1 /*
   2  * Copyright (c) 1997, 2014, 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 "compiler/disassembler.hpp"
  28 #include "memory/gcLocker.hpp"
  29 #include "oops/methodData.hpp"
  30 #include "oops/oop.inline.hpp"
  31 #include "utilities/copy.hpp"
  32 #include "utilities/xmlstream.hpp"
  33 
  34 // The structure of a CodeSection:
  35 //
  36 //    _start ->           +----------------+
  37 //                        | machine code...|
  38 //    _end ->             |----------------|
  39 //                        |                |
  40 //                        |    (empty)     |
  41 //                        |                |
  42 //                        |                |
  43 //                        +----------------+
  44 //    _limit ->           |                |
  45 //
  46 //    _locs_start ->      +----------------+
  47 //                        |reloc records...|
  48 //                        |----------------|
  49 //    _locs_end ->        |                |
  50 //                        |                |
  51 //                        |    (empty)     |
  52 //                        |                |
  53 //                        |                |
  54 //                        +----------------+
  55 //    _locs_limit ->      |                |
  56 // The _end (resp. _limit) pointer refers to the first
  57 // unused (resp. unallocated) byte.
  58 
  59 // The structure of the CodeBuffer while code is being accumulated:
  60 //
  61 //    _total_start ->    \
  62 //    _insts._start ->              +----------------+
  63 //                                  |                |
  64 //                                  |     Code       |
  65 //                                  |                |
  66 //    _stubs._start ->              |----------------|
  67 //                                  |                |
  68 //                                  |    Stubs       | (also handlers for deopt/exception)
  69 //                                  |                |
  70 //    _consts._start ->             |----------------|
  71 //                                  |                |
  72 //                                  |   Constants    |
  73 //                                  |                |
  74 //                                  +----------------+
  75 //    + _total_size ->              |                |
  76 //
  77 // When the code and relocations are copied to the code cache,
  78 // the empty parts of each section are removed, and everything
  79 // is copied into contiguous locations.
  80 
  81 typedef CodeBuffer::csize_t csize_t;  // file-local definition
  82 
  83 // External buffer, in a predefined CodeBlob.
  84 // Important: The code_start must be taken exactly, and not realigned.
  85 CodeBuffer::CodeBuffer(CodeBlob* blob) {
  86   initialize_misc("static buffer");
  87   initialize(blob->content_begin(), blob->content_size());
  88   verify_section_allocation();
  89 }
  90 
  91 void CodeBuffer::initialize(csize_t code_size, csize_t locs_size) {
  92   // Compute maximal alignment.
  93   int align = _insts.alignment();
  94   // Always allow for empty slop around each section.
  95   int slop = (int) CodeSection::end_slop();
  96 
  97   assert(blob() == NULL, "only once");
  98   set_blob(BufferBlob::create(_name, code_size + (align+slop) * (SECT_LIMIT+1)));
  99   if (blob() == NULL) {
 100     // The assembler constructor will throw a fatal on an empty CodeBuffer.
 101     return;  // caller must test this
 102   }
 103 
 104   // Set up various pointers into the blob.
 105   initialize(_total_start, _total_size);
 106 
 107   assert((uintptr_t)insts_begin() % CodeEntryAlignment == 0, "instruction start not code entry aligned");
 108 
 109   pd_initialize();
 110 
 111   if (locs_size != 0) {
 112     _insts.initialize_locs(locs_size / sizeof(relocInfo));
 113   }
 114 
 115   verify_section_allocation();
 116 }
 117 
 118 
 119 CodeBuffer::~CodeBuffer() {
 120   verify_section_allocation();
 121 
 122   // If we allocate our code buffer from the CodeCache
 123   // via a BufferBlob, and it's not permanent, then
 124   // free the BufferBlob.
 125   // The rest of the memory will be freed when the ResourceObj
 126   // is released.
 127   for (CodeBuffer* cb = this; cb != NULL; cb = cb->before_expand()) {
 128     // Previous incarnations of this buffer are held live, so that internal
 129     // addresses constructed before expansions will not be confused.
 130     cb->free_blob();
 131   }
 132 
 133   // free any overflow storage
 134   delete _overflow_arena;
 135 
 136   // Claim is that stack allocation ensures resources are cleaned up.
 137   // This is resource clean up, let's hope that all were properly copied out.
 138   free_strings();
 139 
 140 #ifdef ASSERT
 141   // Save allocation type to execute assert in ~ResourceObj()
 142   // which is called after this destructor.
 143   assert(_default_oop_recorder.allocated_on_stack(), "should be embedded object");
 144   ResourceObj::allocation_type at = _default_oop_recorder.get_allocation_type();
 145   Copy::fill_to_bytes(this, sizeof(*this), badResourceValue);
 146   ResourceObj::set_allocation_type((address)(&_default_oop_recorder), at);
 147 #endif
 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::freeze_section(CodeSection* cs) {
 175   CodeSection* next_cs = (cs == consts())? NULL: code_section(cs->index()+1);
 176   csize_t frozen_size = cs->size();
 177   if (next_cs != NULL) {
 178     frozen_size = next_cs->align_at_start(frozen_size);
 179   }
 180   address old_limit = cs->limit();
 181   address new_limit = cs->start() + frozen_size;
 182   relocInfo* old_locs_limit = cs->locs_limit();
 183   relocInfo* new_locs_limit = cs->locs_end();
 184   // Patch the limits.
 185   cs->_limit = new_limit;
 186   cs->_locs_limit = new_locs_limit;
 187   cs->_frozen = true;
 188   if (!next_cs->is_allocated() && !next_cs->is_frozen()) {
 189     // Give remaining buffer space to the following section.
