1 /*
2 * Copyright (c) 1997, 2025, 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 "asm/codeBuffer.hpp"
26 #include "code/aotCodeCache.hpp"
27 #include "code/compiledIC.hpp"
28 #include "code/oopRecorder.inline.hpp"
29 #include "compiler/disassembler.hpp"
30 #include "logging/log.hpp"
31 #include "oops/klass.inline.hpp"
32 #include "oops/methodCounters.hpp"
33 #include "oops/methodData.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/icache.hpp"
36 #include "runtime/safepointVerifiers.hpp"
37 #include "utilities/align.hpp"
38 #include "utilities/copy.hpp"
39 #include "utilities/powerOfTwo.hpp"
40 #include "utilities/xmlstream.hpp"
41
42 // The structure of a CodeSection:
43 //
44 // _start -> +----------------+
45 // | machine code...|
46 // _end -> |----------------|
47 // | |
48 // | (empty) |
49 // | |
50 // | |
51 // +----------------+
52 // _limit -> | |
53 //
54 // _locs_start -> +----------------+
55 // |reloc records...|
56 // |----------------|
57 // _locs_end -> | |
58 // | |
59 // | (empty) |
60 // | |
61 // | |
62 // +----------------+
63 // _locs_limit -> | |
64 // The _end (resp. _limit) pointer refers to the first
65 // unused (resp. unallocated) byte.
66
67 // The structure of the CodeBuffer while code is being accumulated:
68 //
69 // _total_start -> \
70 // _consts._start -> +----------------+
71 // | |
72 // | Constants |
73 // | |
74 // _insts._start -> |----------------|
75 // | |
76 // | Code |
77 // | |
78 // _stubs._start -> |----------------|
79 // | |
80 // | Stubs | (also handlers for deopt/exception)
81 // | |
82 // +----------------+
83 // + _total_size -> | |
84 //
85 // When the code and relocations are copied to the code cache,
86 // the empty parts of each section are removed, and everything
87 // is copied into contiguous locations.
88
89 typedef CodeBuffer::csize_t csize_t; // file-local definition
90
91 // External buffer, in a predefined CodeBlob.
92 // Important: The code_start must be taken exactly, and not realigned.
93 CodeBuffer::CodeBuffer(CodeBlob* blob) DEBUG_ONLY(: Scrubber(this, sizeof(*this))) {
94 // Provide code buffer with meaningful name
95 initialize_misc(blob->name());
96 initialize(blob->content_begin(), blob->content_size());
97 DEBUG_ONLY(verify_section_allocation();)
98 }
99
100 void CodeBuffer::initialize(csize_t code_size, csize_t locs_size) {
101 // Always allow for empty slop around each section.
102 int slop = (int) CodeSection::end_slop();
103
104 assert(SECT_LIMIT == 3, "total_size explicitly lists all section alignments");
105 int total_size = code_size + _consts.alignment() + _insts.alignment() + _stubs.alignment() + SECT_LIMIT * slop;
106
107 assert(blob() == nullptr, "only once");
108 set_blob(BufferBlob::create(_name, total_size));
109 if (blob() == nullptr) {
110 // The assembler constructor will throw a fatal on an empty CodeBuffer.
111 return; // caller must test this
112 }
113
114 // Set up various pointers into the blob.
115 initialize(_total_start, _total_size);
116
117 assert((uintptr_t)insts_begin() % CodeEntryAlignment == 0, "instruction start not code entry aligned");
118
119 pd_initialize();
120
121 if (locs_size != 0) {
122 _insts.initialize_locs(locs_size / sizeof(relocInfo));
123 }
124
125 DEBUG_ONLY(verify_section_allocation();)
126 }
127
128
129 CodeBuffer::~CodeBuffer() {
130 verify_section_allocation();
131
132 // If we allocated our code buffer from the CodeCache via a BufferBlob, and
133 // it's not permanent, then free the BufferBlob. The rest of the memory
134 // will be freed when the ResourceObj is released.
135 for (CodeBuffer* cb = this; cb != nullptr; cb = cb->before_expand()) {
136 // Previous incarnations of this buffer are held live, so that internal
137 // addresses constructed before expansions will not be confused.
138 cb->free_blob();
139 }
140 if (_overflow_arena != nullptr) {
141 // free any overflow storage
142 delete _overflow_arena;
143 }
144 if (_shared_trampoline_requests != nullptr) {
145 delete _shared_trampoline_requests;
146 }
147
148 NOT_PRODUCT(clear_strings());
149 }
150
151 void CodeBuffer::initialize_oop_recorder(OopRecorder* r) {
152 assert(_oop_recorder == &_default_oop_recorder && _default_oop_recorder.is_unused(), "do this once");
153 DEBUG_ONLY(_default_oop_recorder.freeze()); // force unused OR to be frozen
154 _oop_recorder = r;
155 }
156
157 void CodeBuffer::initialize_section_size(CodeSection* cs, csize_t size) {
158 assert(cs != &_insts, "insts is the memory provider, not the consumer");
159 csize_t slop = CodeSection::end_slop(); // margin between sections
160 int align = cs->alignment();
161 assert(is_power_of_2(align), "sanity");
162 address start = _insts._start;
163 address limit = _insts._limit;
164 address middle = limit - size;
165 middle -= (intptr_t)middle & (align-1); // align the division point downward
166 guarantee(middle - slop > start, "need enough space to divide up");
167 _insts._limit = middle - slop; // subtract desired space, plus slop
168 cs->initialize(middle, limit - middle);
169 assert(cs->start() == middle, "sanity");
170 assert(cs->limit() == limit, "sanity");
171 // give it some relocations to start with, if the main section has them
172 if (_insts.has_locs()) cs->initialize_locs(1);
173 }
174
175 void CodeBuffer::set_blob(BufferBlob* blob) {
176 _blob = blob;
177 if (blob != nullptr) {
178 address start = blob->content_begin();
179 address end = blob->content_end();
180 // Round up the starting address.
181 int align = _insts.alignment();
182 start += (-(intptr_t)start) & (align-1);
183 _total_start = start;
184 _total_size = end - start;
185 } else {
186 #ifdef ASSERT
187 // Clean out dangling pointers.
