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 // Finds a slot for the identity hash-code.
212 // Same basic algorithm as above add() method, but simplified
213 // and does not actually insert the field.
214 int FieldLayout::find_hash_offset() {
215 LayoutRawBlock* start = this->_start;
216 LayoutRawBlock* last = last_block();
217 LayoutRawBlock* cursor = start;
218 while (cursor != last) {
219 assert(cursor != nullptr, "Sanity check");
220 if (cursor->kind() == LayoutRawBlock::EMPTY && cursor->fit(4, 1)) {
221 break;
222 }
223 cursor = cursor->next_block();
224 }
225 return cursor->offset();
226 }
227
228 // Used for classes with hard coded field offsets, insert a field at the specified offset */
229 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
230 assert(block != nullptr, "Sanity check");
231 block->set_offset(offset);
232 if (start == nullptr) {
233 start = this->_start;
234 }
235 LayoutRawBlock* slot = start;
236 while (slot != nullptr) {
237 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
238 slot == _last){
239 assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
240 assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
241 if (slot->offset() < block->offset()) {
242 int adjustment = block->offset() - slot->offset();
243 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
244 insert(slot, adj);
245 }
246 insert(slot, block);
247 if (slot->size() == 0) {
248 remove(slot);
249 }
250 _field_info->adr_at(block->field_index())->set_offset(block->offset());
251 return;
252 }
253 slot = slot->next_block();
254 }
255 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
256 }
257
258 // The allocation logic uses a best fit strategy: the set of fields is allocated
259 // in the first empty slot big enough to contain the whole set ((including padding
260 // to fit alignment constraints).
261 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
262 if (list == nullptr) return;
263 if (start == nullptr) {
264 start = _start;
265 }
266 // This code assumes that if the first block is well aligned, the following
267 // blocks would naturally be well aligned (no need for adjustment)
268 int size = 0;
269 for (int i = 0; i < list->length(); i++) {
270 size += list->at(i)->size();
271 }
272
273 LayoutRawBlock* candidate = nullptr;
274 if (start == last_block()) {
275 candidate = last_block();
276 } else {
277 LayoutRawBlock* first = list->at(0);
278 candidate = last_block()->prev_block();
279 while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
280 if (candidate == start) {
281 candidate = last_block();
282 break;
283 }
284 candidate = candidate->prev_block();
285 }
286 assert(candidate != nullptr, "Candidate must not be null");
287 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
288 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
289 }
290
291 for (int i = 0; i < list->length(); i++) {
292 LayoutRawBlock* b = list->at(i);
293 insert_field_block(candidate, b);
294 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
295 }
296 }
297
298 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
299 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
300 if (slot->offset() % block->alignment() != 0) {
301 int adjustment = block->alignment() - (slot->offset() % block->alignment());
302 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
303 insert(slot, adj);
304 }
305 insert(slot, block);
306 if (slot->size() == 0) {
307 remove(slot);
308 }
309 _field_info->adr_at(block->field_index())->set_offset(block->offset());
310 return block;
311 }
312
313 bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
314 bool has_instance_fields = false;
315 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
316 while (ik != nullptr) {
317 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
318 BasicType type = Signature::basic_type(fs.signature());
319 // distinction between static and non-static fields is missing
320 if (fs.access_flags().is_static()) continue;
321 has_instance_fields = true;
322 int size = type2aelembytes(type);
323 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
324 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
325 block->set_offset(fs.offset());
326 all_fields->append(block);
327 }
328 ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
329 }
330
331 all_fields->sort(LayoutRawBlock::compare_offset);
332 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
333 _blocks->set_offset(0);
334 _last = _blocks;
335
336 for(int i = 0; i < all_fields->length(); i++) {
337 LayoutRawBlock* b = all_fields->at(i);
338 _last->set_next_block(b);
339 b->set_prev_block(_last);
340 _last = b;
341 }
342 _start = _blocks;
343 return has_instance_fields;
344 }
345
346 // Called during the reconstruction of a layout, after fields from super
347 // classes have been inserted. It fills unused slots between inserted fields
348 // with EMPTY blocks, so the regular field insertion methods would work.
