1 /*
2 * Copyright (c) 2020, 2024, 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 "precompiled.hpp"
26 #include "classfile/classFileParser.hpp"
27 #include "classfile/fieldLayoutBuilder.hpp"
28 #include "jvm.h"
29 #include "memory/resourceArea.hpp"
30 #include "oops/array.hpp"
31 #include "oops/fieldStreams.inline.hpp"
32 #include "oops/instanceMirrorKlass.hpp"
33 #include "oops/instanceKlass.inline.hpp"
34 #include "oops/klass.inline.hpp"
35 #include "runtime/fieldDescriptor.inline.hpp"
36
37
38 LayoutRawBlock::LayoutRawBlock(Kind kind, int size) :
39 _next_block(nullptr),
40 _prev_block(nullptr),
41 _kind(kind),
42 _offset(-1),
43 _alignment(1),
44 _size(size),
45 _field_index(-1),
46 _is_reference(false) {
47 assert(kind == EMPTY || kind == RESERVED || kind == PADDING || kind == INHERITED,
48 "Otherwise, should use the constructor with a field index argument");
49 assert(size > 0, "Sanity check");
50 }
51
52
53 LayoutRawBlock::LayoutRawBlock(int index, Kind kind, int size, int alignment, bool is_reference) :
54 _next_block(nullptr),
55 _prev_block(nullptr),
56 _kind(kind),
57 _offset(-1),
58 _alignment(alignment),
59 _size(size),
60 _field_index(index),
61 _is_reference(is_reference) {
62 assert(kind == REGULAR || kind == FLATTENED || kind == INHERITED,
63 "Other kind do not have a field index");
64 assert(size > 0, "Sanity check");
65 assert(alignment > 0, "Sanity check");
66 }
67
68 bool LayoutRawBlock::fit(int size, int alignment) {
69 int adjustment = 0;
70 if ((_offset % alignment) != 0) {
71 adjustment = alignment - (_offset % alignment);
72 }
73 return _size >= size + adjustment;
74 }
75
76 FieldGroup::FieldGroup(int contended_group) :
77 _next(nullptr),
78 _primitive_fields(nullptr),
79 _oop_fields(nullptr),
80 _contended_group(contended_group), // -1 means no contended group, 0 means default contended group
81 _oop_count(0) {}
82
83 void FieldGroup::add_primitive_field(int idx, BasicType type) {
84 int size = type2aelembytes(type);
85 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */, false);
86 if (_primitive_fields == nullptr) {
87 _primitive_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
88 }
89 _primitive_fields->append(block);
90 }
91
92 void FieldGroup::add_oop_field(int idx) {
93 int size = type2aelembytes(T_OBJECT);
94 LayoutRawBlock* block = new LayoutRawBlock(idx, LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */, true);
95 if (_oop_fields == nullptr) {
96 _oop_fields = new GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
97 }
98 _oop_fields->append(block);
99 _oop_count++;
100 }
101
102 void FieldGroup::sort_by_size() {
103 if (_primitive_fields != nullptr) {
104 _primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
105 }
106 }
107
108 FieldLayout::FieldLayout(GrowableArray<FieldInfo>* field_info, ConstantPool* cp) :
109 _field_info(field_info),
110 _cp(cp),
111 _blocks(nullptr),
112 _start(_blocks),
113 _last(_blocks) {}
114
115 void FieldLayout::initialize_static_layout() {
116 _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
117 _blocks->set_offset(0);
118 _last = _blocks;
119 _start = _blocks;
120 // Note: at this stage, InstanceMirrorKlass::offset_of_static_fields() could be zero, because
121 // during bootstrapping, the size of the java.lang.Class is still not known when layout
122 // of static field is computed. Field offsets are fixed later when the size is known
123 // (see java_lang_Class::fixup_mirror())
124 if (InstanceMirrorKlass::offset_of_static_fields() > 0) {
125 insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, InstanceMirrorKlass::offset_of_static_fields()));