188 _total_start = badAddress;
189 _consts._start = _consts._end = badAddress;
190 _insts._start = _insts._end = badAddress;
191 _stubs._start = _stubs._end = badAddress;
192 #endif //ASSERT
193 }
194 }
195
196 void CodeBuffer::free_blob() {
197 if (_blob != nullptr) {
198 BufferBlob::free(_blob);
199 set_blob(nullptr);
200 }
201 }
202
203 const char* CodeBuffer::code_section_name(int n) {
204 #ifdef PRODUCT
205 return nullptr;
206 #else //PRODUCT
207 switch (n) {
208 case SECT_CONSTS: return "consts";
209 case SECT_INSTS: return "insts";
210 case SECT_STUBS: return "stubs";
211 default: return nullptr;
212 }
213 #endif //PRODUCT
214 }
215
216 int CodeBuffer::section_index_of(address addr) const {
217 for (int n = 0; n < (int)SECT_LIMIT; n++) {
218 const CodeSection* cs = code_section(n);
219 if (cs->allocates(addr)) return n;
220 }
221 return SECT_NONE;
222 }
223
224 int CodeBuffer::locator(address addr) const {
225 for (int n = 0; n < (int)SECT_LIMIT; n++) {
226 const CodeSection* cs = code_section(n);
227 if (cs->allocates(addr)) {
228 return locator(addr - cs->start(), n);
229 }
230 }
231 return -1;
232 }
233
234
235 bool CodeBuffer::is_backward_branch(Label& L) {
236 return L.is_bound() && insts_end() <= locator_address(L.loc());
237 }
238
239 #ifndef PRODUCT
240 address CodeBuffer::decode_begin() {
241 address begin = _insts.start();
242 if (_decode_begin != nullptr && _decode_begin > begin)
243 begin = _decode_begin;
244 return begin;
245 }
246 #endif // !PRODUCT
247
248 GrowableArray<int>* CodeBuffer::create_patch_overflow() {
249 if (_overflow_arena == nullptr) {
250 _overflow_arena = new (mtCode) Arena(mtCode);
251 }
252 return new (_overflow_arena) GrowableArray<int>(_overflow_arena, 8, 0, 0);
253 }
254
255
256 // Helper function for managing labels and their target addresses.
257 // Returns a sensible address, and if it is not the label's final
258 // address, notes the dependency (at 'branch_pc') on the label.
259 address CodeSection::target(Label& L, address branch_pc) {
260 if (L.is_bound()) {
261 int loc = L.loc();
262 if (index() == CodeBuffer::locator_sect(loc)) {
263 return start() + CodeBuffer::locator_pos(loc);
264 } else {
265 return outer()->locator_address(loc);
266 }
267 } else {
268 assert(allocates2(branch_pc), "sanity");
269 address base = start();
270 int patch_loc = CodeBuffer::locator(branch_pc - base, index());
271 L.add_patch_at(outer(), patch_loc);
272
273 // Need to return a pc, doesn't matter what it is since it will be
274 // replaced during resolution later.
275 // Don't return null or badAddress, since branches shouldn't overflow.
276 // Don't return base either because that could overflow displacements
277 // for shorter branches. It will get checked when bound.
278 return branch_pc;
279 }
280 }
281
282 void CodeSection::relocate(address at, relocInfo::relocType rtype, int format, jint method_index) {
283 RelocationHolder rh;
284 switch (rtype) {
285 case relocInfo::none: return;
286 case relocInfo::opt_virtual_call_type: {
287 rh = opt_virtual_call_Relocation::spec(method_index);
288 break;
289 }
290 case relocInfo::static_call_type: {
291 rh = static_call_Relocation::spec(method_index);
292 break;
293 }
294 case relocInfo::virtual_call_type: {
295 assert(method_index == 0, "resolved method overriding is not supported");
296 rh = Relocation::spec_simple(rtype);
297 break;
298 }
299 default: {
300 rh = Relocation::spec_simple(rtype);
301 break;
302 }
303 }
304 relocate(at, rh, format);
305 }
306
307 void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {
308 // Do not relocate in scratch buffers.
309 if (scratch_emit()) { return; }
310 Relocation* reloc = spec.reloc();
311 relocInfo::relocType rtype = (relocInfo::relocType) reloc->type();
312 if (rtype == relocInfo::none) return;
313
314 // The assertion below has been adjusted, to also work for
315 // relocation for fixup. Sometimes we want to put relocation
316 // information for the next instruction, since it will be patched
317 // with a call.
318 assert(start() <= at && at <= end()+1,
319 "cannot relocate data outside code boundaries");
320
321 if (!has_locs()) {
322 // no space for relocation information provided => code cannot be
323 // relocated. Make sure that relocate is only called with rtypes
324 // that can be ignored for this kind of code.
325 assert(rtype == relocInfo::none ||
326 rtype == relocInfo::runtime_call_type ||
327 rtype == relocInfo::internal_word_type||
328 rtype == relocInfo::section_word_type ||
329 rtype == relocInfo::external_word_type||
330 rtype == relocInfo::barrier_type,
331 "code needs relocation information");
332 // leave behind an indication that we attempted a relocation
333 DEBUG_ONLY(_locs_start = _locs_limit = (relocInfo*)badAddress);
334 return;
335 }
336
337 // Advance the point, noting the offset we'll have to record.
338 csize_t offset = at - locs_point();
339 set_locs_point(at);
340
341 // Test for a couple of overflow conditions; maybe expand the buffer.
342 relocInfo* end = locs_end();
343 relocInfo* req = end + relocInfo::length_limit;
344 // Check for (potential) overflow
345 if (req >= locs_limit() || offset >= relocInfo::offset_limit()) {
346 req += (uint)offset / (uint)relocInfo::offset_limit();
347 if (req >= locs_limit()) {
348 // Allocate or reallocate.
349 expand_locs(locs_count() + (req - end));
350 // reload pointer
351 end = locs_end();
352 }
353 }
354
355 // If the offset is giant, emit filler relocs, of type 'none', but
356 // each carrying the largest possible offset, to advance the locs_point.
