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, bool& super_ends_with_oop) {
130 if (super_klass == nullptr) {
131 super_ends_with_oop = false;
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 super_has_instance_fields = false;
139 reconstruct_layout(super_klass, super_has_instance_fields, super_ends_with_oop);
140 fill_holes(super_klass);
141 if (!super_klass->has_contended_annotations() || !super_has_instance_fields) {
142 _start = _blocks; // start allocating fields from the first empty block
143 } else {
144 _start = _last; // append fields at the end of the reconstructed layout
145 }
146 }
147 }
148
149 LayoutRawBlock* FieldLayout::first_field_block() {
150 LayoutRawBlock* block = _start;
151 while (block->kind() != LayoutRawBlock::INHERITED && block->kind() != LayoutRawBlock::REGULAR
152 && block->kind() != LayoutRawBlock::FLATTENED && block->kind() != LayoutRawBlock::PADDING) {
153 block = block->next_block();
154 }
155 return block;
156 }
157
158
159 // Insert a set of fields into a layout using a best-fit strategy.
160 // For each field, search for the smallest empty slot able to fit the field
161 // (satisfying both size and alignment requirements), if none is found,
162 // add the field at the end of the layout.
163 // Fields cannot be inserted before the block specified in the "start" argument
164 void FieldLayout::add(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
165 if (list == nullptr) return;
166 if (start == nullptr) start = this->_start;
167 bool last_search_success = false;
168 int last_size = 0;
169 int last_alignment = 0;
170 for (int i = 0; i < list->length(); i ++) {
171 LayoutRawBlock* b = list->at(i);
172 LayoutRawBlock* cursor = nullptr;
173 LayoutRawBlock* candidate = nullptr;
174
175 // if start is the last block, just append the field
176 if (start == last_block()) {
177 candidate = last_block();
178 }
179 // Before iterating over the layout to find an empty slot fitting the field's requirements,
180 // check if the previous field had the same requirements and if the search for a fitting slot
181 // was successful. If the requirements were the same but the search failed, a new search will
182 // fail the same way, so just append the field at the of the layout.
183 else if (b->size() == last_size && b->alignment() == last_alignment && !last_search_success) {
184 candidate = last_block();
185 } else {
186 // Iterate over the layout to find an empty slot fitting the field's requirements
187 last_size = b->size();
188 last_alignment = b->alignment();
189 cursor = last_block()->prev_block();
190 assert(cursor != nullptr, "Sanity check");
191 last_search_success = true;
192 while (cursor != start) {
193 if (cursor->kind() == LayoutRawBlock::EMPTY && cursor->fit(b->size(), b->alignment())) {
194 if (candidate == nullptr || cursor->size() < candidate->size()) {
195 candidate = cursor;
196 }
197 }
198 cursor = cursor->prev_block();
199 }
200 if (candidate == nullptr) {
201 candidate = last_block();
202 last_search_success = false;
203 }
204 assert(candidate != nullptr, "Candidate must not be null");
205 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
206 assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
207 }
208
209 insert_field_block(candidate, b);
210 }
211 }
212
213 // Used for classes with hard coded field offsets, insert a field at the specified offset */
214 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
215 assert(block != nullptr, "Sanity check");
216 block->set_offset(offset);
217 if (start == nullptr) {
218 start = this->_start;
219 }
220 LayoutRawBlock* slot = start;
221 while (slot != nullptr) {
222 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
223 slot == _last){
224 assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
225 assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
226 if (slot->offset() < block->offset()) {
227 int adjustment = block->offset() - slot->offset();
228 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
229 insert(slot, adj);
230 }
231 insert(slot, block);
232 if (slot->size() == 0) {
233 remove(slot);
234 }
235 _field_info->adr_at(block->field_index())->set_offset(block->offset());
236 return;
237 }
238 slot = slot->next_block();
239 }
240 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
241 }
242
243 // The allocation logic uses a best fit strategy: the set of fields is allocated
244 // in the first empty slot big enough to contain the whole set ((including padding
245 // to fit alignment constraints).
