1 /*
   2  * Copyright (c) 1997, 2024, 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 "asm/codeBuffer.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     // free any overflow storage
 140     delete cb->_overflow_arena;
 141   }
 142 
 143   if (_shared_trampoline_requests != nullptr) {
 144     delete _shared_trampoline_requests;
 145   }
 146 
 147   NOT_PRODUCT(clear_strings());
 148 }
 149 
 150 void CodeBuffer::initialize_oop_recorder(OopRecorder* r) {
 151   assert(_oop_recorder == &_default_oop_recorder && _default_oop_recorder.is_unused(), "do this once");
 152   DEBUG_ONLY(_default_oop_recorder.freeze());  // force unused OR to be frozen
 153   _oop_recorder = r;
 154 }
 155 
 156 void CodeBuffer::initialize_section_size(CodeSection* cs, csize_t size) {
 157   assert(cs != &_insts, "insts is the memory provider, not the consumer");
 158   csize_t slop = CodeSection::end_slop();  // margin between sections
 159   int align = cs->alignment();
 160   assert(is_power_of_2(align), "sanity");
 161   address start  = _insts._start;
 162   address limit  = _insts._limit;
 163   address middle = limit - size;
 164   middle -= (intptr_t)middle & (align-1);  // align the division point downward
 165   guarantee(middle - slop > start, "need enough space to divide up");
 166   _insts._limit = middle - slop;  // subtract desired space, plus slop
 167   cs->initialize(middle, limit - middle);
 168   assert(cs->start() == middle, "sanity");
 169   assert(cs->limit() == limit,  "sanity");
 170   // give it some relocations to start with, if the main section has them
 171   if (_insts.has_locs())  cs->initialize_locs(1);
 172 }
 173 
 174 void CodeBuffer::set_blob(BufferBlob* blob) {
 175   _blob = blob;
 176   if (blob != nullptr) {
 177     address start = blob->content_begin();
 178     address end   = blob->content_end();
 179     // Round up the starting address.
 180     int align = _insts.alignment();
 181     start += (-(intptr_t)start) & (align-1);
 182     _total_start = start;
 183     _total_size  = end - start;
 184   } else {
 185 #ifdef ASSERT
 186     // Clean out dangling pointers.
 187     _total_start    = badAddress;
 188     _consts._start  = _consts._end  = badAddress;
 189     _insts._start   = _insts._end   = badAddress;
 190     _stubs._start   = _stubs._end   = badAddress;
 191 #endif //ASSERT
 192   }
 193 }
 194 
 195 void CodeBuffer::free_blob() {
 196   if (_blob != nullptr) {
 197     BufferBlob::free(_blob);
 198     set_blob(nullptr);
 199   }
 200 }
 201 
 202 const char* CodeBuffer::code_section_name(int n) {
 203 #ifdef PRODUCT
 204   return nullptr;
 205 #else //PRODUCT
 206   switch (n) {
 207   case SECT_CONSTS:            return "consts";
 208   case SECT_INSTS:             return "insts";
 209   case SECT_STUBS:             return "stubs";
 210   default:                     return nullptr;
 211   }
 212 #endif //PRODUCT
 213 }
 214 
 215 int CodeBuffer::section_index_of(address addr) const {
 216   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 217     const CodeSection* cs = code_section(n);
 218     if (cs->allocates(addr))  return n;
 219   }
 220   return SECT_NONE;
 221 }
 222 
 223 int CodeBuffer::locator(address addr) const {
 224   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 225     const CodeSection* cs = code_section(n);
 226     if (cs->allocates(addr)) {
 227       return locator(addr - cs->start(), n);
 228     }
 229   }
 230   return -1;
 231 }
 232 
 233 
 234 bool CodeBuffer::is_backward_branch(Label& L) {
 235   return L.is_bound() && insts_end() <= locator_address(L.loc());
 236 }
 237 
 238 #ifndef PRODUCT
 239 address CodeBuffer::decode_begin() {
 240   address begin = _insts.start();
 241   if (_decode_begin != nullptr && _decode_begin > begin)
 242     begin = _decode_begin;
 243   return begin;
 244 }
 245 #endif // !PRODUCT
 246 
 247 GrowableArray<int>* CodeBuffer::create_patch_overflow() {
 248   if (_overflow_arena == nullptr) {
 249     _overflow_arena = new (mtCode) Arena(mtCode);
 250   }
 251   return new (_overflow_arena) GrowableArray<int>(_overflow_arena, 8, 0, 0);
 252 }
 253 
 254 
 255 // Helper function for managing labels and their target addresses.
 256 // Returns a sensible address, and if it is not the label's final
 257 // address, notes the dependency (at 'branch_pc') on the label.
 258 address CodeSection::target(Label& L, address branch_pc) {
 259   if (L.is_bound()) {
 260     int loc = L.loc();
 261     if (index() == CodeBuffer::locator_sect(loc)) {
 262       return start() + CodeBuffer::locator_pos(loc);
 263     } else {
 264       return outer()->locator_address(loc);
 265     }
 266   } else {
 267     assert(allocates2(branch_pc), "sanity");
 268     address base = start();
 269     int patch_loc = CodeBuffer::locator(branch_pc - base, index());
 270     L.add_patch_at(outer(), patch_loc);
 271 
 272     // Need to return a pc, doesn't matter what it is since it will be
 273     // replaced during resolution later.
 274     // Don't return null or badAddress, since branches shouldn't overflow.
 275     // Don't return base either because that could overflow displacements
 276     // for shorter branches.  It will get checked when bound.
 277     return branch_pc;
 278   }
 279 }
 280 
 281 void CodeSection::relocate(address at, relocInfo::relocType rtype, int format, jint method_index) {
 282   RelocationHolder rh;
 283   switch (rtype) {
 284     case relocInfo::none: return;
 285     case relocInfo::opt_virtual_call_type: {
 286       rh = opt_virtual_call_Relocation::spec(method_index);
 287       break;
 288     }
 289     case relocInfo::static_call_type: {
 290       rh = static_call_Relocation::spec(method_index);
 291       break;
 292     }
 293     case relocInfo::virtual_call_type: {
 294       assert(method_index == 0, "resolved method overriding is not supported");
 295       rh = Relocation::spec_simple(rtype);
 296       break;
 297     }
 298     default: {
 299       rh = Relocation::spec_simple(rtype);
 300       break;
 301     }
 302   }
 303   relocate(at, rh, format);
 304 }
 305 
 306 void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {
 307   // Do not relocate in scratch buffers.
