignment = vk->layout_alignment(lk);
217
218 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::FLAT, size, alignment);
219 block->set_inline_klass(vk);
220 block->set_layout_kind(lk);
221 if (block->size() >= heapOopSize) {
222 add_to_big_primitive_list(block);
223 } else {
224 assert(!vk->contains_oops(), "Size of Inline klass with oops should be >= heapOopSize");
225 add_to_small_primitive_list(block);
226 }
227 }
228
229 void FieldGroup::sort_by_size() {
230 if (_small_primitive_fields != nullptr) {
231 _small_primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
232 }
233 if (_big_primitive_fields != nullptr) {
234 _big_primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
235 }
236 }
237
238 void FieldGroup::add_to_small_primitive_list(LayoutRawBlock* block) {
239 if (_small_primitive_fields == nullptr) {
240 _small_primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
241 }
242 _small_primitive_fields->append(block);
243 }
244
245 void FieldGroup::add_to_big_primitive_list(LayoutRawBlock* block) {
246 if (_big_primitive_fields == nullptr) {
247 _big_primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
248 }
249 _big_primitive_fields->append(block);
250 }
251
252 FieldLayout::FieldLayout(GrowableArray<FieldInfo>* field_info, Array<InlineLayoutInfo>* inline_layout_info_array, ConstantPool* cp) :
253 _field_info(field_info),
254 _inline_layout_info_array(inline_layout_info_array),
255 _cp(cp),
256 _blocks(nullptr),
257 _start(_blocks),
258 _last(_blocks),
259 _super_first_field_offset(-1),
260 _super_alignment(-1),
261 _super_min_align_required(-1),
262 _null_reset_value_offset(-1),
263 _acmp_maps_offset(-1),
264 _super_has_nonstatic_fields(false),
265 _has_inherited_fields(false) {}
266
267 void FieldLayout::initialize_static_layout() {
268 _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
269 _blocks->set_offset(0);
270 _last = _blocks;
271 _start = _blocks;
272 // Note: at this stage, InstanceMirrorKlass::offset_of_static_fields() could be zero, because
273 // during bootstrapping, the size of the java.lang.Class is still not known when layout
274 // of static field is computed. Field offsets are fixed later when the size is known
275 // (see java_lang_Class::fixup_mirror())
276 if (InstanceMirrorKlass::offset_of_static_fields() > 0) {
277 insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, InstanceMirrorKlass::offset_of_static_fields()));
278 _blocks->set_offset(0);
279 }
280 }
281
282 void FieldLayout::initialize_instance_layout(const InstanceKlass* super_klass, bool& super_ends_with_oop) {
283 if (super_klass == nullptr) {
284 super_ends_with_oop = false;
285 _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
286 _blocks->set_offset(0);
287 _last = _blocks;
288 _start = _blocks;
289 insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes()));
290 } else {
291 reconstruct_layout(super_klass, _super_has_nonstatic_fields, super_ends_with_oop);
292 fill_holes(super_klass);
293 if ((!super_klass->has_contended_annotations()) || !_super_has_nonstatic_fields) {
294 _start = _blocks; // start allocating fields from the first empty block
295 } else {
296 _start = _last; // append fields at the end of the reconstructed layout
297 }
298 }
299 }
300
301 LayoutRawBlock* FieldLayout::first_field_block() {
302 LayoutRawBlock* block = _blocks;
303 while (block != nullptr
304 && block->block_kind() != LayoutRawBlock::INHERITED
305 && block->block_kind() != LayoutRawBlock::REGULAR
306 && block->block_kind() != LayoutRawBlock::FLAT
307 && block->block_kind() != LayoutRawBlock::NULL_MARKER) {
308 block = block->next_block();
309 }
310 return block;
311 }
312
313 // Insert a set of fields into a layout.
314 // For each field, search for an empty slot able to fit the field
315 // (satisfying both size and alignment requirements), if none is found,
316 // add the field at the end of the layout.
317 // Fields cannot be inserted before the block specified in the "start" argument
318 void FieldLayout::add(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
319 if (list == nullptr) return;
320 if (start == nullptr) start = this->_start;
321 bool last_search_success = false;
322 int last_size = 0;
323 int last_alignment = 0;
324 for (int i = 0; i < list->length(); i ++) {
325 LayoutRawBlock* b = list->at(i);
326 LayoutRawBlock* cursor = nullptr;
327 LayoutRawBlock* candidate = nullptr;
328 // if start is the last block, just append the field
329 if (start == last_block()) {
330 candidate = last_block();
331 }
332 // Before iterating over the layout to find an empty slot fitting the field's requirements,
333 // check if the previous field had the same requirements and if the search for a fitting slot
334 // was successful. If the requirements were the same but the search failed, a new search will
335 // fail the same way, so just append the field at the of the layout.
336 else if (b->size() == last_size && b->alignment() == last_alignment && !last_search_success) {
337 candidate = last_block();
338 } else {
339 // Iterate over the layout to find an empty slot fitting the field's requirements
340 last_size = b->size();
341 last_alignment = b->alignment();
342 cursor = last_block()->prev_block();
343 assert(cursor != nullptr, "Sanity check");
344 last_search_success = true;
345
346 assert(start->block_kind() != LayoutRawBlock::EMPTY, "");
347 while (cursor != start) {
348 if (cursor->block_kind() == LayoutRawBlock::EMPTY && cursor->fit(b->size(), b->alignment())) {
349 if (candidate == nullptr || cursor->size() < candidate->size()) {
350 candidate = cursor;
351 }
352 }
353 cursor = cursor->prev_block();
354 }
355 if (candidate == nullptr) {
356 candidate = last_block();
357 last_search_success = false;
358 }
359 assert(candidate != nullptr, "Candidate must not be null");
360 assert(candidate->block_kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
361 assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
362 }
363 insert_field_block(candidate, b);
364 }
365 }
366
367 // Used for classes with hard coded field offsets, insert a field at the specified offset */
368 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
369 assert(block != nullptr, "Sanity check");
370 block->set_offset(offset);
371 if (start == nullptr) {
372 start = this->_start;
373 }
374 LayoutRawBlock* slot = start;
375 while (slot != nullptr) {
376 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
377 slot == _last){
378 assert(slot->block_kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
379 assert(slot->size() >= block->offset() - slot->offset() + block->size() ,"Matching slot must be big enough");
380 if (slot->offset() < block->offset()) {
381 int adjustment = block->offset() - slot->offset();
382 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
383 insert(slot, adj);
384 }
385 insert(slot, block);
386 if (slot->size() == 0) {
387 remove(slot);
388 }
389 if (block->block_kind() == LayoutRawBlock::REGULAR || block->block_kind() == LayoutRawBlock::FLAT) {
390 _field_info->adr_at(block->field_index())->set_offset(block->offset());
391 }
392 return;
393 }
394 slot = slot->next_block();
395 }
396 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
397 }
398
399 // The allocation logic uses a best fit strategy: the set of fields is allocated
400 // in the first empty slot big enough to contain the whole set ((including padding
401 // to fit alignment constraints).
