1 /*
2 * Copyright (c) 2020, 2023, 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 ((UseEmptySlotsInSupers && !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 // Used for classes with hard coded field offsets, insert a field at the specified offset */
213 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
214 assert(block != nullptr, "Sanity check");
215 block->set_offset(offset);
216 if (start == nullptr) {
217 start = this->_start;
218 }
219 LayoutRawBlock* slot = start;
220 while (slot != nullptr) {
221 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
222 slot == _last){
223 assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
224 assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
225 if (slot->offset() < block->offset()) {
226 int adjustment = block->offset() - slot->offset();
227 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
228 insert(slot, adj);
229 }
230 insert(slot, block);
231 if (slot->size() == 0) {
232 remove(slot);
233 }
234 _field_info->adr_at(block->field_index())->set_offset(block->offset());
235 return;
236 }
237 slot = slot->next_block();
238 }
239 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
240 }
241
242 // The allocation logic uses a best fit strategy: the set of fields is allocated
243 // in the first empty slot big enough to contain the whole set ((including padding
244 // to fit alignment constraints).
245 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
246 if (list == nullptr) return;
247 if (start == nullptr) {
248 start = _start;
249 }
250 // This code assumes that if the first block is well aligned, the following
251 // blocks would naturally be well aligned (no need for adjustment)
252 int size = 0;
253 for (int i = 0; i < list->length(); i++) {
254 size += list->at(i)->size();
255 }
256
257 LayoutRawBlock* candidate = nullptr;
258 if (start == last_block()) {
259 candidate = last_block();
260 } else {
261 LayoutRawBlock* first = list->at(0);
262 candidate = last_block()->prev_block();
263 while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
264 if (candidate == start) {
265 candidate = last_block();
266 break;
267 }
268 candidate = candidate->prev_block();
269 }
270 assert(candidate != nullptr, "Candidate must not be null");
271 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
272 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
273 }
274
275 for (int i = 0; i < list->length(); i++) {
276 LayoutRawBlock* b = list->at(i);
277 insert_field_block(candidate, b);
278 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
279 }
280 }
281
282 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
283 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
284 if (slot->offset() % block->alignment() != 0) {
285 int adjustment = block->alignment() - (slot->offset() % block->alignment());
286 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
287 insert(slot, adj);
288 }
289 insert(slot, block);
290 if (slot->size() == 0) {
291 remove(slot);
292 }
293 _field_info->adr_at(block->field_index())->set_offset(block->offset());
294 return block;
295 }
296
297 bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
298 bool has_instance_fields = false;
299 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
300 while (ik != nullptr) {
301 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
302 BasicType type = Signature::basic_type(fs.signature());
303 // distinction between static and non-static fields is missing
304 if (fs.access_flags().is_static()) continue;
305 has_instance_fields = true;
306 int size = type2aelembytes(type);
307 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
308 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
309 block->set_offset(fs.offset());
310 all_fields->append(block);
311 }
312 ik = ik->super() == nullptr ? nullptr : InstanceKlass::cast(ik->super());
313 }
314
315 all_fields->sort(LayoutRawBlock::compare_offset);
316 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
317 _blocks->set_offset(0);
318 _last = _blocks;
319
320 for(int i = 0; i < all_fields->length(); i++) {
321 LayoutRawBlock* b = all_fields->at(i);
322 _last->set_next_block(b);
323 b->set_prev_block(_last);
324 _last = b;
325 }
326 _start = _blocks;
327 return has_instance_fields;
328 }
329
330 // Called during the reconstruction of a layout, after fields from super
331 // classes have been inserted. It fills unused slots between inserted fields
332 // with EMPTY blocks, so the regular field insertion methods would work.
333 // This method handles classes with @Contended annotations differently
334 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
335 // fields to interfere with contended fields/classes.
