1 /*
2 * Copyright (c) 2020, 2025, 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 "jvm.h"
28 #include "memory/resourceArea.hpp"
29 #include "oops/array.hpp"
30 #include "oops/fieldStreams.inline.hpp"
31 #include "oops/instanceMirrorKlass.hpp"
32 #include "oops/instanceKlass.inline.hpp"
33 #include "oops/klass.inline.hpp"
34 #include "runtime/fieldDescriptor.inline.hpp"
35
36
37 LayoutRawBlock::LayoutRawBlock(Kind kind, int size) :
38 _next_block(nullptr),
39 _prev_block(nullptr),
40 _kind(kind),
41 _offset(-1),
42 _alignment(1),
43 _size(size),
44 _field_index(-1),
45 _is_reference(false) {
46 assert(kind == EMPTY || kind == RESERVED || kind == PADDING || kind == INHERITED,
47 "Otherwise, should use the constructor with a field index argument");
48 assert(size > 0, "Sanity check");
49 }
50
51
52 LayoutRawBlock::LayoutRawBlock(int index, Kind kind, int size, int alignment, bool is_reference) :
53 _next_block(nullptr),
54 _prev_block(nullptr),
55 _kind(kind),
56 _offset(-1),
57 _alignment(alignment),
58 _size(size),
59 _field_index(index),
60 _is_reference(is_reference) {
61 assert(kind == REGULAR || kind == FLATTENED || kind == INHERITED,
62 "Other kind do not have a field index");
63 assert(size > 0, "Sanity check");
64 assert(alignment > 0, "Sanity check");
65 }
66
67 bool LayoutRawBlock::fit(int size, int alignment) {
68 int adjustment = 0;
69 if ((_offset % alignment) != 0) {
70 adjustment = alignment - (_offset % alignment);
71 }
72 return _size >= size + adjustment;
73 }
74
75 FieldGroup::FieldGroup(int contended_group) :
76 _next(nullptr),
77 _primitive_fields(nullptr),
78 _oop_fields(nullptr),
79 _contended_group(contended_group), // -1 means no contended group, 0 means default contended group
80 _oop_count(0) {}
81
82 void FieldGroup::add_primitive_field(int idx, BasicType type) {
83 int size = type2aelembytes(type);
84 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */, false);
85 if (_primitive_fields == nullptr) {
86 _primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
87 }
88 _primitive_fields->append(block);
89 }
90
91 void FieldGroup::add_oop_field(int idx) {
92 int size = type2aelembytes(T_OBJECT);
93 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */, true);
94 if (_oop_fields == nullptr) {
95 _oop_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
96 }
97 _oop_fields->append(block);
98 _oop_count++;
99 }
100
101 void FieldGroup::sort_by_size() {
102 if (_primitive_fields != nullptr) {
103 _primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
104 }
105 }
106
107 FieldLayout::FieldLayout(GrowableArray<FieldInfo>* field_info, ConstantPool* cp) :
108 _field_info(field_info),
109 _cp(cp),
110 _blocks(nullptr),
111 _start(_blocks),
112 _last(_blocks) {}
113
114 void FieldLayout::initialize_static_layout() {
115 _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
116 _blocks->set_offset(0);
117 _last = _blocks;
118 _start = _blocks;
119 // Note: at this stage, InstanceMirrorKlass::offset_of_static_fields() could be zero, because
120 // during bootstrapping, the size of the java.lang.Class is still not known when layout
121 // of static field is computed. Field offsets are fixed later when the size is known
122 // (see java_lang_Class::fixup_mirror())
123 if (InstanceMirrorKlass::offset_of_static_fields() > 0) {
124 insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, InstanceMirrorKlass::offset_of_static_fields()));
125 _blocks->set_offset(0);
126 }
127 }
128
129 void FieldLayout::initialize_instance_layout(const InstanceKlass* super_klass) {
130 if (super_klass == nullptr) {
131 _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
132 _blocks->set_offset(0);
133 _last = _blocks;
134 _start = _blocks;
135 insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes()));
136 } else {
137 bool has_fields = reconstruct_layout(super_klass);
138 fill_holes(super_klass);
139 if (!super_klass->has_contended_annotations() || !has_fields) {
140 _start = _blocks; // start allocating fields from the first empty block
141 } else {
142 _start = _last; // append fields at the end of the reconstructed layout
143 }
144 }
145 }
146
147 LayoutRawBlock* FieldLayout::first_field_block() {
148 LayoutRawBlock* block = _start;
149 while (block->kind() != LayoutRawBlock::INHERITED && block->kind() != LayoutRawBlock::REGULAR
150 && block->kind() != LayoutRawBlock::FLATTENED && block->kind() != LayoutRawBlock::PADDING) {
151 block = block->next_block();
152 }
153 return block;
154 }
155
156
157 // Insert a set of fields into a layout using a best-fit strategy.