349 // This method handles classes with @Contended annotations differently
350 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
351 // fields to interfere with contended fields/classes.
352 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
353 assert(_blocks != nullptr, "Sanity check");
354 assert(_blocks->offset() == 0, "first block must be at offset zero");
355 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
356 LayoutRawBlock* b = _blocks;
357 while (b->next_block() != nullptr) {
358 if (b->next_block()->offset() > (b->offset() + b->size())) {
359 int size = b->next_block()->offset() - (b->offset() + b->size());
360 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
361 empty->set_offset(b->offset() + b->size());
362 empty->set_next_block(b->next_block());
363 b->next_block()->set_prev_block(empty);
364 b->set_next_block(empty);
365 empty->set_prev_block(b);
366 }
367 b = b->next_block();
368 }
369 assert(b->next_block() == nullptr, "Invariant at this point");
370 assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
371
372 // If the super class has @Contended annotation, a padding block is
373 // inserted at the end to ensure that fields from the subclasses won't share
374 // the cache line of the last field of the contended class
375 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
376 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
377 p->set_offset(b->offset() + b->size());
378 b->set_next_block(p);
379 p->set_prev_block(b);
380 b = p;
381 }
382
383 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
384 last->set_offset(b->offset() + b->size());
385 assert(last->offset() > 0, "Sanity check");
386 b->set_next_block(last);
387 last->set_prev_block(b);
388 _last = last;
389 }
390
391 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
392 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
393 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
394 block->set_offset(slot->offset());
395 slot->set_offset(slot->offset() + block->size());
396 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
397 assert(slot->size() - block->size() >= 0, "no negative size allowed");
398 slot->set_size(slot->size() - block->size());
399 block->set_prev_block(slot->prev_block());
400 block->set_next_block(slot);
401 slot->set_prev_block(block);
402 if (block->prev_block() != nullptr) {
403 block->prev_block()->set_next_block(block);
404 }
405 if (_blocks == slot) {
406 _blocks = block;
407 }
408 return block;
409 }
410
411 void FieldLayout::remove(LayoutRawBlock* block) {
412 assert(block != nullptr, "Sanity check");
413 assert(block != _last, "Sanity check");
414 if (_blocks == block) {
415 _blocks = block->next_block();
416 if (_blocks != nullptr) {
417 _blocks->set_prev_block(nullptr);
418 }
419 } else {
420 assert(block->prev_block() != nullptr, "_prev should be set for non-head blocks");
421 block->prev_block()->set_next_block(block->next_block());
422 block->next_block()->set_prev_block(block->prev_block());
423 }
424 if (block == _start) {
425 _start = block->prev_block();
426 }
427 }
428
429 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
430 ResourceMark rm;
431 LayoutRawBlock* b = _blocks;
432 while(b != _last) {
433 switch(b->kind()) {
434 case LayoutRawBlock::REGULAR: {
435 FieldInfo* fi = _field_info->adr_at(b->field_index());
436 output->print_cr(" @%d \"%s\" %s %d/%d %s",
437 b->offset(),
438 fi->name(_cp)->as_C_string(),
439 fi->signature(_cp)->as_C_string(),
440 b->size(),
441 b->alignment(),
442 "REGULAR");
443 break;
444 }
445 case LayoutRawBlock::FLATTENED: {
446 FieldInfo* fi = _field_info->adr_at(b->field_index());
447 output->print_cr(" @%d \"%s\" %s %d/%d %s",
448 b->offset(),
449 fi->name(_cp)->as_C_string(),
450 fi->signature(_cp)->as_C_string(),
451 b->size(),
452 b->alignment(),
453 "FLATTENED");
454 break;
455 }
456 case LayoutRawBlock::RESERVED: {
457 output->print_cr(" @%d %d/- %s",
458 b->offset(),
459 b->size(),
460 "RESERVED");
461 break;
462 }
463 case LayoutRawBlock::INHERITED: {
