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/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(NULL),
 40   _prev_block(NULL),
 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(NULL),
 55  _prev_block(NULL),
 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(NULL),
 78   _primitive_fields(NULL),
 79   _oop_fields(NULL),
 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(AllFieldStream fs, BasicType type) {
 84   int size = type2aelembytes(type);
 85   LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::REGULAR, size, size /* alignment == size for primitive types */, false);
 86   if (_primitive_fields == NULL) {
 87     _primitive_fields = new(ResourceObj::RESOURCE_AREA, mtInternal) GrowableArray<LayoutRawBlock*>(INITIAL_LIST_SIZE);
 88   }
 89   _primitive_fields->append(block);
 90 }
 91 
 92 void FieldGroup::add_oop_field(AllFieldStream fs) {
 93   int size = type2aelembytes(T_OBJECT);
 94   LayoutRawBlock* block = new LayoutRawBlock(fs.index(), LayoutRawBlock::REGULAR, size, size /* alignment == size for oops */, true);
 95   if (_oop_fields == NULL) {
 96     _oop_fields = new(ResourceObj::RESOURCE_AREA, mtInternal) 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 != NULL) {
104     _primitive_fields->sort(LayoutRawBlock::compare_size_inverted);
105   }
106 }
107 
108 FieldLayout::FieldLayout(Array<u2>* fields, ConstantPool* cp) :
109   _fields(fields),
110   _cp(cp),
111   _blocks(NULL),
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 == NULL) {
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 == NULL) return;
165   if (start == NULL) 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 = NULL;
172     LayoutRawBlock* candidate = NULL;
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 != NULL, "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 == NULL || cursor->size() < candidate->size()) {
194             candidate = cursor;
195           }
196         }
197         cursor = cursor->prev_block();
198       }
199       if (candidate == NULL) {
200         candidate = last_block();
201         last_search_success = false;
202       }
203       assert(candidate != NULL, "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 != NULL, "Sanity check");
215   block->set_offset(offset);
216   if (start == NULL) {
217     start = this->_start;
218   }
219   LayoutRawBlock* slot = start;
220   while (slot != NULL) {
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       FieldInfo::from_field_array(_fields, 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 == NULL) return;
247   if (start == NULL) {
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 = NULL;
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 != NULL, "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   FieldInfo::from_field_array(_fields, 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 != NULL) {
301     for (AllFieldStream fs(ik->fields(), 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() == NULL ? NULL : 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 != NULL, "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() != NULL) {
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() == NULL, "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() != NULL) {
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 != NULL, "Sanity check");
411   assert(block != _last, "Sanity check");
412   if (_blocks == block) {
413     _blocks = block->next_block();
414     if (_blocks != NULL) {
415       _blocks->set_prev_block(NULL);
416     }
417   } else {
418     assert(block->prev_block() != NULL, "_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 = FieldInfo::from_field_array(_fields, 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 = FieldInfo::from_field_array(_fields, 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 != NULL, "super klass must be provided to retrieve inherited fields info");
464         bool found = false;
465         const InstanceKlass* ik = super;
466         while (!found && ik != NULL) {
467           for (AllFieldStream fs(ik->fields(), 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       Array<u2>* fields, bool is_contended, FieldLayoutInfo* info) :
503   _classname(classname),
504   _super_klass(super_klass),
505   _constant_pool(constant_pool),
506   _fields(fields),
507   _info(info),
508   _root_group(NULL),
509   _contended_groups(GrowableArray<FieldGroup*>(8)),
510   _static_fields(NULL),
511   _layout(NULL),
512   _static_layout(NULL),
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 = NULL;
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(_fields, _constant_pool);
533   const InstanceKlass* super_klass = _super_klass;
534   _layout->initialize_instance_layout(super_klass);
535   if (super_klass != NULL) {
536     _has_nonstatic_fields = super_klass->has_nonstatic_fields();
537   }