 190     next_cs->initialize(new_limit, old_limit - new_limit);
 191     next_cs->initialize_shared_locs(new_locs_limit,
 192                                     old_locs_limit - new_locs_limit);
 193   }
 194 }
 195 
 196 void CodeBuffer::set_blob(BufferBlob* blob) {
 197   _blob = blob;
 198   if (blob != NULL) {
 199     address start = blob->content_begin();
 200     address end   = blob->content_end();
 201     // Round up the starting address.
 202     int align = _insts.alignment();
 203     start += (-(intptr_t)start) & (align-1);
 204     _total_start = start;
 205     _total_size  = end - start;
 206   } else {
 207 #ifdef ASSERT
 208     // Clean out dangling pointers.
 209     _total_start    = badAddress;
 210     _consts._start  = _consts._end  = badAddress;
 211     _insts._start   = _insts._end   = badAddress;
 212     _stubs._start   = _stubs._end   = badAddress;
 213 #endif //ASSERT
 214   }
 215 }
 216 
 217 void CodeBuffer::free_blob() {
 218   if (_blob != NULL) {
 219     BufferBlob::free(_blob);
 220     set_blob(NULL);
 221   }
 222 }
 223 
 224 const char* CodeBuffer::code_section_name(int n) {
 225 #ifdef PRODUCT
 226   return NULL;
 227 #else //PRODUCT
 228   switch (n) {
 229   case SECT_CONSTS:            return "consts";
 230   case SECT_INSTS:             return "insts";
 231   case SECT_STUBS:             return "stubs";
 232   default:                     return NULL;
 233   }
 234 #endif //PRODUCT
 235 }
 236 
 237 int CodeBuffer::section_index_of(address addr) const {
 238   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 239     const CodeSection* cs = code_section(n);
 240     if (cs->allocates(addr))  return n;
 241   }
 242   return SECT_NONE;
 243 }
 244 
 245 int CodeBuffer::locator(address addr) const {
 246   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 247     const CodeSection* cs = code_section(n);
 248     if (cs->allocates(addr)) {
 249       return locator(addr - cs->start(), n);
 250     }
 251   }
 252   return -1;
 253 }
 254 
 255 address CodeBuffer::locator_address(int locator) const {
 256   if (locator < 0)  return NULL;
 257   address start = code_section(locator_sect(locator))->start();
 258   return start + locator_pos(locator);
 259 }
 260 
 261 bool CodeBuffer::is_backward_branch(Label& L) {
 262   return L.is_bound() && insts_end() <= locator_address(L.loc());
 263 }
 264 
 265 address CodeBuffer::decode_begin() {
 266   address begin = _insts.start();
 267   if (_decode_begin != NULL && _decode_begin > begin)
 268     begin = _decode_begin;
 269   return begin;
 270 }
 271 
 272 
 273 GrowableArray<int>* CodeBuffer::create_patch_overflow() {
 274   if (_overflow_arena == NULL) {
 275     _overflow_arena = new (mtCode) Arena(mtCode);
 276   }
 277   return new (_overflow_arena) GrowableArray<int>(_overflow_arena, 8, 0, 0);
 278 }
 279 
 280 
 281 // Helper function for managing labels and their target addresses.
 282 // Returns a sensible address, and if it is not the label's final
 283 // address, notes the dependency (at 'branch_pc') on the label.
 284 address CodeSection::target(Label& L, address branch_pc) {
 285   if (L.is_bound()) {
 286     int loc = L.loc();
 287     if (index() == CodeBuffer::locator_sect(loc)) {
 288       return start() + CodeBuffer::locator_pos(loc);
 289     } else {
 290       return outer()->locator_address(loc);
 291     }
 292   } else {
 293     assert(allocates2(branch_pc), "sanity");
 294     address base = start();
 295     int patch_loc = CodeBuffer::locator(branch_pc - base, index());
 296     L.add_patch_at(outer(), patch_loc);
 297 
 298     // Need to return a pc, doesn't matter what it is since it will be
 299     // replaced during resolution later.
 300     // Don't return NULL or badAddress, since branches shouldn't overflow.
 301     // Don't return base either because that could overflow displacements
 302     // for shorter branches.  It will get checked when bound.
 303     return branch_pc;
 304   }
 305 }
 306 
 307 void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {
 308   Relocation* reloc = spec.reloc();
 309   relocInfo::relocType rtype = (relocInfo::relocType) reloc->type();
 310   if (rtype == relocInfo::none)  return;
 311 
 312   // The assertion below has been adjusted, to also work for
 313   // relocation for fixup.  Sometimes we want to put relocation
 314   // information for the next instruction, since it will be patched
 315   // with a call.
 316   assert(start() <= at && at <= end()+1,
 317          "cannot relocate data outside code boundaries");
 318 
 319   if (!has_locs()) {
 320     // no space for relocation information provided => code cannot be
 321     // relocated.  Make sure that relocate is only called with rtypes
 322     // that can be ignored for this kind of code.
 323     assert(rtype == relocInfo::none              ||
 324            rtype == relocInfo::runtime_call_type ||
 325            rtype == relocInfo::internal_word_type||
 326            rtype == relocInfo::section_word_type ||
 327            rtype == relocInfo::external_word_type,
 328            "code needs relocation information");
 329     // leave behind an indication that we attempted a relocation
 330     DEBUG_ONLY(_locs_start = _locs_limit = (relocInfo*)badAddress);
 331     return;
 332   }
 333 
 334   // Advance the point, noting the offset we'll have to record.
 335   csize_t offset = at - locs_point();
 336   set_locs_point(at);
 337 
 338   // Test for a couple of overflow conditions; maybe expand the buffer.
 339   relocInfo* end = locs_end();
 340   relocInfo* req = end + relocInfo::length_limit;
 341   // Check for (potential) overflow
 342   if (req >= locs_limit() || offset >= relocInfo::offset_limit()) {
 343     req += (uint)offset / (uint)relocInfo::offset_limit();
 344     if (req >= locs_limit()) {
 345       // Allocate or reallocate.