402 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
403 if (list == nullptr) return;
404 if (start == nullptr) {
405 start = _start;
406 }
407 // This code assumes that if the first block is well aligned, the following
408 // blocks would naturally be well aligned (no need for adjustment)
409 int size = 0;
410 for (int i = 0; i < list->length(); i++) {
411 size += list->at(i)->size();
412 }
413
414 LayoutRawBlock* candidate = nullptr;
415 if (start == last_block()) {
416 candidate = last_block();
417 } else {
418 LayoutRawBlock* first = list->at(0);
419 candidate = last_block()->prev_block();
420 while (candidate->block_kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
421 if (candidate == start) {
422 candidate = last_block();
423 break;
424 }
425 candidate = candidate->prev_block();
426 }
427 assert(candidate != nullptr, "Candidate must not be null");
428 assert(candidate->block_kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
429 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
430 }
431
432 for (int i = 0; i < list->length(); i++) {
433 LayoutRawBlock* b = list->at(i);
434 insert_field_block(candidate, b);
435 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
436 }
437 }
438
439 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
440 assert(slot->block_kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
441 if (slot->offset() % block->alignment() != 0) {
442 int adjustment = block->alignment() - (slot->offset() % block->alignment());
443 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
444 insert(slot, adj);
445 }
446 assert(slot->size() >= block->size(), "Enough space must remain after adjustment");
447 insert(slot, block);
448 if (slot->size() == 0) {
449 remove(slot);
450 }
451 // NULL_MARKER blocks are not real fields, so they don't have an entry in the FieldInfo array
452 if (block->block_kind() != LayoutRawBlock::NULL_MARKER) {
453 _field_info->adr_at(block->field_index())->set_offset(block->offset());
454 if (_field_info->adr_at(block->field_index())->name(_cp) == vmSymbols::null_reset_value_name()) {
455 _null_reset_value_offset = block->offset();
456 }
457 if (_field_info->adr_at(block->field_index())->name(_cp) == vmSymbols::acmp_maps_name()) {
458 _acmp_maps_offset = block->offset();
459 }
460 }
461 if (LayoutKindHelper::is_nullable_flat(block->layout_kind())) {
462 int nm_offset = block->inline_klass()->null_marker_offset() - block->inline_klass()->payload_offset() + block->offset();
463 _field_info->adr_at(block->field_index())->set_null_marker_offset(nm_offset);
464 _inline_layout_info_array->adr_at(block->field_index())->set_null_marker_offset(nm_offset);
465 }
466
467 return block;
468 }
469
470 void FieldLayout::reconstruct_layout(const InstanceKlass* ik, bool& has_nonstatic_fields, bool& ends_with_oop) {
471 has_nonstatic_fields = ends_with_oop = false;
472 if (ik->is_abstract() && !ik->is_identity_class()) {
473 _super_alignment = type2aelembytes(BasicType::T_LONG);
474 }
475 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
476 BasicType last_type;
477 int last_offset = -1;
478 while (ik != nullptr) {
479 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
480 BasicType type = Signature::basic_type(fs.signature());
481 // distinction between static and non-static fields is missing
482 if (fs.access_flags().is_static()) continue;
483 has_nonstatic_fields = true;
484 _has_inherited_fields = true;
485 if (_super_first_field_offset == -1 || fs.offset() < _super_first_field_offset) {
486 _super_first_field_offset = fs.offset();
487 }
488 LayoutRawBlock* block;
489 if (fs.is_flat()) {
490 InlineLayoutInfo layout_info = ik->inline_layout_info(fs.index());
491 InlineKlass* vk = layout_info.klass();
492 block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED,
493 vk->layout_size_in_bytes(layout_info.kind()),
494 vk->layout_alignment(layout_info.kind()));
495 assert(_super_alignment == -1 || _super_alignment >= vk->payload_alignment(), "Invalid value alignment");
496 _super_min_align_required = _super_min_align_required > vk->payload_alignment() ? _super_min_align_required : vk->payload_alignment();
497 } else {
498 int size = type2aelembytes(type);
499 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
500 block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size);
501 // For primitive types, the alignment is equal to the size
502 assert(_super_alignment == -1 || _super_alignment >= size, "Invalid value alignment");
503 _super_min_align_required = _super_min_align_required > size ? _super_min_align_required : size;
504 }
505 if (fs.offset() > last_offset) {
506 last_offset = fs.offset();
507 last_type = type;
508 }
509 block->set_offset(fs.offset());
510 all_fields->append(block);
511 }
512 ik = ik->super() == nullptr ? nullptr : ik->super();
513 }
514 assert(last_offset == -1 || last_offset > 0, "Sanity");
515 if (last_offset > 0 &&
516 (last_type == BasicType::T_ARRAY || last_type == BasicType::T_OBJECT)) {
517 ends_with_oop = true;
518 }
519
520 all_fields->sort(LayoutRawBlock::compare_offset);
521 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
522 _blocks->set_offset(0);
523 _last = _blocks;
524 for(int i = 0; i < all_fields->length(); i++) {
525 LayoutRawBlock* b = all_fields->at(i);
526 _last->set_next_block(b);
527 b->set_prev_block(_last);
528 _last = b;
529 }
530 _start = _blocks;
531 }
532
533 // Called during the reconstruction of a layout, after fields from super
534 // classes have been inserted. It fills unused slots between inserted fields
535 // with EMPTY blocks, so the regular field insertion methods would work.
536 // This method handles classes with @Contended annotations differently
537 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
538 // fields to interfere with contended fields/classes.
539 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
540 assert(_blocks != nullptr, "Sanity check");
541 assert(_blocks->offset() == 0, "first block must be at offset zero");
542 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
543 LayoutRawBlock* b = _blocks;
544 while (b->next_block() != nullptr) {
545 if (b->next_block()->offset() > (b->offset() + b->size())) {
546 int size = b->next_block()->offset() - (b->offset() + b->size());
547 // FIXME it would be better if initial empty blocks were tagged as PADDING for value classes
548 // Tracked by JDK-8383383
549 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
550 empty->set_offset(b->offset() + b->size());
551 empty->set_next_block(b->next_block());
552 b->next_block()->set_prev_block(empty);
553 b->set_next_block(empty);
554 empty->set_prev_block(b);
555 }
556 b = b->next_block();
557 }
558 assert(b->next_block() == nullptr, "Invariant at this point");
559 assert(b->block_kind() != LayoutRawBlock::EMPTY, "Sanity check");
560 // If the super class has @Contended annotation, a padding block is
561 // inserted at the end to ensure that fields from the subclasses won't share
562 // the cache line of the last field of the contended class
563 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
564 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
565 p->set_offset(b->offset() + b->size());
566 b->set_next_block(p);
567 p->set_prev_block(b);
568 b = p;
569 }
570
571 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
572 last->set_offset(b->offset() + b->size());
573 assert(last->offset() > 0, "Sanity check");
574 b->set_next_block(last);
575 last->set_prev_block(b);
576 _last = last;
577 }
578
579 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
580 assert(slot->block_kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
581 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
582 block->set_offset(slot->offset());
583 slot->set_offset(slot->offset() + block->size());
584 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
585 assert(slot->size() - block->size() >= 0, "no negative size allowed");
586 slot->set_size(slot->size() - block->size());
587 block->set_prev_block(slot->prev_block());
588 block->set_next_block(slot);
589 slot->set_prev_block(block);
590 if (block->prev_block() != nullptr) {
591 block->prev_block()->set_next_block(block);
592 }
593 if (_blocks == slot) {
594 _blocks = block;
595 }
596 if (_start == slot) {
597 _start = block;
598 }
599 return block;
600 }
601
602 void FieldLayout::remove(LayoutRawBlock* block) {
603 assert(block != nullptr, "Sanity check");
604 assert(block != _last, "Sanity check");
605 if (_blocks == block) {
606 _blocks = block->next_block();
607 if (_blocks != nullptr) {
608 _blocks->set_prev_block(nullptr);
609 }
610 } else {
611 assert(block->prev_block() != nullptr, "_prev should be set for non-head blocks");
612 block->prev_block()->set_next_block(block->next_block());
613 block->next_block()->set_prev_block(block->prev_block());
614 }
615 if (block == _start) {
616 _start = block->prev_block();
617 }
618 }
619
620 void FieldLayout::shift_fields(int shift) {
621 LayoutRawBlock* b = first_field_block();
622 assert(b != nullptr, "shift_fields must not be called if layout has no fields");
623 LayoutRawBlock* previous = b->prev_block();
624 if (previous->block_kind() == LayoutRawBlock::EMPTY) {
625 previous->set_size(previous->size() + shift);
626 } else {
627 LayoutRawBlock* nb = new LayoutRawBlock(LayoutRawBlock::PADDING, shift);
628 nb->set_offset(b->offset());
629 previous->set_next_block(nb);
630 nb->set_prev_block(previous);
631 b->set_prev_block(nb);
632 nb->set_next_block(b);
633 }
634 while (b != nullptr) {
635 b->set_offset(b->offset() + shift);
636 if (b->block_kind() == LayoutRawBlock::REGULAR || b->block_kind() == LayoutRawBlock::FLAT) {
637 _field_info->adr_at(b->field_index())->set_offset(b->offset());
638 if (LayoutKindHelper::is_nullable_flat(b->layout_kind())) {
639 int new_nm_offset = _field_info->adr_at(b->field_index())->null_marker_offset() + shift;
640 _field_info->adr_at(b->field_index())->set_null_marker_offset(new_nm_offset);
641 _inline_layout_info_array->adr_at(b->field_index())->set_null_marker_offset(new_nm_offset);
642 }
643 }
644 assert(b->block_kind() == LayoutRawBlock::EMPTY || b->offset() % b->alignment() == 0, "Must still be correctly aligned");
645 b = b->next_block();
646 }
647 }
648
649 LayoutRawBlock* FieldLayout::find_null_marker() {
650 LayoutRawBlock* b = _blocks;
651 while (b != nullptr) {
652 if (b->block_kind() == LayoutRawBlock::NULL_MARKER) {
653 return b;
654 }
655 b = b->next_block();
656 }
657 ShouldNotReachHere();
658 return nullptr;
659 }
660
661 void FieldLayout::remove_null_marker() {
662 LayoutRawBlock* b = first_field_block();
663 while (b != nullptr) {
664 if (b->block_kind() == LayoutRawBlock::NULL_MARKER) {
665 if (b->next_block()->block_kind() == LayoutRawBlock::EMPTY) {
666 LayoutRawBlock* n = b->next_block();
667 remove(b);
668 n->set_offset(b->offset());
669 n->set_size(n->size() + b->size());
670 } else {
671 b->set_block_kind(LayoutRawBlock::EMPTY);
672 }
673 return;
674 }
675 b = b->next_block();