336 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
337 assert(_blocks != nullptr, "Sanity check");
338 assert(_blocks->offset() == 0, "first block must be at offset zero");
339 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
340 LayoutRawBlock* b = _blocks;
341 while (b->next_block() != nullptr) {
342 if (b->next_block()->offset() > (b->offset() + b->size())) {
343 int size = b->next_block()->offset() - (b->offset() + b->size());
344 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
345 empty->set_offset(b->offset() + b->size());
346 empty->set_next_block(b->next_block());
347 b->next_block()->set_prev_block(empty);
348 b->set_next_block(empty);
349 empty->set_prev_block(b);
350 }
351 b = b->next_block();
352 }
353 assert(b->next_block() == nullptr, "Invariant at this point");
354 assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
355
356 // If the super class has @Contended annotation, a padding block is
357 // inserted at the end to ensure that fields from the subclasses won't share
358 // the cache line of the last field of the contended class
359 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
360 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
361 p->set_offset(b->offset() + b->size());
362 b->set_next_block(p);
363 p->set_prev_block(b);
364 b = p;
365 }
366
367 if (!UseEmptySlotsInSupers) {
368 // Add an empty slots to align fields of the subclass on a heapOopSize boundary
369 // in order to emulate the behavior of the previous algorithm
370 int align = (b->offset() + b->size()) % heapOopSize;
371 if (align != 0) {
372 int sz = heapOopSize - align;
373 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::EMPTY, sz);
374 p->set_offset(b->offset() + b->size());
375 b->set_next_block(p);
376 p->set_prev_block(b);
377 b = p;
378 }
379 }
380
381 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
382 last->set_offset(b->offset() + b->size());
383 assert(last->offset() > 0, "Sanity check");
384 b->set_next_block(last);
385 last->set_prev_block(b);
386 _last = last;
387 }
388
389 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
390 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
391 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
392 block->set_offset(slot->offset());
393 slot->set_offset(slot->offset() + block->size());
394 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
395 assert(slot->size() - block->size() >= 0, "no negative size allowed");
396 slot->set_size(slot->size() - block->size());
397 block->set_prev_block(slot->prev_block());
398 block->set_next_block(slot);
399 slot->set_prev_block(block);
400 if (block->prev_block() != nullptr) {
401 block->prev_block()->set_next_block(block);
402 }
403 if (_blocks == slot) {
404 _blocks = block;
405 }
406 return block;
407 }
408
409 void FieldLayout::remove(LayoutRawBlock* block) {
410 assert(block != nullptr, "Sanity check");
411 assert(block != _last, "Sanity check");
412 if (_blocks == block) {
413 _blocks = block->next_block();
414 if (_blocks != nullptr) {
415 _blocks->set_prev_block(nullptr);
416 }
417 } else {
418 assert(block->prev_block() != nullptr, "_prev should be set for non-head blocks");
419 block->prev_block()->set_next_block(block->next_block());
420 block->next_block()->set_prev_block(block->prev_block());
421 }
422 if (block == _start) {
423 _start = block->prev_block();
424 }
425 }
426
427 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
428 ResourceMark rm;
429 LayoutRawBlock* b = _blocks;
430 while(b != _last) {
431 switch(b->kind()) {
432 case LayoutRawBlock::REGULAR: {
433 FieldInfo* fi = _field_info->adr_at(b->field_index());
434 output->print_cr(" @%d \"%s\" %s %d/%d %s",
435 b->offset(),
436 fi->name(_cp)->as_C_string(),
437 fi->signature(_cp)->as_C_string(),
438 b->size(),
439 b->alignment(),
440 "REGULAR");
441 break;
442 }
443 case LayoutRawBlock::FLATTENED: {
444 FieldInfo* fi = _field_info->adr_at(b->field_index());
445 output->print_cr(" @%d \"%s\" %s %d/%d %s",
446 b->offset(),
447 fi->name(_cp)->as_C_string(),
448 fi->signature(_cp)->as_C_string(),
449 b->size(),
450 b->alignment(),
451 "FLATTENED");
452 break;
453 }
454 case LayoutRawBlock::RESERVED: {
