1 /*
2 * Copyright (c) 2020, 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 "jvm.h"
27 #include "classfile/classFileParser.hpp"
28 #include "classfile/fieldLayoutBuilder.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/array.hpp"
31 #include "oops/fieldStreams.inline.hpp"
32 #include "oops/instanceMirrorKlass.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(NULL),
39 _prev_block(NULL),
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(NULL),
54 _prev_block(NULL),
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(NULL),
77 _primitive_fields(NULL),
78 _oop_fields(NULL),
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(AllFieldStream fs, BasicType type) {
83 int size = type2aelembytes(type);
84 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */, false);
85 if (_primitive_fields == NULL) {
86 _primitive_fields = new(ResourceObj::RESOURCE_AREA, mtInternal) GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
87 }
88 _primitive_fields->append(block);
89 }
90
91 void FieldGroup::add_oop_field(AllFieldStream fs) {
92 int size = type2aelembytes(T_OBJECT);
93 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */, true);
94 if (_oop_fields == NULL) {
95 _oop_fields = new(ResourceObj::RESOURCE_AREA, mtInternal) 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 != NULL) {
103 _primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
104 }
105 }
106
107 FieldLayout::FieldLayout(Array<u2>* fields, ConstantPool* cp) :
108 _fields(fields),
109 _cp(cp),
110 _blocks(NULL),
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 == NULL) {
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 ((UseEmptySlotsInSupers && !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 == NULL) return;
164 if (start == NULL) 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 = NULL;
171 LayoutRawBlock* candidate = NULL;
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 != NULL, "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 == NULL || cursor->size() < candidate->size()) {
193 candidate = cursor;
194 }
195 }
196 cursor = cursor->prev_block();
197 }
198 if (candidate == NULL) {
199 candidate = last_block();
200 last_search_success = false;
201 }
202 assert(candidate != NULL, "Candidate must not be null");
203 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
204 assert(candidate->fit(b->size(), b->alignment()), "Candidate must be able to store the block");
205 }
206
207 insert_field_block(candidate, b);
208 }
209 }
210
211 // Used for classes with hard coded field offsets, insert a field at the specified offset */
212 void FieldLayout::add_field_at_offset(LayoutRawBlock* block, int offset, LayoutRawBlock* start) {
213 assert(block != NULL, "Sanity check");
214 block->set_offset(offset);
215 if (start == NULL) {
216 start = this->_start;
217 }
218 LayoutRawBlock* slot = start;
219 while (slot != NULL) {
220 if ((slot->offset() <= block->offset() && (slot->offset() + slot->size()) > block->offset()) ||
221 slot == _last){
222 assert(slot->kind() == LayoutRawBlock::EMPTY, "Matching slot must be an empty slot");
223 assert(slot->size() >= block->offset() + block->size() ,"Matching slot must be big enough");
224 if (slot->offset() < block->offset()) {
225 int adjustment = block->offset() - slot->offset();
226 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
227 insert(slot, adj);
228 }
229 insert(slot, block);
230 if (slot->size() == 0) {
231 remove(slot);
232 }
233 FieldInfo::from_field_array(_fields, block->field_index())->set_offset(block->offset());
234 return;
235 }
236 slot = slot->next_block();
237 }
238 fatal("Should have found a matching slot above, corrupted layout or invalid offset");
239 }
240
241 // The allocation logic uses a best fit strategy: the set of fields is allocated
242 // in the first empty slot big enough to contain the whole set ((including padding
243 // to fit alignment constraints).