 308   if (scratch_emit()) { return; }
 309   Relocation* reloc = spec.reloc();
 310   relocInfo::relocType rtype = (relocInfo::relocType) reloc->type();
 311   if (rtype == relocInfo::none)  return;
 312 
 313   // The assertion below has been adjusted, to also work for
 314   // relocation for fixup.  Sometimes we want to put relocation
 315   // information for the next instruction, since it will be patched
 316   // with a call.
 317   assert(start() <= at && at <= end()+1,
 318          "cannot relocate data outside code boundaries");
 319 
 320   if (!has_locs()) {
 321     // no space for relocation information provided => code cannot be
 322     // relocated.  Make sure that relocate is only called with rtypes
 323     // that can be ignored for this kind of code.
 324     assert(rtype == relocInfo::none              ||
 325            rtype == relocInfo::runtime_call_type ||
 326            rtype == relocInfo::internal_word_type||
 327            rtype == relocInfo::section_word_type ||
 328            rtype == relocInfo::external_word_type||
 329            rtype == relocInfo::barrier_type,
 330            "code needs relocation information");
 331     // leave behind an indication that we attempted a relocation
 332     DEBUG_ONLY(_locs_start = _locs_limit = (relocInfo*)badAddress);
 333     return;
 334   }
 335 
 336   // Advance the point, noting the offset we'll have to record.
 337   csize_t offset = at - locs_point();
 338   set_locs_point(at);
 339 
 340   // Test for a couple of overflow conditions; maybe expand the buffer.
 341   relocInfo* end = locs_end();
 342   relocInfo* req = end + relocInfo::length_limit;
 343   // Check for (potential) overflow
 344   if (req >= locs_limit() || offset >= relocInfo::offset_limit()) {
 345     req += (uint)offset / (uint)relocInfo::offset_limit();
 346     if (req >= locs_limit()) {
 347       // Allocate or reallocate.
 348       expand_locs(locs_count() + (req - end));
 349       // reload pointer
 350       end = locs_end();
 351     }
 352   }
 353 
 354   // If the offset is giant, emit filler relocs, of type 'none', but
 355   // each carrying the largest possible offset, to advance the locs_point.
 356   while (offset >= relocInfo::offset_limit()) {
 357     assert(end < locs_limit(), "adjust previous paragraph of code");
 358     *end++ = relocInfo::filler_info();
 359     offset -= relocInfo::filler_info().addr_offset();
 360   }
 361 
 362   // If it's a simple reloc with no data, we'll just write (rtype | offset).
 363   (*end) = relocInfo(rtype, offset, format);
 364 
 365   // If it has data, insert the prefix, as (data_prefix_tag | data1), data2.
 366   end->initialize(this, reloc);
 367 }
 368 
 369 void CodeSection::initialize_locs(int locs_capacity) {
 370   assert(_locs_start == nullptr, "only one locs init step, please");
 371   // Apply a priori lower limits to relocation size:
 372   csize_t min_locs = MAX2(size() / 16, (csize_t)4);
 373   if (locs_capacity < min_locs)  locs_capacity = min_locs;
 374   relocInfo* locs_start = NEW_RESOURCE_ARRAY(relocInfo, locs_capacity);
 375   _locs_start    = locs_start;
 376   _locs_end      = locs_start;
 377   _locs_limit    = locs_start + locs_capacity;
 378   _locs_own      = true;
 379 }
 380 
 381 void CodeSection::initialize_shared_locs(relocInfo* buf, int length) {
 382   assert(_locs_start == nullptr, "do this before locs are allocated");
 383   // Internal invariant:  locs buf must be fully aligned.
 384   // See copy_relocations_to() below.
 385   while ((uintptr_t)buf % HeapWordSize != 0 && length > 0) {
 386     ++buf; --length;
 387   }
 388   if (length > 0) {
 389     _locs_start = buf;
 390     _locs_end   = buf;
 391     _locs_limit = buf + length;
 392     _locs_own   = false;
 393   }
 394 }
 395 
 396 void CodeSection::initialize_locs_from(const CodeSection* source_cs) {
 397   int lcount = source_cs->locs_count();
 398   if (lcount != 0) {
 399     initialize_shared_locs(source_cs->locs_start(), lcount);
 400     _locs_end = _locs_limit = _locs_start + lcount;
 401     assert(is_allocated(), "must have copied code already");
 402     set_locs_point(start() + source_cs->locs_point_off());
 403   }
 404   assert(this->locs_count() == source_cs->locs_count(), "sanity");
 405 }
 406 
 407 void CodeSection::expand_locs(int new_capacity) {
 408   if (_locs_start == nullptr) {
 409     initialize_locs(new_capacity);
 410     return;
 411   } else {
 412     int old_count    = locs_count();
 413     int old_capacity = locs_capacity();
 414     if (new_capacity < old_capacity * 2)
 415       new_capacity = old_capacity * 2;
 416     relocInfo* locs_start;
 417     if (_locs_own) {
 418       locs_start = REALLOC_RESOURCE_ARRAY(relocInfo, _locs_start, old_capacity, new_capacity);
 419     } else {
 420       locs_start = NEW_RESOURCE_ARRAY(relocInfo, new_capacity);
 421       Copy::conjoint_jbytes(_locs_start, locs_start, old_capacity * sizeof(relocInfo));
 422       _locs_own = true;
 423     }
 424     _locs_start    = locs_start;
 425     _locs_end      = locs_start + old_count;
 426     _locs_limit    = locs_start + new_capacity;
 427   }
 428 }
 429 
 430 int CodeSection::alignment() const {
 431   if (_index == CodeBuffer::SECT_CONSTS) {
 432     // CodeBuffer controls the alignment of the constants section
 433     return _outer->_const_section_alignment;
 434   }
 435   if (_index == CodeBuffer::SECT_INSTS) {
 436     return (int) CodeEntryAlignment;
 437   }
 438   if (_index == CodeBuffer::SECT_STUBS) {
 439     // CodeBuffer installer expects sections to be HeapWordSize aligned
 440     return HeapWordSize;
 441   }
 442   ShouldNotReachHere();
 443   return 0;
 444 }
 445 
 446 /// Support for emitting the code to its final location.