126 _blocks->set_offset(0);
127 }
128 }
129
130 void FieldLayout::initialize_instance_layout(const InstanceKlass* super_klass) {
131 if (super_klass == nullptr) {
132 _blocks = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
133 _blocks->set_offset(0);
134 _last = _blocks;
135 _start = _blocks;
136 insert(first_empty_block(), new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes()));
137 } else {
138 bool has_fields = reconstruct_layout(super_klass);
139 fill_holes(super_klass);
140 if (!super_klass->has_contended_annotations() || !has_fields) {
141 _start = _blocks; // start allocating fields from the first empty block
142 } else {
143 _start = _last; // append fields at the end of the reconstructed layout
144 }
145 }
146 }
147
148 LayoutRawBlock* FieldLayout::first_field_block() {
149 LayoutRawBlock* block = _start;
150 while (block->kind() != LayoutRawBlock::INHERITED && block->kind() != LayoutRawBlock::REGULAR
151 && block->kind() != LayoutRawBlock::FLATTENED && block->kind() != LayoutRawBlock::PADDING) {
152 block = block->next_block();
153 }
154 return block;
155 }
156
157
158 // Insert a set of fields into a layout using a best-fit strategy.
159 // For each field, search for the smallest empty slot able to fit the field
160 // (satisfying both size and alignment requirements), if none is found,
161 // add the field at the end of the layout.
162 // Fields cannot be inserted before the block specified in the "start" argument
163 void FieldLayout::add(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
164 if (list == nullptr) return;
165 if (start == nullptr) start = this->_start;
166 bool last_search_success = false;
167 int last_size = 0;
168 int last_alignment = 0;
169 for (int i = 0; i < list->length(); i ++) {
170 LayoutRawBlock* b = list->at(i);
171 LayoutRawBlock* cursor = nullptr;
172 LayoutRawBlock* candidate = nullptr;
173
174 // if start is the last block, just append the field
175 if (start == last_block()) {
176 candidate = last_block();
177 }
178 // Before iterating over the layout to find an empty slot fitting the field's requirements,
179 // check if the previous field had the same requirements and if the search for a fitting slot
180 // was successful. If the requirements were the same but the search failed, a new search will
181 // fail the same way, so just append the field at the of the layout.
182 else if (b->size() == last_size && b->alignment() == last_alignment && !last_search_success) {
183 candidate = last_block();
184 } else {
185 // Iterate over the layout to find an empty slot fitting the field's requirements
186 last_size = b->size();
187 last_alignment = b->alignment();
188 cursor = last_block()->prev_block();
189 assert(cursor != nullptr, "Sanity check");
190 last_search_success = true;
191 while (cursor != start) {
192 if (cursor->kind() == LayoutRawBlock::EMPTY && cursor->fit(b->size(), b->alignment())) {
193 if (candidate == nullptr || cursor->size() < candidate->size()) {
194 candidate = cursor;
195 }
196 }
197 cursor = cursor->prev_block();
198 }
199 if (candidate == nullptr) {
200 candidate = last_block();
201 last_search_success = false;
202 }
203 assert(candidate != nullptr, "Candidate must not be null");
204 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
205 assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
206 }
207
208 insert_field_block(candidate, b);
209 }
210 }
211
212 // Finds a slot for the identity hash-code.
213 // Same basic algorithm as above add() method, but simplified
214 // and does not actually insert the field.