 346       expand_locs(locs_count() + (req - end));
 347       // reload pointer
 348       end = locs_end();
 349     }
 350   }
 351 
 352   // If the offset is giant, emit filler relocs, of type 'none', but
 353   // each carrying the largest possible offset, to advance the locs_point.
 354   while (offset >= relocInfo::offset_limit()) {
 355     assert(end < locs_limit(), "adjust previous paragraph of code");
 356     *end++ = filler_relocInfo();
 357     offset -= filler_relocInfo().addr_offset();
 358   }
 359 
 360   // If it's a simple reloc with no data, we'll just write (rtype | offset).
 361   (*end) = relocInfo(rtype, offset, format);
 362 
 363   // If it has data, insert the prefix, as (data_prefix_tag | data1), data2.
 364   end->initialize(this, reloc);
 365 }
 366 
 367 void CodeSection::initialize_locs(int locs_capacity) {
 368   assert(_locs_start == NULL, "only one locs init step, please");
 369   // Apply a priori lower limits to relocation size:
 370   csize_t min_locs = MAX2(size() / 16, (csize_t)4);
 371   if (locs_capacity < min_locs)  locs_capacity = min_locs;
 372   relocInfo* locs_start = NEW_RESOURCE_ARRAY(relocInfo, locs_capacity);
 373   _locs_start    = locs_start;
 374   _locs_end      = locs_start;
 375   _locs_limit    = locs_start + locs_capacity;
 376   _locs_own      = true;
 377 }
 378 
 379 void CodeSection::initialize_shared_locs(relocInfo* buf, int length) {
 380   assert(_locs_start == NULL, "do this before locs are allocated");
 381   // Internal invariant:  locs buf must be fully aligned.
 382   // See copy_relocations_to() below.
 383   while ((uintptr_t)buf % HeapWordSize != 0 && length > 0) {
 384     ++buf; --length;
 385   }
 386   if (length > 0) {
 387     _locs_start = buf;
 388     _locs_end   = buf;
 389     _locs_limit = buf + length;
 390     _locs_own   = false;
 391   }
 392 }
 393 
 394 void CodeSection::initialize_locs_from(const CodeSection* source_cs) {
 395   int lcount = source_cs->locs_count();
 396   if (lcount != 0) {
 397     initialize_shared_locs(source_cs->locs_start(), lcount);
 398     _locs_end = _locs_limit = _locs_start + lcount;
 399     assert(is_allocated(), "must have copied code already");
 400     set_locs_point(start() + source_cs->locs_point_off());
 401   }
 402   assert(this->locs_count() == source_cs->locs_count(), "sanity");
 403 }
 404 
 405 void CodeSection::expand_locs(int new_capacity) {
 406   if (_locs_start == NULL) {
 407     initialize_locs(new_capacity);
 408     return;
 409   } else {
 410     int old_count    = locs_count();
 411     int old_capacity = locs_capacity();
 412     if (new_capacity < old_capacity * 2)
 413       new_capacity = old_capacity * 2;
 414     relocInfo* locs_start;
 415     if (_locs_own) {
 416       locs_start = REALLOC_RESOURCE_ARRAY(relocInfo, _locs_start, old_capacity, new_capacity);
 417     } else {
 418       locs_start = NEW_RESOURCE_ARRAY(relocInfo, new_capacity);
 419       Copy::conjoint_jbytes(_locs_start, locs_start, old_capacity * sizeof(relocInfo));
 420       _locs_own = true;
 421     }
 422     _locs_start    = locs_start;
 423     _locs_end      = locs_start + old_count;
 424     _locs_limit    = locs_start + new_capacity;
 425   }
 426 }
 427 
 428 
 429 /// Support for emitting the code to its final location.
 430 /// The pattern is the same for all functions.
 431 /// We iterate over all the sections, padding each to alignment.
 432 
 433 csize_t CodeBuffer::total_content_size() const {
 434   csize_t size_so_far = 0;
 435   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 436     const CodeSection* cs = code_section(n);
 437     if (cs->is_empty())  continue;  // skip trivial section
 438     size_so_far = cs->align_at_start(size_so_far);
 439     size_so_far += cs->size();
 440   }
 441   return size_so_far;
 442 }
 443 
 444 void CodeBuffer::compute_final_layout(CodeBuffer* dest) const {
 445   address buf = dest->_total_start;
 446   csize_t buf_offset = 0;
 447   assert(dest->_total_size >= total_content_size(), "must be big enough");
 448 
 449   {
 450     // not sure why this is here, but why not...
 451     int alignSize = MAX2((intx) sizeof(jdouble), CodeEntryAlignment);
 452     assert( (dest->_total_start - _insts.start()) % alignSize == 0, "copy must preserve alignment");
 453   }
 454 
 455   const CodeSection* prev_cs      = NULL;
 456   CodeSection*       prev_dest_cs = NULL;
 457 
 458   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 459     // figure compact layout of each section
 460     const CodeSection* cs = code_section(n);
 461     csize_t csize = cs->size();
 462 
 463     CodeSection* dest_cs = dest->code_section(n);
 464     if (!cs->is_empty()) {
 465       // Compute initial padding; assign it to the previous non-empty guy.
 466       // Cf. figure_expanded_capacities.
 467       csize_t padding = cs->align_at_start(buf_offset) - buf_offset;
 468       if (padding != 0) {
 469         buf_offset += padding;
 470         assert(prev_dest_cs != NULL, "sanity");
 471         prev_dest_cs->_limit += padding;
 472       }
 473       #ifdef ASSERT
 474       if (prev_cs != NULL && prev_cs->is_frozen() && n < (SECT_LIMIT - 1)) {
 475         // Make sure the ends still match up.