158 // For each field, search for the smallest empty slot able to fit the field
159 // (satisfying both size and alignment requirements), if none is found,
160 // add the field at the end of the layout.
161 // Fields cannot be inserted before the block specified in the "start" argument
162 void FieldLayout::add(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
163 if (list == nullptr) return;
164 if (start == nullptr) start = this->_start;
165 bool last_search_success = false;
166 int last_size = 0;
167 int last_alignment = 0;
168 for (int i = 0; i < list->length(); i ++) {
169 LayoutRawBlock* b = list->at(i);
170 LayoutRawBlock* cursor = nullptr;
171 LayoutRawBlock* candidate = nullptr;
172
173 // if start is the last block, just append the field
174 if (start == last_block()) {
175 candidate = last_block();
176 }
177 // Before iterating over the layout to find an empty slot fitting the field's requirements,
178 // check if the previous field had the same requirements and if the search for a fitting slot
179 // was successful. If the requirements were the same but the search failed, a new search will
180 // fail the same way, so just append the field at the of the layout.
181 else if (b->size() == last_size && b->alignment() == last_alignment && !last_search_success) {
182 candidate = last_block();
183 } else {
184 // Iterate over the layout to find an empty slot fitting the field's requirements
185 last_size = b->size();
186 last_alignment = b->alignment();
187 cursor = last_block()->prev_block();
188 assert(cursor != nullptr, "Sanity check");
189 last_search_success = true;
190 while (cursor != start) {
191 if (cursor->kind() == LayoutRawBlock::EMPTY && cursor->fit(b->size(), b->alignment())) {
192 if (candidate == nullptr || cursor->size() < candidate->size()) {
193 candidate = cursor;
194 }
195 }
196 cursor = cursor->prev_block();
197 }
198 if (candidate == nullptr) {
199 candidate = last_block();
200 last_search_success = false;
201 }
202 assert(candidate != nullptr, "Candidate must not be null");
203 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
204 assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
205 }
206
207 insert_field_block(candidate, b);
208 }
209 }
210
211 // Used for classes with hard coded field offsets, insert a field at the specified offset */
212 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
213 assert(block != nullptr, "Sanity check");
214 block->set_offset(offset);
215 if (start == nullptr) {
216 start = this->_start;
217 }
218 LayoutRawBlock* slot = start;
219 while (slot != nullptr) {
220 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
221 slot == _last){
222 assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
223 assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
224 if (slot->offset() < block->offset()) {
225 int adjustment = block->offset() - slot->offset();
226 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
227 insert(slot, adj);
228 }
229 insert(slot, block);
230 if (slot->size() == 0) {
231 remove(slot);
232 }
233 _field_info->adr_at(block->field_index())->set_offset(block->offset());
234 return;
235 }
236 slot = slot->next_block();
237 }
238 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
239 }
240
241 // The allocation logic uses a best fit strategy: the set of fields is allocated
242 // in the first empty slot big enough to contain the whole set ((including padding
243 // to fit alignment constraints).