357 while (offset >= relocInfo::offset_limit()) {
358 assert(end < locs_limit(), "adjust previous paragraph of code");
359 *end++ = relocInfo::filler_info();
360 offset -= relocInfo::filler_info().addr_offset();
361 }
362
363 // If it's a simple reloc with no data, we'll just write (rtype | offset).
364 (*end) = relocInfo(rtype, offset, format);
365
366 // If it has data, insert the prefix, as (data_prefix_tag | data1), data2.
367 end->initialize(this, reloc);
368 }
369
370 void CodeSection::initialize_locs(int locs_capacity) {
371 assert(_locs_start == nullptr, "only one locs init step, please");
372 // Apply a priori lower limits to relocation size:
373 csize_t min_locs = MAX2(size() / 16, (csize_t)4);
374 if (locs_capacity < min_locs) locs_capacity = min_locs;
375 relocInfo* locs_start = NEW_RESOURCE_ARRAY(relocInfo, locs_capacity);
376 _locs_start = locs_start;
377 _locs_end = locs_start;
378 _locs_limit = locs_start + locs_capacity;
379 _locs_own = true;
380 }
381
382 void CodeSection::initialize_shared_locs(relocInfo* buf, int length) {
383 assert(_locs_start == nullptr, "do this before locs are allocated");
384 // Internal invariant: locs buf must be fully aligned.
385 // See copy_relocations_to() below.
386 while ((uintptr_t)buf % HeapWordSize != 0 && length > 0) {
387 ++buf; --length;
388 }
389 if (length > 0) {
390 _locs_start = buf;
391 _locs_end = buf;
392 _locs_limit = buf + length;
393 _locs_own = false;
394 }
395 }
396
397 void CodeSection::initialize_locs_from(const CodeSection* source_cs) {
398 int lcount = source_cs->locs_count();
399 if (lcount != 0) {
400 initialize_shared_locs(source_cs->locs_start(), lcount);
401 _locs_end = _locs_limit = _locs_start + lcount;
402 assert(is_allocated(), "must have copied code already");
403 set_locs_point(start() + source_cs->locs_point_off());
404 }
405 assert(this->locs_count() == source_cs->locs_count(), "sanity");
406 }
407
408 void CodeSection::expand_locs(int new_capacity) {
409 if (_locs_start == nullptr) {
410 initialize_locs(new_capacity);
411 return;
412 } else {
413 int old_count = locs_count();
414 int old_capacity = locs_capacity();
415 if (new_capacity < old_capacity * 2)
416 new_capacity = old_capacity * 2;
417 relocInfo* locs_start;
418 if (_locs_own) {
419 locs_start = REALLOC_RESOURCE_ARRAY(relocInfo, _locs_start, old_capacity, new_capacity);
420 } else {
421 locs_start = NEW_RESOURCE_ARRAY(relocInfo, new_capacity);
422 Copy::conjoint_jbytes(_locs_start, locs_start, old_capacity * sizeof(relocInfo));
423 _locs_own = true;
424 }
425 _locs_start = locs_start;
426 _locs_end = locs_start + old_count;
427 _locs_limit = locs_start + new_capacity;
428 }
429 }
430
431 int CodeSection::alignment() const {
432 if (_index == CodeBuffer::SECT_CONSTS) {
433 // CodeBuffer controls the alignment of the constants section
434 return _outer->_const_section_alignment;
435 }
436 if (_index == CodeBuffer::SECT_INSTS) {
437 return (int) CodeEntryAlignment;
438 }
439 if (_index == CodeBuffer::SECT_STUBS) {
440 // CodeBuffer installer expects sections to be HeapWordSize aligned
441 return HeapWordSize;
442 }
443 ShouldNotReachHere();
444 return 0;
445 }
446
447 /// Support for emitting the code to its final location.
448 /// The pattern is the same for all functions.
449 /// We iterate over all the sections, padding each to alignment.
450
451 csize_t CodeBuffer::total_content_size() const {
452 csize_t size_so_far = 0;
453 for (int n = 0; n < (int)SECT_LIMIT; n++) {
454 const CodeSection* cs = code_section(n);
455 if (cs->is_empty()) continue; // skip trivial section
456 size_so_far = cs->align_at_start(size_so_far);
457 size_so_far += cs->size();
458 }
459 return size_so_far;
460 }
461
462 void CodeBuffer::compute_final_layout(CodeBuffer* dest) const {
463 address buf = dest->_total_start;
464 csize_t buf_offset = 0;
465 assert(dest->_total_size >= total_content_size(), "must be big enough");
466 assert(!_finalize_stubs, "non-finalized stubs");
467
468 {
469 // not sure why this is here, but why not...
470 int alignSize = MAX2((intx) sizeof(jdouble), CodeEntryAlignment);
471 assert( (dest->_total_start - _insts.start()) % alignSize == 0, "copy must preserve alignment");
472 }
473
474 const CodeSection* prev_cs = nullptr;
475 CodeSection* prev_dest_cs = nullptr;
476
477 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
478 // figure compact layout of each section
479 const CodeSection* cs = code_section(n);
480 csize_t csize = cs->size();
481
482 CodeSection* dest_cs = dest->code_section(n);
483 if (!cs->is_empty()) {
484 // Compute initial padding; assign it to the previous non-empty guy.
485 // Cf. figure_expanded_capacities.
486 csize_t padding = cs->align_at_start(buf_offset) - buf_offset;
487 if (prev_dest_cs != nullptr) {
488 if (padding != 0) {
489 buf_offset += padding;
490 prev_dest_cs->_limit += padding;
491 }
492 } else {
493 guarantee(padding == 0, "In first iteration no padding should be needed.");
494 }
495 prev_dest_cs = dest_cs;
496 prev_cs = cs;
497 }
498
499 DEBUG_ONLY(dest_cs->_start = nullptr); // defeat double-initialization assert
500 dest_cs->initialize(buf+buf_offset, csize);
501 dest_cs->set_end(buf+buf_offset+csize);
502 assert(dest_cs->is_allocated(), "must always be allocated");
503 assert(cs->is_empty() == dest_cs->is_empty(), "sanity");
504
505 buf_offset += csize;
506 }
507
508 // Done calculating sections; did it come out to the right end?