244 void FieldLayout::add_contiguously(GrowableArray<LayoutRawBlock*>* list, LayoutRawBlock* start) {
245 if (list == NULL) return;
246 if (start == NULL) {
247 start = _start;
248 }
249 // This code assumes that if the first block is well aligned, the following
250 // blocks would naturally be well aligned (no need for adjustment)
251 int size = 0;
252 for (int i = 0; i < list->length(); i++) {
253 size += list->at(i)->size();
254 }
255
256 LayoutRawBlock* candidate = NULL;
257 if (start == last_block()) {
258 candidate = last_block();
259 } else {
260 LayoutRawBlock* first = list->at(0);
261 candidate = last_block()->prev_block();
262 while (candidate->kind() != LayoutRawBlock::EMPTY || !candidate->fit(size, first->alignment())) {
263 if (candidate == start) {
264 candidate = last_block();
265 break;
266 }
267 candidate = candidate->prev_block();
268 }
269 assert(candidate != NULL, "Candidate must not be null");
270 assert(candidate->kind() == LayoutRawBlock::EMPTY, "Candidate must be an empty block");
271 assert(candidate->fit(size, first->alignment()), "Candidate must be able to store the whole contiguous block");
272 }
273
274 for (int i = 0; i < list->length(); i++) {
275 LayoutRawBlock* b = list->at(i);
276 insert_field_block(candidate, b);
277 assert((candidate->offset() % b->alignment() == 0), "Contiguous blocks must be naturally well aligned");
278 }
279 }
280
281 LayoutRawBlock* FieldLayout::insert_field_block(LayoutRawBlock* slot, LayoutRawBlock* block) {
282 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
283 if (slot->offset() % block->alignment() != 0) {
284 int adjustment = block->alignment() - (slot->offset() % block->alignment());
285 LayoutRawBlock* adj = new LayoutRawBlock(LayoutRawBlock::EMPTY, adjustment);
286 insert(slot, adj);
287 }
288 insert(slot, block);
289 if (slot->size() == 0) {
290 remove(slot);
291 }
292 FieldInfo::from_field_array(_fields, block->field_index())->set_offset(block->offset());
293 return block;
294 }
295
296 bool FieldLayout::reconstruct_layout(const InstanceKlass* ik) {
297 bool has_instance_fields = false;
298 GrowableArray<LayoutRawBlock*>* all_fields = new GrowableArray<LayoutRawBlock*>(32);
299 while (ik != NULL) {
300 for (AllFieldStream fs(ik->fields(), ik->constants()); !fs.done(); fs.next()) {
301 BasicType type = Signature::basic_type(fs.signature());
302 // distinction between static and non-static fields is missing
303 if (fs.access_flags().is_static()) continue;
304 has_instance_fields = true;
305 int size = type2aelembytes(type);
306 // INHERITED blocks are marked as non-reference because oop_maps are handled by their holder class
307 LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::INHERITED, size, size, false);
308 block->set_offset(fs.offset());
309 all_fields->append(block);
310 }
311 ik = ik->super() == NULL ? NULL : InstanceKlass::cast(ik->super());
312 }
313
314 all_fields->sort(LayoutRawBlock::compare_offset);
315 _blocks = new LayoutRawBlock(LayoutRawBlock::RESERVED, instanceOopDesc::base_offset_in_bytes());
316 _blocks->set_offset(0);
317 _last = _blocks;
318
319 for(int i = 0; i < all_fields->length(); i++) {
320 LayoutRawBlock* b = all_fields->at(i);
321 _last->set_next_block(b);
322 b->set_prev_block(_last);
323 _last = b;
324 }
325 _start = _blocks;
326 return has_instance_fields;
327 }
328
329 // Called during the reconstruction of a layout, after fields from super
330 // classes have been inserted. It fills unused slots between inserted fields
331 // with EMPTY blocks, so the regular field insertion methods would work.
332 // This method handles classes with @Contended annotations differently
333 // by inserting PADDING blocks instead of EMPTY block to prevent subclasses'
334 // fields to interfere with contended fields/classes.