244 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
245 if (list == nullptr) return;
246 if (start == nullptr) {
247 start = _start;
248 }
249 // This code assumes that if the first block is well aligned, the following
250 // blocks would naturally be well aligned (no need for adjustment)
251 int size = 0;
252 for (int i = 0; i < list->length(); i++) {
253 size += list->at(i)->size();
254 }
255
256 LayoutRawBlock* candidate = nullptr;
257 if (start == last_block()) {
258 candidate = last_block();
259 } else {
260 LayoutRawBlock* first = list->at(0);
261 candidate = last_block()->prev_block();
262 while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
263 if (candidate == start) {
264 candidate = last_block();
265 break;
266 }
267 candidate = candidate->prev_block();
268 }
269 assert(candidate != nullptr, "Candidate must not be null");
270 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
271 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
272 }
273
274 for (int i = 0; i < list->length(); i++) {
275 LayoutRawBlock* b = list->at(i);
276 insert_field_block(candidate, b);
277 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
278 }
279 }
280
281 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
282 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
283 if (slot->offset() % block->alignment() != 0) {
284 int adjustment = block->alignment() - (slot->offset() % block->alignment());
285 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
286 insert(slot, adj);
287 }
288 insert(slot, block);
289 if (slot->size() == 0) {
290 remove(slot);
291 }
292 _field_info->adr_at(block->field_index())->set_offset(block->offset());
293 return block;
294 }
295
296 bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
297 bool has_instance_fields = false;
298 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
299 while (ik != nullptr) {
300 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
301 BasicType type = Signature::basic_type(fs.signature());
302 // distinction between static and non-static fields is missing
303 if (fs.access_flags().is_static()) continue;
304 has_instance_fields = true;
305 int size = type2aelembytes(type);
306 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
307 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
308 block->set_offset(fs.offset());
309 all_fields->append(block);
310 }
311 ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
312 }
313
314 all_fields->sort(LayoutRawBlock::compare_offset);
315 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
316 _blocks->set_offset(0);
317 _last = _blocks;
318
319 for(int i = 0; i < all_fields->length(); i++) {
320 LayoutRawBlock* b = all_fields->at(i);
321 _last->set_next_block(b);
322 b->set_prev_block(_last);
323 _last = b;
324 }
325 _start = _blocks;
326 return has_instance_fields;
327 }
328
329 // Called during the reconstruction of a layout, after fields from super
330 // classes have been inserted. It fills unused slots between inserted fields
331 // with EMPTY blocks, so the regular field insertion methods would work.
332 // This method handles classes with @Contended annotations differently
333 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
334 // fields to interfere with contended fields/classes.
335 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
336 assert(_blocks != nullptr, "Sanity check");
337 assert(_blocks->offset() == 0, "first block must be at offset zero");
338 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
339 LayoutRawBlock* b = _blocks;
340 while (b->next_block() != nullptr) {
341 if (b->next_block()->offset() > (b->offset() + b->size())) {
342 int size = b->next_block()->offset() - (b->offset() + b->size());
343 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
344 empty->set_offset(b->offset() + b->size());
345 empty->set_next_block(b->next_block());
346 b->next_block()->set_prev_block(empty);
347 b->set_next_block(empty);
348 empty->set_prev_block(b);
349 }
350 b = b->next_block();
351 }
352 assert(b->next_block() == nullptr, "Invariant at this point");
353 assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
354
355 // If the super class has @Contended annotation, a padding block is
356 // inserted at the end to ensure that fields from the subclasses won't share
357 // the cache line of the last field of the contended class
358 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
359 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
360 p->set_offset(b->offset() + b->size());
361 b->set_next_block(p);
362 p->set_prev_block(b);
363 b = p;
364 }
365
366 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
367 last->set_offset(b->offset() + b->size());
368 assert(last->offset() > 0, "Sanity check");
369 b->set_next_block(last);
370 last->set_prev_block(b);
371 _last = last;
372 }
373
374 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
375 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
376 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
377 block->set_offset(slot->offset());