509 assert(buf_offset == total_content_size(), "sanity");
510 DEBUG_ONLY(dest->verify_section_allocation();)
511 }
512
513 // Append an oop reference that keeps the class alive.
514 static void append_oop_references(GrowableArray<oop>* oops, Klass* k) {
515 oop cl = k->klass_holder();
516 if (cl != nullptr && !oops->contains(cl)) {
517 oops->append(cl);
518 }
519 }
520
521 void CodeBuffer::finalize_oop_references(const methodHandle& mh) {
522 NoSafepointVerifier nsv;
523
524 GrowableArray<oop> oops;
525
526 // Make sure that immediate metadata records something in the OopRecorder
527 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
528 // pull code out of each section
529 CodeSection* cs = code_section(n);
530 if (cs->is_empty() || (cs->locs_count() == 0)) continue; // skip trivial section
531 RelocIterator iter(cs);
532 while (iter.next()) {
533 if (iter.type() == relocInfo::metadata_type) {
534 metadata_Relocation* md = iter.metadata_reloc();
535 if (md->metadata_is_immediate()) {
536 Metadata* m = md->metadata_value();
537 if (oop_recorder()->is_real(m)) {
538 if (m->is_methodData()) {
539 m = ((MethodData*)m)->method();
540 }
541 if (m->is_methodCounters()) {
542 m = ((MethodCounters*)m)->method();
543 }
544 if (m->is_method()) {
545 m = ((Method*)m)->method_holder();
546 }
547 if (m->is_klass()) {
548 append_oop_references(&oops, (Klass*)m);
549 } else {
550 // XXX This will currently occur for MDO which don't
551 // have a backpointer. This has to be fixed later.
552 m->print();
553 ShouldNotReachHere();
554 }
555 }
556 }
557 }
558 }
559 }
560
561 if (!oop_recorder()->is_unused()) {
562 for (int i = 0; i < oop_recorder()->metadata_count(); i++) {
563 Metadata* m = oop_recorder()->metadata_at(i);
564 if (oop_recorder()->is_real(m)) {
565 if (m->is_methodData()) {
566 m = ((MethodData*)m)->method();
567 }
568 if (m->is_methodCounters()) {
569 m = ((MethodCounters*)m)->method();
570 }
571 if (m->is_method()) {
572 m = ((Method*)m)->method_holder();
573 }
574 if (m->is_klass()) {
575 append_oop_references(&oops, (Klass*)m);
576 } else {
577 m->print();
578 ShouldNotReachHere();
579 }
580 }
581 }
582
583 }
584
585 // Add the class loader of Method* for the nmethod itself
586 append_oop_references(&oops, mh->method_holder());
587
588 // Add any oops that we've found
589 Thread* thread = Thread::current();
590 for (int i = 0; i < oops.length(); i++) {
591 oop_recorder()->find_index((jobject)thread->handle_area()->allocate_handle(oops.at(i)));
592 }
593 }
594
595
596
597 csize_t CodeBuffer::total_offset_of(const CodeSection* cs) const {
598 csize_t size_so_far = 0;
599 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
600 const CodeSection* cur_cs = code_section(n);
601 if (!cur_cs->is_empty()) {
602 size_so_far = cur_cs->align_at_start(size_so_far);
603 }
604 if (cur_cs->index() == cs->index()) {
605 return size_so_far;
606 }
607 size_so_far += cur_cs->size();
608 }
609 ShouldNotReachHere();
610 return -1;
611 }
612
613 int CodeBuffer::total_skipped_instructions_size() const {
614 int total_skipped_size = 0;
615 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
616 const CodeSection* cur_cs = code_section(n);
617 if (!cur_cs->is_empty()) {
618 total_skipped_size += cur_cs->_skipped_instructions_size;
619 }
620 }
621 return total_skipped_size;
622 }
623
624 csize_t CodeBuffer::total_relocation_size() const {
625 csize_t total = copy_relocations_to(nullptr); // dry run only
626 return (csize_t) align_up(total, HeapWordSize);
627 }
628
629 csize_t CodeBuffer::copy_relocations_to(address buf, csize_t buf_limit, bool only_inst) const {
630 csize_t buf_offset = 0;
631 csize_t code_end_so_far = 0;
632 csize_t code_point_so_far = 0;
633
634 assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");
635 assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");
636
637 for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
638 if (only_inst && (n != (int)SECT_INSTS)) {
639 // Need only relocation info for code.
640 continue;
641 }
642 // pull relocs out of each section
643 const CodeSection* cs = code_section(n);
644 assert(!(cs->is_empty() && cs->locs_count() > 0), "sanity");
645 if (cs->is_empty()) continue; // skip trivial section
646 relocInfo* lstart = cs->locs_start();
647 relocInfo* lend = cs->locs_end();
648 csize_t lsize = (csize_t)( (address)lend - (address)lstart );
649 csize_t csize = cs->size();
650 code_end_so_far = cs->align_at_start(code_end_so_far);
651
652 if (lsize > 0) {
653 // Figure out how to advance the combined relocation point
654 // first to the beginning of this section.
655 // We'll insert one or more filler relocs to span that gap.
656 // (Don't bother to improve this by editing the first reloc's offset.)
657 csize_t new_code_point = code_end_so_far;
658 for (csize_t jump;
659 code_point_so_far < new_code_point;
660 code_point_so_far += jump) {
661 jump = new_code_point - code_point_so_far;
662 relocInfo filler = relocInfo::filler_info();
663 if (jump >= filler.addr_offset()) {
664 jump = filler.addr_offset();
665 } else { // else shrink the filler to fit
666 filler = relocInfo(relocInfo::none, jump);
667 }
668 if (buf != nullptr) {
669 assert(buf_offset + (csize_t)sizeof(filler) <= buf_limit, "filler in bounds");
670 *(relocInfo*)(buf+buf_offset) = filler;
671 }
672 buf_offset += sizeof(filler);
673 }
674
675 // Update code point and end to skip past this section:
676 csize_t last_code_point = code_end_so_far + cs->locs_point_off();
677 assert(code_point_so_far <= last_code_point, "sanity");
678 code_point_so_far = last_code_point; // advance past this guy's relocs
679 }
680 code_end_so_far += csize; // advance past this guy's instructions too
681
682 // Done with filler; emit the real relocations:
683 if (buf != nullptr && lsize != 0) {
684 assert(buf_offset + lsize <= buf_limit, "target in bounds");
685 assert((uintptr_t)lstart % HeapWordSize == 0, "sane start");
686 if (buf_offset % HeapWordSize == 0) {
687 // Use wordwise copies if possible:
688 Copy::disjoint_words((HeapWord*)lstart,
689 (HeapWord*)(buf+buf_offset),
690 (lsize + HeapWordSize-1) / HeapWordSize);
691 } else {
692 Copy::conjoint_jbytes(lstart, buf+buf_offset, lsize);
693 }
694 }
695 buf_offset += lsize;
696 }
697
698 // Align end of relocation info in target.
