1 /*
2 * Copyright (c) 1997, 2015, 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 *
38
39 CodeHeap::CodeHeap(const char* name, const int code_blob_type)
40 : _code_blob_type(code_blob_type) {
41 _name = name;
42 _number_of_committed_segments = 0;
43 _number_of_reserved_segments = 0;
44 _segment_size = 0;
45 _log2_segment_size = 0;
46 _next_segment = 0;
47 _freelist = NULL;
48 _freelist_segments = 0;
49 _freelist_length = 0;
50 _max_allocated_capacity = 0;
51 _blob_count = 0;
52 _nmethod_count = 0;
53 _adapter_count = 0;
54 _full_count = 0;
55 }
56
57
58 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
59 assert( beg < _number_of_committed_segments, "interval begin out of bounds");
60 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
61 // setup _segmap pointers for faster indexing
62 address p = (address)_segmap.low() + beg;
63 address q = (address)_segmap.low() + end;
64 // initialize interval
65 while (p < q) *p++ = free_sentinel;
66 }
67
68
69 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
70 assert( beg < _number_of_committed_segments, "interval begin out of bounds");
71 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
72 // setup _segmap pointers for faster indexing
73 address p = (address)_segmap.low() + beg;
74 address q = (address)_segmap.low() + end;
75 // initialize interval
76 int i = 0;
77 while (p < q) {
78 *p++ = i++;
79 if (i == free_sentinel) i = 1;
80 }
81 }
82
83
84 static size_t align_to_page_size(size_t size) {
85 const size_t alignment = (size_t)os::vm_page_size();
86 assert(is_power_of_2(alignment), "no kidding ???");
87 return (size + alignment - 1) & ~(alignment - 1);
88 }
89
90
91 void CodeHeap::on_code_mapping(char* base, size_t size) {
92 #ifdef LINUX
93 extern void linux_wrap_code(char* base, size_t size);
94 linux_wrap_code(base, size);
95 #endif
96 }
97
98
99 bool CodeHeap::reserve(ReservedSpace rs, size_t committed_size, size_t segment_size) {
100 assert(rs.size() >= committed_size, "reserved < committed");
123
124 on_code_mapping(_memory.low(), _memory.committed_size());
125 _number_of_committed_segments = size_to_segments(_memory.committed_size());
126 _number_of_reserved_segments = size_to_segments(_memory.reserved_size());
127 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
128 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity);
129 const size_t reserved_segments_size = align_up(_number_of_reserved_segments, reserved_segments_alignment);
130 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments);
131
132 // reserve space for _segmap
133 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) {
134 return false;
135 }
136
137 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode);
138
139 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
140 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
141 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
142
143 // initialize remaining instance variables
144 clear();
145 return true;
146 }
147
148
149 bool CodeHeap::expand_by(size_t size) {
150 // expand _memory space
151 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
152 if (dm > 0) {
153 // Use at least the available uncommitted space if 'size' is larger
154 if (_memory.uncommitted_size() != 0 && dm > _memory.uncommitted_size()) {
155 dm = _memory.uncommitted_size();
156 }
157 char* base = _memory.low() + _memory.committed_size();
158 if (!_memory.expand_by(dm)) return false;
159 on_code_mapping(base, dm);
160 size_t i = _number_of_committed_segments;
161 _number_of_committed_segments = size_to_segments(_memory.committed_size());
162 assert(_number_of_reserved_segments == size_to_segments(_memory.reserved_size()), "number of reserved segments should not change");
163 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
164 // expand _segmap space
165 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
166 if ((ds > 0) && !_segmap.expand_by(ds)) {
167 return false;
168 }
169 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
170 // initialize additional segmap entries
171 mark_segmap_as_free(i, _number_of_committed_segments);
172 }
173 return true;
174 }
175
176 void CodeHeap::clear() {
177 _next_segment = 0;
178 mark_segmap_as_free(0, _number_of_committed_segments);
179 }
180
181
182 void* CodeHeap::allocate(size_t instance_size) {
183 size_t number_of_segments = size_to_segments(instance_size + header_size());
184 assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList");
185
186 // First check if we can satisfy request from freelist
187 NOT_PRODUCT(verify());
188 HeapBlock* block = search_freelist(number_of_segments);
189 NOT_PRODUCT(verify());
190
191 if (block != NULL) {
192 assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check");
193 assert(!block->free(), "must be marked free");
194 guarantee((char*) block >= _memory.low_boundary() && (char*) block < _memory.high(),
195 "The newly allocated block " INTPTR_FORMAT " is not within the heap "
196 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
197 p2i(block), p2i(_memory.low_boundary()), p2i(_memory.high()));
198 DEBUG_ONLY(memset((void*)block->allocated_space(), badCodeHeapNewVal, instance_size));
199 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());
200 _blob_count++;
201 return block->allocated_space();
202 }
203
204 // Ensure minimum size for allocation to the heap.