246 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
247 if (list == nullptr) return;
248 if (start == nullptr) {
249 start = _start;
250 }
251 // This code assumes that if the first block is well aligned, the following
252 // blocks would naturally be well aligned (no need for adjustment)
253 int size = 0;
254 for (int i = 0; i < list->length(); i++) {
255 size += list->at(i)->size();
256 }
257
258 LayoutRawBlock* candidate = nullptr;
259 if (start == last_block()) {
260 candidate = last_block();
261 } else {
262 LayoutRawBlock* first = list->at(0);
263 candidate = last_block()->prev_block();
264 while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
265 if (candidate == start) {
266 candidate = last_block();
267 break;
268 }
269 candidate = candidate->prev_block();
270 }
271 assert(candidate != nullptr, "Candidate must not be null");
272 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
273 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
274 }
275
276 for (int i = 0; i < list->length(); i++) {
277 LayoutRawBlock* b = list->at(i);
278 insert_field_block(candidate, b);
279 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
280 }
281 }
282
283 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
284 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
285 if (slot->offset() % block->alignment() != 0) {
286 int adjustment = block->alignment() - (slot->offset() % block->alignment());
287 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
288 insert(slot, adj);
289 }
290 insert(slot, block);
291 if (slot->size() == 0) {
292 remove(slot);
293 }
294 _field_info->adr_at(block->field_index())->set_offset(block->offset());
295 return block;
296 }
297
298 void FieldLayout::reconstruct_layout(const InstanceKlass* ik, bool& has_instance_fields, bool& ends_with_oop) {
299 has_instance_fields = ends_with_oop = false;
300 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
301 BasicType last_type;
302 int last_offset = -1;
303 while (ik != nullptr) {
304 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
305 BasicType type = Signature::basic_type(fs.signature());
306 // distinction between static and non-static fields is missing
307 if (fs.access_flags().is_static()) continue;
308 has_instance_fields = true;
309 if (fs.offset() > last_offset) {
310 last_offset = fs.offset();
311 last_type = type;
312 }
313 int size = type2aelembytes(type);
314 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
315 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
316 block->set_offset(fs.offset());
317 all_fields->append(block);
318 }
319 ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
320 }
321 assert(last_offset == -1 || last_offset > 0, "Sanity");
322 if (last_offset > 0 &&
323 (last_type == BasicType::T_ARRAY || last_type == BasicType::T_OBJECT)) {
324 ends_with_oop = true;
325 }
326
327 all_fields->sort(LayoutRawBlock::compare_offset);
328 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
329 _blocks->set_offset(0);
330 _last = _blocks;
331
332 for(int i = 0; i < all_fields->length(); i++) {
333 LayoutRawBlock* b = all_fields->at(i);
334 _last->set_next_block(b);
335 b->set_prev_block(_last);
336 _last = b;
337 }
338 _start = _blocks;
339 }
340
341 // Called during the reconstruction of a layout, after fields from super
342 // classes have been inserted. It fills unused slots between inserted fields
343 // with EMPTY blocks, so the regular field insertion methods would work.
344 // This method handles classes with @Contended annotations differently
345 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
346 // fields to interfere with contended fields/classes.
347 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
348 assert(_blocks != nullptr, "Sanity check");
349 assert(_blocks->offset() == 0, "first block must be at offset zero");
350 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
351 LayoutRawBlock* b = _blocks;
352 while (b->next_block() != nullptr) {
353 if (b->next_block()->offset() > (b->offset() + b->size())) {
354 int size = b->next_block()->offset() - (b->offset() + b->size());
355 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
356 empty->set_offset(b->offset() + b->size());
357 empty->set_next_block(b->next_block());
358 b->next_block()->set_prev_block(empty);
359 b->set_next_block(empty);
360 empty->set_prev_block(b);
361 }
362 b = b->next_block();
363 }
364 assert(b->next_block() == nullptr, "Invariant at this point");
365 assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
366
367 // If the super class has @Contended annotation, a padding block is
368 // inserted at the end to ensure that fields from the subclasses won't share
369 // the cache line of the last field of the contended class
370 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
371 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
372 p->set_offset(b->offset() + b->size());
373 b->set_next_block(p);
374 p->set_prev_block(b);
375 b = p;
376 }
377
378 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
379 last->set_offset(b->offset() + b->size());
380 assert(last->offset() > 0, "Sanity check");
381 b->set_next_block(last);
382 last->set_prev_block(b);
383 _last = last;
384 }
385
386 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