378 slot->set_offset(slot->offset() + block->size());
379 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
380 assert(slot->size() - block->size() >= 0, "no negative size allowed");
381 slot->set_size(slot->size() - block->size());
382 block->set_prev_block(slot->prev_block());
383 block->set_next_block(slot);
384 slot->set_prev_block(block);
385 if (block->prev_block() != nullptr) {
386 block->prev_block()->set_next_block(block);
387 }
388 if (_blocks == slot) {
389 _blocks = block;
390 }
391 return block;
392 }
393
394 void FieldLayout::remove(LayoutRawBlock* block) {
395 assert(block != nullptr, "Sanity check");
396 assert(block != _last, "Sanity check");
397 if (_blocks == block) {
398 _blocks = block->next_block();
399 if (_blocks != nullptr) {
400 _blocks->set_prev_block(nullptr);
401 }
402 } else {
403 assert(block->prev_block() != nullptr, "_prev should be set for non-head blocks");
404 block->prev_block()->set_next_block(block->next_block());
405 block->next_block()->set_prev_block(block->prev_block());
406 }
407 if (block == _start) {
408 _start = block->prev_block();
409 }
410 }
411
412 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
413 ResourceMark rm;
414 LayoutRawBlock* b = _blocks;
415 while(b != _last) {
416 switch(b->kind()) {
417 case LayoutRawBlock::REGULAR: {
418 FieldInfo* fi = _field_info->adr_at(b->field_index());
419 output->print_cr(" @%d \"%s\" %s %d/%d %s",
420 b->offset(),
421 fi->name(_cp)->as_C_string(),
422 fi->signature(_cp)->as_C_string(),
423 b->size(),
424 b->alignment(),
425 "REGULAR");
426 break;
427 }
428 case LayoutRawBlock::FLATTENED: {
429 FieldInfo* fi = _field_info->adr_at(b->field_index());
430 output->print_cr(" @%d \"%s\" %s %d/%d %s",
431 b->offset(),
432 fi->name(_cp)->as_C_string(),
433 fi->signature(_cp)->as_C_string(),
434 b->size(),
435 b->alignment(),
436 "FLATTENED");
437 break;
438 }
439 case LayoutRawBlock::RESERVED: {
440 output->print_cr(" @%d %d/- %s",
441 b->offset(),
442 b->size(),
443 "RESERVED");
444 break;
445 }
446 case LayoutRawBlock::INHERITED: {
447 assert(!is_static, "Static fields are not inherited in layouts");
448 assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
449 bool found = false;
450 const InstanceKlass* ik = super;
451 while (!found && ik != nullptr) {
452 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
453 if (fs.offset() == b->offset()) {
454 output->print_cr(" @%d \"%s\" %s %d/%d %s",
455 b->offset(),
456 fs.name()->as_C_string(),
457 fs.signature()->as_C_string(),
458 b->size(),
459 b->size(), // so far, alignment constraint == size, will change with Valhalla
460 "INHERITED");
461 found = true;
462 break;
463 }
464 }
465 ik = ik->java_super();
466 }
467 break;
468 }
469 case LayoutRawBlock::EMPTY:
470 output->print_cr(" @%d %d/1 %s",
471 b->offset(),
472 b->size(),
473 "EMPTY");
474 break;
475 case LayoutRawBlock::PADDING:
476 output->print_cr(" @%d %d/1 %s",
477 b->offset(),
478 b->size(),
479 "PADDING");
480 break;
481 }
482 b = b->next_block();
483 }
484 }
485
486 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
487 GrowableArray<FieldInfo>* field_info, bool is_contended, FieldLayoutInfo* info) :
488 _classname(classname),
489 _super_klass(super_klass),
490 _constant_pool(constant_pool),
491 _field_info(field_info),
492 _info(info),
493 _root_group(nullptr),
494 _contended_groups(GrowableArray<FieldGroup*>(8)),
495 _static_fields(nullptr),
496 _layout(nullptr),
497 _static_layout(nullptr),
498 _nonstatic_oopmap_count(0),
499 _alignment(-1),
500 _has_nonstatic_fields(false),
501 _is_contended(is_contended) {}
502
503
504 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
505 assert(g > 0, "must only be called for named contended groups");
506 FieldGroup* fg = nullptr;
507 for (int i = 0; i < _contended_groups.length(); i++) {
508 fg = _contended_groups.at(i);
509 if (fg->contended_group() == g) return fg;
510 }
511 fg = new FieldGroup(g);
512 _contended_groups.append(fg);
513 return fg;
514 }
515
516 void FieldLayoutBuilder::prologue() {
517 _layout = new FieldLayout(_field_info, _constant_pool);
518 const InstanceKlass* super_klass = _super_klass;
519 _layout->initialize_instance_layout(super_klass);
520 if (super_klass != nullptr) {
521 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
522 }
523 _static_layout = new FieldLayout(_field_info, _constant_pool);
524 _static_layout->initialize_static_layout();
525 _static_fields = new FieldGroup();
526 _root_group = new FieldGroup();
527 }
528
529 // Field sorting for regular classes:
530 // - fields are sorted in static and non-static fields
531 // - non-static fields are also sorted according to their contention group
532 // (support of the @Contended annotation)
533 // - @Contended annotation is ignored for static fields
534 void FieldLayoutBuilder::regular_field_sorting() {
535 int idx = 0;
536 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
537 FieldInfo ctrl = _field_info->at(0);
538 FieldGroup* group = nullptr;
539 FieldInfo fieldinfo = *it;