205 number_of_segments = MAX2((int)CodeCacheMinBlockLength, (int)number_of_segments);
206
207 if (_next_segment + number_of_segments <= _number_of_committed_segments) {
208 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments);
209 HeapBlock* b = block_at(_next_segment);
210 b->initialize(number_of_segments);
211 _next_segment += number_of_segments;
212 guarantee((char*) b >= _memory.low_boundary() && (char*) block < _memory.high(),
213 "The newly allocated block " INTPTR_FORMAT " is not within the heap "
214 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
215 p2i(b), p2i(_memory.low_boundary()), p2i(_memory.high()));
216 DEBUG_ONLY(memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size));
217 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());
218 _blob_count++;
219 return b->allocated_space();
220 } else {
221 return NULL;
222 }
223 }
224
225 void CodeHeap::deallocate_tail(void* p, size_t used_size) {
226 assert(p == find_start(p), "illegal deallocation");
227 // Find start of HeapBlock
228 HeapBlock* b = (((HeapBlock *)p) - 1);
229 assert(b->allocated_space() == p, "sanity check");
230 size_t used_number_of_segments = size_to_segments(used_size + header_size());
231 size_t actual_number_of_segments = b->length();
232 guarantee(used_number_of_segments <= actual_number_of_segments, "Must be!");
233 guarantee(b == block_at(_next_segment - actual_number_of_segments), "Intermediate allocation!");
234 size_t number_of_segments_to_deallocate = actual_number_of_segments - used_number_of_segments;
235 _next_segment -= number_of_segments_to_deallocate;
236 mark_segmap_as_free(_next_segment, _next_segment + number_of_segments_to_deallocate);
237 b->initialize(used_number_of_segments);
238 }
239
240 void CodeHeap::deallocate(void* p) {
241 assert(p == find_start(p), "illegal deallocation");
242 // Find start of HeapBlock
243 HeapBlock* b = (((HeapBlock *)p) - 1);
244 assert(b->allocated_space() == p, "sanity check");
245 guarantee((char*) b >= _memory.low_boundary() && (char*) b < _memory.high(),
246 "The block to be deallocated " INTPTR_FORMAT " is not within the heap "
247 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
248 p2i(b), p2i(_memory.low_boundary()), p2i(_memory.high()));
249 DEBUG_ONLY(memset((void *)b->allocated_space(), badCodeHeapFreeVal,
250 segments_to_size(b->length()) - sizeof(HeapBlock)));
251 add_to_freelist(b);
252 NOT_PRODUCT(verify());
253 }
254
255 /**
256 * Uses segment map to find the the start (header) of a nmethod. This works as follows:
257 * The memory of the code cache is divided into 'segments'. The size of a segment is
258 * determined by -XX:CodeCacheSegmentSize=XX. Allocation in the code cache can only
259 * happen at segment boundaries. A pointer in the code cache can be mapped to a segment
260 * by calling segment_for(addr). Each time memory is requested from the code cache,
261 * the segmap is updated accordingly. See the following example, which illustrates the
262 * state of code cache and the segment map: (seg -> segment, nm ->nmethod)
263 *
