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 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/heap.hpp"
27 #include "oops/oop.inline.hpp"
28 #include "runtime/os.hpp"
29 #include "services/memTracker.hpp"
30 #include "utilities/align.hpp"
31
header_size()32 size_t CodeHeap::header_size() {
33 return sizeof(HeapBlock);
34 }
35
36
37 // Implementation of Heap
38
CodeHeap(const char * name,const int code_blob_type)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
mark_segmap_as_free(size_t beg,size_t end)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
mark_segmap_as_used(size_t beg,size_t end)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
invalidate(size_t beg,size_t end,size_t hdr_size)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
clear(size_t beg,size_t end)109 void CodeHeap::clear(size_t beg, size_t end) {
110 mark_segmap_as_free(beg, end);
111 invalidate(beg, end, 0);
112 }
113
clear()114 void CodeHeap::clear() {
115 _next_segment = 0;
116 clear(_next_segment, _number_of_committed_segments);
117 }
118
119
align_to_page_size(size_t size)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
on_code_mapping(char * base,size_t size)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
reserve(ReservedSpace rs,size_t committed_size,size_t segment_size)135 bool CodeHeap::reserve(ReservedSpace rs, size_t committed_size, size_t segment_size) {
136 assert(rs.size() >= committed_size, "reserved < committed");
137 assert(segment_size >= sizeof(FreeBlock), "segment size is too small");
138 assert(is_power_of_2(segment_size), "segment_size must be a power of 2");
139
140 _segment_size = segment_size;
141 _log2_segment_size = exact_log2(segment_size);
142
143 // Reserve and initialize space for _memory.
144 size_t page_size = os::vm_page_size();
145 if (os::can_execute_large_page_memory()) {
146 const size_t min_pages = 8;
147 page_size = MIN2(os::page_size_for_region_aligned(committed_size, min_pages),
148 os::page_size_for_region_aligned(rs.size(), min_pages));
149 }
150
151 const size_t granularity = os::vm_allocation_granularity();
152 const size_t c_size = align_up(committed_size, page_size);
153
154 os::trace_page_sizes(_name, committed_size, rs.size(), page_size,
155 rs.base(), rs.size());
156 if (!_memory.initialize(rs, c_size)) {
157 return false;
158 }
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
expand_by(size_t size)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
allocate(size_t instance_size)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.
split_block(HeapBlock * b,size_t split_at)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
deallocate_tail(void * p,size_t used_size)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
deallocate(void * p)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 |
326 * ... | nm 2 | -> | 2 |
327 * ... | nm 2 | -> | .. |
328 * ... | nm 2 | -> | 0xFE |
329 * seg m+n | nm 2 | -> | 1 |
330 * ... | nm 2 | -> | |
331 *
332 * A value of '0' in the segmap indicates that this segment contains the beginning of
333 * an nmethod. Let's walk through a simple example: If we want to find the start of
334 * an nmethod that falls into seg 2, we read the value of the segmap[2]. The value
335 * is an offset that points to the segment that contains the start of the nmethod.
336 * Another example: If we want to get the start of nm 2, and we happen to get a pointer
337 * that points to seg m+n, we first read seg[n+m], which returns '1'. So we have to
338 * do one more read of the segmap[m+n-1] to finally get the segment header.
339 */
find_start(void * p) const340 void* CodeHeap::find_start(void* p) const {
341 if (!contains(p)) {
342 return NULL;
343 }
344 size_t seg_idx = segment_for(p);
345 address seg_map = (address)_segmap.low();
346 if (is_segment_unused(seg_map[seg_idx])) {
347 return NULL;
348 }
349 while (seg_map[seg_idx] > 0) {
350 seg_idx -= (int)seg_map[seg_idx];
351 }
352
353 HeapBlock* h = block_at(seg_idx);
354 if (h->free()) {
355 return NULL;
356 }
357 return h->allocated_space();
358 }
359
find_blob_unsafe(void * start) const360 CodeBlob* CodeHeap::find_blob_unsafe(void* start) const {
361 CodeBlob* result = (CodeBlob*)CodeHeap::find_start(start);
362 if (result != NULL && result->blob_contains((address)start)) {
363 return result;
364 }
365 return NULL;
366 }
367
alignment_unit() const368 size_t CodeHeap::alignment_unit() const {
369 // this will be a power of two
370 return _segment_size;
371 }
372
373
alignment_offset() const374 size_t CodeHeap::alignment_offset() const {
375 // The lowest address in any allocated block will be
376 // equal to alignment_offset (mod alignment_unit).