 476         // This is important because a branch in a frozen section
 477         // might target code in a following section, via a Label,
 478         // and without a relocation record.  See Label::patch_instructions.
 479         address dest_start = buf+buf_offset;
 480         csize_t start2start = cs->start() - prev_cs->start();
 481         csize_t dest_start2start = dest_start - prev_dest_cs->start();
 482         assert(start2start == dest_start2start, "cannot stretch frozen sect");
 483       }
 484       #endif //ASSERT
 485       prev_dest_cs = dest_cs;
 486       prev_cs      = cs;
 487     }
 488 
 489     debug_only(dest_cs->_start = NULL);  // defeat double-initialization assert
 490     dest_cs->initialize(buf+buf_offset, csize);
 491     dest_cs->set_end(buf+buf_offset+csize);
 492     assert(dest_cs->is_allocated(), "must always be allocated");
 493     assert(cs->is_empty() == dest_cs->is_empty(), "sanity");
 494 
 495     buf_offset += csize;
 496   }
 497 
 498   // Done calculating sections; did it come out to the right end?
 499   assert(buf_offset == total_content_size(), "sanity");
 500   dest->verify_section_allocation();
 501 }
 502 
 503 // Append an oop reference that keeps the class alive.
 504 static void append_oop_references(GrowableArray<oop>* oops, Klass* k) {
 505   oop cl = k->klass_holder();
 506   if (cl != NULL && !oops->contains(cl)) {
 507     oops->append(cl);
 508   }
 509 }
 510 
 511 void CodeBuffer::finalize_oop_references(methodHandle mh) {
 512   No_Safepoint_Verifier nsv;
 513 
 514   GrowableArray<oop> oops;
 515 
 516   // Make sure that immediate metadata records something in the OopRecorder
 517   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 518     // pull code out of each section
 519     CodeSection* cs = code_section(n);
 520     if (cs->is_empty())  continue;  // skip trivial section
 521     RelocIterator iter(cs);
 522     while (iter.next()) {
 523       if (iter.type() == relocInfo::metadata_type) {
 524         metadata_Relocation* md = iter.metadata_reloc();
 525         if (md->metadata_is_immediate()) {
 526           Metadata* m = md->metadata_value();
 527           if (oop_recorder()->is_real(m)) {
 528             if (m->is_methodData()) {
 529               m = ((MethodData*)m)->method();
 530             }
 531             if (m->is_method()) {
 532               m = ((Method*)m)->method_holder();
 533             }
 534             if (m->is_klass()) {
 535               append_oop_references(&oops, (Klass*)m);
 536             } else {
 537               // XXX This will currently occur for MDO which don't
 538               // have a backpointer.  This has to be fixed later.
 539               m->print();
 540               ShouldNotReachHere();
 541             }
 542           }
 543         }
 544       }
 545     }
 546   }
 547 
 548   if (!oop_recorder()->is_unused()) {
 549     for (int i = 0; i < oop_recorder()->metadata_count(); i++) {
 550       Metadata* m = oop_recorder()->metadata_at(i);
 551       if (oop_recorder()->is_real(m)) {
 552         if (m->is_methodData()) {
 553           m = ((MethodData*)m)->method();
 554         }
 555         if (m->is_method()) {
 556           m = ((Method*)m)->method_holder();
 557         }
 558         if (m->is_klass()) {
 559           append_oop_references(&oops, (Klass*)m);
 560         } else {
 561           m->print();
 562           ShouldNotReachHere();
 563         }
 564       }
 565     }
 566 
 567   }
 568 
 569   // Add the class loader of Method* for the nmethod itself
 570   append_oop_references(&oops, mh->method_holder());
 571 
 572   // Add any oops that we've found
 573   Thread* thread = Thread::current();
 574   for (int i = 0; i < oops.length(); i++) {
 575     oop_recorder()->find_index((jobject)thread->handle_area()->allocate_handle(oops.at(i)));
 576   }
 577 }
 578 
 579 
 580 
 581 csize_t CodeBuffer::total_offset_of(CodeSection* cs) const {
 582   csize_t size_so_far = 0;
 583   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 584     const CodeSection* cur_cs = code_section(n);
 585     if (!cur_cs->is_empty()) {
 586       size_so_far = cur_cs->align_at_start(size_so_far);
 587     }
 588     if (cur_cs->index() == cs->index()) {
 589       return size_so_far;
 590     }
 591     size_so_far += cur_cs->size();
 592   }
 593   ShouldNotReachHere();
 594   return -1;
 595 }
 596 
 597 csize_t CodeBuffer::total_relocation_size() const {
 598   csize_t lsize = copy_relocations_to(NULL);  // dry run only
 599   csize_t csize = total_content_size();
 600   csize_t total = RelocIterator::locs_and_index_size(csize, lsize);
 601   return (csize_t) align_size_up(total, HeapWordSize);
 602 }
 603 
 604 csize_t CodeBuffer::copy_relocations_to(CodeBlob* dest) const {
 605   address buf = NULL;
 606   csize_t buf_offset = 0;
 607   csize_t buf_limit = 0;
 608   if (dest != NULL) {
 609     buf = (address)dest->relocation_begin();
 610     buf_limit = (address)dest->relocation_end() - buf;
 611     assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");
 612     assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");
 613   }
 614   // if dest == NULL, this is just the sizing pass
 615 
 616   csize_t code_end_so_far = 0;
 617   csize_t code_point_so_far = 0;
 618   for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
 619     // pull relocs out of each section
 620     const CodeSection* cs = code_section(n);
 621     assert(!(cs->is_empty() && cs->locs_count() > 0), "sanity");
 622     if (cs->is_empty())  continue;  // skip trivial section
 623     relocInfo* lstart = cs->locs_start();
 624     relocInfo* lend   = cs->locs_end();
 625     csize_t    lsize  = (csize_t)( (address)lend - (address)lstart );
 626     csize_t    csize  = cs->size();
 627     code_end_so_far = cs->align_at_start(code_end_so_far);
 628 
 629     if (lsize > 0) {
 630       // Figure out how to advance the combined relocation point
 631       // first to the beginning of this section.