538   _static_layout = new FieldLayout(_fields, _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   for (AllFieldStream fs(_fields, _constant_pool); !fs.done(); fs.next()) {
551     FieldGroup* group = NULL;
552     if (fs.access_flags().is_static()) {
553       group = _static_fields;
554     } else {
555       _has_nonstatic_fields = true;
556       if (fs.is_contended()) {
557         int g = fs.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 != NULL, "invariant");
569     BasicType type = Signature::basic_type(fs.signature());
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(fs, type);
580         break;
581       case T_OBJECT:
582       case T_ARRAY:
583         if (group != _static_fields) _nonstatic_oopmap_count++;
584         group->add_oop_field(fs);
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 //   - then oop fields are allocated, either in existing gaps or at the end of
610 //     the layout
611 void FieldLayoutBuilder::compute_regular_layout() {
612   bool need_tail_padding = false;
613   prologue();
614   regular_field_sorting();
615 
616   if (_is_contended) {
617     _layout->set_start(_layout->last_block());
618     // insertion is currently easy because the current strategy doesn't try to fill holes
619     // in super classes layouts => the _start block is by consequence the _last_block
620     insert_contended_padding(_layout->start());
621     need_tail_padding = true;
622   }
623   _layout->add(_root_group->primitive_fields());
624   _layout->add(_root_group->oop_fields());
625 
626   if (!_contended_groups.is_empty()) {
627     for (int i = 0; i < _contended_groups.length(); i++) {
628       FieldGroup* cg = _contended_groups.at(i);
629       LayoutRawBlock* start = _layout->last_block();
630       insert_contended_padding(start);
631       _layout->add(cg->primitive_fields(), start);
632       _layout->add(cg->oop_fields(), start);
633       need_tail_padding = true;
634     }
635   }
636 
637   if (need_tail_padding) {
638     insert_contended_padding(_layout->last_block());
639   }
640 
641   _static_layout->add_contiguously(this->_static_fields->oop_fields());
642   _static_layout->add(this->_static_fields->primitive_fields());
643 
644   epilogue();
645 }
646 
647 void FieldLayoutBuilder::epilogue() {
648   // Computing oopmaps
649   int super_oop_map_count = (_super_klass == NULL) ? 0 :_super_klass->nonstatic_oop_map_count();
650   int max_oop_map_count = super_oop_map_count + _nonstatic_oopmap_count;
651 
652   OopMapBlocksBuilder* nonstatic_oop_maps =
653       new OopMapBlocksBuilder(max_oop_map_count);
654   if (super_oop_map_count > 0) {
655     nonstatic_oop_maps->initialize_inherited_blocks(_super_klass->start_of_nonstatic_oop_maps(),
656     _super_klass->nonstatic_oop_map_count());
657   }
658 
659   if (_root_group->oop_fields() != NULL) {
660     for (int i = 0; i < _root_group->oop_fields()->length(); i++) {
661       LayoutRawBlock* b = _root_group->oop_fields()->at(i);
662       nonstatic_oop_maps->add(b->offset(), 1);
663     }
664   }
665 
666   if (!_contended_groups.is_empty()) {
667     for (int i = 0; i < _contended_groups.length(); i++) {
668       FieldGroup* cg = _contended_groups.at(i);
669       if (cg->oop_count() > 0) {
670         assert(cg->oop_fields() != NULL && cg->oop_fields()->at(0) != NULL, "oop_count > 0 but no oop fields found");
671         nonstatic_oop_maps->add(cg->oop_fields()->at(0)->offset(), cg->oop_count());
672       }
673     }
674   }
675 
676   nonstatic_oop_maps->compact();
677 
678   int instance_end = align_up(_layout->last_block()->offset(), wordSize);
679   int static_fields_end = align_up(_static_layout->last_block()->offset(), wordSize);
680   int static_fields_size = (static_fields_end -
681       InstanceMirrorKlass::offset_of_static_fields()) / wordSize;
682   int nonstatic_field_end = align_up(_layout->last_block()->offset(), heapOopSize);
683 
684   // Pass back information needed for InstanceKlass creation
685 
686   _info->oop_map_blocks = nonstatic_oop_maps;
687   _info->_instance_size = align_object_size(instance_end / wordSize);
688   _info->_static_field_size = static_fields_size;
689   _info->_nonstatic_field_size = (nonstatic_field_end - instanceOopDesc::base_offset_in_bytes()) / heapOopSize;
690   _info->_has_nonstatic_fields = _has_nonstatic_fields;
691 
692   if (PrintFieldLayout) {
693     ResourceMark rm;
694     tty->print_cr("Layout of class %s", _classname->as_C_string());
695     tty->print_cr("Instance fields:");
696     _layout->print(tty, false, _super_klass);
697     tty->print_cr("Static fields:");
698     _static_layout->print(tty, true, NULL);
699     tty->print_cr("Instance size = %d bytes", _info->_instance_size * wordSize);
700     tty->print_cr("---");
701   }
702 }
703 
704 void FieldLayoutBuilder::build_layout() {
705   compute_regular_layout();
706 }