264 * code cache segmap
265 * ----------- ---------
266 * seg 1 | nm 1 | -> | 0 |
267 * seg 2 | nm 1 | -> | 1 |
268 * ... | nm 1 | -> | .. |
269 * seg m | nm 2 | -> | 0 |
270 * seg m+1 | nm 2 | -> | 1 |
393 // Link b into the list after a
394 b->set_link(a->link());
395 a->set_link(b);
396
397 // See if we can merge blocks
398 merge_right(b); // Try to make b bigger
399 merge_right(a); // Try to make a include b
400 }
401
402 // Try to merge this block with the following block
403 bool CodeHeap::merge_right(FreeBlock* a) {
404 assert(a->free(), "must be a free block");
405 if (following_block(a) == a->link()) {
406 assert(a->link() != NULL && a->link()->free(), "must be free too");
407 // Update block a to include the following block
408 a->set_length(a->length() + a->link()->length());
409 a->set_link(a->link()->link());
410 // Update find_start map
411 size_t beg = segment_for(a);
412 mark_segmap_as_used(beg, beg + a->length());
413 _freelist_length--;
414 return true;
415 }
416 return false;
417 }
418
419
420 void CodeHeap::add_to_freelist(HeapBlock* a) {
421 FreeBlock* b = (FreeBlock*)a;
422 _freelist_length++;
423
424 assert(b != _freelist, "cannot be removed twice");
425
426
427 // Mark as free and update free space count
428 _freelist_segments += b->length();
429 b->set_free();
430
431 // First element in list?
432 if (_freelist == NULL) {
433 _freelist = b;
434 b->set_link(NULL);
435 return;
436 }
437
438 // Since the freelist is ordered (smaller addresses -> larger addresses) and the
439 // element we want to insert into the freelist has a smaller address than the first
440 // element, we can simply add 'b' as the first element and we are done.
441 if (b < _freelist) {
442 // Insert first in list
443 b->set_link(_freelist);
444 _freelist = b;
445 merge_right(_freelist);
446 return;
447 }
448
449 // Scan for right place to put into list. List
450 // is sorted by increasing addresses
451 FreeBlock* prev = _freelist;
452 FreeBlock* cur = _freelist->link();
453 while(cur != NULL && cur < b) {
454 assert(prev < cur, "Freelist must be ordered");
455 prev = cur;
456 cur = cur->link();
457 }
458 assert((prev < b) && (cur == NULL || b < cur), "free-list must be ordered");
459 insert_after(prev, b);
460 }
461
462 /**
463 * Search freelist for an entry on the list with the best fit.
464 * @return NULL, if no one was found
465 */
466 FreeBlock* CodeHeap::search_freelist(size_t length) {
467 FreeBlock* found_block = NULL;
468 FreeBlock* found_prev = NULL;
469 size_t found_length = 0;
470
471 FreeBlock* prev = NULL;
472 FreeBlock* cur = _freelist;
473
474 // Search for first block that fits
475 while(cur != NULL) {
476 if (cur->length() >= length) {
477 // Remember block, its previous element, and its length
478 found_block = cur;
479 found_prev = prev;
480 found_length = found_block->length();
481
482 break;
483 }
484 // Next element in list
485 prev = cur;
486 cur = cur->link();
487 }
488
489 if (found_block == NULL) {
490 // None found
491 return NULL;
492 }
493
494 // Exact (or at least good enough) fit. Remove from list.