215 int FieldLayout::find_hash_offset() {
216 LayoutRawBlock* start = this->_start;
217 LayoutRawBlock* last = last_block();
218 LayoutRawBlock* cursor = start;
219 while (cursor != last) {
220 assert(cursor != nullptr, "Sanity check");
221 if (cursor->kind() == LayoutRawBlock::EMPTY && cursor->fit(4, 1)) {
222 break;
223 }
224 cursor = cursor->next_block();
225 }
226 return cursor->offset();
227 }
228
229 // Used for classes with hard coded field offsets, insert a field at the specified offset */
230 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
231 assert(block != nullptr, "Sanity check");
232 block->set_offset(offset);
233 if (start == nullptr) {
234 start = this->_start;
235 }
236 LayoutRawBlock* slot = start;
237 while (slot != nullptr) {
238 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
239 slot == _last){
240 assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
241 assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
242 if (slot->offset() < block->offset()) {
243 int adjustment = block->offset() - slot->offset();
244 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
245 insert(slot, adj);
246 }
247 insert(slot, block);
248 if (slot->size() == 0) {
249 remove(slot);
250 }
251 _field_info->adr_at(block->field_index())->set_offset(block->offset());
252 return;
253 }
254 slot = slot->next_block();
255 }
256 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
257 }
258
259 // The allocation logic uses a best fit strategy: the set of fields is allocated
260 // in the first empty slot big enough to contain the whole set ((including padding
261 // to fit alignment constraints).
262 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
263 if (list == nullptr) return;
264 if (start == nullptr) {
265 start = _start;
266 }
267 // This code assumes that if the first block is well aligned, the following
268 // blocks would naturally be well aligned (no need for adjustment)
269 int size = 0;
270 for (int i = 0; i < list->length(); i++) {
271 size += list->at(i)->size();
272 }
273
274 LayoutRawBlock* candidate = nullptr;
275 if (start == last_block()) {
276 candidate = last_block();
277 } else {
278 LayoutRawBlock* first = list->at(0);
279 candidate = last_block()->prev_block();
280 while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
281 if (candidate == start) {
282 candidate = last_block();
283 break;
284 }
285 candidate = candidate->prev_block();
286 }
287 assert(candidate != nullptr, "Candidate must not be null");
288 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
289 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
290 }
291
292 for (int i = 0; i < list->length(); i++) {
293 LayoutRawBlock* b = list->at(i);
294 insert_field_block(candidate, b);
295 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
296 }
297 }
298
299 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
300 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
301 if (slot->offset() % block->alignment() != 0) {
302 int adjustment = block->alignment() - (slot->offset() % block->alignment());
303 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
304 insert(slot, adj);
305 }
306 insert(slot, block);
307 if (slot->size() == 0) {
308 remove(slot);
309 }
310 _field_info->adr_at(block->field_index())->set_offset(block->offset());
311 return block;
312 }
313
314 bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
315 bool has_instance_fields = false;
316 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
317 while (ik != nullptr) {
318 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
319 BasicType type = Signature::basic_type(fs.signature());
320 // distinction between static and non-static fields is missing
321 if (fs.access_flags().is_static()) continue;
322 has_instance_fields = true;
323 int size = type2aelembytes(type);
324 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
325 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
326 block->set_offset(fs.offset());
327 all_fields->append(block);
328 }
329 ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
330 }
331
332 all_fields->sort(LayoutRawBlock::compare_offset);
333 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
334 _blocks->set_offset(0);
335 _last = _blocks;
336
337 for(int i = 0; i < all_fields->length(); i++) {
338 LayoutRawBlock* b = all_fields->at(i);
339 _last->set_next_block(b);
340 b->set_prev_block(_last);
341 _last = b;
342 }
343 _start = _blocks;
344 return has_instance_fields;
345 }
346
347 // Called during the reconstruction of a layout, after fields from super
348 // classes have been inserted. It fills unused slots between inserted fields
349 // with EMPTY blocks, so the regular field insertion methods would work.
350 // This method handles classes with @Contended annotations differently
351 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
352 // fields to interfere with contended fields/classes.