464 assert(!is_static, "Static fields are not inherited in layouts");
465 assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
466 bool found = false;
467 const InstanceKlass* ik = super;
468 while (!found && ik != nullptr) {
469 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
470 if (fs.offset() == b->offset()) {
471 output->print_cr(" @%d \"%s\" %s %d/%d %s",
472 b->offset(),
473 fs.name()->as_C_string(),
474 fs.signature()->as_C_string(),
475 b->size(),
476 b->size(), // so far, alignment constraint == size, will change with Valhalla
477 "INHERITED");
478 found = true;
479 break;
480 }
481 }
482 ik = ik->java_super();
483 }
484 break;
485 }
486 case LayoutRawBlock::EMPTY:
487 output->print_cr(" @%d %d/1 %s",
488 b->offset(),
489 b->size(),
490 "EMPTY");
491 break;
492 case LayoutRawBlock::PADDING:
493 output->print_cr(" @%d %d/1 %s",
494 b->offset(),
495 b->size(),
496 "PADDING");
497 break;
498 }
499 b = b->next_block();
500 }
501 }
502
503 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
504 GrowableArray<FieldInfo>* field_info, bool is_contended, FieldLayoutInfo* info) :
505 _classname(classname),
506 _super_klass(super_klass),
507 _constant_pool(constant_pool),
508 _field_info(field_info),
509 _info(info),
510 _root_group(nullptr),
511 _contended_groups(GrowableArray<FieldGroup*>(8)),
512 _static_fields(nullptr),
513 _layout(nullptr),
514 _static_layout(nullptr),
515 _nonstatic_oopmap_count(0),
516 _alignment(-1),
517 _has_nonstatic_fields(false),
518 _is_contended(is_contended) {}
519
520
521 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
522 assert(g > 0, "must only be called for named contended groups");
523 FieldGroup* fg = nullptr;
524 for (int i = 0; i < _contended_groups.length(); i++) {
525 fg = _contended_groups.at(i);
526 if (fg->contended_group() == g) return fg;
527 }
528 fg = new FieldGroup(g);
529 _contended_groups.append(fg);
530 return fg;
531 }
532
533 void FieldLayoutBuilder::prologue() {
534 _layout = new FieldLayout(_field_info, _constant_pool);
535 const InstanceKlass* super_klass = _super_klass;
536 _layout->initialize_instance_layout(super_klass);
537 if (super_klass != nullptr) {
538 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
539 }
540 _static_layout = new FieldLayout(_field_info, _constant_pool);
541 _static_layout->initialize_static_layout();
542 _static_fields = new FieldGroup();
543 _root_group = new FieldGroup();
544 }
545
546 // Field sorting for regular classes:
547 // - fields are sorted in static and non-static fields
548 // - non-static fields are also sorted according to their contention group
549 // (support of the @Contended annotation)
550 // - @Contended annotation is ignored for static fields
551 void FieldLayoutBuilder::regular_field_sorting() {
552 int idx = 0;
553 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
554 FieldInfo ctrl = _field_info->at(0);
555 FieldGroup* group = nullptr;
556 FieldInfo fieldinfo = *it;
557 if (fieldinfo.access_flags().is_static()) {
558 group = _static_fields;
559 } else {
560 _has_nonstatic_fields = true;
561 if (fieldinfo.field_flags().is_contended()) {
562 int g = fieldinfo.contended_group();
563 if (g == 0) {
564 group = new FieldGroup(true);
565 _contended_groups.append(group);
566 } else {
567 group = get_or_create_contended_group(g);
568 }
569 } else {
570 group = _root_group;
571 }
572 }
573 assert(group != nullptr, "invariant");
574 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
575 switch(type) {
576 case T_BYTE:
577 case T_CHAR:
578 case T_DOUBLE:
579 case T_FLOAT:
580 case T_INT:
581 case T_LONG:
582 case T_SHORT:
583 case T_BOOLEAN:
584 group->add_primitive_field(idx, type);
585 break;
586 case T_OBJECT:
587 case T_ARRAY:
588 if (group != _static_fields) _nonstatic_oopmap_count++;
589 group->add_oop_field(idx);
590 break;
591 default:
592 fatal("Something wrong?");
593 }
594 }
595 _root_group->sort_by_size();
596 _static_fields->sort_by_size();
597 if (!_contended_groups.is_empty()) {
598 for (int i = 0; i < _contended_groups.length(); i++) {