 447 /// The pattern is the same for all functions.
 448 /// We iterate over all the sections, padding each to alignment.
 449 
 450 csize_t CodeBuffer::total_content_size() const {
 451   csize_t size_so_far = 0;
 452   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 453     const CodeSection* cs = code_section(n);
 454     if (cs->is_empty())  continue;  // skip trivial section
 455     size_so_far = cs->align_at_start(size_so_far);
 456     size_so_far += cs->size();
 457   }
 458   return size_so_far;
 459 }
 460 
 461 void CodeBuffer::compute_final_layout(CodeBuffer* dest) const {
 462   address buf = dest->_total_start;
 463   csize_t buf_offset = 0;
 464   assert(dest->_total_size >= total_content_size(), "must be big enough");
 465   assert(!_finalize_stubs, "non-finalized stubs");
 466 
 467   {
 468     // not sure why this is here, but why not...
 469     int alignSize = MAX2((intx) sizeof(jdouble), CodeEntryAlignment);
 470     assert( (dest->_total_start - _insts.start()) % alignSize == 0, "copy must preserve alignment");
 471   }
 472 
 473   const CodeSection* prev_cs      = nullptr;
 474   CodeSection*       prev_dest_cs = nullptr;
 475 
 476   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 477     // figure compact layout of each section
 478     const CodeSection* cs = code_section(n);
 479     csize_t csize = cs->size();
 480 
 481     CodeSection* dest_cs = dest->code_section(n);
 482     if (!cs->is_empty()) {
 483       // Compute initial padding; assign it to the previous non-empty guy.
 484       // Cf. figure_expanded_capacities.
 485       csize_t padding = cs->align_at_start(buf_offset) - buf_offset;
 486       if (prev_dest_cs != nullptr) {
 487         if (padding != 0) {
 488           buf_offset += padding;
 489           prev_dest_cs->_limit += padding;
 490         }
 491       } else {
 492         guarantee(padding == 0, "In first iteration no padding should be needed.");
 493       }
 494       prev_dest_cs = dest_cs;
 495       prev_cs      = cs;
 496     }
 497 
 498     debug_only(dest_cs->_start = nullptr);  // defeat double-initialization assert
 499     dest_cs->initialize(buf+buf_offset, csize);
 500     dest_cs->set_end(buf+buf_offset+csize);
 501     assert(dest_cs->is_allocated(), "must always be allocated");
 502     assert(cs->is_empty() == dest_cs->is_empty(), "sanity");
 503 
 504     buf_offset += csize;
 505   }
 506 
 507   // Done calculating sections; did it come out to the right end?
 508   assert(buf_offset == total_content_size(), "sanity");
 509   debug_only(dest->verify_section_allocation();)
 510 }
 511 
 512 // Append an oop reference that keeps the class alive.
 513 static void append_oop_references(GrowableArray<oop>* oops, Klass* k) {
 514   oop cl = k->klass_holder();
 515   if (cl != nullptr && !oops->contains(cl)) {
 516     oops->append(cl);
 517   }
 518 }
 519 
 520 void CodeBuffer::finalize_oop_references(const methodHandle& mh) {
 521   NoSafepointVerifier nsv;
 522 
 523   GrowableArray<oop> oops;
 524 
 525   // Make sure that immediate metadata records something in the OopRecorder
 526   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 527     // pull code out of each section
 528     CodeSection* cs = code_section(n);
 529     if (cs->is_empty() || (cs->locs_count() == 0)) continue;  // skip trivial section
 530     RelocIterator iter(cs);
 531     while (iter.next()) {
 532       if (iter.type() == relocInfo::metadata_type) {
 533         metadata_Relocation* md = iter.metadata_reloc();
 534         if (md->metadata_is_immediate()) {
 535           Metadata* m = md->metadata_value();
 536           if (oop_recorder()->is_real(m)) {
 537             if (m->is_methodData()) {
 538               m = ((MethodData*)m)->method();
 539             }
 540             if (m->is_methodCounters()) {
 541               m = ((MethodCounters*)m)->method();
 542             }
 543             if (m->is_method()) {
 544               m = ((Method*)m)->method_holder();
 545             }
 546             if (m->is_klass()) {
 547               append_oop_references(&oops, (Klass*)m);
 548             } else {
 549               // XXX This will currently occur for MDO which don't
 550               // have a backpointer.  This has to be fixed later.
 551               m->print();
 552               ShouldNotReachHere();
 553             }
 554           }
 555         }
 556       }
 557     }
 558   }
 559 
 560   if (!oop_recorder()->is_unused()) {
 561     for (int i = 0; i < oop_recorder()->metadata_count(); i++) {
 562       Metadata* m = oop_recorder()->metadata_at(i);
 563       if (oop_recorder()->is_real(m)) {
 564         if (m->is_methodData()) {
 565           m = ((MethodData*)m)->method();
 566         }
 567         if (m->is_methodCounters()) {
 568           m = ((MethodCounters*)m)->method();
 569         }
 570         if (m->is_method()) {
 571           m = ((Method*)m)->method_holder();
 572         }
 573         if (m->is_klass()) {
 574           append_oop_references(&oops, (Klass*)m);
 575         } else {
 576           m->print();
 577           ShouldNotReachHere();
 578         }
 579       }
 580     }
 581 
 582   }
 583 
 584   // Add the class loader of Method* for the nmethod itself
 585   append_oop_references(&oops, mh->method_holder());
 586 
 587   // Add any oops that we've found
 588   Thread* thread = Thread::current();
 589   for (int i = 0; i < oops.length(); i++) {
 590     oop_recorder()->find_index((jobject)thread->handle_area()->allocate_handle(oops.at(i)));
 591   }
 592 }
 593 
 594 
 595 
 596 csize_t CodeBuffer::total_offset_of(const CodeSection* cs) const {
 597   csize_t size_so_far = 0;
 598   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 599     const CodeSection* cur_cs = code_section(n);
 600     if (!cur_cs->is_empty()) {
 601       size_so_far = cur_cs->align_at_start(size_so_far);
 602     }
 603     if (cur_cs->index() == cs->index()) {
 604       return size_so_far;
 605     }
 606     size_so_far += cur_cs->size();
 607   }
 608   ShouldNotReachHere();
 609   return -1;
 610 }
 611 
 612 int CodeBuffer::total_skipped_instructions_size() const {
 613   int total_skipped_size = 0;
 614   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 615     const CodeSection* cur_cs = code_section(n);
 616     if (!cur_cs->is_empty()) {
 617       total_skipped_size += cur_cs->_skipped_instructions_size;
 618     }
 619   }
 620   return total_skipped_size;
 621 }
 622 
 623 csize_t CodeBuffer::total_relocation_size() const {
 624   csize_t total = copy_relocations_to(nullptr);  // dry run only
 625   return (csize_t) align_up(total, HeapWordSize);
 626 }
 627 
 628 csize_t CodeBuffer::copy_relocations_to(address buf, csize_t buf_limit, bool only_inst) const {
 629   csize_t buf_offset = 0;
 630   csize_t code_end_so_far = 0;
 631   csize_t code_point_so_far = 0;
 632 
 633   assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");
 634   assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");
 635 
 636   for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
 637     if (only_inst && (n != (int)SECT_INSTS)) {
 638       // Need only relocation info for code.