495 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
496 if (found_length - length < CodeCacheMinBlockLength) {
497 _freelist_length--;
498 length = found_length;
499 if (found_prev == NULL) {
500 assert(_freelist == found_block, "sanity check");
501 _freelist = _freelist->link();
502 } else {
503 assert((found_prev->link() == found_block), "sanity check");
504 // Unmap element
505 found_prev->set_link(found_block->link());
506 }
507 } else {
508 // Truncate block and return a pointer to the following block
509 // Set used bit and length on new block
510 found_block->set_length(found_length - length);
511 found_block = following_block(found_block);
512
513 size_t beg = segment_for(found_block);
514 mark_segmap_as_used(beg, beg + length);
515 found_block->set_length(length);
516 }
517
518 found_block->set_used();
519 _freelist_segments -= length;
520 return found_block;
521 }
522
523 //----------------------------------------------------------------------------
524 // Non-product code
525
526 #ifndef PRODUCT
527
528 void CodeHeap::print() {
529 tty->print_cr("The Heap");
530 }
531
532 void CodeHeap::verify() {
533 if (VerifyCodeCache) {
534 size_t len = 0;
535 int count = 0;
536 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
537 len += b->length();
538 count++;
539 // Check if we have merged all free blocks
540 assert(merge_right(b) == false, "Missed merging opportunity");
541 }
542 // Verify that freelist contains the right amount of free space
543 assert(len == _freelist_segments, "wrong freelist");
544
545 for(HeapBlock* h = first_block(); h != NULL; h = next_block(h)) {
546 if (h->free()) count--;
547 }
548 // Verify that the freelist contains the same number of blocks
549 // than free blocks found on the full list.
550 assert(count == 0, "missing free blocks");
551
552 // Verify that the number of free blocks is not out of hand.
553 static int free_block_threshold = 10000;
554 if (count > free_block_threshold) {
555 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
556 // Double the warning limit
557 free_block_threshold *= 2;
558 }
559 }
560 }
561
562 #endif
|
1 /*
2 * Copyright (c) 1997, 2019, 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 *
38
39 CodeHeap::CodeHeap(const char* name, const int code_blob_type)
40 : _code_blob_type(code_blob_type) {
41 _name = name;
42 _number_of_committed_segments = 0;
43 _number_of_reserved_segments = 0;
44 _segment_size = 0;
45 _log2_segment_size = 0;
46 _next_segment = 0;
47 _freelist = NULL;
48 _freelist_segments = 0;
49 _freelist_length = 0;
50 _max_allocated_capacity = 0;
51 _blob_count = 0;
52 _nmethod_count = 0;
53 _adapter_count = 0;
54 _full_count = 0;
55 }
56
57
58 // The segmap is marked free for that part of the heap
59 // which has not been allocated yet (beyond _next_segment).
60 // "Allocated" space in this context means there exists a
61 // HeapBlock or a FreeBlock describing this space.
62 // This method takes segment map indices as range boundaries
63 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
64 assert( beg < _number_of_committed_segments, "interval begin out of bounds");
65 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
66 // Don't do unpredictable things in PRODUCT build
67 if (beg < end) {
68 // setup _segmap pointers for faster indexing
69 address p = (address)_segmap.low() + beg;
70 address q = (address)_segmap.low() + end;
71 // initialize interval
72 memset(p, free_sentinel, q-p);
73 }
74 }
75
76 // Don't get confused here.
77 // All existing blocks, no matter if they are used() or free(),
78 // have their segmap marked as used. This allows to find the
79 // block header (HeapBlock or FreeBlock) for any pointer
80 // within the allocated range (upper limit: _next_segment).
81 // This method takes segment map indices as range boundaries
82 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
83 assert( beg < _number_of_committed_segments, "interval begin out of bounds");
84 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
85 // Don't do unpredictable things in PRODUCT build
86 if (beg < end) {
87 // setup _segmap pointers for faster indexing
88 address p = (address)_segmap.low() + beg;
89 address q = (address)_segmap.low() + end;
90 // initialize interval
91 int i = 0;
92 while (p < q) {
93 *p++ = i++;
94 if (i == free_sentinel) i = 1;
95 }
96 }
97 }
98
99 void CodeHeap::invalidate(size_t beg, size_t end, size_t hdr_size) {
100 #ifndef PRODUCT
101 // Fill the given range with some bad value.