377 return sizeof(HeapBlock) & (_segment_size - 1);
378 }
379
380 // Returns the current block if available and used.
381 // If not, it returns the subsequent block (if available), NULL otherwise.
382 // Free blocks are merged, therefore there is at most one free block
383 // between two used ones. As a result, the subsequent block (if available) is
384 // guaranteed to be used.
next_used(HeapBlock * b) const385 void* CodeHeap::next_used(HeapBlock* b) const {
386 if (b != NULL && b->free()) b = next_block(b);
387 assert(b == NULL || !b->free(), "must be in use or at end of heap");
388 return (b == NULL) ? NULL : b->allocated_space();
389 }
390
391 // Returns the first used HeapBlock
first_block() const392 HeapBlock* CodeHeap::first_block() const {
393 if (_next_segment > 0)
394 return block_at(0);
395 return NULL;
396 }
397
block_start(void * q) const398 HeapBlock* CodeHeap::block_start(void* q) const {
399 HeapBlock* b = (HeapBlock*)find_start(q);
400 if (b == NULL) return NULL;
401 return b - 1;
402 }
403
404 // Returns the next Heap block an offset into one
next_block(HeapBlock * b) const405 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
406 if (b == NULL) return NULL;
407 size_t i = segment_for(b) + b->length();
408 if (i < _next_segment)
409 return block_at(i);
410 return NULL;
411 }
412
413
414 // Returns current capacity
capacity() const415 size_t CodeHeap::capacity() const {
416 return _memory.committed_size();
417 }
418
max_capacity() const419 size_t CodeHeap::max_capacity() const {
420 return _memory.reserved_size();
421 }
422
allocated_segments() const423 int CodeHeap::allocated_segments() const {
424 return (int)_next_segment;
425 }
426
allocated_capacity() const427 size_t CodeHeap::allocated_capacity() const {
428 // size of used heap - size on freelist
429 return segments_to_size(_next_segment - _freelist_segments);
430 }
431
432 // Returns size of the unallocated heap block
heap_unallocated_capacity() const433 size_t CodeHeap::heap_unallocated_capacity() const {
434 // Total number of segments - number currently used
435 return segments_to_size(_number_of_reserved_segments - _next_segment);
436 }
437
438 // Free list management
439
following_block(FreeBlock * b)440 FreeBlock* CodeHeap::following_block(FreeBlock *b) {
441 return (FreeBlock*)(((address)b) + _segment_size * b->length());
442 }
443
444 // Inserts block b after a
insert_after(FreeBlock * a,FreeBlock * b)445 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
446 assert(a != NULL && b != NULL, "must be real pointers");
447
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
merge_right(FreeBlock * a)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
add_to_freelist(HeapBlock * a)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 _blob_count--;
482 assert(_blob_count >= 0, "sanity");
483
484 assert(b != _freelist, "cannot be removed twice");
485
486 // Mark as free and update free space count
487 _freelist_segments += b->length();
488 b->set_free();
489 invalidate(bseg, bseg + b->length(), sizeof(FreeBlock));
490
491 // First element in list?
492 if (_freelist == NULL) {
493 b->set_link(NULL);
494 _freelist = b;
495 return;
496 }
497
498 // Since the freelist is ordered (smaller addresses -> larger addresses) and the
499 // element we want to insert into the freelist has a smaller address than the first
500 // element, we can simply add 'b' as the first element and we are done.
501 if (b < _freelist) {
502 // Insert first in list
503 b->set_link(_freelist);
504 _freelist = b;
505 merge_right(_freelist);
506 return;
507 }
508
509 // Scan for right place to put into list. List
510 // is sorted by increasing addresses
511 FreeBlock* prev = _freelist;
512 FreeBlock* cur = _freelist->link();
513 while(cur != NULL && cur < b) {
514 assert(prev < cur, "Freelist must be ordered");
515 prev = cur;
516 cur = cur->link();
517 }
518 assert((prev < b) && (cur == NULL || b < cur), "free-list must be ordered");
519 insert_after(prev, b);
520 }
521
522 /**
523 * Search freelist for an entry on the list with the best fit.