 639       continue;
 640     }
 641     // pull relocs out of each section
 642     const CodeSection* cs = code_section(n);
 643     assert(!(cs->is_empty() && cs->locs_count() > 0), "sanity");
 644     if (cs->is_empty())  continue;  // skip trivial section
 645     relocInfo* lstart = cs->locs_start();
 646     relocInfo* lend   = cs->locs_end();
 647     csize_t    lsize  = (csize_t)( (address)lend - (address)lstart );
 648     csize_t    csize  = cs->size();
 649     code_end_so_far = cs->align_at_start(code_end_so_far);
 650 
 651     if (lsize > 0) {
 652       // Figure out how to advance the combined relocation point
 653       // first to the beginning of this section.
 654       // We'll insert one or more filler relocs to span that gap.
 655       // (Don't bother to improve this by editing the first reloc's offset.)
 656       csize_t new_code_point = code_end_so_far;
 657       for (csize_t jump;
 658            code_point_so_far < new_code_point;
 659            code_point_so_far += jump) {
 660         jump = new_code_point - code_point_so_far;
 661         relocInfo filler = relocInfo::filler_info();
 662         if (jump >= filler.addr_offset()) {
 663           jump = filler.addr_offset();
 664         } else {  // else shrink the filler to fit
 665           filler = relocInfo(relocInfo::none, jump);
 666         }
 667         if (buf != nullptr) {
 668           assert(buf_offset + (csize_t)sizeof(filler) <= buf_limit, "filler in bounds");
 669           *(relocInfo*)(buf+buf_offset) = filler;
 670         }
 671         buf_offset += sizeof(filler);
 672       }
 673 
 674       // Update code point and end to skip past this section:
 675       csize_t last_code_point = code_end_so_far + cs->locs_point_off();
 676       assert(code_point_so_far <= last_code_point, "sanity");
 677       code_point_so_far = last_code_point; // advance past this guy's relocs
 678     }
 679     code_end_so_far += csize;  // advance past this guy's instructions too
 680 
 681     // Done with filler; emit the real relocations:
 682     if (buf != nullptr && lsize != 0) {
 683       assert(buf_offset + lsize <= buf_limit, "target in bounds");
 684       assert((uintptr_t)lstart % HeapWordSize == 0, "sane start");
 685       if (buf_offset % HeapWordSize == 0) {
 686         // Use wordwise copies if possible:
 687         Copy::disjoint_words((HeapWord*)lstart,
 688                              (HeapWord*)(buf+buf_offset),
 689                              (lsize + HeapWordSize-1) / HeapWordSize);
 690       } else {
 691         Copy::conjoint_jbytes(lstart, buf+buf_offset, lsize);
 692       }
 693     }
 694     buf_offset += lsize;
 695   }
 696 
 697   // Align end of relocation info in target.
 698   while (buf_offset % HeapWordSize != 0) {
 699     if (buf != nullptr) {
 700       relocInfo padding = relocInfo(relocInfo::none, 0);
 701       assert(buf_offset + (csize_t)sizeof(padding) <= buf_limit, "padding in bounds");
 702       *(relocInfo*)(buf+buf_offset) = padding;
 703     }
 704     buf_offset += sizeof(relocInfo);
 705   }
 706 
 707   assert(only_inst || code_end_so_far == total_content_size(), "sanity");
 708 
 709   return buf_offset;
 710 }
 711 
 712 csize_t CodeBuffer::copy_relocations_to(CodeBlob* dest) const {
 713   address buf = nullptr;
 714   csize_t buf_offset = 0;
 715   csize_t buf_limit = 0;
 716 
 717   if (dest != nullptr) {
 718     buf = (address)dest->relocation_begin();
 719     buf_limit = (address)dest->relocation_end() - buf;
 720   }
 721   // if dest is null, this is just the sizing pass
 722   //
 723   buf_offset = copy_relocations_to(buf, buf_limit, false);
 724 
 725   return buf_offset;
 726 }
 727 
 728 void CodeBuffer::copy_code_to(CodeBlob* dest_blob) {
 729 #ifndef PRODUCT
 730   if (PrintNMethods && (WizardMode || Verbose)) {
 731     tty->print("done with CodeBuffer:");
 732     ((CodeBuffer*)this)->print_on(tty);
 733   }
 734 #endif //PRODUCT
 735 
 736   CodeBuffer dest(dest_blob);
 737   assert(dest_blob->content_size() >= total_content_size(), "good sizing");
 738   this->compute_final_layout(&dest);
 739 
 740   // Set beginning of constant table before relocating.
 741   dest_blob->set_ctable_begin(dest.consts()->start());
 742 
 743   relocate_code_to(&dest);
 744 
 745   // Share assembly remarks and debug strings with the blob.
 746   NOT_PRODUCT(dest_blob->use_remarks(_asm_remarks));
 747   NOT_PRODUCT(dest_blob->use_strings(_dbg_strings));
 748 
 749   // Done moving code bytes; were they the right size?