455 output->print_cr(" @%d %d/- %s",
456 b->offset(),
457 b->size(),
458 "RESERVED");
459 break;
460 }
461 case LayoutRawBlock::INHERITED: {
462 assert(!is_static, "Static fields are not inherited in layouts");
463 assert(super != nullptr, "super klass must be provided to retrieve inherited fields info");
464 bool found = false;
465 const InstanceKlass* ik = super;
466 while (!found && ik != nullptr) {
467 for (AllFieldStream fs(ik->fieldinfo_stream(), ik->constants()); !fs.done(); fs.next()) {
468 if (fs.offset() == b->offset()) {
469 output->print_cr(" @%d \"%s\" %s %d/%d %s",
470 b->offset(),
471 fs.name()->as_C_string(),
472 fs.signature()->as_C_string(),
473 b->size(),
474 b->size(), // so far, alignment constraint == size, will change with Valhalla
475 "INHERITED");
476 found = true;
477 break;
478 }
479 }
480 ik = ik->java_super();
481 }
482 break;
483 }
484 case LayoutRawBlock::EMPTY:
485 output->print_cr(" @%d %d/1 %s",
486 b->offset(),
487 b->size(),
488 "EMPTY");
489 break;
490 case LayoutRawBlock::PADDING:
491 output->print_cr(" @%d %d/1 %s",
492 b->offset(),
493 b->size(),
494 "PADDING");
495 break;
496 }
497 b = b->next_block();
498 }
499 }
500
501 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
502 GrowableArray<FieldInfo>* field_info, bool is_contended, FieldLayoutInfo* info) :
503 _classname(classname),
504 _super_klass(super_klass),
505 _constant_pool(constant_pool),
506 _field_info(field_info),
507 _info(info),
508 _root_group(nullptr),
509 _contended_groups(GrowableArray<FieldGroup*>(8)),
510 _static_fields(nullptr),
511 _layout(nullptr),
512 _static_layout(nullptr),
513 _nonstatic_oopmap_count(0),
514 _alignment(-1),
515 _has_nonstatic_fields(false),
516 _is_contended(is_contended) {}
517
518
519 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
520 assert(g > 0, "must only be called for named contended groups");
521 FieldGroup* fg = nullptr;
522 for (int i = 0; i < _contended_groups.length(); i++) {
523 fg = _contended_groups.at(i);
524 if (fg->contended_group() == g) return fg;
525 }
526 fg = new FieldGroup(g);
527 _contended_groups.append(fg);
528 return fg;
529 }
530
531 void FieldLayoutBuilder::prologue() {
532 _layout = new FieldLayout(_field_info, _constant_pool);
533 const InstanceKlass* super_klass = _super_klass;
534 _layout->initialize_instance_layout(super_klass);
535 if (super_klass != nullptr) {
536 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
537 }
538 _static_layout = new FieldLayout(_field_info, _constant_pool);
539 _static_layout->initialize_static_layout();
540 _static_fields = new FieldGroup();
541 _root_group = new FieldGroup();
542 }
543
544 // Field sorting for regular classes:
545 // - fields are sorted in static and non-static fields
546 // - non-static fields are also sorted according to their contention group
547 // (support of the @Contended annotation)
548 // - @Contended annotation is ignored for static fields
549 void FieldLayoutBuilder::regular_field_sorting() {
550 int idx = 0;
551 for (GrowableArrayIterator<FieldInfo> it = _field_info->begin(); it != _field_info->end(); ++it, ++idx) {
552 FieldInfo ctrl = _field_info->at(0);
553 FieldGroup* group = nullptr;
554 FieldInfo fieldinfo = *it;
555 if (fieldinfo.access_flags().is_static()) {
556 group = _static_fields;
557 } else {
558 _has_nonstatic_fields = true;
559 if (fieldinfo.field_flags().is_contended()) {
560 int g = fieldinfo.contended_group();
561 if (g == 0) {
562 group = new FieldGroup(true);
563 _contended_groups.append(group);
564 } else {
565 group = get_or_create_contended_group(g);
566 }
567 } else {
568 group = _root_group;
569 }
570 }
571 assert(group != nullptr, "invariant");
572 BasicType type = Signature::basic_type(fieldinfo.signature(_constant_pool));
573 switch(type) {
574 case T_BYTE:
575 case T_CHAR:
576 case T_DOUBLE:
577 case T_FLOAT:
578 case T_INT:
579 case T_LONG:
580 case T_SHORT:
581 case T_BOOLEAN:
582 group->add_primitive_field(idx, type);
583 break;
584 case T_OBJECT:
585 case T_ARRAY:
586 if (group != _static_fields) _nonstatic_oopmap_count++;
587 group->add_oop_field(idx);
588 break;
589 default:
590 fatal("Something wrong?");
591 }
592 }