 632       // We'll insert one or more filler relocs to span that gap.
 633       // (Don't bother to improve this by editing the first reloc's offset.)
 634       csize_t new_code_point = code_end_so_far;
 635       for (csize_t jump;
 636            code_point_so_far < new_code_point;
 637            code_point_so_far += jump) {
 638         jump = new_code_point - code_point_so_far;
 639         relocInfo filler = filler_relocInfo();
 640         if (jump >= filler.addr_offset()) {
 641           jump = filler.addr_offset();
 642         } else {  // else shrink the filler to fit
 643           filler = relocInfo(relocInfo::none, jump);
 644         }
 645         if (buf != NULL) {
 646           assert(buf_offset + (csize_t)sizeof(filler) <= buf_limit, "filler in bounds");
 647           *(relocInfo*)(buf+buf_offset) = filler;
 648         }
 649         buf_offset += sizeof(filler);
 650       }
 651 
 652       // Update code point and end to skip past this section:
 653       csize_t last_code_point = code_end_so_far + cs->locs_point_off();
 654       assert(code_point_so_far <= last_code_point, "sanity");
 655       code_point_so_far = last_code_point; // advance past this guy's relocs
 656     }
 657     code_end_so_far += csize;  // advance past this guy's instructions too
 658 
 659     // Done with filler; emit the real relocations:
 660     if (buf != NULL && lsize != 0) {
 661       assert(buf_offset + lsize <= buf_limit, "target in bounds");
 662       assert((uintptr_t)lstart % HeapWordSize == 0, "sane start");
 663       if (buf_offset % HeapWordSize == 0) {
 664         // Use wordwise copies if possible:
 665         Copy::disjoint_words((HeapWord*)lstart,
 666                              (HeapWord*)(buf+buf_offset),
 667                              (lsize + HeapWordSize-1) / HeapWordSize);
 668       } else {
 669         Copy::conjoint_jbytes(lstart, buf+buf_offset, lsize);
 670       }
 671     }
 672     buf_offset += lsize;
 673   }
 674 
 675   // Align end of relocation info in target.
 676   while (buf_offset % HeapWordSize != 0) {
 677     if (buf != NULL) {
 678       relocInfo padding = relocInfo(relocInfo::none, 0);
 679       assert(buf_offset + (csize_t)sizeof(padding) <= buf_limit, "padding in bounds");
 680       *(relocInfo*)(buf+buf_offset) = padding;
 681     }
 682     buf_offset += sizeof(relocInfo);
 683   }
 684 
 685   assert(code_end_so_far == total_content_size(), "sanity");
 686 
 687   // Account for index:
 688   if (buf != NULL) {
 689     RelocIterator::create_index(dest->relocation_begin(),
 690                                 buf_offset / sizeof(relocInfo),
 691                                 dest->relocation_end());
 692   }
 693 
 694   return buf_offset;
 695 }
 696 
 697 void CodeBuffer::copy_code_to(CodeBlob* dest_blob) {
 698 #ifndef PRODUCT
 699   if (PrintNMethods && (WizardMode || Verbose)) {
 700     tty->print("done with CodeBuffer:");
 701     ((CodeBuffer*)this)->print();
 702   }
 703 #endif //PRODUCT
 704 
 705   CodeBuffer dest(dest_blob);
 706   assert(dest_blob->content_size() >= total_content_size(), "good sizing");
 707   this->compute_final_layout(&dest);
 708   relocate_code_to(&dest);
 709 
 710   // transfer strings and comments from buffer to blob
 711   dest_blob->set_strings(_code_strings);
 712 
 713   // Done moving code bytes; were they the right size?
 714   assert(round_to(dest.total_content_size(), oopSize) == dest_blob->content_size(), "sanity");
 715 
 716   // Flush generated code
 717   ICache::invalidate_range(dest_blob->code_begin(), dest_blob->code_size());
 718 }
 719 
 720 // Move all my code into another code buffer.  Consult applicable
 721 // relocs to repair embedded addresses.  The layout in the destination
 722 // CodeBuffer is different to the source CodeBuffer: the destination
 723 // CodeBuffer gets the final layout (consts, insts, stubs in order of
 724 // ascending address).
 725 void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
 726   address dest_end = dest->_total_start + dest->_total_size;
 727   address dest_filled = NULL;
 728   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 729     // pull code out of each section
 730     const CodeSection* cs = code_section(n);
 731     if (cs->is_empty())  continue;  // skip trivial section
 732     CodeSection* dest_cs = dest->code_section(n);
 733     assert(cs->size() == dest_cs->size(), "sanity");
 734     csize_t usize = dest_cs->size();
 735     csize_t wsize = align_size_up(usize, HeapWordSize);
 736     assert(dest_cs->start() + wsize <= dest_end, "no overflow");
 737     // Copy the code as aligned machine words.
 738     // This may also include an uninitialized partial word at the end.
 739     Copy::disjoint_words((HeapWord*)cs->start(),
 740                          (HeapWord*)dest_cs->start(),
 741                          wsize / HeapWordSize);
 742 
 743     if (dest->blob() == NULL) {
 744       // Destination is a final resting place, not just another buffer.
 745       // Normalize uninitialized bytes in the final padding.
 746       Copy::fill_to_bytes(dest_cs->end(), dest_cs->remaining(),
 747                           Assembler::code_fill_byte());
 748     }
 749     // Keep track of the highest filled address
 750     dest_filled = MAX2(dest_filled, dest_cs->end() + dest_cs->remaining());
 751 
 752     assert(cs->locs_start() != (relocInfo*)badAddress,
 753            "this section carries no reloc storage, but reloc was attempted");
 754 
 755     // Make the new code copy use the old copy's relocations:
 756     dest_cs->initialize_locs_from(cs);
 757   }
 758 
 759   // Do relocation after all sections are copied.