699 while (buf_offset % HeapWordSize != 0) {
700 if (buf != nullptr) {
701 relocInfo padding = relocInfo(relocInfo::none, 0);
702 assert(buf_offset + (csize_t)sizeof(padding) <= buf_limit, "padding in bounds");
703 *(relocInfo*)(buf+buf_offset) = padding;
704 }
705 buf_offset += sizeof(relocInfo);
706 }
707
708 assert(only_inst || code_end_so_far == total_content_size(), "sanity");
709
710 return buf_offset;
711 }
712
713 csize_t CodeBuffer::copy_relocations_to(CodeBlob* dest) const {
714 address buf = nullptr;
715 csize_t buf_offset = 0;
716 csize_t buf_limit = 0;
717
718 if (dest != nullptr) {
719 buf = (address)dest->relocation_begin();
720 buf_limit = (address)dest->relocation_end() - buf;
721 }
722 // if dest is null, this is just the sizing pass
723 //
724 buf_offset = copy_relocations_to(buf, buf_limit, false);
725
726 return buf_offset;
727 }
728
729 void CodeBuffer::copy_code_to(CodeBlob* dest_blob) {
730 #ifndef PRODUCT
731 if (PrintNMethods && (WizardMode || Verbose)) {
732 tty->print("done with CodeBuffer:");
733 ((CodeBuffer*)this)->print_on(tty);
734 }
735 #endif //PRODUCT
736
737 CodeBuffer dest(dest_blob);
738 assert(dest_blob->content_size() >= total_content_size(), "good sizing");
739 this->compute_final_layout(&dest);
740
741 // Set beginning of constant table before relocating.
742 dest_blob->set_ctable_begin(dest.consts()->start());
743
744 relocate_code_to(&dest);
745
746 // Share assembly remarks and debug strings with the blob.
747 NOT_PRODUCT(dest_blob->use_remarks(_asm_remarks));
748 NOT_PRODUCT(dest_blob->use_strings(_dbg_strings));
749
750 // Done moving code bytes; were they the right size?
751 assert((int)align_up(dest.total_content_size(), oopSize) == dest_blob->content_size(), "sanity");
752
753 // Flush generated code
754 ICache::invalidate_range(dest_blob->code_begin(), dest_blob->code_size());
755 }
756
757 // Move all my code into another code buffer. Consult applicable
758 // relocs to repair embedded addresses. The layout in the destination
759 // CodeBuffer is different to the source CodeBuffer: the destination
760 // CodeBuffer gets the final layout (consts, insts, stubs in order of
761 // ascending address).
762 void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
763 address dest_end = dest->_total_start + dest->_total_size;
764 address dest_filled = nullptr;
765 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
766 // pull code out of each section
767 const CodeSection* cs = code_section(n);
768 if (cs->is_empty()) continue; // skip trivial section
769 CodeSection* dest_cs = dest->code_section(n);
770 assert(cs->size() == dest_cs->size(), "sanity");
771 csize_t usize = dest_cs->size();
772 csize_t wsize = align_up(usize, HeapWordSize);
773 assert(dest_cs->start() + wsize <= dest_end, "no overflow");
774 // Copy the code as aligned machine words.
775 // This may also include an uninitialized partial word at the end.
776 Copy::disjoint_words((HeapWord*)cs->start(),
777 (HeapWord*)dest_cs->start(),
778 wsize / HeapWordSize);
779
780 if (dest->blob() == nullptr) {
781 // Destination is a final resting place, not just another buffer.
782 // Normalize uninitialized bytes in the final padding.
783 Copy::fill_to_bytes(dest_cs->end(), dest_cs->remaining(),
784 Assembler::code_fill_byte());
785 }
786 // Keep track of the highest filled address
787 dest_filled = MAX2(dest_filled, dest_cs->end() + dest_cs->remaining());
788
789 assert(cs->locs_start() != (relocInfo*)badAddress,
790 "this section carries no reloc storage, but reloc was attempted");
791
792 // Make the new code copy use the old copy's relocations:
793 dest_cs->initialize_locs_from(cs);
794 }
795
796 // Do relocation after all sections are copied.
797 // This is necessary if the code uses constants in stubs, which are
798 // relocated when the corresponding instruction in the code (e.g., a
799 // call) is relocated. Stubs are placed behind the main code
800 // section, so that section has to be copied before relocating.
801 for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
802 CodeSection* dest_cs = dest->code_section(n);
803 if (dest_cs->is_empty() || (dest_cs->locs_count() == 0)) continue; // skip trivial section
804 { // Repair the pc relative information in the code after the move
805 RelocIterator iter(dest_cs);
806 while (iter.next()) {
807 iter.reloc()->fix_relocation_after_move(this, dest);
808 }
809 }
810 }
811
812 if (dest->blob() == nullptr && dest_filled != nullptr) {
813 // Destination is a final resting place, not just another buffer.
814 // Normalize uninitialized bytes in the final padding.
815 Copy::fill_to_bytes(dest_filled, dest_end - dest_filled,
816 Assembler::code_fill_byte());
817
818 }
819 }
820
821 csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,
822 csize_t amount,
823 csize_t* new_capacity) {
824 csize_t new_total_cap = 0;
825
826 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
827 const CodeSection* sect = code_section(n);
828
829 if (!sect->is_empty()) {
830 // Compute initial padding; assign it to the previous section,
831 // even if it's empty (e.g. consts section can be empty).