353 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
354 assert(_blocks != nullptr, "Sanity check");
355 assert(_blocks->offset() == 0, "first block must be at offset zero");
356 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
357 LayoutRawBlock* b = _blocks;
358 while (b->next_block() != nullptr) {
359 if (b->next_block()->offset() > (b->offset() + b->size())) {
360 int size = b->next_block()->offset() - (b->offset() + b->size());
361 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
362 empty->set_offset(b->offset() + b->size());
363 empty->set_next_block(b->next_block());
364 b->next_block()->set_prev_block(empty);
365 b->set_next_block(empty);
366 empty->set_prev_block(b);
367 }
368 b = b->next_block();
369 }
370 assert(b->next_block() == nullptr, "Invariant at this point");
371 assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
372
373 // If the super class has @Contended annotation, a padding block is
374 // inserted at the end to ensure that fields from the subclasses won't share
375 // the cache line of the last field of the contended class
376 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
377 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
378 p->set_offset(b->offset() + b->size());
379 b->set_next_block(p);
380 p->set_prev_block(b);
381 b = p;
382 }
383
384 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
385 last->set_offset(b->offset() + b->size());
386 assert(last->offset() > 0, "Sanity check");
387 b->set_next_block(last);
388 last->set_prev_block(b);
389 _last = last;
390 }
391
392 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
393 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
394 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
395 block->set_offset(slot->offset());
396 slot->set_offset(slot->offset() + block->size());
397 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
398 assert(slot->size() - block->size() >= 0, "no negative size allowed");
399 slot->set_size(slot->size() - block->size());
400 block->set_prev_block(slot->prev_block());
401 block->set_next_block(slot);
402 slot->set_prev_block(block);
403 if (block->prev_block() != nullptr) {
404 block->prev_block()->set_next_block(block);
405 }
406 if (_blocks == slot) {
407 _blocks = block;
408 }
409 return block;
410 }
411
412 void FieldLayout::remove(LayoutRawBlock* block) {
413 assert(block != nullptr, "Sanity check");
414 assert(block != _last, "Sanity check");
415 if (_blocks == block) {
416 _blocks = block->next_block();
417 if (_blocks != nullptr) {
418 _blocks->set_prev_block(nullptr);
419 }
420 } else {
421 assert(block->prev_block() != nullptr, "_prev should be set for non-head blocks");
422 block->prev_block()->set_next_block(block->next_block());
423 block->next_block()->set_prev_block(block->prev_block());
424 }
425 if (block == _start) {
426 _start = block->prev_block();
427 }
428 }
429
430 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
431 ResourceMark rm;
432 LayoutRawBlock* b = _blocks;
433 while(b != _last) {
434 switch(b->kind()) {
435 case LayoutRawBlock::REGULAR: {
436 FieldInfo* fi = _field_info->adr_at(b->field_index());
437 output->print_cr(" @%d \"%s\" %s %d/%d %s",
438 b->offset(),
439 fi->name(_cp)->as_C_string(),
440 fi->signature(_cp)->as_C_string(),
441 b->size(),
442 b->alignment(),
443 "REGULAR");
444 break;
445 }
446 case LayoutRawBlock::FLATTENED: {
447 FieldInfo* fi = _field_info->adr_at(b->field_index());
448 output->print_cr(" @%d \"%s\" %s %d/%d %s",
449 b->offset(),
450 fi->name(_cp)->as_C_string(),
451 fi->signature(_cp)->as_C_string(),
452 b->size(),
453 b->alignment(),
454 "FLATTENED");
455 break;
456 }
457 case LayoutRawBlock::RESERVED: {
458 output->print_cr(" @%d %d/- %s",
459 b->offset(),
460 b->size(),
461 "RESERVED");
462 break;
463 }
464 case LayoutRawBlock::INHERITED: {
465 assert(!is_static, "Static fields are not inherited in layouts");
466 assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