335 void FieldLayout::fill_holes(const InstanceKlass* super_klass) {
336 assert(_blocks != NULL, "Sanity check");
337 assert(_blocks->offset() == 0, "first block must be at offset zero");
338 LayoutRawBlock::Kind filling_type = super_klass->has_contended_annotations() ? LayoutRawBlock::PADDING: LayoutRawBlock::EMPTY;
339 LayoutRawBlock* b = _blocks;
340 while (b->next_block() != NULL) {
341 if (b->next_block()->offset() > (b->offset() + b->size())) {
342 int size = b->next_block()->offset() - (b->offset() + b->size());
343 LayoutRawBlock* empty = new LayoutRawBlock(filling_type, size);
344 empty->set_offset(b->offset() + b->size());
345 empty->set_next_block(b->next_block());
346 b->next_block()->set_prev_block(empty);
347 b->set_next_block(empty);
348 empty->set_prev_block(b);
349 }
350 b = b->next_block();
351 }
352 assert(b->next_block() == NULL, "Invariant at this point");
353 assert(b->kind() != LayoutRawBlock::EMPTY, "Sanity check");
354
355 // If the super class has @Contended annotation, a padding block is
356 // inserted at the end to ensure that fields from the subclasses won't share
357 // the cache line of the last field of the contended class
358 if (super_klass->has_contended_annotations() && ContendedPaddingWidth > 0) {
359 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
360 p->set_offset(b->offset() + b->size());
361 b->set_next_block(p);
362 p->set_prev_block(b);
363 b = p;
364 }
365
366 if (!UseEmptySlotsInSupers) {
367 // Add an empty slots to align fields of the subclass on a heapOopSize boundary
368 // in order to emulate the behavior of the previous algorithm
369 int align = (b->offset() + b->size()) % heapOopSize;
370 if (align != 0) {
371 int sz = heapOopSize - align;
372 LayoutRawBlock* p = new LayoutRawBlock(LayoutRawBlock::EMPTY, sz);
373 p->set_offset(b->offset() + b->size());
374 b->set_next_block(p);
375 p->set_prev_block(b);
376 b = p;
377 }
378 }
379
380 LayoutRawBlock* last = new LayoutRawBlock(LayoutRawBlock::EMPTY, INT_MAX);
381 last->set_offset(b->offset() + b->size());
382 assert(last->offset() > 0, "Sanity check");
383 b->set_next_block(last);
384 last->set_prev_block(b);
385 _last = last;
386 }
387
388 LayoutRawBlock* FieldLayout::insert(LayoutRawBlock* slot, LayoutRawBlock* block) {
389 assert(slot->kind() == LayoutRawBlock::EMPTY, "Blocks can only be inserted in empty blocks");
390 assert(slot->offset() % block->alignment() == 0, "Incompatible alignment");
391 block->set_offset(slot->offset());
392 slot->set_offset(slot->offset() + block->size());
393 assert((slot->size() - block->size()) < slot->size(), "underflow checking");
394 assert(slot->size() - block->size() >= 0, "no negative size allowed");
395 slot->set_size(slot->size() - block->size());
396 block->set_prev_block(slot->prev_block());
397 block->set_next_block(slot);
398 slot->set_prev_block(block);
399 if (block->prev_block() != NULL) {
400 block->prev_block()->set_next_block(block);
401 }
402 if (_blocks == slot) {
403 _blocks = block;
404 }
405 return block;
406 }
407
408 void FieldLayout::remove(LayoutRawBlock* block) {
409 assert(block != NULL, "Sanity check");
410 assert(block != _last, "Sanity check");
411 if (_blocks == block) {
412 _blocks = block->next_block();
413 if (_blocks != NULL) {
414 _blocks->set_prev_block(NULL);
415 }
416 } else {
417 assert(block->prev_block() != NULL, "_prev should be set for non-head blocks");
418 block->prev_block()->set_next_block(block->next_block());
419 block->next_block()->set_prev_block(block->prev_block());
420 }
421 if (block == _start) {
422 _start = block->prev_block();
423 }
424 }
425
426 void FieldLayout::print(outputStream* output, bool is_static, const InstanceKlass* super) {
427 ResourceMark rm;
428 LayoutRawBlock* b = _blocks;
429 while(b != _last) {
430 switch(b->kind()) {
431 case LayoutRawBlock::REGULAR: {
432 FieldInfo* fi = FieldInfo::from_field_array(_fields, b->field_index());
433 output->print_cr(" @%d \"%s\" %s %d/%d %s",
434 b->offset(),
435 fi->name(_cp)->as_C_string(),
436 fi->signature(_cp)->as_C_string(),