524 * @return NULL, if no one was found
525 */
search_freelist(size_t length)526 HeapBlock* CodeHeap::search_freelist(size_t length) {
527 FreeBlock* found_block = NULL;
528 FreeBlock* found_prev = NULL;
529 size_t found_length = _next_segment; // max it out to begin with
530
531 HeapBlock* res = NULL;
532 FreeBlock* prev = NULL;
533 FreeBlock* cur = _freelist;
534
535 length = length < CodeCacheMinBlockLength ? CodeCacheMinBlockLength : length;
536
537 // Search for best-fitting block
538 while(cur != NULL) {
539 size_t cur_length = cur->length();
540 if (cur_length == length) {
541 // We have a perfect fit
542 found_block = cur;
543 found_prev = prev;
544 found_length = cur_length;
545 break;
546 } else if ((cur_length > length) && (cur_length < found_length)) {
547 // This is a new, closer fit. Remember block, its previous element, and its length
548 found_block = cur;
549 found_prev = prev;
550 found_length = cur_length;
551 }
552 // Next element in list
553 prev = cur;
554 cur = cur->link();
555 }
556
557 if (found_block == NULL) {
558 // None found
559 return NULL;
560 }
561
562 // Exact (or at least good enough) fit. Remove from list.
563 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
564 if (found_length - length < CodeCacheMinBlockLength) {
565 _freelist_length--;
566 length = found_length;
567 if (found_prev == NULL) {
568 assert(_freelist == found_block, "sanity check");
569 _freelist = _freelist->link();
570 } else {
571 assert((found_prev->link() == found_block), "sanity check");
572 // Unmap element
573 found_prev->set_link(found_block->link());
574 }
575 res = found_block;
576 } else {
577 // Truncate the free block and return the truncated part
578 // as new HeapBlock. The remaining free block does not
579 // need to be updated, except for it's length. Truncating
580 // the segment map does not invalidate the leading part.
581 res = split_block(found_block, found_length - length);
582 }
583
584 res->set_used();
585 _freelist_segments -= length;
586 return res;
587 }
588
589 //----------------------------------------------------------------------------
590 // Non-product code
591
592 #ifndef PRODUCT
593
print()594 void CodeHeap::print() {
595 tty->print_cr("The Heap");
596 }
597
verify()598 void CodeHeap::verify() {
599 if (VerifyCodeCache) {
600 size_t len = 0;
601 int count = 0;
602 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
603 len += b->length();
604 count++;
605 // Check if we have merged all free blocks
606 assert(merge_right(b) == false, "Missed merging opportunity");
607 }
608 // Verify that freelist contains the right amount of free space
609 assert(len == _freelist_segments, "wrong freelist");
610
611 for(HeapBlock* h = first_block(); h != NULL; h = next_block(h)) {
612 if (h->free()) count--;
613 }
614 // Verify that the freelist contains the same number of blocks
615 // than free blocks found on the full list.
616 assert(count == 0, "missing free blocks");
617
618 //---< all free block memory must have been invalidated >---
619 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
620 for (char* c = (char*)b + sizeof(FreeBlock); c < (char*)b + segments_to_size(b->length()); c++) {
621 assert(*c == (char)badCodeHeapNewVal, "FreeBlock@" PTR_FORMAT "(" PTR_FORMAT ") not invalidated @byte %d", p2i(b), b->length(), (int)(c - (char*)b));
622 }
623 }
624
625 // Verify segment map marking.
626 // All allocated segments, no matter if in a free or used block,
627 // must be marked "in use".
628 address seg_map = (address)_segmap.low();
629 size_t nseg = 0;
630 for(HeapBlock* b = first_block(); b != NULL; b = next_block(b)) {
631 size_t seg1 = segment_for(b);
632 size_t segn = seg1 + b->length();
633 for (size_t i = seg1; i < segn; i++) {
634 nseg++;
635 assert(!is_segment_unused(seg_map[i]), "CodeHeap: unused segment. %d [%d..%d], %s block", (int)i, (int)seg1, (int)segn, b->free()? "free":"used");
636 }
637 }
638 assert(nseg == _next_segment, "CodeHeap: segment count mismatch. found %d, expected %d.", (int)nseg, (int)_next_segment);
639
640 // Verify that the number of free blocks is not out of hand.
641 static int free_block_threshold = 10000;
642 if (count > free_block_threshold) {
643 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
644 // Double the warning limit
645 free_block_threshold *= 2;
646 }
647 }
648 }
649
650 #endif
651