 750   assert((int)align_up(dest.total_content_size(), oopSize) == dest_blob->content_size(), "sanity");
 751 
 752   // Flush generated code
 753   ICache::invalidate_range(dest_blob->code_begin(), dest_blob->code_size());
 754 }
 755 
 756 // Move all my code into another code buffer.  Consult applicable
 757 // relocs to repair embedded addresses.  The layout in the destination
 758 // CodeBuffer is different to the source CodeBuffer: the destination
 759 // CodeBuffer gets the final layout (consts, insts, stubs in order of
 760 // ascending address).
 761 void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
 762   address dest_end = dest->_total_start + dest->_total_size;
 763   address dest_filled = nullptr;
 764   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 765     // pull code out of each section
 766     const CodeSection* cs = code_section(n);
 767     if (cs->is_empty())  continue;  // skip trivial section
 768     CodeSection* dest_cs = dest->code_section(n);
 769     assert(cs->size() == dest_cs->size(), "sanity");
 770     csize_t usize = dest_cs->size();
 771     csize_t wsize = align_up(usize, HeapWordSize);
 772     assert(dest_cs->start() + wsize <= dest_end, "no overflow");
 773     // Copy the code as aligned machine words.
 774     // This may also include an uninitialized partial word at the end.
 775     Copy::disjoint_words((HeapWord*)cs->start(),
 776                          (HeapWord*)dest_cs->start(),
 777                          wsize / HeapWordSize);
 778 
 779     if (dest->blob() == nullptr) {
 780       // Destination is a final resting place, not just another buffer.
 781       // Normalize uninitialized bytes in the final padding.
 782       Copy::fill_to_bytes(dest_cs->end(), dest_cs->remaining(),
 783                           Assembler::code_fill_byte());
 784     }
 785     // Keep track of the highest filled address
 786     dest_filled = MAX2(dest_filled, dest_cs->end() + dest_cs->remaining());
 787 
 788     assert(cs->locs_start() != (relocInfo*)badAddress,
 789            "this section carries no reloc storage, but reloc was attempted");
 790 
 791     // Make the new code copy use the old copy's relocations:
 792     dest_cs->initialize_locs_from(cs);
 793   }
 794 
 795   // Do relocation after all sections are copied.
 796   // This is necessary if the code uses constants in stubs, which are
 797   // relocated when the corresponding instruction in the code (e.g., a
 798   // call) is relocated. Stubs are placed behind the main code
 799   // section, so that section has to be copied before relocating.
 800   for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
 801     CodeSection* dest_cs = dest->code_section(n);
 802     if (dest_cs->is_empty() || (dest_cs->locs_count() == 0)) continue;  // skip trivial section
 803     { // Repair the pc relative information in the code after the move
 804       RelocIterator iter(dest_cs);
 805       while (iter.next()) {
 806         iter.reloc()->fix_relocation_after_move(this, dest);
 807       }
 808     }
 809   }
 810 
 811   if (dest->blob() == nullptr && dest_filled != nullptr) {
 812     // Destination is a final resting place, not just another buffer.
 813     // Normalize uninitialized bytes in the final padding.
 814     Copy::fill_to_bytes(dest_filled, dest_end - dest_filled,
 815                         Assembler::code_fill_byte());
 816 
 817   }
 818 }
 819 
 820 csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,
 821                                                csize_t amount,
 822                                                csize_t* new_capacity) {
 823   csize_t new_total_cap = 0;
 824 
 825   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 826     const CodeSection* sect = code_section(n);
 827 
 828     if (!sect->is_empty()) {
 829       // Compute initial padding; assign it to the previous section,
 830       // even if it's empty (e.g. consts section can be empty).
 831       // Cf. compute_final_layout
 832       csize_t padding = sect->align_at_start(new_total_cap) - new_total_cap;
 833       if (padding != 0) {
 834         new_total_cap += padding;
 835         assert(n - 1 >= SECT_FIRST, "sanity");
 836         new_capacity[n - 1] += padding;
 837       }
 838     }
 839 
 840     csize_t exp = sect->size();  // 100% increase
 841     if ((uint)exp < 4*K)  exp = 4*K;       // minimum initial increase
 842     if (sect == which_cs) {
 843       if (exp < amount)  exp = amount;
 844       if (StressCodeBuffers)  exp = amount;  // expand only slightly
 845     } else if (n == SECT_INSTS) {
 846       // scale down inst increases to a more modest 25%
 847       exp = 4*K + ((exp - 4*K) >> 2);
 848       if (StressCodeBuffers)  exp = amount / 2;  // expand only slightly
 849     } else if (sect->is_empty()) {
 850       // do not grow an empty secondary section
 851       exp = 0;
 852     }
 853     // Allow for inter-section slop:
 854     exp += CodeSection::end_slop();
 855     csize_t new_cap = sect->size() + exp;
 856     if (new_cap < sect->capacity()) {
 857       // No need to expand after all.
 858       new_cap = sect->capacity();
 859     }
 860     new_capacity[n] = new_cap;
 861     new_total_cap += new_cap;
 862   }
 863 
 864   return new_total_cap;
 865 }
 866 
 867 void CodeBuffer::expand(CodeSection* which_cs, csize_t amount) {
 868 #ifndef PRODUCT
 869   if (PrintNMethods && (WizardMode || Verbose)) {
 870     tty->print("expanding CodeBuffer:");
 871     this->print_on(tty);
 872   }
 873 
 874   if (StressCodeBuffers && blob() != nullptr) {
 875     static int expand_count = 0;
 876     if (expand_count >= 0)  expand_count += 1;
 877     if (expand_count > 100 && is_power_of_2(expand_count)) {
 878       tty->print_cr("StressCodeBuffers: have expanded %d times", expand_count);
 879       // simulate an occasional allocation failure:
 880       free_blob();
 881     }
 882   }
 883 #endif //PRODUCT
 884 
 885   // Resizing must be allowed
 886   {
 887     if (blob() == nullptr)  return;  // caller must check if blob is null
 888   }
 889 
 890   // Figure new capacity for each section.