540 if (fieldinfo.access_flags().is_static()) {
541 group = _static_fields;
542 } else {
543 _has_nonstatic_fields = true;
544 if (fieldinfo.field_flags().is_contended()) {
545 int g = fieldinfo.contended_group();
546 if (g == 0) {
547 group = new FieldGroup(true);
548 _contended_groups.append(group);
549 } else {
550 group = get_or_create_contended_group(g);
551 }
552 } else {
553 group = _root_group;
554 }
555 }
556 assert(group != nullptr, "invariant");
557 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
558 switch(type) {
559 case T_BYTE:
560 case T_CHAR:
561 case T_DOUBLE:
562 case T_FLOAT:
563 case T_INT:
564 case T_LONG:
565 case T_SHORT:
566 case T_BOOLEAN:
567 group->add_primitive_field(idx, type);
568 break;
569 case T_OBJECT:
570 case T_ARRAY:
571 if (group != _static_fields) _nonstatic_oopmap_count++;
572 group->add_oop_field(idx);
573 break;
574 default:
575 fatal("Something wrong?");
576 }
577 }
578 _root_group->sort_by_size();
579 _static_fields->sort_by_size();
580 if (!_contended_groups.is_empty()) {
581 for (int i = 0; i < _contended_groups.length(); i++) {
582 _contended_groups.at(i)->sort_by_size();
583 }
584 }
585 }
586
587 void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
588 if (ContendedPaddingWidth > 0) {
589 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
590 _layout->insert(slot, padding);
591 }
592 }
593
594 // Computation of regular classes layout is an evolution of the previous default layout
595 // (FieldAllocationStyle 1):
596 // - primitive fields are allocated first (from the biggest to the smallest)
597 // - then oop fields are allocated, either in existing gaps or at the end of
598 // the layout
599 void FieldLayoutBuilder::compute_regular_layout() {
600 bool need_tail_padding = false;
601 prologue();
602 regular_field_sorting();
603
604 if (_is_contended) {
605 _layout->set_start(_layout->last_block());
606 // insertion is currently easy because the current strategy doesn't try to fill holes
607 // in super classes layouts => the _start block is by consequence the _last_block
608 insert_contended_padding(_layout->start());
609 need_tail_padding = true;
610 }
611 _layout->add(_root_group->primitive_fields());
612 _layout->add(_root_group->oop_fields());
613
614 if (!_contended_groups.is_empty()) {
615 for (int i = 0; i < _contended_groups.length(); i++) {
616 FieldGroup* cg = _contended_groups.at(i);
617 LayoutRawBlock* start = _layout->last_block();
618 insert_contended_padding(start);
619 _layout->add(cg->primitive_fields(), start);
620 _layout->add(cg->oop_fields(), start);
621 need_tail_padding = true;
622 }
623 }
624
625 if (need_tail_padding) {
626 insert_contended_padding(_layout->last_block());
627 }
628
629 _static_layout->add_contiguously(this->_static_fields->oop_fields());
630 _static_layout->add(this->_static_fields->primitive_fields());
631
632 epilogue();
633 }
634
635 void FieldLayoutBuilder::epilogue() {
636 // Computing oopmaps
637 int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
638 int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
639
640 OopMapBlocksBuilder* nonstatic_oop_maps =
641 new OopMapBlocksBuilder(max_oop_map_count);
642 if (super_oop_map_count > 0) {
643 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
644 _super_klass->nonstatic_oop_map_count());
645 }
646
647 if (_root_group->oop_fields() != nullptr) {
648 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
649 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
650 nonstatic_oop_maps->add(b->offset(), 1);
651 }
652 }
653
654 if (!_contended_groups.is_empty()) {
655 for (int i = 0; i < _contended_groups.length(); i++) {
656 FieldGroup* cg = _contended_groups.at(i);
657 if (cg->oop_count() > 0) {
658 assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
659 nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
660 }
661 }
662 }
663
664 nonstatic_oop_maps->compact();
665
666 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
667 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
668 int static_fields_size = (static_fields_end -
669 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
670 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
671
672 // Pass back information needed for InstanceKlass creation
673
674 _info->oop_map_blocks = nonstatic_oop_maps;
675 _info->_instance_size = align_object_size(instance_end / wordSize);
676 _info->_static_field_size = static_fields_size;
677 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
678 _info->_has_nonstatic_fields = _has_nonstatic_fields;
679
680 if (PrintFieldLayout) {
681 ResourceMark rm;
682 tty->print_cr("Layout of class %s", _classname->as_C_string());
683 tty->print_cr("Instance fields:");
684 _layout->print(tty, false, _super_klass);
685 tty->print_cr("Static fields:");
686 _static_layout->print(tty, true, nullptr);
687 tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
688 tty->print_cr("---");
689 }
690 }
691
692 void FieldLayoutBuilder::build_layout() {
693 compute_regular_layout();
694 }