676 }
677 ShouldNotReachHere(); // if we reach this point, the null marker was not found!
678 }
679
680 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super, Array<InlineLayoutInfo>* inline_fields, bool dummy_field_is_reused_as_null_marker) {
681 ResourceMark rm;
682 LayoutRawBlock* b = _blocks;
683 while(b != _last) {
684 switch(b->block_kind()) {
685 case LayoutRawBlock::REGULAR: {
686 FieldInfo* fi = _field_info->adr_at(b->field_index());
687 output->print(" @%d %s %d/%d \"%s\" %s",
688 b->offset(),
689 "REGULAR",
690 b->size(),
691 b->alignment(),
692 fi->name(_cp)->as_C_string(),
693 fi->signature(_cp)->as_C_string());
694
695 if (dummy_field_is_reused_as_null_marker) {
696 const bool is_dummy_field = fi->name(_cp)->fast_compare(vmSymbols::symbol_at(VM_SYMBOL_ENUM_NAME(empty_marker_name))) == 0;
697 if (is_dummy_field) {
698 output->print(" (reused as null-marker)");
699 }
700 }
701
702 output->cr();
703 break;
704 }
705 case LayoutRawBlock::FLAT: {
706 FieldInfo* fi = _field_info->adr_at(b->field_index());
707 InlineKlass* ik = inline_fields->adr_at(fi->index())->klass();
708 assert(ik != nullptr, "");
709 output->print_cr(" @%d %s %d/%d \"%s\" %s %s@%p %s",
710 b->offset(),
711 "FLAT",
712 b->size(),
713 b->alignment(),
714 fi->name(_cp)->as_C_string(),
715 fi->signature(_cp)->as_C_string(),
716 ik->name()->as_C_string(),
717 ik->class_loader_data(),
718 LayoutKindHelper::layout_kind_as_string(b->layout_kind()));
719 break;
720 }
721 case LayoutRawBlock::RESERVED: {
722 output->print_cr(" @%d %s %d/-",
723 b->offset(),
724 "RESERVED",
725 b->size());
726 break;
727 }
728 case LayoutRawBlock::INHERITED: {
729 assert(!is_static, "Static fields are not inherited in layouts");
730 assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
731 bool found = false;
732 const InstanceKlass* ik = super;
733 while (!found && ik != nullptr) {
734 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
735 if (fs.offset() == b->offset() && fs.access_flags().is_static() == is_static) {
736 output->print_cr(" @%d %s %d/%d \"%s\" %s",
737 b->offset(),
738 "INHERITED",
739 b->size(),
740 b->alignment(),
741 fs.name()->as_C_string(),
742 fs.signature()->as_C_string());
743 found = true;
744 break;
745 }
746 }
747 ik = ik->super();
748 }
749 break;
750 }
751 case LayoutRawBlock::EMPTY:
752 output->print_cr(" @%d %s %d/1",
753 b->offset(),
754 "EMPTY",
755 b->size());
756 break;
757 case LayoutRawBlock::PADDING:
758 output->print_cr(" @%d %s %d/1",
759 b->offset(),
760 "PADDING",
761 b->size());
762 break;
763 case LayoutRawBlock::NULL_MARKER:
764 {
765 output->print_cr(" @%d %s %d/1 ",
766 b->offset(),
767 "NULL_MARKER",
768 b->size());
769 break;
770 }
771 default:
772 fatal("Unknown block type");
773 }
774 b = b->next_block();
775 }
776 }
777
778 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, ClassLoaderData* loader_data, const InstanceKlass* super_klass, ConstantPool* constant_pool,
779 GrowableArray<FieldInfo>* field_info, bool is_contended, bool is_inline_type,bool is_abstract_value,
780 bool must_be_atomic, FieldLayoutInfo* info, Array<InlineLayoutInfo>* inline_layout_info_array) :
781 _classname(classname),
782 _loader_data(loader_data),
783 _super_klass(super_klass),
784 _constant_pool(constant_pool),
785 _field_info(field_info),
786 _info(info),
787 _inline_layout_info_array(inline_layout_info_array),
788 _root_group(nullptr),
789 _contended_groups(GrowableArray<FieldGroup*>(8)),
790 _static_fields(nullptr),
791 _layout(nullptr),
792 _static_layout(nullptr),
793 _nonstatic_oopmap_count(0),
794 _payload_alignment(-1),
795 _payload_offset(-1),
796 _null_marker_offset(-1),
797 _payload_size_in_bytes(-1),
798 _null_free_non_atomic_layout_size_in_bytes(-1),
799 _null_free_non_atomic_layout_alignment(-1),
800 _null_free_atomic_layout_size_in_bytes(-1),
801 _nullable_atomic_layout_size_in_bytes(-1),
802 _nullable_non_atomic_layout_size_in_bytes(-1),
803 _fields_size_sum(0),
804 _declared_nonstatic_fields_count(0),
805 _flattening_budget((int)FlatteningBudget), // uint -> int convertion but FlatteningBudget value has
806 // been validated in VM flags parsing (range [0, 1024 * 1024]).