 760   // This is necessary if the code uses constants in stubs, which are
 761   // relocated when the corresponding instruction in the code (e.g., a
 762   // call) is relocated. Stubs are placed behind the main code
 763   // section, so that section has to be copied before relocating.
 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     { // Repair the pc relative information in the code after the move
 770       RelocIterator iter(dest_cs);
 771       while (iter.next()) {
 772         iter.reloc()->fix_relocation_after_move(this, dest);
 773       }
 774     }
 775   }
 776 
 777   if (dest->blob() == NULL && dest_filled != NULL) {
 778     // Destination is a final resting place, not just another buffer.
 779     // Normalize uninitialized bytes in the final padding.
 780     Copy::fill_to_bytes(dest_filled, dest_end - dest_filled,
 781                         Assembler::code_fill_byte());
 782 
 783   }
 784 }
 785 
 786 csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,
 787                                                csize_t amount,
 788                                                csize_t* new_capacity) {
 789   csize_t new_total_cap = 0;
 790 
 791   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 792     const CodeSection* sect = code_section(n);
 793 
 794     if (!sect->is_empty()) {
 795       // Compute initial padding; assign it to the previous section,
 796       // even if it's empty (e.g. consts section can be empty).
 797       // Cf. compute_final_layout
 798       csize_t padding = sect->align_at_start(new_total_cap) - new_total_cap;
 799       if (padding != 0) {
 800         new_total_cap += padding;
 801         assert(n - 1 >= SECT_FIRST, "sanity");
 802         new_capacity[n - 1] += padding;
 803       }
 804     }
 805 
 806     csize_t exp = sect->size();  // 100% increase
 807     if ((uint)exp < 4*K)  exp = 4*K;       // minimum initial increase
 808     if (sect == which_cs) {
 809       if (exp < amount)  exp = amount;
 810       if (StressCodeBuffers)  exp = amount;  // expand only slightly
 811     } else if (n == SECT_INSTS) {
 812       // scale down inst increases to a more modest 25%
 813       exp = 4*K + ((exp - 4*K) >> 2);
 814       if (StressCodeBuffers)  exp = amount / 2;  // expand only slightly
 815     } else if (sect->is_empty()) {
 816       // do not grow an empty secondary section
 817       exp = 0;
 818     }
 819     // Allow for inter-section slop:
 820     exp += CodeSection::end_slop();
 821     csize_t new_cap = sect->size() + exp;
 822     if (new_cap < sect->capacity()) {
 823       // No need to expand after all.
 824       new_cap = sect->capacity();
 825     }
 826     new_capacity[n] = new_cap;
 827     new_total_cap += new_cap;
 828   }
 829 
 830   return new_total_cap;
 831 }
 832 
 833 void CodeBuffer::expand(CodeSection* which_cs, csize_t amount) {
 834 #ifndef PRODUCT
 835   if (PrintNMethods && (WizardMode || Verbose)) {
 836     tty->print("expanding CodeBuffer:");
 837     this->print();
 838   }
 839 
 840   if (StressCodeBuffers && blob() != NULL) {
 841     static int expand_count = 0;
 842     if (expand_count >= 0)  expand_count += 1;
 843     if (expand_count > 100 && is_power_of_2(expand_count)) {
 844       tty->print_cr("StressCodeBuffers: have expanded %d times", expand_count);
 845       // simulate an occasional allocation failure:
 846       free_blob();
 847     }
 848   }
 849 #endif //PRODUCT
 850 
 851   // Resizing must be allowed
 852   {
 853     if (blob() == NULL)  return;  // caller must check for blob == NULL
 854     for (int n = 0; n < (int)SECT_LIMIT; n++) {
 855       guarantee(!code_section(n)->is_frozen(), "resizing not allowed when frozen");
 856     }
 857   }
 858 
 859   // Figure new capacity for each section.
 860   csize_t new_capacity[SECT_LIMIT];
 861   csize_t new_total_cap
 862     = figure_expanded_capacities(which_cs, amount, new_capacity);
 863 
 864   // Create a new (temporary) code buffer to hold all the new data
 865   CodeBuffer cb(name(), new_total_cap, 0);
 866   if (cb.blob() == NULL) {
 867     // Failed to allocate in code cache.
 868     free_blob();
 869     return;
 870   }
 871 
 872   // Create an old code buffer to remember which addresses used to go where.
 873   // This will be useful when we do final assembly into the code cache,
 874   // because we will need to know how to warp any internal address that
 875   // has been created at any time in this CodeBuffer's past.
 876   CodeBuffer* bxp = new CodeBuffer(_total_start, _total_size);
 877   bxp->take_over_code_from(this);  // remember the old undersized blob
 878   DEBUG_ONLY(this->_blob = NULL);  // silence a later assert
 879   bxp->_before_expand = this->_before_expand;
 880   this->_before_expand = bxp;
 881 
 882   // Give each section its required (expanded) capacity.
 883   for (int n = (int)SECT_LIMIT-1; n >= SECT_FIRST; n--) {
 884     CodeSection* cb_sect   = cb.code_section(n);
 885     CodeSection* this_sect = code_section(n);
 886     if (new_capacity[n] == 0)  continue;  // already nulled out
 887     if (n != SECT_INSTS) {
 888       cb.initialize_section_size(cb_sect, new_capacity[n]);
 889     }
 890     assert(cb_sect->capacity() >= new_capacity[n], "big enough");
 891     address cb_start = cb_sect->start();
 892     cb_sect->set_end(cb_start + this_sect->size());
 893     if (this_sect->mark() == NULL) {
 894       cb_sect->clear_mark();
 895     } else {
 896       cb_sect->set_mark(cb_start + this_sect->mark_off());
 897     }
 898   }
 899 
 900   // Move all the code and relocations to the new blob:
 901   relocate_code_to(&cb);
 902 
 903   // Copy the temporary code buffer into the current code buffer.