 891   csize_t new_capacity[SECT_LIMIT];
 892   memset(new_capacity, 0, sizeof(csize_t) * SECT_LIMIT);
 893   csize_t new_total_cap
 894     = figure_expanded_capacities(which_cs, amount, new_capacity);
 895 
 896   // Create a new (temporary) code buffer to hold all the new data
 897   CodeBuffer cb(name(), new_total_cap, 0);
 898   if (cb.blob() == nullptr) {
 899     // Failed to allocate in code cache.
 900     free_blob();
 901     return;
 902   }
 903 
 904   // Create an old code buffer to remember which addresses used to go where.
 905   // This will be useful when we do final assembly into the code cache,
 906   // because we will need to know how to warp any internal address that
 907   // has been created at any time in this CodeBuffer's past.
 908   CodeBuffer* bxp = new CodeBuffer(_total_start, _total_size);
 909   bxp->take_over_code_from(this);  // remember the old undersized blob
 910   DEBUG_ONLY(this->_blob = nullptr);  // silence a later assert
 911   bxp->_before_expand = this->_before_expand;
 912   this->_before_expand = bxp;
 913 
 914   // Give each section its required (expanded) capacity.
 915   for (int n = (int)SECT_LIMIT-1; n >= SECT_FIRST; n--) {
 916     CodeSection* cb_sect   = cb.code_section(n);
 917     CodeSection* this_sect = code_section(n);
 918     if (new_capacity[n] == 0)  continue;  // already nulled out
 919     if (n != SECT_INSTS) {
 920       cb.initialize_section_size(cb_sect, new_capacity[n]);
 921     }
 922     assert(cb_sect->capacity() >= new_capacity[n], "big enough");
 923     address cb_start = cb_sect->start();
 924     cb_sect->set_end(cb_start + this_sect->size());
 925     if (this_sect->mark() == nullptr) {
 926       cb_sect->clear_mark();
 927     } else {
 928       cb_sect->set_mark(cb_start + this_sect->mark_off());
 929     }
 930   }
 931 
 932   // Needs to be initialized when calling fix_relocation_after_move.
 933   cb.blob()->set_ctable_begin(cb.consts()->start());
 934 
 935   // Move all the code and relocations to the new blob:
 936   relocate_code_to(&cb);
 937 
 938   // some internal addresses, _last_insn _last_label, are used during code emission,
 939   // adjust them in expansion
 940   adjust_internal_address(insts_begin(), cb.insts_begin());
 941 
 942   // Copy the temporary code buffer into the current code buffer.
 943   // Basically, do {*this = cb}, except for some control information.
 944   this->take_over_code_from(&cb);
 945   cb.set_blob(nullptr);
 946 
 947   // Zap the old code buffer contents, to avoid mistakenly using them.
 948   debug_only(Copy::fill_to_bytes(bxp->_total_start, bxp->_total_size,
 949                                  badCodeHeapFreeVal);)
 950 
 951   // Make certain that the new sections are all snugly inside the new blob.
 952   debug_only(verify_section_allocation();)
 953 
 954 #ifndef PRODUCT
 955   _decode_begin = nullptr;  // sanity
 956   if (PrintNMethods && (WizardMode || Verbose)) {
 957     tty->print("expanded CodeBuffer:");
 958     this->print_on(tty);
 959   }
 960 #endif //PRODUCT
 961 }
 962 
 963 void CodeBuffer::adjust_internal_address(address from, address to) {
 964   if (_last_insn != nullptr) {
 965     _last_insn += to - from;
 966   }
 967   if (_last_label != nullptr) {
 968     _last_label += to - from;
 969   }
 970 }
 971 
 972 void CodeBuffer::take_over_code_from(CodeBuffer* cb) {
 973   // Must already have disposed of the old blob somehow.
 974   assert(blob() == nullptr, "must be empty");
 975   // Take the new blob away from cb.
 976   set_blob(cb->blob());
 977   // Take over all the section pointers.
 978   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 979     CodeSection* cb_sect   = cb->code_section(n);
 980     CodeSection* this_sect = code_section(n);
 981     this_sect->take_over_code_from(cb_sect);
 982   }
 983   _overflow_arena = cb->_overflow_arena;
 984   cb->_overflow_arena = nullptr;
 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 == badAddress)  return;  // smashed by set_blob(nullptr)
 992   address tend   = tstart + _total_size;
 993   if (_blob != nullptr) {
 994     guarantee(tstart >= _blob->content_begin(), "sanity");
 995     guarantee(tend   <= _blob->content_end(),   "sanity");
 996   }
 997   // Verify disjointness.