807 _has_non_naturally_atomic_fields(false),
808 _is_naturally_atomic(false),
809 _must_be_atomic(must_be_atomic),
810 _has_nonstatic_fields(false),
811 _has_inlineable_fields(false),
812 _has_inlined_fields(false),
813 _is_contended(is_contended),
814 _is_inline_type(is_inline_type),
815 _is_abstract_value(is_abstract_value),
816 _is_empty_inline_class(false) {}
817
818 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
819 assert(g > 0, "must only be called for named contended groups");
820 FieldGroup* fg = nullptr;
821 for (int i = 0; i < _contended_groups.length(); i++) {
822 fg = _contended_groups.at(i);
823 if (fg->contended_group() == g) return fg;
824 }
825 fg = new FieldGroup(g);
826 _contended_groups.append(fg);
827 return fg;
828 }
829
830 void FieldLayoutBuilder::prologue() {
831 _layout = new FieldLayout(_field_info, _inline_layout_info_array, _constant_pool);
832 const InstanceKlass* super_klass = _super_klass;
833 _layout->initialize_instance_layout(super_klass, _super_ends_with_oop);
834 _nonstatic_oopmap_count = super_klass == nullptr ? 0 : super_klass->nonstatic_oop_map_count();
835 if (super_klass != nullptr) {
836 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
837 }
838 _static_layout = new FieldLayout(_field_info, _inline_layout_info_array, _constant_pool);
839 _static_layout->initialize_static_layout();
840 _static_fields = new FieldGroup();
841 _root_group = new FieldGroup();
842 }
843
844 // Field sorting for regular (non-inline) classes:
845 // - fields are sorted in static and non-static fields
846 // - non-static fields are also sorted according to their contention group
847 // (support of the @Contended annotation)
848 // - @Contended annotation is ignored for static fields
849 // - field flattening decisions are taken in this method
850 void FieldLayoutBuilder::regular_field_sorting() {
851 int idx = 0;
852 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
853 FieldGroup* group = nullptr;
854 FieldInfo fieldinfo = *it;
855 if (fieldinfo.access_flags().is_static()) {
856 group = _static_fields;
857 } else {
858 _has_nonstatic_fields = true;
859 if (fieldinfo.field_flags().is_contended()) {
860 int g = fieldinfo.contended_group();
861 if (g == 0) {
862 group = new FieldGroup(true);
863 _contended_groups.append(group);
864 } else {
865 group = get_or_create_contended_group(g);
866 }
867 } else {
868 group = _root_group;
869 }
870 }
871 assert(group != nullptr, "invariant");
872 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
873 switch(type) {
874 case T_BYTE:
875 case T_CHAR:
876 case T_DOUBLE:
877 case T_FLOAT:
878 case T_INT:
879 case T_LONG:
880 case T_SHORT:
881 case T_BOOLEAN:
882 group->add_primitive_field(idx, type);
883 break;
884 case T_OBJECT:
885 case T_ARRAY:
886 {
887 LayoutKind lk = field_layout_selection(fieldinfo, _inline_layout_info_array, true);
888 lk = adjust_with_budget(fieldinfo, _inline_layout_info_array, lk, _flattening_budget);
889 if (field_is_inlineable(fieldinfo, lk, _inline_layout_info_array)) {
890 _has_inlineable_fields = true;
891 }
892
893 if (lk == LayoutKind::REFERENCE) {
894 if (group != _static_fields) _nonstatic_oopmap_count++;
895 group->add_oop_field(idx);
896 } else {
897 assert(group != _static_fields, "Static fields are not flattened");
898 assert(lk != LayoutKind::BUFFERED && lk != LayoutKind::UNKNOWN,
899 "Invalid layout kind for flat field: %s", LayoutKindHelper::layout_kind_as_string(lk));
900
901 const int field_index = (int)fieldinfo.index();
902 assert(_inline_layout_info_array != nullptr, "Array must have been created");
903 assert(_inline_layout_info_array->adr_at(field_index)->klass() != nullptr, "Klass must have been set");
904 _has_inlined_fields = true;
905 InlineKlass* vk = _inline_layout_info_array->adr_at(field_index)->klass();
906 group->add_flat_field(idx, vk, lk);
907 _inline_layout_info_array->adr_at(field_index)->set_kind(lk);
908 _nonstatic_oopmap_count += vk->nonstatic_oop_map_count();
909 _field_info->adr_at(idx)->field_flags_addr()->update_flat(true);
910 _field_info->adr_at(idx)->set_layout_kind(lk);
911 // no need to update _must_be_atomic if vk->must_be_atomic() is true because current class is not an inline class
912 }
913 break;
914 }
915 default:
916 fatal("Something wrong?");
917 }
918 }
919 _root_group->sort_by_size();
920 _static_fields->sort_by_size();
921 if (!_contended_groups.is_empty()) {
922 for (int i = 0; i < _contended_groups.length(); i++) {
923 _contended_groups.at(i)->sort_by_size();
924 }
925 }
926 }
927
928 /* Field sorting for inline classes:
929 * - because inline classes are immutable, the @Contended annotation is ignored
930 * when computing their layout (with only read operation, there's no false
931 * sharing issue)
932 * - this method also records the alignment of the field with the most
933 * constraining alignment, this value is then used as the alignment
934 * constraint when flattening this inline type into another container
935 * - field flattening decisions are taken in this method (those decisions are
936 * currently only based in the size of the fields to be flattened, the size
937 * of the resulting instance is not considered)
938 */
939 void FieldLayoutBuilder::inline_class_field_sorting() {
940 assert(_is_inline_type || _is_abstract_value, "Should only be used for inline classes");
941 int alignment = -1;
942 int idx = 0;
943 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
944 FieldGroup* group = nullptr;
945 FieldInfo fieldinfo = *it;
946 int field_alignment = 1;
947 if (fieldinfo.access_flags().is_static()) {
948 group = _static_fields;
949 } else {
950 _has_nonstatic_fields = true;
951 _declared_nonstatic_fields_count++;
952 group = _root_group;
953 }
954 assert(group != nullptr, "invariant");
955 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
956 switch(type) {
957 case T_BYTE:
958 case T_CHAR:
959 case T_DOUBLE:
960 case T_FLOAT:
961 case T_INT:
962 case T_LONG:
963 case T_SHORT:
964 case T_BOOLEAN:
965 if (group != _static_fields) {
966 field_alignment = type2aelembytes(type); // alignment == size for primitive types
967 }
968 group->add_primitive_field(idx, type);
969 break;
970 case T_OBJECT:
971 case T_ARRAY:
972 {
973 bool use_atomic_flat = _must_be_atomic; // flatten atomic fields only if the container is itself atomic
974 LayoutKind lk = field_layout_selection(fieldinfo, _inline_layout_info_array, use_atomic_flat);
975 lk = adjust_with_budget(fieldinfo, _inline_layout_info_array, lk, _flattening_budget);
976 if (field_is_inlineable(fieldinfo, lk, _inline_layout_info_array)) {
977 _has_inlineable_fields = true;
978 }
979
980 if (lk == LayoutKind::REFERENCE) {
981 if (group != _static_fields) {
982 _nonstatic_oopmap_count++;
983 field_alignment = type2aelembytes(type); // alignment == size for oops
984 }
985 group->add_oop_field(idx);
986 } else {
987 assert(group != _static_fields, "Static fields are not flattened");
988 assert(lk != LayoutKind::BUFFERED && lk != LayoutKind::UNKNOWN,
989 "Invalid layout kind for flat field: %s", LayoutKindHelper::layout_kind_as_string(lk));
990
991 const int field_index = (int)fieldinfo.index();
992 assert(_inline_layout_info_array != nullptr, "Array must have been created");
993 assert(_inline_layout_info_array->adr_at(field_index)->klass() != nullptr, "Klass must have been set");
994 _has_inlined_fields = true;
995 InlineKlass* vk = _inline_layout_info_array->adr_at(field_index)->klass();
996 if (!vk->is_naturally_atomic(LayoutKindHelper::is_null_free_flat(lk))) _has_non_naturally_atomic_fields = true;
997 group->add_flat_field(idx, vk, lk);
998 _inline_layout_info_array->adr_at(field_index)->set_kind(lk);
999 _nonstatic_oopmap_count += vk->nonstatic_oop_map_count();
1000 field_alignment = vk->layout_alignment(lk);
1001 _field_info->adr_at(idx)->field_flags_addr()->update_flat(true);
1002 _field_info->adr_at(idx)->set_layout_kind(lk);
1003 }
1004 break;
1005 }
1006 default:
1007 fatal("Unexpected BasicType");
1008 }
1009 if (!fieldinfo.access_flags().is_static() && field_alignment > alignment) alignment = field_alignment;
1010 }
1011 _root_group->sort_by_size();
1012 _static_fields->sort_by_size();
1013 _payload_alignment = alignment;
1014 assert(_has_nonstatic_fields || _is_abstract_value, "Concrete value types do not support zero instance size yet");
1015 }
1016
1017 LayoutRawBlock* FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
1018 LayoutRawBlock* padding = nullptr;
1019 if (ContendedPaddingWidth > 0) {
1020 padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
1021 _layout->insert(slot, padding);
1022 }
1023 return padding;
1024 }
1025
1026 // Computation of regular classes layout is an evolution of the previous default layout
1027 // (FieldAllocationStyle 1):
1028 // - primitive fields (both primitive types and flat inline types) are allocated
1029 // first (from the biggest to the smallest)
1030 // - oop fields are allocated, either in existing gaps or at the end of
1031 // the layout. We allocate oops in a single block to have a single oop map entry.
1032 // - if the super class ended with an oop, we lead with oops. That will cause the
1033 // trailing oop map entry of the super class and the oop map entry of this class
1034 // to be folded into a single entry later. Correspondingly, if the super class
1035 // ends with a primitive field, we gain nothing by leading with oops; therefore
1036 // we let oop fields trail, thus giving future derived classes the chance to apply
1037 // the same trick.
1038 void FieldLayoutBuilder::compute_regular_layout() {
1039 bool need_tail_padding = false;
1040 prologue();
1041 regular_field_sorting();
1042 if (_is_contended) {
1043 // insertion is currently easy because the current strategy doesn't try to fill holes
1044 // in super classes layouts => the _start block is by consequence the _last_block
1045 _layout->set_start(_layout->last_block());
1046 LayoutRawBlock* padding = insert_contended_padding(_layout->start());
1047 if (padding != nullptr) {
1048 // Setting the padding block as start ensures we do not insert past it.