593 _root_group->sort_by_size();
594 _static_fields->sort_by_size();
595 if (!_contended_groups.is_empty()) {
596 for (int i = 0; i < _contended_groups.length(); i++) {
597 _contended_groups.at(i)->sort_by_size();
598 }
599 }
600 }
601
602 void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
603 if (ContendedPaddingWidth > 0) {
604 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
605 _layout->insert(slot, padding);
606 }
607 }
608
609 // Computation of regular classes layout is an evolution of the previous default layout
610 // (FieldAllocationStyle 1):
611 // - primitive fields are allocated first (from the biggest to the smallest)
612 // - then oop fields are allocated, either in existing gaps or at the end of
613 // the layout
614 void FieldLayoutBuilder::compute_regular_layout() {
615 bool need_tail_padding = false;
616 prologue();
617 regular_field_sorting();
618
619 if (_is_contended) {
620 _layout->set_start(_layout->last_block());
621 // insertion is currently easy because the current strategy doesn't try to fill holes
622 // in super classes layouts => the _start block is by consequence the _last_block
623 insert_contended_padding(_layout->start());
624 need_tail_padding = true;
625 }
626 _layout->add(_root_group->primitive_fields());
627 _layout->add(_root_group->oop_fields());
628
629 if (!_contended_groups.is_empty()) {
630 for (int i = 0; i < _contended_groups.length(); i++) {
631 FieldGroup* cg = _contended_groups.at(i);
632 LayoutRawBlock* start = _layout->last_block();
633 insert_contended_padding(start);
634 _layout->add(cg->primitive_fields(), start);
635 _layout->add(cg->oop_fields(), start);
636 need_tail_padding = true;
637 }
638 }
639
640 if (need_tail_padding) {
641 insert_contended_padding(_layout->last_block());
642 }
643
644 _static_layout->add_contiguously(this->_static_fields->oop_fields());
645 _static_layout->add(this->_static_fields->primitive_fields());
646
647 epilogue();
648 }
649
650 void FieldLayoutBuilder::epilogue() {
651 // Computing oopmaps
652 int super_oop_map_count = (_super_klass == nullptr) ? 0 :_super_klass->nonstatic_oop_map_count();
653 int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
654
655 OopMapBlocksBuilder* nonstatic_oop_maps =
656 new OopMapBlocksBuilder(max_oop_map_count);
657 if (super_oop_map_count > 0) {
658 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
659 _super_klass->nonstatic_oop_map_count());
660 }
661
662 if (_root_group->oop_fields() != nullptr) {
663 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
664 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
665 nonstatic_oop_maps->add(b->offset(), 1);
666 }
667 }
668
669 if (!_contended_groups.is_empty()) {
670 for (int i = 0; i < _contended_groups.length(); i++) {
671 FieldGroup* cg = _contended_groups.at(i);
672 if (cg->oop_count() > 0) {
673 assert(cg->oop_fields() != nullptr && cg->oop_fields()->at(0) != nullptr, "oop_count > 0 but no oop fields found");
674 nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
675 }
676 }
677 }
678
679 nonstatic_oop_maps->compact();
680
681 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
682 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
683 int static_fields_size = (static_fields_end -
684 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
685 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
686
687 // Pass back information needed for InstanceKlass creation
688
689 _info->oop_map_blocks = nonstatic_oop_maps;
690 _info->_instance_size = align_object_size(instance_end / wordSize);
691 _info->_static_field_size = static_fields_size;
692 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
693 _info->_has_nonstatic_fields = _has_nonstatic_fields;
694
695 if (PrintFieldLayout) {
696 ResourceMark rm;
697 tty->print_cr("Layout of class %s", _classname->as_C_string());
698 tty->print_cr("Instance fields:");
699 _layout->print(tty, false, _super_klass);
700 tty->print_cr("Static fields:");
701 _static_layout->print(tty, true, nullptr);
702 tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
703 tty->print_cr("---");
704 }
705 }
706
707 void FieldLayoutBuilder::build_layout() {
708 compute_regular_layout();
709 }