437 b->size(),
438 b->alignment(),
439 "REGULAR");
440 break;
441 }
442 case LayoutRawBlock::FLATTENED: {
443 FieldInfo* fi = FieldInfo::from_field_array(_fields, b->field_index());
444 output->print_cr(" @%d \"%s\" %s %d/%d %s",
445 b->offset(),
446 fi->name(_cp)->as_C_string(),
447 fi->signature(_cp)->as_C_string(),
448 b->size(),
449 b->alignment(),
450 "FLATTENED");
451 break;
452 }
453 case LayoutRawBlock::RESERVED: {
454 output->print_cr(" @%d %d/- %s",
455 b->offset(),
456 b->size(),
457 "RESERVED");
458 break;
459 }
460 case LayoutRawBlock::INHERITED: {
461 assert(!is_static, "Static fields are not inherited in layouts");
462 assert(super != NULL, "super klass must be provided to retrieve inherited fields info");
463 bool found = false;
464 const InstanceKlass* ik = super;
465 while (!found && ik != NULL) {
466 for (AllFieldStream fs(ik->fields(), ik->constants()); !fs.done(); fs.next()) {
467 if (fs.offset() == b->offset()) {
468 output->print_cr(" @%d \"%s\" %s %d/%d %s",
469 b->offset(),
470 fs.name()->as_C_string(),
471 fs.signature()->as_C_string(),
472 b->size(),
473 b->size(), // so far, alignment constraint == size, will change with Valhalla
474 "INHERITED");
475 found = true;
476 break;
477 }
478 }
479 ik = ik->java_super();
480 }
481 break;
482 }
483 case LayoutRawBlock::EMPTY:
484 output->print_cr(" @%d %d/1 %s",
485 b->offset(),
486 b->size(),
487 "EMPTY");
488 break;
489 case LayoutRawBlock::PADDING:
490 output->print_cr(" @%d %d/1 %s",
491 b->offset(),
492 b->size(),
493 "PADDING");
494 break;
495 }
496 b = b->next_block();
497 }
498 }
499
500 FieldLayoutBuilder::FieldLayoutBuilder(const Symbol* classname, const InstanceKlass* super_klass, ConstantPool* constant_pool,
501 Array<u2>* fields, bool is_contended, FieldLayoutInfo* info) :
502 _classname(classname),
503 _super_klass(super_klass),
504 _constant_pool(constant_pool),
505 _fields(fields),
506 _info(info),
507 _root_group(NULL),
508 _contended_groups(GrowableArray<FieldGroup*>(8)),
509 _static_fields(NULL),
510 _layout(NULL),
511 _static_layout(NULL),
512 _nonstatic_oopmap_count(0),
513 _alignment(-1),
514 _has_nonstatic_fields(false),
515 _is_contended(is_contended) {}
516
517
518 FieldGroup* FieldLayoutBuilder::get_or_create_contended_group(int g) {
519 assert(g > 0, "must only be called for named contended groups");
520 FieldGroup* fg = NULL;
521 for (int i = 0; i < _contended_groups.length(); i++) {
522 fg = _contended_groups.at(i);
523 if (fg->contended_group() == g) return fg;
524 }
525 fg = new FieldGroup(g);
526 _contended_groups.append(fg);
527 return fg;
528 }
529
530 void FieldLayoutBuilder::prologue() {
531 _layout = new FieldLayout(_fields, _constant_pool);
532 const InstanceKlass* super_klass = _super_klass;
533 _layout->initialize_instance_layout(super_klass);
534 if (super_klass != NULL) {
535 _has_nonstatic_fields = super_klass->has_nonstatic_fields();
536 }
537 _static_layout = new FieldLayout(_fields, _constant_pool);
538 _static_layout->initialize_static_layout();
539 _static_fields = new FieldGroup();
540 _root_group = new FieldGroup();
541 }
542
543 // Field sorting for regular classes:
544 // - fields are sorted in static and non-static fields
545 // - non-static fields are also sorted according to their contention group
546 // (support of the @Contended annotation)
547 // - @Contended annotation is ignored for static fields
548 void FieldLayoutBuilder::regular_field_sorting() {
549 for (AllFieldStream fs(_fields, _constant_pool); !fs.done(); fs.next()) {
550 FieldGroup* group = NULL;
551 if (fs.access_flags().is_static()) {
552 group = _static_fields;
553 } else {
554 _has_nonstatic_fields = true;
555 if (fs.is_contended()) {
556 int g = fs.contended_group();
557 if (g == 0) {
558 group = new FieldGroup(true);
559 _contended_groups.append(group);
560 } else {
561 group = get_or_create_contended_group(g);
562 }
563 } else {
564 group = _root_group;
565 }
566 }
567 assert(group != NULL, "invariant");
568 BasicType type = Signature::basic_type(fs.signature());