 904   // Basically, do {*this = cb}, except for some control information.
 905   this->take_over_code_from(&cb);
 906   cb.set_blob(NULL);
 907 
 908   // Zap the old code buffer contents, to avoid mistakenly using them.
 909   debug_only(Copy::fill_to_bytes(bxp->_total_start, bxp->_total_size,
 910                                  badCodeHeapFreeVal));
 911 
 912   _decode_begin = NULL;  // sanity
 913 
 914   // Make certain that the new sections are all snugly inside the new blob.
 915   verify_section_allocation();
 916 
 917 #ifndef PRODUCT
 918   if (PrintNMethods && (WizardMode || Verbose)) {
 919     tty->print("expanded CodeBuffer:");
 920     this->print();
 921   }
 922 #endif //PRODUCT
 923 }
 924 
 925 void CodeBuffer::take_over_code_from(CodeBuffer* cb) {
 926   // Must already have disposed of the old blob somehow.
 927   assert(blob() == NULL, "must be empty");
 928 #ifdef ASSERT
 929 
 930 #endif
 931   // Take the new blob away from cb.
 932   set_blob(cb->blob());
 933   // Take over all the section pointers.
 934   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 935     CodeSection* cb_sect   = cb->code_section(n);
 936     CodeSection* this_sect = code_section(n);
 937     this_sect->take_over_code_from(cb_sect);
 938   }
 939   _overflow_arena = cb->_overflow_arena;
 940   // Make sure the old cb won't try to use it or free it.
 941   DEBUG_ONLY(cb->_blob = (BufferBlob*)badAddress);
 942 }
 943 
 944 void CodeBuffer::verify_section_allocation() {
 945   address tstart = _total_start;
 946   if (tstart == badAddress)  return;  // smashed by set_blob(NULL)
 947   address tend   = tstart + _total_size;
 948   if (_blob != NULL) {
 949 
 950     guarantee(tstart >= _blob->content_begin(), "sanity");
 951     guarantee(tend   <= _blob->content_end(),   "sanity");
 952   }
 953   // Verify disjointness.
 954   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 955     CodeSection* sect = code_section(n);
 956     if (!sect->is_allocated() || sect->is_empty())  continue;
 957     guarantee((intptr_t)sect->start() % sect->alignment() == 0
 958            || sect->is_empty() || _blob == NULL,
 959            "start is aligned");
 960     for (int m = (int) SECT_FIRST; m < (int) SECT_LIMIT; m++) {
 961       CodeSection* other = code_section(m);
 962       if (!other->is_allocated() || other == sect)  continue;
 963       guarantee(!other->contains(sect->start()    ), "sanity");
 964       // limit is an exclusive address and can be the start of another
 965       // section.
 966       guarantee(!other->contains(sect->limit() - 1), "sanity");
 967     }
 968     guarantee(sect->end() <= tend, "sanity");
 969     guarantee(sect->end() <= sect->limit(), "sanity");
 970   }
 971 }
 972 
 973 void CodeBuffer::log_section_sizes(const char* name) {
 974   if (xtty != NULL) {
 975     // log info about buffer usage
 976     xtty->print_cr("<blob name='%s' size='%d'>", name, _total_size);
 977     for (int n = (int) CodeBuffer::SECT_FIRST; n < (int) CodeBuffer::SECT_LIMIT; n++) {
 978       CodeSection* sect = code_section(n);
 979       if (!sect->is_allocated() || sect->is_empty())  continue;
 980       xtty->print_cr("<sect index='%d' size='" SIZE_FORMAT "' free='" SIZE_FORMAT "'/>",
 981                      n, sect->limit() - sect->start(), sect->limit() - sect->end());
 982     }
 983     xtty->print_cr("</blob>");
 984   }
 985 }
 986 
 987 #ifndef PRODUCT
 988 
 989 void CodeSection::dump() {
 990   address ptr = start();
 991   for (csize_t step; ptr < end(); ptr += step) {
 992     step = end() - ptr;
 993     if (step > jintSize * 4)  step = jintSize * 4;
 994     tty->print(INTPTR_FORMAT ": ", p2i(ptr));
 995     while (step > 0) {
 996       tty->print(" " PTR32_FORMAT, *(jint*)ptr);
 997       ptr += jintSize;
 998     }
 999     tty->cr();
1000   }
1001 }
1002 
1003 
1004 void CodeSection::decode() {
1005   Disassembler::decode(start(), end());
1006 }
1007 
1008 
1009 void CodeBuffer::block_comment(intptr_t offset, const char * comment) {
1010   _code_strings.add_comment(offset, comment);
1011 }
1012 
1013 const char* CodeBuffer::code_string(const char* str) {
1014   return _code_strings.add_string(str);
1015 }
1016 
1017 class CodeString: public CHeapObj<mtCode> {
1018  private:
1019   friend class CodeStrings;
1020   const char * _string;
1021   CodeString*  _next;
1022   intptr_t     _offset;
1023 
1024   ~CodeString() {
1025     assert(_next == NULL, "wrong interface for freeing list");
1026     os::free((void*)_string, mtCode);
1027   }
1028 
1029   bool is_comment() const { return _offset >= 0; }
1030 
1031  public:
1032   CodeString(const char * string, intptr_t offset = -1)
1033     : _next(NULL), _offset(offset) {
1034     _string = os::strdup(string, mtCode);
1035   }
1036 
1037   const char * string() const { return _string; }
1038   intptr_t     offset() const { assert(_offset >= 0, "offset for non comment?"); return _offset;  }
1039   CodeString* next()    const { return _next; }
1040 
1041   void set_next(CodeString* next) { _next = next; }
1042 
1043   CodeString* first_comment() {
1044     if (is_comment()) {
1045       return this;
1046     } else {
1047       return next_comment();
1048     }
1049   }
1050   CodeString* next_comment() const {
1051     CodeString* s = _next;
1052     while (s != NULL && !s->is_comment()) {
1053       s = s->_next;
1054     }
1055     return s;
1056   }
1057 };
1058 
1059 CodeString* CodeStrings::find(intptr_t offset) const {
1060   CodeString* a = _strings->first_comment();
1061   while (a != NULL && a->offset() != offset) {
1062     a = a->next_comment();
1063   }
1064   return a;
1065 }
1066 
1067 // Convenience for add_comment.