832 // Cf. compute_final_layout
833 csize_t padding = sect->align_at_start(new_total_cap) - new_total_cap;
834 if (padding != 0) {
835 new_total_cap += padding;
836 assert(n - 1 >= SECT_FIRST, "sanity");
837 new_capacity[n - 1] += padding;
838 }
839 }
840
841 csize_t exp = sect->size(); // 100% increase
842 if ((uint)exp < 4*K) exp = 4*K; // minimum initial increase
843 if (sect == which_cs) {
844 if (exp < amount) exp = amount;
845 if (StressCodeBuffers) exp = amount; // expand only slightly
846 } else if (n == SECT_INSTS) {
847 // scale down inst increases to a more modest 25%
848 exp = 4*K + ((exp - 4*K) >> 2);
849 if (StressCodeBuffers) exp = amount / 2; // expand only slightly
850 } else if (sect->is_empty()) {
851 // do not grow an empty secondary section
852 exp = 0;
853 }
854 // Allow for inter-section slop:
855 exp += CodeSection::end_slop();
856 csize_t new_cap = sect->size() + exp;
857 if (new_cap < sect->capacity()) {
858 // No need to expand after all.
859 new_cap = sect->capacity();
860 }
861 new_capacity[n] = new_cap;
862 new_total_cap += new_cap;
863 }
864
865 return new_total_cap;
866 }
867
868 void CodeBuffer::expand(CodeSection* which_cs, csize_t amount) {
869 #ifndef PRODUCT
870 if (PrintNMethods && (WizardMode || Verbose)) {
871 tty->print("expanding CodeBuffer:");
872 this->print_on(tty);
873 }
874
875 if (StressCodeBuffers && blob() != nullptr) {
876 static int expand_count = 0;
877 if (expand_count >= 0) expand_count += 1;
878 if (expand_count > 100 && is_power_of_2(expand_count)) {
879 tty->print_cr("StressCodeBuffers: have expanded %d times", expand_count);
880 // simulate an occasional allocation failure:
881 free_blob();
882 }
883 }
884 #endif //PRODUCT
885
886 // Resizing must be allowed
887 {
888 if (blob() == nullptr) return; // caller must check if blob is null
889 }
890
891 // Figure new capacity for each section.
892 csize_t new_capacity[SECT_LIMIT];
893 memset(new_capacity, 0, sizeof(csize_t) * SECT_LIMIT);
894 csize_t new_total_cap
895 = figure_expanded_capacities(which_cs, amount, new_capacity);
896
897 // Create a new (temporary) code buffer to hold all the new data
898 CodeBuffer cb(name(), new_total_cap, 0);
899 cb.set_const_section_alignment(_const_section_alignment);
900 if (cb.blob() == nullptr) {
901 // Failed to allocate in code cache.
902 free_blob();
903 return;
904 }
905
906 // Create an old code buffer to remember which addresses used to go where.
907 // This will be useful when we do final assembly into the code cache,
908 // because we will need to know how to warp any internal address that
909 // has been created at any time in this CodeBuffer's past.
910 CodeBuffer* bxp = new CodeBuffer(_total_start, _total_size);
911 bxp->take_over_code_from(this); // remember the old undersized blob
912 DEBUG_ONLY(this->_blob = nullptr); // silence a later assert
913 bxp->_before_expand = this->_before_expand;
914 this->_before_expand = bxp;
915
916 // Give each section its required (expanded) capacity.
917 for (int n = (int)SECT_LIMIT-1; n >= SECT_FIRST; n--) {
918 CodeSection* cb_sect = cb.code_section(n);
919 CodeSection* this_sect = code_section(n);
920 if (new_capacity[n] == 0) continue; // already nulled out
921 if (n != SECT_INSTS) {
922 cb.initialize_section_size(cb_sect, new_capacity[n]);
923 }
924 assert(cb_sect->capacity() >= new_capacity[n], "big enough");
925 address cb_start = cb_sect->start();
926 cb_sect->set_end(cb_start + this_sect->size());
927 if (this_sect->mark() == nullptr) {
928 cb_sect->clear_mark();
929 } else {
930 cb_sect->set_mark(cb_start + this_sect->mark_off());
931 }
932 }
933
934 // Needs to be initialized when calling fix_relocation_after_move.
935 cb.blob()->set_ctable_begin(cb.consts()->start());
936
937 // Move all the code and relocations to the new blob:
938 relocate_code_to(&cb);
939
940 // some internal addresses, _last_insn _last_label, are used during code emission,
941 // adjust them in expansion
942 adjust_internal_address(insts_begin(), cb.insts_begin());
943
944 // Copy the temporary code buffer into the current code buffer.
945 // Basically, do {*this = cb}, except for some control information.
946 this->take_over_code_from(&cb);
947 cb.set_blob(nullptr);
948
949 // Zap the old code buffer contents, to avoid mistakenly using them.
950 DEBUG_ONLY(Copy::fill_to_bytes(bxp->_total_start, bxp->_total_size,
951 badCodeHeapFreeVal);)
952
953 // Make certain that the new sections are all snugly inside the new blob.
954 DEBUG_ONLY(verify_section_allocation();)
955
956 #ifndef PRODUCT
957 _decode_begin = nullptr; // sanity
958 if (PrintNMethods && (WizardMode || Verbose)) {
959 tty->print("expanded CodeBuffer:");
960 this->print_on(tty);
961 }
962 #endif //PRODUCT
963 }
964
965 void CodeBuffer::adjust_internal_address(address from, address to) {
966 if (_last_insn != nullptr) {
967 _last_insn += to - from;
968 }
969 if (_last_label != nullptr) {
970 _last_label += to - from;
971 }
972 }
973
974 void CodeBuffer::take_over_code_from(CodeBuffer* cb) {
975 // Must already have disposed of the old blob somehow.
976 assert(blob() == nullptr, "must be empty");
977 // Take the new blob away from cb.
978 set_blob(cb->blob());
979 // Take over all the section pointers.
980 for (int n = 0; n < (int)SECT_LIMIT; n++) {
981 CodeSection* cb_sect = cb->code_section(n);
982 CodeSection* this_sect = code_section(n);
983 this_sect->take_over_code_from(cb_sect);
984 }
985 // Make sure the old cb won't try to use it or free it.