387 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
388 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
389 block->set_offset(slot->offset());
390 slot->set_offset(slot->offset() + block->size());
391 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
392 assert(slot->size() - block->size() >= 0, "no negative size allowed");
393 slot->set_size(slot->size() - block->size());
394 block->set_prev_block(slot->prev_block());
395 block->set_next_block(slot);
396 slot->set_prev_block(block);
397 if (block->prev_block() != nullptr) {
398 block->prev_block()->set_next_block(block);
399 }
400 if (_blocks == slot) {
401 _blocks = block;
402 }
403 return block;
404 }
405
406 void FieldLayout::remove(LayoutRawBlock* block) {
407 assert(block != nullptr, "Sanity check");
408 assert(block != _last, "Sanity check");
409 if (_blocks == block) {
410 _blocks = block->next_block();
411 if (_blocks != nullptr) {
412 _blocks->set_prev_block(nullptr);
413 }
414 } else {
415 assert(block->prev_block() != nullptr, "_prev should be set for non-head blocks");
416 block->prev_block()->set_next_block(block->next_block());
417 block->next_block()->set_prev_block(block->prev_block());
418 }
419 if (block == _start) {
420 _start = block->prev_block();
421 }
422 }
423
424 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
425 ResourceMark rm;
426 LayoutRawBlock* b = _blocks;
427 while(b != _last) {
428 switch(b->kind()) {
429 case LayoutRawBlock::REGULAR: {
430 FieldInfo* fi = _field_info->adr_at(b->field_index());
431 output->print_cr(" @%d \"%s\" %s %d/%d %s",
432 b->offset(),
433 fi->name(_cp)->as_C_string(),
434 fi->signature(_cp)->as_C_string(),
435 b->size(),
436 b->alignment(),
437 "REGULAR");
438 break;
439 }
440 case LayoutRawBlock::FLATTENED: {
441 FieldInfo* fi = _field_info->adr_at(b->field_index());
442 output->print_cr(" @%d \"%s\" %s %d/%d %s",
443 b->offset(),
444 fi->name(_cp)->as_C_string(),
445 fi->signature(_cp)->as_C_string(),
446 b->size(),
447 b->alignment(),
448 "FLATTENED");
449 break;
450 }
451 case LayoutRawBlock::RESERVED: {
452 output->print_cr(" @%d %d/- %s",
453 b->offset(),
454 b->size(),
455 "RESERVED");
456 break;
457 }
458 case LayoutRawBlock::INHERITED: {
459 assert(!is_static, "Static fields are not inherited in layouts");
460 assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
461 bool found = false;
462 const InstanceKlass* ik = super;
463 while (!found && ik != nullptr) {
464 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
465 if (fs.offset() == b->offset()) {
466 output->print_cr(" @%d \"%s\" %s %d/%d %s",
467 b->offset(),
468 fs.name()->as_C_string(),
469 fs.signature()->as_C_string(),
470 b->size(),
471 b->size(), // so far, alignment constraint == size, will change with Valhalla
472 "INHERITED");
473 found = true;
474 break;
475 }
476 }
477 ik = ik->java_super();
478 }
479 break;
480 }
481 case LayoutRawBlock::EMPTY:
482 output->print_cr(" @%d %d/1 %s",
483 b->offset(),
484 b->size(),
485 "EMPTY");
486 break;
487 case LayoutRawBlock::PADDING:
488 output->print_cr(" @%d %d/1 %s",
489 b->offset(),
490 b->size(),
491 "PADDING");
492 break;
493 }
494 b = b->next_block();
495 }
496 }
497
498 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
499 GrowableArray<FieldInfo>* field_info, bool is_contended, FieldLayoutInfo* info) :
500 _classname(classname),
501 _super_klass(super_klass),
502 _constant_pool(constant_pool),
503 _field_info(field_info),
504 _info(info),
505 _root_group(nullptr),
506 _contended_groups(GrowableArray<FieldGroup*>(8)),
507 _static_fields(nullptr),
508 _layout(nullptr),
509 _static_layout(nullptr),
510 _nonstatic_oopmap_count(0),
511 _alignment(-1),
512 _has_nonstatic_fields(false),
513 _is_contended(is_contended) {}
514
515
516 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
517 assert(g > 0, "must only be called for named contended groups");
518 FieldGroup* fg = nullptr;
519 for (int i = 0; i < _contended_groups.length(); i++) {
520 fg = _contended_groups.at(i);
521 if (fg->contended_group() == g) return fg;
522 }
523 fg = new FieldGroup(g);
524 _contended_groups.append(fg);
525 return fg;
526 }
527
528 void FieldLayoutBuilder::prologue() {
529 _layout = new FieldLayout(_field_info, _constant_pool);
530 const InstanceKlass* super_klass = _super_klass;
531 _layout->initialize_instance_layout(super_klass, _super_ends_with_oop);
532 if (super_klass != nullptr) {
533 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
534 }
535 _static_layout = new FieldLayout(_field_info, _constant_pool);
536 _static_layout->initialize_static_layout();
537 _static_fields = new FieldGroup();
538 _root_group = new FieldGroup();
539 }
540
541 // Field sorting for regular classes:
542 // - fields are sorted in static and non-static fields
543 // - non-static fields are also sorted according to their contention group
544 // (support of the @Contended annotation)
545 // - @Contended annotation is ignored for static fields
546 void FieldLayoutBuilder::regular_field_sorting() {
547 int idx = 0;
548 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
549 FieldInfo ctrl = _field_info->at(0);
550 FieldGroup* group = nullptr;
551 FieldInfo fieldinfo = *it;