569 switch(type) {
570 case T_BYTE:
571 case T_CHAR:
572 case T_DOUBLE:
573 case T_FLOAT:
574 case T_INT:
575 case T_LONG:
576 case T_SHORT:
577 case T_BOOLEAN:
578 group->add_primitive_field(fs, type);
579 break;
580 case T_OBJECT:
581 case T_ARRAY:
582 if (group != _static_fields) _nonstatic_oopmap_count++;
583 group->add_oop_field(fs);
584 break;
585 default:
586 fatal("Something wrong?");
587 }
588 }
589 _root_group->sort_by_size();
590 _static_fields->sort_by_size();
591 if (!_contended_groups.is_empty()) {
592 for (int i = 0; i < _contended_groups.length(); i++) {
593 _contended_groups.at(i)->sort_by_size();
594 }
595 }
596 }
597
598 void FieldLayoutBuilder::insert_contended_padding(LayoutRawBlock* slot) {
599 if (ContendedPaddingWidth > 0) {
600 LayoutRawBlock* padding = new LayoutRawBlock(LayoutRawBlock::PADDING, ContendedPaddingWidth);
601 _layout->insert(slot, padding);
602 }
603 }
604
605 // Computation of regular classes layout is an evolution of the previous default layout
606 // (FieldAllocationStyle 1):
607 // - primitive fields are allocated first (from the biggest to the smallest)
608 // - then oop fields are allocated, either in existing gaps or at the end of
609 // the layout
610 void FieldLayoutBuilder::compute_regular_layout() {
611 bool need_tail_padding = false;
612 prologue();
613 regular_field_sorting();
614
615 if (_is_contended) {
616 _layout->set_start(_layout->last_block());
617 // insertion is currently easy because the current strategy doesn't try to fill holes
618 // in super classes layouts => the _start block is by consequence the _last_block
619 insert_contended_padding(_layout->start());
620 need_tail_padding = true;
621 }
622 _layout->add(_root_group->primitive_fields());
623 _layout->add(_root_group->oop_fields());
624
625 if (!_contended_groups.is_empty()) {
626 for (int i = 0; i < _contended_groups.length(); i++) {
627 FieldGroup* cg = _contended_groups.at(i);
628 LayoutRawBlock* start = _layout->last_block();
629 insert_contended_padding(start);
630 _layout->add(cg->primitive_fields(), start);
631 _layout->add(cg->oop_fields(), start);
632 need_tail_padding = true;
633 }
634 }
635
636 if (need_tail_padding) {
637 insert_contended_padding(_layout->last_block());
638 }
639
640 _static_layout->add_contiguously(this->_static_fields->oop_fields());
641 _static_layout->add(this->_static_fields->primitive_fields());
642
643 epilogue();
644 }
645
646 // Compute layout of the java/lang/ref/Reference class according
647 // to the hard coded offsets of its fields
648 void FieldLayoutBuilder::compute_java_lang_ref_Reference_layout() {
649 prologue();
650 regular_field_sorting();
651
652 assert(_contended_groups.is_empty(), "java.lang.Reference has no @Contended annotations");
653 assert(_root_group->primitive_fields() == NULL, "java.lang.Reference has no nonstatic primitive fields");
654 int field_count = 0;
655 int offset = -1;
656 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
657 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
658 FieldInfo* fi = FieldInfo::from_field_array(_fields, b->field_index());
659 if (fi->name(_constant_pool)->equals("referent")) {
660 offset = java_lang_ref_Reference::referent_offset;
661 } else if (fi->name(_constant_pool)->equals("queue")) {
662 offset = java_lang_ref_Reference::queue_offset;
663 } else if (fi->name(_constant_pool)->equals("next")) {
664 offset = java_lang_ref_Reference::next_offset;
665 } else if (fi->name(_constant_pool)->equals("discovered")) {
666 offset = java_lang_ref_Reference::discovered_offset;
667 }
668 assert(offset != -1, "Unknown field");
669 _layout->add_field_at_offset(b, offset);
670 field_count++;
671 }
672 assert(field_count == 4, "Wrong number of fields in java.lang.ref.Reference");
673
674 _static_layout->add_contiguously(this->_static_fields->oop_fields());
675 _static_layout->add(this->_static_fields->primitive_fields());
676
677 epilogue();
678 }
679
680 // Compute layout of the boxing class according
681 // to the hard coded offsets of their fields