986 DEBUG_ONLY(cb->_blob = (BufferBlob*)badAddress);
987 }
988
989 void CodeBuffer::verify_section_allocation() {
990 address tstart = _total_start;
991 if (tstart == nullptr) return; // ignore not fully initialized buffer
992 if (tstart == badAddress) return; // smashed by set_blob(nullptr)
993 address tend = tstart + _total_size;
994 if (_blob != nullptr) {
995 guarantee(tstart >= _blob->content_begin(), "sanity");
996 guarantee(tend <= _blob->content_end(), "sanity");
997 }
998 // Verify disjointness.
999 for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
1000 CodeSection* sect = code_section(n);
1001 if (!sect->is_allocated() || sect->is_empty()) {
1002 continue;
1003 }
1004 guarantee(_blob == nullptr || is_aligned(sect->start(), sect->alignment()),
1005 "start is aligned");
1006 for (int m = n + 1; m < (int) SECT_LIMIT; m++) {
1007 CodeSection* other = code_section(m);
1008 if (!other->is_allocated() || other == sect) {
1009 continue;
1010 }
1011 guarantee(other->disjoint(sect), "sanity");
1012 }
1013 guarantee(sect->end() <= tend, "sanity, sect_end: " PTR_FORMAT " tend: " PTR_FORMAT " size: %d", p2i(sect->end()), p2i(tend), (int)_total_size);
1014 guarantee(sect->end() <= sect->limit(), "sanity, sect_end: " PTR_FORMAT " sect_limit: " PTR_FORMAT, p2i(sect->end()), p2i(sect->limit()));
1015 }
1016 }
1017
1018 void CodeBuffer::log_section_sizes(const char* name) {
1019 if (xtty != nullptr) {
1020 ttyLocker ttyl;
1021 // log info about buffer usage
1022 xtty->head("blob name='%s' total_size='%d'", name, _total_size);
1023 for (int n = (int) CodeBuffer::SECT_FIRST; n < (int) CodeBuffer::SECT_LIMIT; n++) {
1024 CodeSection* sect = code_section(n);
1025 if (!sect->is_allocated() || sect->is_empty()) continue;
1026 xtty->elem("sect index='%d' capacity='%d' size='%d' remaining='%d'",
1027 n, sect->capacity(), sect->size(), sect->remaining());
1028 }
1029 xtty->tail("blob");
1030 }
1031 }
1032
1033 bool CodeBuffer::finalize_stubs() {
1034 if (_finalize_stubs && !pd_finalize_stubs()) {
1035 // stub allocation failure
1036 return false;
1037 }
1038 _finalize_stubs = false;
1039 return true;
1040 }
1041
1042 void CodeBuffer::shared_stub_to_interp_for(ciMethod* callee, csize_t call_offset) {
1043 if (_shared_stub_to_interp_requests == nullptr) {
1044 _shared_stub_to_interp_requests = new SharedStubToInterpRequests(8);
1045 }
1046 SharedStubToInterpRequest request(callee, call_offset);
1047 _shared_stub_to_interp_requests->push(request);
1048 _finalize_stubs = true;
1049 }
1050
1051 #ifndef PRODUCT
1052 void CodeBuffer::block_comment(ptrdiff_t offset, const char* comment) {
1053 if (insts()->scratch_emit()) {
1054 return;
1055 }
1056 if (_collect_comments) {
1057 const char* str = _asm_remarks.insert(offset, comment);
1058 postcond(str != comment);
1059 }
1060 }
1061
1062 const char* CodeBuffer::code_string(const char* str) {
1063 if (insts()->scratch_emit()) {
1064 return str;
1065 }
1066 const char* tmp = _dbg_strings.insert(str);
1067 postcond(tmp != str);
1068 return tmp;
1069 }
1070
1071 void CodeBuffer::decode() {
1072 ttyLocker ttyl;
1073 Disassembler::decode(decode_begin(), insts_end(), tty NOT_PRODUCT(COMMA &asm_remarks()));
1074 _decode_begin = insts_end();
1075 }
1076
1077 void CodeSection::print_on(outputStream* st, const char* name) {
1078 csize_t locs_size = locs_end() - locs_start();
1079 st->print_cr(" %7s.code = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d)",
1080 name, p2i(start()), p2i(end()), p2i(limit()), size(), capacity());
1081 st->print_cr(" %7s.locs = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d) point=%d",
1082 name, p2i(locs_start()), p2i(locs_end()), p2i(locs_limit()), locs_size, locs_capacity(), locs_point_off());
1083 if (PrintRelocations && (locs_size != 0)) {
1084 RelocIterator iter(this);
1085 iter.print_on(st);
1086 }
1087 }
1088
1089 void CodeBuffer::print_on(outputStream* st) {
1090 st->print_cr("CodeBuffer:%s", name());
1091 for (int n = 0; n < (int)SECT_LIMIT; n++) {
1092 // print each section
1093 CodeSection* cs = code_section(n);
1094 cs->print_on(st, code_section_name(n));
1095 }
1096 }
1097
1098 CHeapString::~CHeapString() {
1099 os::free((void*)_string);
1100 _string = nullptr;
1101 }
1102
1103 // ----- AsmRemarks ------------------------------------------------------------
1104 //
1105 // Acting as interface to reference counted mapping [offset -> remark], where
1106 // offset is a byte offset into an instruction stream (CodeBuffer, CodeBlob or
1107 // other memory buffer) and remark is a string (comment).