102 // length is expected to be in segment_size units.
103 // This prevents inadvertent execution of code leftover from previous use.
104 char* p = low_boundary() + segments_to_size(beg) + hdr_size;
105 memset(p, badCodeHeapNewVal, segments_to_size(end-beg)-hdr_size);
106 #endif
107 }
108
109 void CodeHeap::clear(size_t beg, size_t end) {
110 mark_segmap_as_free(beg, end);
111 invalidate(beg, end, 0);
112 }
113
114 void CodeHeap::clear() {
115 _next_segment = 0;
116 clear(_next_segment, _number_of_committed_segments);
117 }
118
119
120 static size_t align_to_page_size(size_t size) {
121 const size_t alignment = (size_t)os::vm_page_size();
122 assert(is_power_of_2(alignment), "no kidding ???");
123 return (size + alignment - 1) & ~(alignment - 1);
124 }
125
126
127 void CodeHeap::on_code_mapping(char* base, size_t size) {
128 #ifdef LINUX
129 extern void linux_wrap_code(char* base, size_t size);
130 linux_wrap_code(base, size);
131 #endif
132 }
133
134
135 bool CodeHeap::reserve(ReservedSpace rs, size_t committed_size, size_t segment_size) {
136 assert(rs.size() >= committed_size, "reserved < committed");
159
160 on_code_mapping(_memory.low(), _memory.committed_size());
161 _number_of_committed_segments = size_to_segments(_memory.committed_size());
162 _number_of_reserved_segments = size_to_segments(_memory.reserved_size());
163 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
164 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity);
165 const size_t reserved_segments_size = align_up(_number_of_reserved_segments, reserved_segments_alignment);
166 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments);
167
168 // reserve space for _segmap
169 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) {
170 return false;
171 }
172
173 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode);
174
175 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
176 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
177 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
178
179 // initialize remaining instance variables, heap memory and segmap
180 clear();
181 return true;
182 }
183
184
185 bool CodeHeap::expand_by(size_t size) {
186 // expand _memory space
187 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
188 if (dm > 0) {
189 // Use at least the available uncommitted space if 'size' is larger
190 if (_memory.uncommitted_size() != 0 && dm > _memory.uncommitted_size()) {
191 dm = _memory.uncommitted_size();
192 }
193 char* base = _memory.low() + _memory.committed_size();
194 if (!_memory.expand_by(dm)) return false;
195 on_code_mapping(base, dm);
196 size_t i = _number_of_committed_segments;
197 _number_of_committed_segments = size_to_segments(_memory.committed_size());
198 assert(_number_of_reserved_segments == size_to_segments(_memory.reserved_size()), "number of reserved segments should not change");
199 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
200 // expand _segmap space
201 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
202 if ((ds > 0) && !_segmap.expand_by(ds)) {
203 return false;
204 }
205 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
206 // initialize additional space (heap memory and segmap)
207 clear(i, _number_of_committed_segments);
208 }
209 return true;
210 }
211
212
213 void* CodeHeap::allocate(size_t instance_size) {
214 size_t number_of_segments = size_to_segments(instance_size + header_size());
215 assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList");
216
217 // First check if we can satisfy request from freelist
218 NOT_PRODUCT(verify());
219 HeapBlock* block = search_freelist(number_of_segments);
220 NOT_PRODUCT(verify());
221
222 if (block != NULL) {
223 assert(!block->free(), "must be marked free");
224 guarantee((char*) block >= _memory.low_boundary() && (char*) block < _memory.high(),
225 "The newly allocated block " INTPTR_FORMAT " is not within the heap "
226 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
227 p2i(block), p2i(_memory.low_boundary()), p2i(_memory.high()));
228 // Invalidate the additional space that FreeBlock occupies. The rest of the block should already be invalidated.