 998   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 999     CodeSection* sect = code_section(n);
1000     if (!sect->is_allocated() || sect->is_empty()) {
1001       continue;
1002     }
1003     guarantee(_blob == nullptr || is_aligned(sect->start(), sect->alignment()),
1004            "start is aligned");
1005     for (int m = n + 1; m < (int) SECT_LIMIT; m++) {
1006       CodeSection* other = code_section(m);
1007       if (!other->is_allocated() || other == sect) {
1008         continue;
1009       }
1010       guarantee(other->disjoint(sect), "sanity");
1011     }
1012     guarantee(sect->end() <= tend, "sanity, sect_end: " PTR_FORMAT " tend: " PTR_FORMAT " size: %d", p2i(sect->end()), p2i(tend), (int)_total_size);
1013     guarantee(sect->end() <= sect->limit(), "sanity, sect_end: " PTR_FORMAT " sect_limit: " PTR_FORMAT, p2i(sect->end()), p2i(sect->limit()));
1014   }
1015 }
1016 
1017 void CodeBuffer::log_section_sizes(const char* name) {
1018   if (xtty != nullptr) {
1019     ttyLocker ttyl;
1020     // log info about buffer usage
1021     xtty->head("blob name='%s' total_size='%d'", name, _total_size);
1022     for (int n = (int) CodeBuffer::SECT_FIRST; n < (int) CodeBuffer::SECT_LIMIT; n++) {
1023       CodeSection* sect = code_section(n);
1024       if (!sect->is_allocated() || sect->is_empty())  continue;
1025       xtty->elem("sect index='%d' capacity='%d' size='%d' remaining='%d'",
1026                  n, sect->capacity(), sect->size(), sect->remaining());
1027     }
1028     xtty->tail("blob");
1029   }
1030 }
1031 
1032 bool CodeBuffer::finalize_stubs() {
1033   if (_finalize_stubs && !pd_finalize_stubs()) {
1034     // stub allocation failure
1035     return false;
1036   }
1037   _finalize_stubs = false;
1038   return true;
1039 }
1040 
1041 void CodeBuffer::shared_stub_to_interp_for(ciMethod* callee, csize_t call_offset) {
1042   if (_shared_stub_to_interp_requests == nullptr) {
1043     _shared_stub_to_interp_requests = new SharedStubToInterpRequests(8);
1044   }
1045   SharedStubToInterpRequest request(callee, call_offset);
1046   _shared_stub_to_interp_requests->push(request);
1047   _finalize_stubs = true;
1048 }
1049 
1050 #ifndef PRODUCT
1051 void CodeBuffer::block_comment(ptrdiff_t offset, const char* comment) {
1052   if (_collect_comments) {
1053     const char* str = _asm_remarks.insert(offset, comment);
1054     postcond(str != comment);
1055   }
1056 }
1057 
1058 const char* CodeBuffer::code_string(const char* str) {
1059   const char* tmp = _dbg_strings.insert(str);
1060   postcond(tmp != str);
1061   return tmp;
1062 }
1063 
1064 void CodeBuffer::decode() {
1065   ttyLocker ttyl;
1066   Disassembler::decode(decode_begin(), insts_end(), tty NOT_PRODUCT(COMMA &asm_remarks()));
1067   _decode_begin = insts_end();
1068 }
1069 
1070 void CodeSection::print_on(outputStream* st, const char* name) {
1071   csize_t locs_size = locs_end() - locs_start();
1072   st->print_cr(" %7s.code = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d)",
1073                name, p2i(start()), p2i(end()), p2i(limit()), size(), capacity());
1074   st->print_cr(" %7s.locs = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d) point=%d",
1075                name, p2i(locs_start()), p2i(locs_end()), p2i(locs_limit()), locs_size, locs_capacity(), locs_point_off());
1076   if (PrintRelocations && (locs_size != 0)) {
1077     RelocIterator iter(this);
1078     iter.print_on(st);
1079   }
1080 }
1081 
1082 void CodeBuffer::print_on(outputStream* st) {
1083 #if 0
1084   if (this == nullptr) { // gcc complains 'nonnull' argument 'this' compared to NULL 
1085     st->print_cr("null CodeBuffer pointer");
1086     return;
1087   }
1088 #endif
1089 
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 -----------------------------------------------------------
1099 
1100 class CHeapString : public CHeapObj<mtCode> {
1101  public:
1102   CHeapString(const char* str) : _string(os::strdup(str)) {}
1103  ~CHeapString() {
1104     os::free((void*)_string);
1105     _string = nullptr;
1106   }
1107   const char* string() const { return _string; }
1108 
1109  private:
1110   const char* _string;
1111 };
1112 
1113 // ----- AsmRemarkCollection ---------------------------------------------------
1114 
1115 class AsmRemarkCollection : public CHeapObj<mtCode> {
1116  public:
1117   AsmRemarkCollection() : _ref_cnt(1), _remarks(nullptr), _next(nullptr) {}
1118  ~AsmRemarkCollection() {
1119     assert(is_empty(), "Must 'clear()' before deleting!");
1120     assert(_ref_cnt == 0, "No uses must remain when deleting!");
1121   }
1122   AsmRemarkCollection* reuse() {
1123     precond(_ref_cnt > 0);
1124     return _ref_cnt++, this;
1125   }
1126 
1127   const char* insert(uint offset, const char* remark);
1128   const char* lookup(uint offset) const;
1129   const char* next(uint offset) const;
1130 
1131   bool is_empty() const { return _remarks == nullptr; }
1132   uint clear();
1133 
1134  private:
1135   struct Cell : CHeapString {
1136     Cell(const char* remark, uint offset) :
1137         CHeapString(remark), offset(offset), prev(nullptr), next(nullptr) {}
1138     void push_back(Cell* cell) {
1139       Cell* head = this;
1140       Cell* tail = prev;
1141       tail->next = cell;
1142       cell->next = head;
1143       cell->prev = tail;
1144       prev = cell;
1145     }
1146     uint offset;
1147     Cell* prev;
1148     Cell* next;
1149   };
1150   uint  _ref_cnt;
1151   Cell* _remarks;
1152   // Using a 'mutable' iteration pointer to allow 'const' on lookup/next (that
1153   // does not change the state of the list per se), supportig a simplistic
1154   // iteration scheme.
1155   mutable Cell* _next;
1156 };
1157 
1158 // ----- DbgStringCollection ---------------------------------------------------
1159 
1160 class DbgStringCollection : public CHeapObj<mtCode> {
1161  public:
1162   DbgStringCollection() : _ref_cnt(1), _strings(nullptr) {}
1163  ~DbgStringCollection() {
1164     assert(is_empty(), "Must 'clear()' before deleting!");
1165     assert(_ref_cnt == 0, "No uses must remain when deleting!");
1166   }
1167   DbgStringCollection* reuse() {
1168     precond(_ref_cnt > 0);
1169     return _ref_cnt++, this;
1170   }
1171 
1172   const char* insert(const char* str);
1173   const char* lookup(const char* str) const;
1174 
1175   bool is_empty() const { return _strings == nullptr; }
1176   uint clear();
1177 
1178  private:
1179   struct Cell : CHeapString {
1180     Cell(const char* dbgstr) :
1181         CHeapString(dbgstr), prev(nullptr), next(nullptr) {}
1182     void push_back(Cell* cell) {
1183       Cell* head = this;
1184       Cell* tail = prev;
1185       tail->next = cell;
1186       cell->next = head;
1187       cell->prev = tail;
1188       prev = cell;
1189     }
1190     Cell* prev;
1191     Cell* next;
1192   };
1193   uint  _ref_cnt;
1194   Cell* _strings;
1195 };
1196 
1197 // ----- AsmRemarks ------------------------------------------------------------
1198 //
1199 // Acting as interface to reference counted mapping [offset -> remark], where
1200 // offset is a byte offset into an instruction stream (CodeBuffer, CodeBlob or
1201 // other memory buffer) and remark is a string (comment).