599 _contended_groups.at(i)->sort_by_size();
600 }
601 }
602 }
603
604 void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
605 if (ContendedPaddingWidth > 0) {
606 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
607 _layout->insert(slot, padding);
608 }
609 }
610
611 // Computation of regular classes layout is an evolution of the previous default layout
612 // (FieldAllocationStyle 1):
613 // - primitive fields are allocated first (from the biggest to the smallest)
614 // - then oop fields are allocated, either in existing gaps or at the end of
615 // the layout
616 void FieldLayoutBuilder::compute_regular_layout() {
617 bool need_tail_padding = false;
618 prologue();
619 regular_field_sorting();
620
621 if (_is_contended) {
622 _layout->set_start(_layout->last_block());
623 // insertion is currently easy because the current strategy doesn't try to fill holes
624 // in super classes layouts => the _start block is by consequence the _last_block
625 insert_contended_padding(_layout->start());
626 need_tail_padding = true;
627 }
628 _layout->add(_root_group->primitive_fields());
629 _layout->add(_root_group->oop_fields());
630
631 if (!_contended_groups.is_empty()) {
632 for (int i = 0; i < _contended_groups.length(); i++) {
633 FieldGroup* cg = _contended_groups.at(i);
634 LayoutRawBlock* start = _layout->last_block();
635 insert_contended_padding(start);
636 _layout->add(cg->primitive_fields(), start);
637 _layout->add(cg->oop_fields(), start);
638 need_tail_padding = true;
639 }
640 }
641
642 if (need_tail_padding) {
643 insert_contended_padding(_layout->last_block());
644 }
645
646 _static_layout->add_contiguously(this->_static_fields->oop_fields());
647 _static_layout->add(this->_static_fields->primitive_fields());
648
649 epilogue();
650 }
651
652 void FieldLayoutBuilder::epilogue() {
653 // Computing oopmaps
654 int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
655 int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
656
657 OopMapBlocksBuilder* nonstatic_oop_maps =
658 new OopMapBlocksBuilder(max_oop_map_count);
659 if (super_oop_map_count > 0) {
660 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
661 _super_klass->nonstatic_oop_map_count());
662 }
663
664 if (_root_group->oop_fields() != nullptr) {
665 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
666 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
667 nonstatic_oop_maps->add(b->offset(), 1);
668 }
669 }
670
671 if (!_contended_groups.is_empty()) {
672 for (int i = 0; i < _contended_groups.length(); i++) {
673 FieldGroup* cg = _contended_groups.at(i);
674 if (cg->oop_count() > 0) {
675 assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
676 nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
677 }
678 }
679 }
680
681 nonstatic_oop_maps->compact();
682
683 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
684 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
685 int static_fields_size = (static_fields_end -
686 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
687 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
688
689 // Pass back information needed for InstanceKlass creation
690
691 _info->oop_map_blocks = nonstatic_oop_maps;
692 _info->_instance_size = align_object_size(instance_end / wordSize);
693 if (UseCompactObjectHeaders) {
694 _info->_hash_offset = _layout->find_hash_offset();
695 }
696 _info->_static_field_size = static_fields_size;
697 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
698 _info->_has_nonstatic_fields = _has_nonstatic_fields;
699
700 if (PrintFieldLayout) {
701 ResourceMark rm;
702 tty->print_cr("Layout of class %s", _classname->as_C_string());
703 tty->print_cr("Instance fields:");
704 _layout->print(tty, false, _super_klass);
705 tty->print_cr("Static fields:");
706 _static_layout->print(tty, true, nullptr);
707 tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
708 tty->print_cr("---");
709 }
710 }
711
712 void FieldLayoutBuilder::build_layout() {
713 compute_regular_layout();
714 }