229 // This is necessary due to a dubious assert in nmethod.cpp(PcDescCache::reset_to()).
230 DEBUG_ONLY(memset((void*)block->allocated_space(), badCodeHeapNewVal, sizeof(FreeBlock) - sizeof(HeapBlock)));
231 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());
232 _blob_count++;
233 return block->allocated_space();
234 }
235
236 // Ensure minimum size for allocation to the heap.
237 number_of_segments = MAX2((int)CodeCacheMinBlockLength, (int)number_of_segments);
238
239 if (_next_segment + number_of_segments <= _number_of_committed_segments) {
240 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments);
241 HeapBlock* b = block_at(_next_segment);
242 b->initialize(number_of_segments);
243 _next_segment += number_of_segments;
244 guarantee((char*) b >= _memory.low_boundary() && (char*) block < _memory.high(),
245 "The newly allocated block " INTPTR_FORMAT " is not within the heap "
246 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
247 p2i(b), p2i(_memory.low_boundary()), p2i(_memory.high()));
248 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());
249 _blob_count++;
250 return b->allocated_space();
251 } else {
252 return NULL;
253 }
254 }
255
256 // Split the given block into two at the given segment.
257 // This is helpful when a block was allocated too large
258 // to trim off the unused space at the end (interpreter).
259 // It also helps with splitting a large free block during allocation.
260 // Usage state (used or free) must be set by caller since
261 // we don't know if the resulting blocks will be used or free.
262 // split_at is the segment number (relative to segment_for(b))
263 // where the split happens. The segment with relative
264 // number split_at is the first segment of the split-off block.
265 HeapBlock* CodeHeap::split_block(HeapBlock *b, size_t split_at) {
266 if (b == NULL) return NULL;
267 // After the split, both blocks must have a size of at least CodeCacheMinBlockLength
268 assert((split_at >= CodeCacheMinBlockLength) && (split_at + CodeCacheMinBlockLength <= b->length()),
269 "split position(%d) out of range [0..%d]", (int)split_at, (int)b->length());
270 size_t split_segment = segment_for(b) + split_at;
271 size_t b_size = b->length();
272 size_t newb_size = b_size - split_at;
273
274 HeapBlock* newb = block_at(split_segment);
275 newb->set_length(newb_size);
276 mark_segmap_as_used(segment_for(newb), segment_for(newb) + newb_size);
277 b->set_length(split_at);
278 return newb;
279 }
280
281 void CodeHeap::deallocate_tail(void* p, size_t used_size) {
282 assert(p == find_start(p), "illegal deallocation");
283 // Find start of HeapBlock
284 HeapBlock* b = (((HeapBlock *)p) - 1);
285 assert(b->allocated_space() == p, "sanity check");
286
287 size_t actual_number_of_segments = b->length();
288 size_t used_number_of_segments = size_to_segments(used_size + header_size());
289 size_t unused_number_of_segments = actual_number_of_segments - used_number_of_segments;
290 guarantee(used_number_of_segments <= actual_number_of_segments, "Must be!");
291
292 HeapBlock* f = split_block(b, used_number_of_segments);
293 add_to_freelist(f);
294 NOT_PRODUCT(verify());
295 }
296
297 void CodeHeap::deallocate(void* p) {
298 assert(p == find_start(p), "illegal deallocation");
299 // Find start of HeapBlock
300 HeapBlock* b = (((HeapBlock *)p) - 1);
301 assert(b->allocated_space() == p, "sanity check");