682 void FieldLayoutBuilder::compute_boxing_class_layout() {
683 prologue();
684 regular_field_sorting();
685
686 assert(_contended_groups.is_empty(), "Boxing classes have no @Contended annotations");
687 assert(_root_group->oop_fields() == NULL, "Boxing classes have no nonstatic oops fields");
688 int field_count = 0;
689 int offset = -1;
690
691 for (int i = 0; i < _root_group->primitive_fields()->length(); i++) {
692 LayoutRawBlock* b = _root_group->primitive_fields()->at(i);
693 FieldInfo* fi = FieldInfo::from_field_array(_fields, b->field_index());
694 assert(fi->name(_constant_pool)->equals("value"), "Boxing classes have a single nonstatic field named 'value'");
695 BasicType type = Signature::basic_type(fi->signature(_constant_pool));
696 offset = java_lang_boxing_object::value_offset_in_bytes(type);
697 assert(offset != -1, "Unknown field");
698 _layout->add_field_at_offset(b, offset);
699 field_count++;
700 }
701 assert(field_count == 1, "Wrong number of fields for a boxing class");
702
703 _static_layout->add_contiguously(this->_static_fields->oop_fields());
704 _static_layout->add(this->_static_fields->primitive_fields());
705
706 epilogue();
707 }
708
709 void FieldLayoutBuilder::epilogue() {
710 // Computing oopmaps
711 int super_oop_map_count = (_super_klass == NULL) ? 0 :_super_klass->nonstatic_oop_map_count();
712 int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
713
714 OopMapBlocksBuilder* nonstatic_oop_maps =
715 new OopMapBlocksBuilder(max_oop_map_count);
716 if (super_oop_map_count > 0) {
717 nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
718 _super_klass->nonstatic_oop_map_count());
719 }
720
721 if (_root_group->oop_fields() != NULL) {
722 for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
723 LayoutRawBlock* b = _root_group->oop_fields()->at(i);
724 nonstatic_oop_maps->add(b->offset(), 1);
725 }
726 }
727
728 if (!_contended_groups.is_empty()) {
729 for (int i = 0; i < _contended_groups.length(); i++) {
730 FieldGroup* cg = _contended_groups.at(i);
731 if (cg->oop_count() > 0) {
732 assert(cg->oop_fields() != NULL && cg->oop_fields()->at(0) != NULL, "oop_count > 0 but no oop fields found");
733 nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
734 }
735 }
736 }
737
738 nonstatic_oop_maps->compact();
739
740 int instance_end = align_up(_layout->last_block()->offset(), wordSize);
741 int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
742 int static_fields_size = (static_fields_end -
743 InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
744 int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
745
746 // Pass back information needed for InstanceKlass creation
747
748 _info->oop_map_blocks = nonstatic_oop_maps;
749 _info->_instance_size = align_object_size(instance_end / wordSize);
750 _info->_static_field_size = static_fields_size;
751 _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
752 _info->_has_nonstatic_fields = _has_nonstatic_fields;
753
754 #ifndef PRODUCT
755 if (PrintFieldLayout) {
756 ResourceMark rm;
757 tty->print_cr("Layout of class %s", _classname->as_C_string());
758 tty->print_cr("Instance fields:");
759 _layout->print(tty, false, _super_klass);
760 tty->print_cr("Static fields:");
761 _static_layout->print(tty, true, NULL);
762 tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
763 tty->print_cr("---");
764 }
765 #endif
766 }
767
768 void FieldLayoutBuilder::build_layout() {
769 if (_classname == vmSymbols::java_lang_ref_Reference()) {
770 compute_java_lang_ref_Reference_layout();
771 } else if (_classname == vmSymbols::java_lang_Boolean() ||
772 _classname == vmSymbols::java_lang_Character() ||
773 _classname == vmSymbols::java_lang_Float() ||
774 _classname == vmSymbols::java_lang_Double() ||
775 _classname == vmSymbols::java_lang_Byte() ||
776 _classname == vmSymbols::java_lang_Short() ||
777 _classname == vmSymbols::java_lang_Integer() ||
778 _classname == vmSymbols::java_lang_Long()) {
779 compute_boxing_class_layout();
780 } else {
781 compute_regular_layout();
782 }
783 }
784