1049 _layout->set_start(padding);
1050 }
1051 need_tail_padding = true;
1052 }
1053
1054 if (_super_ends_with_oop) {
1055 _layout->add(_root_group->oop_fields());
1056 _layout->add(_root_group->big_primitive_fields());
1057 _layout->add(_root_group->small_primitive_fields());
1058 } else {
1059 _layout->add(_root_group->big_primitive_fields());
1060 _layout->add(_root_group->small_primitive_fields());
1061 _layout->add(_root_group->oop_fields());
1062 }
1063
1064 if (!_contended_groups.is_empty()) {
1065 for (int i = 0; i < _contended_groups.length(); i++) {
1066 FieldGroup* cg = _contended_groups.at(i);
1067 LayoutRawBlock* start = _layout->last_block();
1068 LayoutRawBlock* padding = insert_contended_padding(start);
1069
1070 // Do not insert fields past the padding block.
1071 if (padding != nullptr) {
1072 start = padding;
1073 }
1074
1075 _layout->add(cg->big_primitive_fields(), start);
1076 _layout->add(cg->small_primitive_fields(), start);
1077 _layout->add(cg->oop_fields(), start);
1078 need_tail_padding = true;
1079 }
1080 }
1081
1082 if (need_tail_padding) {
1083 insert_contended_padding(_layout->last_block());
1084 }
1085
1086 // Warning: IntanceMirrorKlass expects static oops to be allocated first
1087 _static_layout->add_contiguously(_static_fields->oop_fields());
1088 _static_layout->add(_static_fields->big_primitive_fields());
1089 _static_layout->add(_static_fields->small_primitive_fields());
1090
1091 epilogue();
1092 }
1093
1094 /* Computation of inline classes has a slightly different strategy than for
1095 * regular classes. Regular classes have their oop fields allocated at the end
1096 * of the layout to increase GC performance. Unfortunately, this strategy
1097 * increases the number of empty slots inside an instance. Because the purpose
1098 * of inline classes is to be embedded into other containers, it is critical
1099 * to keep their size as small as possible. For this reason, the allocation
1100 * strategy is:
1101 * - big primitive fields (primitive types and flat inline types larger
1102 * than an oop) are allocated first (from the biggest to the smallest)
1103 * - then oop fields
1104 * - then small primitive fields (from the biggest to the smallest)
1105 */
1106 void FieldLayoutBuilder::compute_inline_class_layout() {
1107
1108 // Test if the concrete inline class is an empty class (no instance fields)
1109 // and insert a dummy field if needed
1110 if (!_is_abstract_value) {
1111 bool declares_nonstatic_fields = false;
1112 for (FieldInfo fieldinfo : *_field_info) {
1113 if (!fieldinfo.access_flags().is_static()) {
1114 declares_nonstatic_fields = true;
1115 break;
1116 }
1117 }
1118
1119 if (!declares_nonstatic_fields) {
1120 bool has_inherited_fields = _super_klass != nullptr && _super_klass->has_nonstatic_fields();
1121 if (!has_inherited_fields) {
1122 // Inject ".empty" dummy field
1123 _is_empty_inline_class = true;
1124 FieldInfo::FieldFlags fflags(0);
1125 fflags.update_injected(true);
1126 AccessFlags aflags;
1127 FieldInfo fi(aflags,
1128 (u2)vmSymbols::as_int(VM_SYMBOL_ENUM_NAME(empty_marker_name)),
1129 (u2)vmSymbols::as_int(VM_SYMBOL_ENUM_NAME(byte_signature)),
1130 0,
1131 fflags);
1132 int idx = _field_info->append(fi);
1133 _field_info->adr_at(idx)->set_index(idx);
1134 }
1135 }
1136 }
1137
1138 prologue();
1139 inline_class_field_sorting();
1140
1141 assert(_layout->start()->block_kind() == LayoutRawBlock::RESERVED, "Unexpected");
1142
1143 if (!_layout->super_has_nonstatic_fields()) {
1144 // No inherited fields, the layout must be empty except for the RESERVED block
1145 // PADDING is inserted if needed to ensure the correct alignment of the payload.
1146 if (_is_abstract_value && _has_nonstatic_fields) {
1147 // Non-static fields of the abstract class must be laid out without knowing
1148 // the alignment constraints of the fields of the sub-classes, so the worst
1149 // case scenario is assumed, which is currently the alignment of T_LONG.
1150 // PADDING is added if needed to ensure the payload will respect this alignment.
1151 _payload_alignment = type2aelembytes(BasicType::T_LONG);
1152 }
1153 assert(_layout->start()->next_block()->block_kind() == LayoutRawBlock::EMPTY, "Unexpected");
1154 LayoutRawBlock* first_empty = _layout->start()->next_block();
1155 if (first_empty->offset() % _payload_alignment != 0) {
1156 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, _payload_alignment - (first_empty->offset() % _payload_alignment));
1157 _layout->insert(first_empty, padding);
1158 if (first_empty->size() == 0) {
1159 _layout->remove(first_empty);
1160 }
1161 _layout->set_start(padding);
1162 }
1163 } else { // the class has inherited some fields from its super(s)
1164 if (!_is_abstract_value) {
1165 // This is the step where the layout of the final concrete value class' layout
1166 // is computed. Super abstract value classes might have been too conservative
1167 // regarding alignment constraints, but now that the full set of non-static fields is
1168 // known, compute which alignment to use, then set first allowed field offset.
1169
1170 assert(_has_nonstatic_fields, "Concrete value classes must have at least one field");
1171 if (_payload_alignment == -1) { // current class declares no local nonstatic fields
1172 _payload_alignment = _layout->super_min_align_required();
1173 }
1174
1175 assert(_layout->super_alignment() >= _payload_alignment, "Incompatible alignment");
1176 assert(_layout->super_alignment() % _payload_alignment == 0, "Incompatible alignment");
1177
1178 if (_payload_alignment < _layout->super_alignment()) {
1179 int new_alignment = _payload_alignment > _layout->super_min_align_required() ? _payload_alignment : _layout->super_min_align_required();
1180 assert(new_alignment % _payload_alignment == 0, "Must be");
1181 assert(new_alignment % _layout->super_min_align_required() == 0, "Must be");
1182 _payload_alignment = new_alignment;
1183 }
1184 _layout->set_start(_layout->first_field_block());
1185 } else {
1186 // Abstract value class inheriting fields, restore the pessimistic alignment
1187 // constraint (see comment above) and ensure no field will be inserted before
1188 // the first inherited field.
1189 _payload_alignment = type2aelembytes(BasicType::T_LONG);
1190 _layout->set_start(_layout->first_field_block());
1191 }
1192 }
1193
1194 _layout->add(_root_group->big_primitive_fields());
1195 _layout->add(_root_group->oop_fields());
1196 _layout->add(_root_group->small_primitive_fields());
1197
1198 LayoutRawBlock* first_field = _layout->first_field_block();
1199 if (first_field != nullptr) {
1200 _payload_offset = _layout->first_field_block()->offset();
1201 _payload_size_in_bytes = _layout->last_block()->offset() - _layout->first_field_block()->offset();
1202 } else {
1203 assert(_is_abstract_value, "Concrete inline types must have at least one field");
1204 _payload_offset = _layout->blocks()->size();
1205 _payload_size_in_bytes = 0;
1206 }
1207
1208 // Determining if the value class is naturally atomic:
1209 if (_declared_nonstatic_fields_count == 0) {
1210 _is_naturally_atomic = _super_klass == vmClasses::Object_klass() || _super_klass->is_naturally_atomic(true /* null-free */);
1211 } else if (_declared_nonstatic_fields_count == 1) {
1212 _is_naturally_atomic = !_layout->super_has_nonstatic_fields() && !_has_non_naturally_atomic_fields;
1213 } else {
1214 _is_naturally_atomic = false;
1215 }
1216
1217 // At this point, the characteristics of the raw layout (used in standalone instances) are known.
1218 // From this, additional layouts will be computed: atomic and nullable layouts.
1219 // Once those additional layouts are computed, the raw layout might need some adjustments.
1220
1221 bool vm_uses_flattening = UseFieldFlattening || UseArrayFlattening;
1222
1223 if (!_is_abstract_value && vm_uses_flattening) { // Flat layouts are only for concrete value classes
1224 // Validation of the non atomic layout
1225 if (UseNullFreeNonAtomicValueFlattening && (!_must_be_atomic || _is_naturally_atomic)) {
1226 _null_free_non_atomic_layout_size_in_bytes = _payload_size_in_bytes;
1227 _null_free_non_atomic_layout_alignment = _payload_alignment;
1228 }
1229
1230 // Next step is to compute the characteristics for a layout enabling atomic updates
1231 if (UseNullFreeAtomicValueFlattening) {
1232 int atomic_size = _payload_size_in_bytes == 0 ? 0 : round_up_power_of_2(_payload_size_in_bytes);
1233 if (atomic_size <= (int)MAX_ATOMIC_OP_SIZE) {
1234 _null_free_atomic_layout_size_in_bytes = atomic_size;
1235 }
1236 }
1237
1238 // Next step is the nullable layouts: they must include a null marker.