302 guarantee((char*) b >= _memory.low_boundary() && (char*) b < _memory.high(),
303 "The block to be deallocated " INTPTR_FORMAT " is not within the heap "
304 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
305 p2i(b), p2i(_memory.low_boundary()), p2i(_memory.high()));
306 add_to_freelist(b);
307 NOT_PRODUCT(verify());
308 }
309
310 /**
311 * Uses segment map to find the the start (header) of a nmethod. This works as follows:
312 * The memory of the code cache is divided into 'segments'. The size of a segment is
313 * determined by -XX:CodeCacheSegmentSize=XX. Allocation in the code cache can only
314 * happen at segment boundaries. A pointer in the code cache can be mapped to a segment
315 * by calling segment_for(addr). Each time memory is requested from the code cache,
316 * the segmap is updated accordingly. See the following example, which illustrates the
317 * state of code cache and the segment map: (seg -> segment, nm ->nmethod)
318 *
319 * code cache segmap
320 * ----------- ---------
321 * seg 1 | nm 1 | -> | 0 |
322 * seg 2 | nm 1 | -> | 1 |
323 * ... | nm 1 | -> | .. |
324 * seg m | nm 2 | -> | 0 |
325 * seg m+1 | nm 2 | -> | 1 |
448 // Link b into the list after a
449 b->set_link(a->link());
450 a->set_link(b);
451
452 // See if we can merge blocks
453 merge_right(b); // Try to make b bigger
454 merge_right(a); // Try to make a include b
455 }
456
457 // Try to merge this block with the following block
458 bool CodeHeap::merge_right(FreeBlock* a) {
459 assert(a->free(), "must be a free block");
460 if (following_block(a) == a->link()) {
461 assert(a->link() != NULL && a->link()->free(), "must be free too");
462 // Update block a to include the following block
463 a->set_length(a->length() + a->link()->length());
464 a->set_link(a->link()->link());
465 // Update find_start map
466 size_t beg = segment_for(a);
467 mark_segmap_as_used(beg, beg + a->length());
468 invalidate(beg, beg + a->length(), sizeof(FreeBlock));
469 _freelist_length--;
470 return true;
471 }
472 return false;
473 }
474
475
476 void CodeHeap::add_to_freelist(HeapBlock* a) {
477 FreeBlock* b = (FreeBlock*)a;
478 size_t bseg = segment_for(b);
479 _freelist_length++;
480
481 assert(b != _freelist, "cannot be removed twice");
482
483 // Mark as free and update free space count
484 _freelist_segments += b->length();
485 b->set_free();
486 invalidate(bseg, bseg + b->length(), sizeof(FreeBlock));
487
488 // First element in list?
489 if (_freelist == NULL) {
490 b->set_link(NULL);
491 _freelist = b;
492 return;
493 }
494
495 // Since the freelist is ordered (smaller addresses -> larger addresses) and the
496 // element we want to insert into the freelist has a smaller address than the first
497 // element, we can simply add 'b' as the first element and we are done.
498 if (b < _freelist) {
499 // Insert first in list
500 b->set_link(_freelist);
501 _freelist = b;
502 merge_right(_freelist);
503 return;
504 }
505
506 // Scan for right place to put into list. List
507 // is sorted by increasing addresses
508 FreeBlock* prev = _freelist;
509 FreeBlock* cur = _freelist->link();
510 while(cur != NULL && cur < b) {
511 assert(prev < cur, "Freelist must be ordered");
512 prev = cur;
513 cur = cur->link();
514 }
515 assert((prev < b) && (cur == NULL || b < cur), "free-list must be ordered");
516 insert_after(prev, b);
517 }
518
519 /**
520 * Search freelist for an entry on the list with the best fit.