1068 CodeString* CodeStrings::find_last(intptr_t offset) const {
1069   CodeString* a = find(offset);
1070   if (a != NULL) {
1071     CodeString* c = NULL;
1072     while (((c = a->next_comment()) != NULL) && (c->offset() == offset)) {
1073       a = c;
1074     }
1075   }
1076   return a;
1077 }
1078 
1079 void CodeStrings::add_comment(intptr_t offset, const char * comment) {
1080   check_valid();
1081   CodeString* c      = new CodeString(comment, offset);
1082   CodeString* inspos = (_strings == NULL) ? NULL : find_last(offset);
1083 
1084   if (inspos) {
1085     // insert after already existing comments with same offset
1086     c->set_next(inspos->next());
1087     inspos->set_next(c);
1088   } else {
1089     // no comments with such offset, yet. Insert before anything else.
1090     c->set_next(_strings);
1091     _strings = c;
1092   }
1093 }
1094 
1095 void CodeStrings::assign(CodeStrings& other) {
1096   other.check_valid();
1097   // Cannot do following because CodeStrings constructor is not alway run!
1098   assert(is_null(), "Cannot assign onto non-empty CodeStrings");
1099   _strings = other._strings;
1100   other.set_null_and_invalidate();
1101 }
1102 
1103 // Deep copy of CodeStrings for consistent memory management.
1104 // Only used for actual disassembly so this is cheaper than reference counting
1105 // for the "normal" fastdebug case.
1106 void CodeStrings::copy(CodeStrings& other) {
1107   other.check_valid();
1108   check_valid();
1109   assert(is_null(), "Cannot copy onto non-empty CodeStrings");
1110   CodeString* n = other._strings;
1111   CodeString** ps = &_strings;
1112   while (n != NULL) {
1113     *ps = new CodeString(n->string(),n->offset());
1114     ps = &((*ps)->_next);
1115     n = n->next();
1116   }
1117 }
1118 
1119 void CodeStrings::print_block_comment(outputStream* stream, intptr_t offset) const {
1120     check_valid();
1121     if (_strings != NULL) {
1122     CodeString* c = find(offset);
1123     while (c && c->offset() == offset) {
1124       stream->bol();
1125       stream->print("  ;; ");
1126       stream->print_cr("%s", c->string());
1127       c = c->next_comment();
1128     }
1129   }
1130 }
1131 
1132 // Also sets isNull()
1133 void CodeStrings::free() {
1134   CodeString* n = _strings;
1135   while (n) {
1136     // unlink the node from the list saving a pointer to the next
1137     CodeString* p = n->next();
1138     n->set_next(NULL);
1139     delete n;
1140     n = p;
1141   }
1142   set_null_and_invalidate();
1143 }
1144 
1145 const char* CodeStrings::add_string(const char * string) {
1146   check_valid();
1147   CodeString* s = new CodeString(string);
1148   s->set_next(_strings);
1149   _strings = s;
1150   assert(s->string() != NULL, "should have a string");
1151   return s->string();
1152 }
1153 
1154 void CodeBuffer::decode() {
1155   ttyLocker ttyl;
1156   Disassembler::decode(decode_begin(), insts_end());
1157   _decode_begin = insts_end();
1158 }
1159 
1160 
1161 void CodeBuffer::skip_decode() {
1162   _decode_begin = insts_end();
1163 }
1164 
1165 
1166 void CodeBuffer::decode_all() {
1167   ttyLocker ttyl;
1168   for (int n = 0; n < (int)SECT_LIMIT; n++) {
1169     // dump contents of each section
1170     CodeSection* cs = code_section(n);
1171     tty->print_cr("! %s:", code_section_name(n));
1172     if (cs != consts())
1173       cs->decode();
1174     else
1175       cs->dump();
1176   }
1177 }
1178 
1179 
1180 void CodeSection::print(const char* name) {
1181   csize_t locs_size = locs_end() - locs_start();
1182   tty->print_cr(" %7s.code = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d)%s",
1183                 name, p2i(start()), p2i(end()), p2i(limit()), size(), capacity(),
1184                 is_frozen()? " [frozen]": "");
1185   tty->print_cr(" %7s.locs = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d) point=%d",
1186                 name, p2i(locs_start()), p2i(locs_end()), p2i(locs_limit()), locs_size, locs_capacity(), locs_point_off());
1187   if (PrintRelocations) {
1188     RelocIterator iter(this);
1189     iter.print();
1190   }
1191 }
1192 
1193 void CodeBuffer::print() {
1194   if (this == NULL) {
1195     tty->print_cr("NULL CodeBuffer pointer");
1196     return;
1197   }
1198 
1199   tty->print_cr("CodeBuffer:");
1200   for (int n = 0; n < (int)SECT_LIMIT; n++) {
1201     // print each section
1202     CodeSection* cs = code_section(n);
1203     cs->print(code_section_name(n));
1204   }
1205 }
1206 
1207 #endif // PRODUCT