552 if (fieldinfo.access_flags().is_static()) {
553 group = _static_fields;
554 } else {
555 _has_nonstatic_fields = true;
556 if (fieldinfo.field_flags().is_contended()) {
557 int g = fieldinfo.contended_group();
558 if (g == 0) {
559 group = new FieldGroup(true);
560 _contended_groups.append(group);
561 } else {
562 group = get_or_create_contended_group(g);
563 }
564 } else {
565 group = _root_group;
566 }
567 }
568 assert(group != nullptr, "invariant");
569 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
570 switch(type) {
571 case T_BYTE:
572 case T_CHAR:
573 case T_DOUBLE:
574 case T_FLOAT:
575 case T_INT:
576 case T_LONG:
577 case T_SHORT:
578 case T_BOOLEAN:
579 group->add_primitive_field(idx, type);
580 break;
581 case T_OBJECT:
582 case T_ARRAY:
583 if (group != _static_fields) _nonstatic_oopmap_count++;
584 group->add_oop_field(idx);
585 break;
586 default:
587 fatal("Something wrong?");
588 }
589 }
590 _root_group->sort_by_size();
591 _static_fields->sort_by_size();
592 if (!_contended_groups.is_empty()) {
593 for (int i = 0; i < _contended_groups.length(); i++) {
594 _contended_groups.at(i)->sort_by_size();
595 }
596 }
597 }
598
599 void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
600 if (ContendedPaddingWidth > 0) {
601 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
602 _layout->insert(slot, padding);
603 }
604 }
605
606 // Computation of regular classes layout is an evolution of the previous default layout
607 // (FieldAllocationStyle 1):
608 // - primitive fields are allocated first (from the biggest to the smallest)
609 // - oop fields are allocated, either in existing gaps or at the end of
610 // the layout. We allocate oops in a single block to have a single oop map entry.
611 // - if the super class ended with an oop, we lead with oops. That will cause the
612 // trailing oop map entry of the super class and the oop map entry of this class
613 // to be folded into a single entry later. Correspondingly, if the super class
614 // ends with a primitive field, we gain nothing by leading with oops; therefore
615 // we let oop fields trail, thus giving future derived classes the chance to apply
616 // the same trick.
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
630 if (_super_ends_with_oop) {
631 _layout->add(_root_group->oop_fields());
632 _layout->add(_root_group->primitive_fields());
633 } else {
634 _layout->add(_root_group->primitive_fields());
635 _layout->add(_root_group->oop_fields());
636 }
637
638 if (!_contended_groups.is_empty()) {
639 for (int i = 0; i < _contended_groups.length(); i++) {
640 FieldGroup* cg = _contended_groups.at(i);
641 LayoutRawBlock* start = _layout->last_block();
642 insert_contended_padding(start);
643 _layout->add(cg->primitive_fields(), start);
644 _layout->add(cg->oop_fields(), start);
645 need_tail_padding = true;
646 }
647 }
648
649 if (need_tail_padding) {
650 insert_contended_padding(_layout->last_block());
651 }
652
653 _static_layout->add_contiguously(this->_static_fields->oop_fields());
654 _static_layout->add(this->_static_fields->primitive_fields());
655
656 epilogue();
657 }
658
659 void FieldLayoutBuilder::epilogue() {
660 // Computing oopmaps
661 int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
662 int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
663
664 OopMapBlocksBuilder* nonstatic_oop_maps =
665 new OopMapBlocksBuilder(max_oop_map_count);
666 if (super_oop_map_count > 0) {
667 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
668 _super_klass->nonstatic_oop_map_count());
669 }
670
671 if (_root_group->oop_fields() != nullptr) {
672 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
673 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
674 nonstatic_oop_maps->add(b->offset(), 1);
675 }
676 }
677
678 if (!_contended_groups.is_empty()) {
679 for (int i = 0; i < _contended_groups.length(); i++) {
680 FieldGroup* cg = _contended_groups.at(i);
681 if (cg->oop_count() > 0) {
682 assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
683 nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
684 }
685 }
686 }
687
688 nonstatic_oop_maps->compact();
689
690 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
691 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
692 int static_fields_size = (static_fields_end -
693 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
694 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
695
696 // Pass back information needed for InstanceKlass creation
697
698 _info->oop_map_blocks = nonstatic_oop_maps;
699 _info->_instance_size = align_object_size(instance_end / wordSize);
700 _info->_static_field_size = static_fields_size;
701 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
702 _info->_has_nonstatic_fields = _has_nonstatic_fields;
703
704 if (PrintFieldLayout) {
705 ResourceMark rm;
706 tty->print_cr("Layout of class %s", _classname->as_C_string());
707 tty->print_cr("Instance fields:");
708 _layout->print(tty, false, _super_klass);
709 tty->print_cr("Static fields:");
710 _static_layout->print(tty, true, nullptr);
711 tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
712 tty->print_cr("---");
713 }
714 }
715
716 void FieldLayoutBuilder::build_layout() {
717 compute_regular_layout();
718 }