467 bool found = false;
468 const InstanceKlass* ik = super;
469 while (!found && ik != nullptr) {
470 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
471 if (fs.offset() == b->offset()) {
472 output->print_cr(" @%d \"%s\" %s %d/%d %s",
473 b->offset(),
474 fs.name()->as_C_string(),
475 fs.signature()->as_C_string(),
476 b->size(),
477 b->size(), // so far, alignment constraint == size, will change with Valhalla
478 "INHERITED");
479 found = true;
480 break;
481 }
482 }
483 ik = ik->java_super();
484 }
485 break;
486 }
487 case LayoutRawBlock::EMPTY:
488 output->print_cr(" @%d %d/1 %s",
489 b->offset(),
490 b->size(),
491 "EMPTY");
492 break;
493 case LayoutRawBlock::PADDING:
494 output->print_cr(" @%d %d/1 %s",
495 b->offset(),
496 b->size(),
497 "PADDING");
498 break;
499 }
500 b = b->next_block();
501 }
502 }
503
504 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
505 GrowableArray<FieldInfo>* field_info, bool is_contended, FieldLayoutInfo* info) :
506 _classname(classname),
507 _super_klass(super_klass),
508 _constant_pool(constant_pool),
509 _field_info(field_info),
510 _info(info),
511 _root_group(nullptr),
512 _contended_groups(GrowableArray<FieldGroup*>(8)),
513 _static_fields(nullptr),
514 _layout(nullptr),
515 _static_layout(nullptr),
516 _nonstatic_oopmap_count(0),
517 _alignment(-1),
518 _has_nonstatic_fields(false),
519 _is_contended(is_contended) {}
520
521
522 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
523 assert(g > 0, "must only be called for named contended groups");
524 FieldGroup* fg = nullptr;
525 for (int i = 0; i < _contended_groups.length(); i++) {
526 fg = _contended_groups.at(i);
527 if (fg->contended_group() == g) return fg;
528 }
529 fg = new FieldGroup(g);
530 _contended_groups.append(fg);
531 return fg;
532 }
533
534 void FieldLayoutBuilder::prologue() {
535 _layout = new FieldLayout(_field_info, _constant_pool);
536 const InstanceKlass* super_klass = _super_klass;
537 _layout->initialize_instance_layout(super_klass);
538 if (super_klass != nullptr) {
539 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
540 }
541 _static_layout = new FieldLayout(_field_info, _constant_pool);
542 _static_layout->initialize_static_layout();
543 _static_fields = new FieldGroup();
544 _root_group = new FieldGroup();
545 }
546
547 // Field sorting for regular classes:
548 // - fields are sorted in static and non-static fields
549 // - non-static fields are also sorted according to their contention group
550 // (support of the @Contended annotation)
551 // - @Contended annotation is ignored for static fields
552 void FieldLayoutBuilder::regular_field_sorting() {
553 int idx = 0;
554 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
555 FieldInfo ctrl = _field_info->at(0);
556 FieldGroup* group = nullptr;
557 FieldInfo fieldinfo = *it;
558 if (fieldinfo.access_flags().is_static()) {
559 group = _static_fields;
560 } else {
561 _has_nonstatic_fields = true;
562 if (fieldinfo.field_flags().is_contended()) {
563 int g = fieldinfo.contended_group();
564 if (g == 0) {
565 group = new FieldGroup(true);
566 _contended_groups.append(group);
567 } else {
568 group = get_or_create_contended_group(g);
569 }
570 } else {
571 group = _root_group;
572 }
573 }
574 assert(group != nullptr, "invariant");
575 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
576 switch(type) {
577 case T_BYTE:
578 case T_CHAR:
579 case T_DOUBLE:
580 case T_FLOAT:
581 case T_INT:
582 case T_LONG:
583 case T_SHORT:
584 case T_BOOLEAN:
585 group->add_primitive_field(idx, type);
586 break;
587 case T_OBJECT:
588 case T_ARRAY:
589 if (group != _static_fields) _nonstatic_oopmap_count++;
590 group->add_oop_field(idx);
591 break;
592 default:
593 fatal("Something wrong?");
594 }
595 }
596 _root_group->sort_by_size();
597 _static_fields->sort_by_size();
598 if (!_contended_groups.is_empty()) {
599 for (int i = 0; i < _contended_groups.length(); i++) {
600 _contended_groups.at(i)->sort_by_size();
601 }