1239 // Note about the special case of j.l.Double and j.l.Long: the introduction of
1240 // the NULLABLE_NON_ATOMIC_FLAT layout caused an increase of the size of their
1241 // instances which causes performance regression (see JDK-8379145).
1242 // The temporary solution is to simply disable nullable layouts for these classes
1243 // until a better fix is implemented (see JDK-8382361).
1244 if ((UseNullableAtomicValueFlattening || UseNullableNonAtomicValueFlattening)
1245 && _classname != vmSymbols::java_lang_Double() && _classname != vmSymbols::java_lang_Long()) {
1246 // Looking if there's an empty slot inside the layout that could be used to store a null marker
1247 LayoutRawBlock* b = _layout->first_field_block();
1248 assert(b != nullptr, "A concrete value class must have at least one (possible dummy) field");
1249 int null_marker_offset = -1;
1250 if (_is_empty_inline_class) {
1251 // Reusing the dummy field as a field marker
1252 assert(_field_info->adr_at(b->field_index())->name(_constant_pool) == vmSymbols::empty_marker_name(), "b must be the dummy field");
1253 null_marker_offset = b->offset();
1254 } else {
1255 while (b != _layout->last_block()) {
1256 if (b->block_kind() == LayoutRawBlock::EMPTY) {
1257 break;
1258 }
1259 b = b->next_block();
1260 }
1261 if (b != _layout->last_block()) {
1262 // found an empty slot, register its offset from the beginning of the payload
1263 null_marker_offset = b->offset();
1264 LayoutRawBlock* marker = new LayoutRawBlock(LayoutRawBlock::NULL_MARKER, 1);
1265 _layout->add_field_at_offset(marker, b->offset());
1266 }
1267 if (null_marker_offset == -1) { // no empty slot available to store the null marker, need to inject one
1268 int last_offset = _layout->last_block()->offset();
1269 LayoutRawBlock* marker = new LayoutRawBlock(LayoutRawBlock::NULL_MARKER, 1);
1270 _layout->insert_field_block(_layout->last_block(), marker);
1271 assert(marker->offset() == last_offset, "Null marker should have been inserted at the end");
1272 null_marker_offset = marker->offset();
1273 }
1274 }
1275 assert(null_marker_offset != -1, "Sanity check");
1276 // Now that the null marker is there, the size of the nullable layout must be computed
1277 int new_raw_size = _layout->last_block()->offset() - _layout->first_field_block()->offset();
1278 if (UseNullableNonAtomicValueFlattening) {
1279 _nullable_non_atomic_layout_size_in_bytes = new_raw_size;
1280 _null_marker_offset = null_marker_offset;
1281 _null_free_non_atomic_layout_alignment = _payload_alignment;
1282 }
1283 if (UseNullableAtomicValueFlattening) {
1284 // For the nullable atomic layout, the size must be compatible with the platform capabilities
1285 int nullable_atomic_size = round_up_power_of_2(new_raw_size);
1286 if (nullable_atomic_size <= (int)MAX_ATOMIC_OP_SIZE) {
1287 _nullable_atomic_layout_size_in_bytes = nullable_atomic_size;
1288 _null_marker_offset = null_marker_offset;
1289 }
1290 }
1291 if (_null_marker_offset == -1) { // No nullable layout has been accepted
1292 // If the nullable layout is rejected, the NULL_MARKER block should be removed
1293 // from the layout, otherwise it will appear anyway if the layout is printer
1294 if (!_is_empty_inline_class) { // empty values don't have a dedicated NULL_MARKER block
1295 _layout->remove_null_marker();
1296 }
1297 }
1298 }
1299 // If the inline class has an atomic or nullable atomic layout,
1300 // we want the raw layout to have the same alignment as those atomic layouts so access codes
1301 // could remain simple (single instruction without intermediate copy). This might require
1302 // shifting all fields in the raw layout, but this operation is possible only if the class
1303 // doesn't have inherited fields (offsets of inherited fields cannot be changed). If a
1304 // field shift is needed but not possible, all atomic layouts are disabled and only reference
1305 // and loosely consistent are supported.
1306 int required_alignment = _payload_alignment;
1307 if (has_null_free_atomic_layout() && required_alignment < null_free_atomic_layout_size_in_bytes()) {
1308 required_alignment = null_free_atomic_layout_size_in_bytes();
1309 }
1310 if (has_nullable_atomic_layout() && required_alignment < nullable_atomic_layout_size_in_bytes()) {
1311 required_alignment = nullable_atomic_layout_size_in_bytes();
1312 }
1313 int shift = (required_alignment - (first_field->offset() % required_alignment)) % required_alignment;
1314 if (shift != 0) {
1315 if (required_alignment > _payload_alignment && !_layout->has_inherited_fields()) {
1316 assert(_layout->first_field_block() != nullptr, "A concrete value class must have at least one (possible dummy) field");
1317 _layout->shift_fields(shift);
1318 _payload_offset = _layout->first_field_block()->offset();
1319 assert(is_aligned(_payload_offset, required_alignment), "Fields should have been shifted to respect the required alignment");
1320 if (has_nullable_atomic_layout() || has_nullable_non_atomic_layout()) {
1321 assert(!_is_empty_inline_class, "Should not get here with empty values");
1322 _null_marker_offset = _layout->find_null_marker()->offset();
1323 }
1324 _payload_alignment = required_alignment;
1325 } else {
1326 _null_free_atomic_layout_size_in_bytes = -1;
1327 if (has_nullable_atomic_layout() && !has_nullable_non_atomic_layout() && !_is_empty_inline_class) { // empty values don't have a dedicated NULL_MARKER block
1328 _layout->remove_null_marker();
1329 _null_marker_offset = -1;
1330 }
1331 _nullable_atomic_layout_size_in_bytes = -1;
1332 }
1333 } else {
1334 _payload_alignment = required_alignment;
1335 }
1336
1337 // If the inline class has a nullable layout, the layout used in heap allocated standalone
1338 // instances must also be the nullable layout, in order to be able to set the null marker to
1339 // non-null before copying the payload to other containers.
1340 if (has_nullable_atomic_layout() && payload_layout_size_in_bytes() < nullable_atomic_layout_size_in_bytes()) {
1341 _payload_size_in_bytes = nullable_atomic_layout_size_in_bytes();
1342 }
1343 if (has_nullable_non_atomic_layout() && payload_layout_size_in_bytes() < nullable_non_atomic_layout_size_in_bytes()) {
1344 _payload_size_in_bytes = nullable_non_atomic_layout_size_in_bytes();
1345 }
1346
1347 // If the inline class has a null-free atomic layout, then the layout used in heap allocated standalone
1348 // instances must have at least equal to the atomic layout to allow safe read/write atomic
1349 // operation.