521 * @return NULL, if no one was found
522 */
523 HeapBlock* CodeHeap::search_freelist(size_t length) {
524 FreeBlock* found_block = NULL;
525 FreeBlock* found_prev = NULL;
526 size_t found_length = _next_segment; // max it out to begin with
527
528 HeapBlock* res = NULL;
529 FreeBlock* prev = NULL;
530 FreeBlock* cur = _freelist;
531
532 length = length < CodeCacheMinBlockLength ? CodeCacheMinBlockLength : length;
533
534 // Search for best-fitting block
535 while(cur != NULL) {
536 size_t cur_length = cur->length();
537 if (cur_length == length) {
538 // We have a perfect fit
539 found_block = cur;
540 found_prev = prev;
541 found_length = cur_length;
542 break;
543 } else if ((cur_length > length) && (cur_length < found_length)) {
544 // This is a new, closer fit. Remember block, its previous element, and its length
545 found_block = cur;
546 found_prev = prev;
547 found_length = cur_length;
548 }
549 // Next element in list
550 prev = cur;
551 cur = cur->link();
552 }
553
554 if (found_block == NULL) {
555 // None found
556 return NULL;
557 }
558
559 // Exact (or at least good enough) fit. Remove from list.
560 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
561 if (found_length - length < CodeCacheMinBlockLength) {
562 _freelist_length--;
563 length = found_length;
564 if (found_prev == NULL) {
565 assert(_freelist == found_block, "sanity check");
566 _freelist = _freelist->link();
567 } else {
568 assert((found_prev->link() == found_block), "sanity check");
569 // Unmap element
570 found_prev->set_link(found_block->link());
571 }
572 res = found_block;
573 } else {
574 // Truncate the free block and return the truncated part
575 // as new HeapBlock. The remaining free block does not
576 // need to be updated, except for it's length. Truncating
577 // the segment map does not invalidate the leading part.
578 res = split_block(found_block, found_length - length);
579 }
580
581 res->set_used();
582 _freelist_segments -= length;
583 return res;
584 }
585
586 //----------------------------------------------------------------------------
587 // Non-product code
588
589 #ifndef PRODUCT
590
591 void CodeHeap::print() {
592 tty->print_cr("The Heap");
593 }
594
595 void CodeHeap::verify() {
596 if (VerifyCodeCache) {
597 size_t len = 0;
598 int count = 0;
599 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
600 len += b->length();
601 count++;
602 // Check if we have merged all free blocks
603 assert(merge_right(b) == false, "Missed merging opportunity");
604 }
605 // Verify that freelist contains the right amount of free space
606 assert(len == _freelist_segments, "wrong freelist");
607
608 for(HeapBlock* h = first_block(); h != NULL; h = next_block(h)) {
609 if (h->free()) count--;
610 }
611 // Verify that the freelist contains the same number of blocks
612 // than free blocks found on the full list.
613 assert(count == 0, "missing free blocks");
614
615 //---< all free block memory must have been invalidated >---
616 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
617 for (char* c = (char*)b + sizeof(FreeBlock); c < (char*)b + segments_to_size(b->length()); c++) {
618 assert(*c == (char)badCodeHeapNewVal, "FreeBlock@" PTR_FORMAT "(" PTR_FORMAT ") not invalidated @byte %d", p2i(b), b->length(), (int)(c - (char*)b));
619 }
620 }
621
622 // Verify segment map marking.
623 // All allocated segments, no matter if in a free or used block,
624 // must be marked "in use".
625 address seg_map = (address)_segmap.low();
626 size_t nseg = 0;
627 for(HeapBlock* b = first_block(); b != NULL; b = next_block(b)) {
628 size_t seg1 = segment_for(b);
629 size_t segn = seg1 + b->length();
630 for (size_t i = seg1; i < segn; i++) {
631 nseg++;
632 if (is_segment_unused(seg_map[i])) {
633 warning("CodeHeap: unused segment. %d [%d..%d], %s block", (int)i, (int)seg1, (int)segn, b->free()? "free":"used");
634 }
635 }
636 }
637 if (nseg != _next_segment) {
638 warning("CodeHeap: segment count mismatch. found %d, expected %d.", (int)nseg, (int)_next_segment);
639 }
640
641 // Verify that the number of free blocks is not out of hand.
642 static int free_block_threshold = 10000;
643 if (count > free_block_threshold) {
644 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
645 // Double the warning limit
646 free_block_threshold *= 2;
647 }
648 }
649 }
650
651 #endif
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