602 }
603 }
604
605 void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
606 if (ContendedPaddingWidth > 0) {
607 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
608 _layout->insert(slot, padding);
609 }
610 }
611
612 // Computation of regular classes layout is an evolution of the previous default layout
613 // (FieldAllocationStyle 1):
614 // - primitive fields are allocated first (from the biggest to the smallest)
615 // - then oop fields are allocated, either in existing gaps or at the end of
616 // the layout
617 void FieldLayoutBuilder::compute_regular_layout() {
618 bool need_tail_padding = false;
619 prologue();
620 regular_field_sorting();
621
622 if (_is_contended) {
623 _layout->set_start(_layout->last_block());
624 // insertion is currently easy because the current strategy doesn't try to fill holes
625 // in super classes layouts => the _start block is by consequence the _last_block
626 insert_contended_padding(_layout->start());
627 need_tail_padding = true;
628 }
629 _layout->add(_root_group->primitive_fields());
630 _layout->add(_root_group->oop_fields());
631
632 if (!_contended_groups.is_empty()) {
633 for (int i = 0; i < _contended_groups.length(); i++) {
634 FieldGroup* cg = _contended_groups.at(i);
635 LayoutRawBlock* start = _layout->last_block();
636 insert_contended_padding(start);
637 _layout->add(cg->primitive_fields(), start);
638 _layout->add(cg->oop_fields(), start);
639 need_tail_padding = true;
640 }
641 }
642
643 if (need_tail_padding) {
644 insert_contended_padding(_layout->last_block());
645 }
646
647 _static_layout->add_contiguously(this->_static_fields->oop_fields());
648 _static_layout->add(this->_static_fields->primitive_fields());
649
650 epilogue();
651 }
652
653 void FieldLayoutBuilder::epilogue() {
654 // Computing oopmaps
655 int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
656 int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
657
658 OopMapBlocksBuilder* nonstatic_oop_maps =
659 new OopMapBlocksBuilder(max_oop_map_count);
660 if (super_oop_map_count > 0) {
661 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
662 _super_klass->nonstatic_oop_map_count());
663 }
664
665 if (_root_group->oop_fields() != nullptr) {
666 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
667 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
668 nonstatic_oop_maps->add(b->offset(), 1);
669 }
670 }
671
672 if (!_contended_groups.is_empty()) {
673 for (int i = 0; i < _contended_groups.length(); i++) {
674 FieldGroup* cg = _contended_groups.at(i);
675 if (cg->oop_count() > 0) {
676 assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
677 nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
678 }
679 }
680 }
681
682 nonstatic_oop_maps->compact();
683
684 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
685 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
686 int static_fields_size = (static_fields_end -
687 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
688 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
689
690 // Pass back information needed for InstanceKlass creation
691
692 _info->oop_map_blocks = nonstatic_oop_maps;
693 _info->_instance_size = align_object_size(instance_end / wordSize);
694 if (UseCompactObjectHeaders) {
695 _info->_hash_offset = _layout->find_hash_offset();
696 }
697 _info->_static_field_size = static_fields_size;
698 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
699 _info->_has_nonstatic_fields = _has_nonstatic_fields;
700
701 if (PrintFieldLayout) {
702 ResourceMark rm;
703 tty->print_cr("Layout of class %s", _classname->as_C_string());
704 tty->print_cr("Instance fields:");
705 _layout->print(tty, false, _super_klass);
706 tty->print_cr("Static fields:");
707 _static_layout->print(tty, true, nullptr);
708 tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
709 tty->print_cr("---");
710 }
711 }
712
713 void FieldLayoutBuilder::build_layout() {
714 compute_regular_layout();
715 }