1350 if (has_null_free_atomic_layout() && payload_layout_size_in_bytes() < null_free_atomic_layout_size_in_bytes()) {
1351 _payload_size_in_bytes = null_free_atomic_layout_size_in_bytes();
1352 }
1353 }
1354 // Warning:: InstanceMirrorKlass expects static oops to be allocated first
1355 _static_layout->add_contiguously(_static_fields->oop_fields());
1356 _static_layout->add(_static_fields->big_primitive_fields());
1357 _static_layout->add(_static_fields->small_primitive_fields());
1358
1359 generate_acmp_maps();
1360 epilogue();
1361 }
1362
1363 void FieldLayoutBuilder::add_flat_field_oopmap(OopMapBlocksBuilder* nonstatic_oop_maps, InlineKlass* vklass, int offset) {
1364 int diff = offset - vklass->payload_offset();
1365 const OopMapBlock* map = vklass->start_of_nonstatic_oop_maps();
1366 const OopMapBlock* last_map = map + vklass->nonstatic_oop_map_count();
1367 while (map < last_map) {
1368 nonstatic_oop_maps->add(map->offset() + diff, map->count());
1369 map++;
1370 }
1371 }
1372
1373 void FieldLayoutBuilder::register_embedded_oops_from_list(OopMapBlocksBuilder* nonstatic_oop_maps, GrowableArray<LayoutRawBlock*>* list) {
1374 if (list == nullptr) {
1375 return;
1376 }
1377
1378 for (int i = 0; i < list->length(); i++) {
1379 LayoutRawBlock* f = list->at(i);
1380 if (f->block_kind() == LayoutRawBlock::FLAT) {
1381 InlineKlass* vk = f->inline_klass();
1382 assert(vk != nullptr, "Should have been initialized");
1383 if (vk->contains_oops()) {
1384 add_flat_field_oopmap(nonstatic_oop_maps, vk, f->offset());
1385 }
1386 }
1387 }
1388 }
1389
1390 void FieldLayoutBuilder::register_embedded_oops(OopMapBlocksBuilder* nonstatic_oop_maps, FieldGroup* group) {
1391 if (group->oop_fields() != nullptr) {
1392 for (int i = 0; i < group->oop_fields()->length(); i++) {
1393 LayoutRawBlock* b = group->oop_fields()->at(i);
1394 nonstatic_oop_maps->add(b->offset(), 1);
1395 }
1396 }
1397 register_embedded_oops_from_list(nonstatic_oop_maps, group->big_primitive_fields());
1398 }
1399
1400 static int insert_segment(GrowableArray<AcmpMapSegment>* map, int offset, int size, int last_idx) {
1401 if (map->is_empty()) {
1402 return map->append(AcmpMapSegment(offset, size));
1403 }
1404 int start = map->adr_at(last_idx)->_offset > offset ? 0 : last_idx;
1405 bool inserted = false;
1406 for (int c = start; c < map->length(); c++) {
1407 if (offset == (map->adr_at(c)->_offset + map->adr_at(c)->_size)) {
1408 //contiguous to the last field, can be coalesced
1409 map->adr_at(c)->_size = map->adr_at(c)->_size + size;
1410 inserted = true;
1411 break; // break out of the for loop
1412 }
1413 if (offset < (map->adr_at(c)->_offset)) {
1414 map->insert_before(c, AcmpMapSegment(offset, size));
1415 last_idx = c;
1416 inserted = true;
1417 break; // break out of the for loop
1418 }
1419 }
1420 if (!inserted) {
1421 last_idx = map->append(AcmpMapSegment(offset, size));
1422 }
1423 return last_idx;
1424 }
1425
1426 static int insert_map_at_offset(GrowableArray<AcmpMapSegment>* nonoop_map, GrowableArray<int>* oop_map,
1427 const InstanceKlass* ik, int field_offset, int last_idx) {
1428 Array<int>* super_map = ik->acmp_maps_array();
1429 assert(super_map != nullptr, "super class must have an acmp map");
1430 int num_nonoop_field = super_map->at(0);
1431 for (int i = 0; i < num_nonoop_field; i++) {
1432 last_idx = insert_segment(nonoop_map,
1433 field_offset + super_map->at( i * 2 + 1),
1434 super_map->at( i * 2 + 2), last_idx);
1435 }
1436 int len = super_map->length();
1437 for (int i = num_nonoop_field * 2 + 1; i < len; i++) {
1438 oop_map->append(field_offset + super_map->at(i));
1439 }
1440 return last_idx;
1441 }
1442
1443 static void split_after(GrowableArray<AcmpMapSegment>* map, int idx, int head) {
1444 int offset = map->adr_at(idx)->_offset;
1445 int size = map->adr_at(idx)->_size;
1446 if (size <= head) return;
1447 map->adr_at(idx)->_offset = offset + head;
1448 map->adr_at(idx)->_size = size - head;
1449 map->insert_before(idx, AcmpMapSegment(offset, head));
1450
1451 }
1452
1453 void FieldLayoutBuilder::generate_acmp_maps() {
1454 assert(_is_inline_type || _is_abstract_value, "Must be done only for value classes (abstract or not)");
1455
1456 // create/initialize current class' maps
1457 _nonoop_acmp_map = new GrowableArray<AcmpMapSegment>();
1458 _oop_acmp_map = new GrowableArray<int>();
1459 if (_is_empty_inline_class) return;
1460 // last_idx remembers the position of the last insertion in order to speed up the next insertion.
1461 // Local fields are processed in ascending offset order, so an insertion is very likely be performed
1462 // next to the previous insertion. However, in some cases local fields and inherited fields can be
1463 // interleaved, in which case the search of the insertion position cannot depend on the previous insertion.
1464 int last_idx = 0;
1465 if (_super_klass != nullptr && _super_klass != vmClasses::Object_klass()) { // Assumes j.l.Object cannot have fields
1466 last_idx = insert_map_at_offset(_nonoop_acmp_map, _oop_acmp_map, _super_klass, 0, last_idx);
1467 }
1468
1469 // Processing local fields
1470 LayoutRawBlock* b = _layout->blocks();
1471 while(b != _layout->last_block()) {
1472 switch(b->block_kind()) {
1473 case LayoutRawBlock::RESERVED:
1474 case LayoutRawBlock::EMPTY:
1475 case LayoutRawBlock::PADDING:
1476 case LayoutRawBlock::NULL_MARKER:
1477 case LayoutRawBlock::INHERITED: // inherited fields are handled during maps creation/initialization
1478 // skip
1479 break;
1480
1481 case LayoutRawBlock::REGULAR:
1482 {
1483 FieldInfo* fi = _field_info->adr_at(b->field_index());
1484 if (fi->signature(_constant_pool)->starts_with("L") || fi->signature(_constant_pool)->starts_with("[")) {
1485 _oop_acmp_map->append(b->offset());
1486 } else {
1487 // Non-oop case
1488 last_idx = insert_segment(_nonoop_acmp_map, b->offset(), b->size(), last_idx);
1489 }
1490 break;
1491 }
1492 case LayoutRawBlock::FLAT:
1493 {
1494 InlineKlass* vk = b->inline_klass();
1495 int field_offset = b->offset() - vk->payload_offset();
1496 last_idx = insert_map_at_offset(_nonoop_acmp_map, _oop_acmp_map, vk, field_offset, last_idx);
1497 if (LayoutKindHelper::is_nullable_flat(b->layout_kind())) {
1498 int null_marker_offset = b->offset() + vk->null_marker_offset_in_payload();
1499 last_idx = insert_segment(_nonoop_acmp_map, null_marker_offset, 1, last_idx);
1500 // Important note: the implementation assumes that for nullable flat fields, if the
1501 // null marker is zero (field is null), then all the fields of the flat field are also
1502 // zeroed. So, nullable flat field are not encoded different than null-free flat fields,
1503 // all fields are included in the map, plus the null marker.
1504 // If it happens that the assumption above is wrong, then nullable flat fields would
1505 // require a dedicated section in the acmp map, and be handled differently: null_marker
1506 // comparison first, and if null markers are identical and non-zero, then conditional
1507 // comparison of the other fields.