1108 //
1109 AsmRemarks::AsmRemarks() : _remarks(new AsmRemarkCollection()) {
1110 assert(_remarks != nullptr, "Allocation failure!");
1111 }
1112
1113 AsmRemarks::~AsmRemarks() {
1114 if (_remarks != nullptr) {
1115 clear();
1116 }
1117 assert(_remarks == nullptr, "Must 'clear()' before deleting!");
1118 }
1119
1120 void AsmRemarks::init(AsmRemarks& asm_remarks) {
1121 asm_remarks._remarks = new AsmRemarkCollection();
1122 }
1123
1124 const char* AsmRemarks::insert(uint offset, const char* remstr) {
1125 precond(remstr != nullptr);
1126 return _remarks->insert(offset, remstr);
1127 }
1128
1129 bool AsmRemarks::is_empty() const {
1130 return _remarks->is_empty();
1131 }
1132
1133 void AsmRemarks::share(const AsmRemarks &src) {
1134 precond(_remarks == nullptr || is_empty());
1135 clear();
1136 _remarks = src._remarks->reuse();
1137 }
1138
1139 void AsmRemarks::clear() {
1140 if (_remarks != nullptr && _remarks->clear() == 0) {
1141 delete _remarks;
1142 }
1143 _remarks = nullptr;
1144 }
1145
1146 uint AsmRemarks::print(uint offset, outputStream* strm) const {
1147 uint count = 0;
1148 const char* prefix = " ;; ";
1149 const char* remstr = _remarks->lookup(offset);
1150 while (remstr != nullptr) {
1151 strm->bol();
1152 strm->print("%s", prefix);
1153 // Don't interpret as format strings since it could contain '%'.
1154 strm->print_raw(remstr);
1155 // Advance to next line iff string didn't contain a cr() at the end.
1156 strm->bol();
1157 remstr = _remarks->next(offset);
1158 count++;
1159 }
1160 return count;
1161 }
1162
1163 // ----- DbgStrings ------------------------------------------------------------
1164 //
1165 // Acting as interface to reference counted collection of (debug) strings used
1166 // in the code generated, and thus requiring a fixed address.
1167 //
1168 DbgStrings::DbgStrings() : _strings(new DbgStringCollection()) {
1169 assert(_strings != nullptr, "Allocation failure!");
1170 }
1171
1172 DbgStrings::~DbgStrings() {
1173 if (_strings != nullptr) {
1174 clear();
1175 }
1176 assert(_strings == nullptr, "Must 'clear()' before deleting!");
1177 }
1178
1179 void DbgStrings::init(DbgStrings& dbg_strings) {
1180 dbg_strings._strings = new DbgStringCollection();
1181 }
1182
1183 const char* DbgStrings::insert(const char* dbgstr) {
1184 const char* str = _strings->lookup(dbgstr);
1185 return str != nullptr ? str : _strings->insert(dbgstr);
1186 }
1187
1188 bool DbgStrings::is_empty() const {
1189 return _strings->is_empty();
1190 }
1191
1192 void DbgStrings::share(const DbgStrings &src) {
1193 precond(_strings == nullptr || is_empty());
1194 clear();
1195 _strings = src._strings->reuse();
1196 }
1197
1198 void DbgStrings::clear() {
1199 if (_strings != nullptr && _strings->clear() == 0) {
1200 delete _strings;
1201 }
1202 _strings = nullptr;
1203 }
1204
1205 // ----- AsmRemarkCollection ---------------------------------------------------
1206
1207 const char* AsmRemarkCollection::insert(uint offset, const char* remstr) {
1208 precond(remstr != nullptr);
1209 Cell* cell = new Cell { remstr, offset };
1210 if (is_empty()) {
1211 cell->prev = cell;
1212 cell->next = cell;
1213 _remarks = cell;
1214 } else {
1215 _remarks->push_back(cell);
1216 }
1217 return cell->string();
1218 }
1219
1220 const char* AsmRemarkCollection::lookup(uint offset) const {
1221 _next = _remarks;
1222 return next(offset);
1223 }
1224
1225 const char* AsmRemarkCollection::next(uint offset) const {
1226 if (_next != nullptr) {
1227 Cell* i = _next;
1228 do {
1229 if (i->offset == offset) {
1230 _next = i->next == _remarks ? nullptr : i->next;
1231 return i->string();
1232 }
1233 i = i->next;
1234 } while (i != _remarks);
1235 _next = nullptr;
1236 }
1237 return nullptr;
1238 }
1239
1240 uint AsmRemarkCollection::clear() {
1241 precond(_ref_cnt > 0);
1242 if (--_ref_cnt > 0) {
1243 return _ref_cnt;
1244 }
1245 if (!is_empty()) {
1246 uint count = 0;
1247 Cell* i = _remarks;
1248 do {
1249 Cell* next = i->next;
1250 delete i;
1251 i = next;
1252 count++;
1253 } while (i != _remarks);
1254
1255 log_debug(codestrings)("Clear %u asm-remark%s.", count, count == 1 ? "" : "s");
1256 _remarks = nullptr;
1257 }
1258 return 0; // i.e. _ref_cnt == 0
1259 }
1260
1261 // ----- DbgStringCollection ---------------------------------------------------
1262
1263 const char* DbgStringCollection::insert(const char* dbgstr) {
1264 precond(dbgstr != nullptr);
1265 Cell* cell = new Cell { dbgstr };
1266
1267 if (is_empty()) {
1268 cell->prev = cell;
1269 cell->next = cell;
1270 _strings = cell;
1271 } else {
1272 _strings->push_back(cell);
1273 }
1274 return cell->string();
1275 }
1276
1277 const char* DbgStringCollection::lookup(const char* dbgstr) const {
1278 precond(dbgstr != nullptr);
1279 if (_strings != nullptr) {
1280 Cell* i = _strings;
1281 do {
1282 if (strcmp(i->string(), dbgstr) == 0) {
1283 return i->string();
1284 }
1285 i = i->next;
1286 } while (i != _strings);
1287 }
1288 return nullptr;
1289 }
1290
1291 uint DbgStringCollection::clear() {
1292 precond(_ref_cnt > 0);
1293 if (--_ref_cnt > 0) {
1294 return _ref_cnt;
1295 }
1296 if (!is_empty()) {
1297 uint count = 0;
1298 Cell* i = _strings;
1299 do {
1300 Cell* next = i->next;
1301 delete i;
1302 i = next;
1303 count++;
1304 } while (i != _strings);
1305
1306 log_debug(codestrings)("Clear %u dbg-string%s.", count, count == 1 ? "" : "s");
1307 _strings = nullptr;
1308 }
1309 return 0; // i.e. _ref_cnt == 0
1310 }
1311
1312 #endif // not PRODUCT