1202 //
1203 AsmRemarks::AsmRemarks() : _remarks(new AsmRemarkCollection()) {
1204   assert(_remarks != nullptr, "Allocation failure!");
1205 }
1206 
1207 AsmRemarks::~AsmRemarks() {
1208   assert(_remarks == nullptr, "Must 'clear()' before deleting!");
1209 }
1210 
1211 const char* AsmRemarks::insert(uint offset, const char* remstr) {
1212   precond(remstr != nullptr);
1213   return _remarks->insert(offset, remstr);
1214 }
1215 
1216 bool AsmRemarks::is_empty() const {
1217   return _remarks->is_empty();
1218 }
1219 
1220 void AsmRemarks::share(const AsmRemarks &src) {
1221   precond(is_empty());
1222   clear();
1223   _remarks = src._remarks->reuse();
1224 }
1225 
1226 void AsmRemarks::clear() {
1227   if (_remarks->clear() == 0) {
1228     delete _remarks;
1229   }
1230   _remarks = nullptr;
1231 }
1232 
1233 uint AsmRemarks::print(uint offset, outputStream* strm) const {
1234   uint count = 0;
1235   const char* prefix = " ;; ";
1236   const char* remstr = _remarks->lookup(offset);
1237   while (remstr != nullptr) {
1238     strm->bol();
1239     strm->print("%s", prefix);
1240     // Don't interpret as format strings since it could contain '%'.
1241     strm->print_raw(remstr);
1242     // Advance to next line iff string didn't contain a cr() at the end.
1243     strm->bol();
1244     remstr = _remarks->next(offset);
1245     count++;
1246   }
1247   return count;
1248 }
1249 
1250 // ----- DbgStrings ------------------------------------------------------------
1251 //
1252 // Acting as interface to reference counted collection of (debug) strings used
1253 // in the code generated, and thus requiring a fixed address.
1254 //
1255 DbgStrings::DbgStrings() : _strings(new DbgStringCollection()) {
1256   assert(_strings != nullptr, "Allocation failure!");
1257 }
1258 
1259 DbgStrings::~DbgStrings() {
1260   assert(_strings == nullptr, "Must 'clear()' before deleting!");
1261 }
1262 
1263 const char* DbgStrings::insert(const char* dbgstr) {
1264   const char* str = _strings->lookup(dbgstr);
1265   return str != nullptr ? str : _strings->insert(dbgstr);
1266 }
1267 
1268 bool DbgStrings::is_empty() const {
1269   return _strings->is_empty();
1270 }
1271 
1272 void DbgStrings::share(const DbgStrings &src) {
1273   precond(is_empty());
1274   clear();
1275   _strings = src._strings->reuse();
1276 }
1277 
1278 void DbgStrings::clear() {
1279   if (_strings->clear() == 0) {
1280     delete _strings;
1281   }
1282   _strings = nullptr;
1283 }
1284 
1285 // ----- AsmRemarkCollection ---------------------------------------------------
1286 
1287 const char* AsmRemarkCollection::insert(uint offset, const char* remstr) {
1288   precond(remstr != nullptr);
1289   Cell* cell = new Cell { remstr, offset };
1290   if (is_empty()) {
1291     cell->prev = cell;
1292     cell->next = cell;
1293     _remarks = cell;
1294   } else {
1295     _remarks->push_back(cell);
1296   }
1297   return cell->string();
1298 }
1299 
1300 const char* AsmRemarkCollection::lookup(uint offset) const {
1301   _next = _remarks;
1302   return next(offset);
1303 }
1304 
1305 const char* AsmRemarkCollection::next(uint offset) const {
1306   if (_next != nullptr) {
1307     Cell* i = _next;
1308     do {
1309       if (i->offset == offset) {
1310         _next = i->next == _remarks ? nullptr : i->next;
1311         return i->string();
1312       }
1313       i = i->next;
1314     } while (i != _remarks);
1315     _next = nullptr;
1316   }
1317   return nullptr;
1318 }
1319 
1320 uint AsmRemarkCollection::clear() {
1321   precond(_ref_cnt > 0);
1322   if (--_ref_cnt > 0) {
1323     return _ref_cnt;
1324   }
1325   if (!is_empty()) {
1326     uint count = 0;
1327     Cell* i = _remarks;
1328     do {
1329       Cell* next = i->next;
1330       delete i;
1331       i = next;
1332       count++;
1333     } while (i != _remarks);
1334 
1335     log_debug(codestrings)("Clear %u asm-remark%s.", count, count == 1 ? "" : "s");
1336     _remarks = nullptr;
1337   }
1338   return 0; // i.e. _ref_cnt == 0
1339 }
1340 
1341 // ----- DbgStringCollection ---------------------------------------------------
1342 
1343 const char* DbgStringCollection::insert(const char* dbgstr) {
1344   precond(dbgstr != nullptr);
1345   Cell* cell = new Cell { dbgstr };
1346 
1347   if (is_empty()) {
1348      cell->prev = cell;
1349      cell->next = cell;
1350      _strings = cell;
1351   } else {
1352     _strings->push_back(cell);
1353   }
1354   return cell->string();
1355 }
1356 
1357 const char* DbgStringCollection::lookup(const char* dbgstr) const {
1358   precond(dbgstr != nullptr);
1359   if (_strings != nullptr) {
1360     Cell* i = _strings;
1361     do {
1362       if (strcmp(i->string(), dbgstr) == 0) {
1363         return i->string();
1364       }
1365       i = i->next;
1366     } while (i != _strings);
1367   }
1368   return nullptr;
1369 }
1370 
1371 uint DbgStringCollection::clear() {
1372   precond(_ref_cnt > 0);
1373   if (--_ref_cnt > 0) {
1374     return _ref_cnt;
1375   }
1376   if (!is_empty()) {
1377     uint count = 0;
1378     Cell* i = _strings;
1379     do {
1380       Cell* next = i->next;
1381       delete i;
1382       i = next;
1383       count++;
1384     } while (i != _strings);
1385 
1386     log_debug(codestrings)("Clear %u dbg-string%s.", count, count == 1 ? "" : "s");
1387     _strings = nullptr;
1388   }
1389   return 0; // i.e. _ref_cnt == 0
1390 }
1391 
1392 #endif // not PRODUCT