1508 }
1509 }
1510 break;
1511
1512 }
1513 b = b->next_block();
1514 }
1515
1516 // split segments into well-aligned blocks
1517 int idx = 0;
1518 while (idx < _nonoop_acmp_map->length()) {
1519 int offset = _nonoop_acmp_map->adr_at(idx)->_offset;
1520 int size = _nonoop_acmp_map->adr_at(idx)->_size;
1521 int mod = offset % 8;
1522 switch (mod) {
1523 case 0:
1524 break;
1525 case 4:
1526 split_after(_nonoop_acmp_map, idx, 4);
1527 break;
1528 case 2:
1529 case 6:
1530 split_after(_nonoop_acmp_map, idx, 2);
1531 break;
1532 case 1:
1533 case 3:
1534 case 5:
1535 case 7:
1536 split_after(_nonoop_acmp_map, idx, 1);
1537 break;
1538 default:
1539 ShouldNotReachHere();
1540 }
1541 idx++;
1542 }
1543 }
1544
1545 void FieldLayoutBuilder::epilogue() {
1546 // Computing oopmaps
1547 OopMapBlocksBuilder* nonstatic_oop_maps =
1548 new OopMapBlocksBuilder(_nonstatic_oopmap_count);
1549 int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
1550 if (super_oop_map_count > 0) {
1551 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
1552 _super_klass->nonstatic_oop_map_count());
1553 }
1554 register_embedded_oops(nonstatic_oop_maps, _root_group);
1555 if (!_contended_groups.is_empty()) {
1556 for (int i = 0; i < _contended_groups.length(); i++) {
1557 FieldGroup* cg = _contended_groups.at(i);
1558 register_embedded_oops(nonstatic_oop_maps, cg);
1559 }
1560 }
1561 nonstatic_oop_maps->compact();
1562
1563 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
1564 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
1565 int static_fields_size = (static_fields_end -
1566 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
1567 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
1568
1569 // Pass back information needed for InstanceKlass creation
1570
1571 _info->oop_map_blocks = nonstatic_oop_maps;
1572 _info->_instance_size = align_object_size(instance_end / wordSize);
1573 _info->_static_field_size = static_fields_size;
1574 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
1575 _info->_has_nonstatic_fields = _has_nonstatic_fields;
1576 _info->_has_inlined_fields = _has_inlined_fields;
1577 _info->_is_naturally_atomic = _is_naturally_atomic;
1578 if (_is_inline_type) {
1579 _info->_must_be_atomic = _must_be_atomic;
1580 _info->_payload_alignment = _payload_alignment;
1581 _info->_payload_offset = _payload_offset;
1582 _info->_payload_size_in_bytes = _payload_size_in_bytes;
1583 _info->_null_free_non_atomic_size_in_bytes = _null_free_non_atomic_layout_size_in_bytes;
1584 _info->_null_free_non_atomic_alignment = _null_free_non_atomic_layout_alignment;
1585 _info->_null_free_atomic_layout_size_in_bytes = _null_free_atomic_layout_size_in_bytes;
1586 _info->_nullable_atomic_layout_size_in_bytes = _nullable_atomic_layout_size_in_bytes;
1587 _info->_nullable_non_atomic_layout_size_in_bytes = _nullable_non_atomic_layout_size_in_bytes;
1588 _info->_null_marker_offset = _null_marker_offset;
1589 _info->_null_reset_value_offset = _static_layout->null_reset_value_offset();
1590 _info->_is_empty_inline_klass = _is_empty_inline_class;
1591 }
1592
1593 // Acmp maps are needed for both concrete and abstract value classes
1594 if (_is_inline_type || _is_abstract_value) {
1595 _info->_acmp_maps_offset = _static_layout->acmp_maps_offset();
1596 _info->_nonoop_acmp_map = _nonoop_acmp_map;
1597 _info->_oop_acmp_map = _oop_acmp_map;
1598 }
1599
1600 // This may be too restrictive, since if all the fields fit in 64
1601 // bits we could make the decision to align instances of this class
1602 // to 64-bit boundaries, and load and store them as single words.
1603 // And on machines which supported larger atomics we could similarly
1604 // allow larger values to be atomic, if properly aligned.
1605
1606 #ifdef ASSERT
1607 // Tests verifying integrity of field layouts are using the output of -XX:+PrintFieldLayout
1608 // which prints the details of LayoutRawBlocks used to compute the layout.
1609 // The code below checks that offsets in the _field_info meta-data match offsets
1610 // in the LayoutRawBlocks.
1611 LayoutRawBlock* b = _layout->blocks();
1612 while(b != _layout->last_block()) {
1613 if (b->block_kind() == LayoutRawBlock::REGULAR || b->block_kind() == LayoutRawBlock::FLAT) {
1614 if (_field_info->adr_at(b->field_index())->offset() != (u4)b->offset()) {
1615 tty->print_cr("Offset from field info = %d, offset from block = %d", (int)_field_info->adr_at(b->field_index())->offset(), b->offset());
1616 }
1617 assert(_field_info->adr_at(b->field_index())->offset() == (u4)b->offset()," Must match");
1618 }
1619 b = b->next_block();
1620 }
1621 b = _static_layout->blocks();
1622 while(b != _static_layout->last_block()) {
1623 if (b->block_kind() == LayoutRawBlock::REGULAR || b->block_kind() == LayoutRawBlock::FLAT) {
1624 assert(_field_info->adr_at(b->field_index())->offset() == (u4)b->offset()," Must match");
1625 }
1626 b = b->next_block();
1627 }
1628 #endif // ASSERT
1629
1630 static bool first_layout_print = true;
1631
1632 if (PrintFieldLayout || (PrintInlineLayout && (_has_inlineable_fields || _is_inline_type || _is_abstract_value))) {
1633 ResourceMark rm;
1634 stringStream st;
1635 if (first_layout_print) {
1636 st.print_cr("Field layout log format: @offset size/alignment [name] [signature] [comment]");
1637 st.print_cr("Heap oop size = %d", heapOopSize);
1638 first_layout_print = false;
1639 }
1640 if (_super_klass != nullptr) {
1641 st.print_cr("Layout of class %s@%p extends %s@%p", _classname->as_C_string(),
1642 _loader_data, _super_klass->name()->as_C_string(), _super_klass->class_loader_data());
1643 } else {
1644 st.print_cr("Layout of class %s@%p", _classname->as_C_string(), _loader_data);
1645 }
1646 st.print_cr("Instance fields:");
1647 const bool dummy_field_is_reused_as_null_marker = _is_empty_inline_class && _null_marker_offset != -1;
1648 _layout->print(&st, false, _super_klass, _inline_layout_info_array, dummy_field_is_reused_as_null_marker);
1649 st.print_cr("Static fields:");
1650 _static_layout->print(&st, true, nullptr, _inline_layout_info_array, false);
1651 st.print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
1652 if (_is_inline_type) {
1653 st.print_cr("First field offset = %d", _payload_offset);
1654 st.print_cr("%s layout: %d/%d", LayoutKindHelper::layout_kind_as_string(LayoutKind::BUFFERED),
1655 _payload_size_in_bytes, _payload_alignment);
1656 if (has_null_free_non_atomic_flat_layout()) {
1657 st.print_cr("%s layout: %d/%d",
1658 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULL_FREE_NON_ATOMIC_FLAT),
1659 _null_free_non_atomic_layout_size_in_bytes, _null_free_non_atomic_layout_alignment);
1660 } else {
1661 st.print_cr("%s layout: -/-",
1662 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULL_FREE_NON_ATOMIC_FLAT));
1663 }
1664 if (has_null_free_atomic_layout()) {
1665 st.print_cr("%s layout: %d/%d",
1666 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULL_FREE_ATOMIC_FLAT),
1667 _null_free_atomic_layout_size_in_bytes, _null_free_atomic_layout_size_in_bytes);
1668 } else {
1669 st.print_cr("%s layout: -/-",
1670 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULL_FREE_ATOMIC_FLAT));
1671 }
1672 if (has_nullable_atomic_layout()) {
1673 st.print_cr("%s layout: %d/%d",
1674 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULLABLE_ATOMIC_FLAT),
1675 _nullable_atomic_layout_size_in_bytes, _nullable_atomic_layout_size_in_bytes);
1676 } else {
1677 st.print_cr("%s layout: -/-",
1678 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULLABLE_ATOMIC_FLAT));
1679 }
1680 if (has_nullable_non_atomic_layout()) {
1681 st.print_cr("%s layout: %d/%d",
1682 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULLABLE_NON_ATOMIC_FLAT),
1683 _nullable_non_atomic_layout_size_in_bytes, _null_free_non_atomic_layout_alignment);
1684 } else {
1685 st.print_cr("%s layout: -/-",
1686 LayoutKindHelper::layout_kind_as_string(LayoutKind::NULLABLE_NON_ATOMIC_FLAT));
1687 }
1688 if (_null_marker_offset != -1) {
1689 st.print_cr("Null marker offset = %d", _null_marker_offset);
1690 }
1691 st.print("Non-oop acmp map <offset,size>: ");
1692 for (int i = 0 ; i < _nonoop_acmp_map->length(); i++) {
1693 st.print("<%d,%d> ", _nonoop_acmp_map->at(i)._offset, _nonoop_acmp_map->at(i)._size);
1694 }
1695 st.print_cr("");
1696 st.print("oop acmp map: ");
1697 for (int i = 0 ; i < _oop_acmp_map->length(); i++) {
1698 st.print("%d ", _oop_acmp_map->at(i));
1699 }
1700 st.print_cr("");
1701 }
1702 st.print_cr("---");
1703 // Print output all together.
1704 tty->print_raw(st.as_string());
1705 }
1706 }
1707
1708 void FieldLayoutBuilder::build_layout() {
1709 if (_is_inline_type || _is_abstract_value) {
1710 compute_inline_class_layout();
1711 } else {
1712 compute_regular_layout();
1713 }
1714 }