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 "runtime/icache.hpp"
  32 #include "utilities/copy.hpp"
  33 #include "utilities/xmlstream.hpp"
  34 
  35 // The structure of a CodeSection:
  36 //
  37 //    _start ->           +----------------+
  38 //                        | machine code...|
  39 //    _end ->             |----------------|
  40 //                        |                |
  41 //                        |    (empty)     |
  42 //                        |                |
  43 //                        |                |
  44 //                        +----------------+
  45 //    _limit ->           |                |
  46 //
  47 //    _locs_start ->      +----------------+
  48 //                        |reloc records...|
  49 //                        |----------------|
  50 //    _locs_end ->        |                |
  51 //                        |                |
  52 //                        |    (empty)     |
  53 //                        |                |
  54 //                        |                |
  55 //                        +----------------+
  56 //    _locs_limit ->      |                |
  57 // The _end (resp. _limit) pointer refers to the first
  58 // unused (resp. unallocated) byte.
  59 
  60 // The structure of the CodeBuffer while code is being accumulated:
  61 //
  62 //    _total_start ->    \
  63 //    _insts._start ->              +----------------+
  64 //                                  |                |
  65 //                                  |     Code       |
  66 //                                  |                |
  67 //    _stubs._start ->              |----------------|
  68 //                                  |                |
  69 //                                  |    Stubs       | (also handlers for deopt/exception)
  70 //                                  |                |
  71 //    _consts._start ->             |----------------|
  72 //                                  |                |
  73 //                                  |   Constants    |
  74 //                                  |                |
  75 //                                  +----------------+
  76 //    + _total_size ->              |                |
  77 //
  78 // When the code and relocations are copied to the code cache,
  79 // the empty parts of each section are removed, and everything
  80 // is copied into contiguous locations.
  81 
  82 typedef CodeBuffer::csize_t csize_t;  // file-local definition
  83 
  84 // External buffer, in a predefined CodeBlob.
  85 // Important: The code_start must be taken exactly, and not realigned.
  86 CodeBuffer::CodeBuffer(CodeBlob* blob) {
  87   initialize_misc("static buffer");
  88   initialize(blob->content_begin(), blob->content_size());
  89   verify_section_allocation();
  90 }
  91 
  92 void CodeBuffer::initialize(csize_t code_size, csize_t locs_size) {
  93   // Compute maximal alignment.
  94   int align = _insts.alignment();
  95   // Always allow for empty slop around each section.
  96   int slop = (int) CodeSection::end_slop();
  97 
  98   assert(blob() == NULL, "only once");
  99   set_blob(BufferBlob::create(_name, code_size + (align+slop) * (SECT_LIMIT+1)));
 100   if (blob() == NULL) {
 101     // The assembler constructor will throw a fatal on an empty CodeBuffer.
 102     return;  // caller must test this
 103   }
 104 
 105   // Set up various pointers into the blob.
 106   initialize(_total_start, _total_size);
 107 
 108   assert((uintptr_t)insts_begin() % CodeEntryAlignment == 0, "instruction start not code entry aligned");
 109 
 110   pd_initialize();
 111 
 112   if (locs_size != 0) {
 113     _insts.initialize_locs(locs_size / sizeof(relocInfo));
 114   }
 115 
 116   verify_section_allocation();
 117 }
 118 
 119 
 120 CodeBuffer::~CodeBuffer() {
 121   verify_section_allocation();
 122 
 123   // If we allocate our code buffer from the CodeCache
 124   // via a BufferBlob, and it's not permanent, then
 125   // free the BufferBlob.
 126   // The rest of the memory will be freed when the ResourceObj
 127   // is released.
 128   for (CodeBuffer* cb = this; cb != NULL; cb = cb->before_expand()) {
 129     // Previous incarnations of this buffer are held live, so that internal
 130     // addresses constructed before expansions will not be confused.
 131     cb->free_blob();
 132   }
 133 
 134   // free any overflow storage
 135   delete _overflow_arena;
 136 
 137   // Claim is that stack allocation ensures resources are cleaned up.
 138   // This is resource clean up, let's hope that all were properly copied out.
 139   free_strings();
 140 
 141 #ifdef ASSERT
 142   // Save allocation type to execute assert in ~ResourceObj()
 143   // which is called after this destructor.
 144   assert(_default_oop_recorder.allocated_on_stack(), "should be embedded object");
 145   ResourceObj::allocation_type at = _default_oop_recorder.get_allocation_type();
 146   Copy::fill_to_bytes(this, sizeof(*this), badResourceValue);
 147   ResourceObj::set_allocation_type((address)(&_default_oop_recorder), at);
 148 #endif
 149 }
 150 
 151 void CodeBuffer::initialize_oop_recorder(OopRecorder* r) {
 152   assert(_oop_recorder == &_default_oop_recorder && _default_oop_recorder.is_unused(), "do this once");
 153   DEBUG_ONLY(_default_oop_recorder.freeze());  // force unused OR to be frozen
 154   _oop_recorder = r;
 155 }
 156 
 157 void CodeBuffer::initialize_section_size(CodeSection* cs, csize_t size) {
 158   assert(cs != &_insts, "insts is the memory provider, not the consumer");
 159   csize_t slop = CodeSection::end_slop();  // margin between sections
 160   int align = cs->alignment();
 161   assert(is_power_of_2(align), "sanity");
 162   address start  = _insts._start;
 163   address limit  = _insts._limit;
 164   address middle = limit - size;
 165   middle -= (intptr_t)middle & (align-1);  // align the division point downward
 166   guarantee(middle - slop > start, "need enough space to divide up");
 167   _insts._limit = middle - slop;  // subtract desired space, plus slop
 168   cs->initialize(middle, limit - middle);
 169   assert(cs->start() == middle, "sanity");
 170   assert(cs->limit() == limit,  "sanity");
 171   // give it some relocations to start with, if the main section has them
 172   if (_insts.has_locs())  cs->initialize_locs(1);
 173 }
 174 
 175 void CodeBuffer::freeze_section(CodeSection* cs) {
 176   CodeSection* next_cs = (cs == consts())? NULL: code_section(cs->index()+1);
 177   csize_t frozen_size = cs->size();
 178   if (next_cs != NULL) {
 179     frozen_size = next_cs->align_at_start(frozen_size);
 180   }
 181   address old_limit = cs->limit();
 182   address new_limit = cs->start() + frozen_size;
 183   relocInfo* old_locs_limit = cs->locs_limit();
 184   relocInfo* new_locs_limit = cs->locs_end();
 185   // Patch the limits.
 186   cs->_limit = new_limit;
 187   cs->_locs_limit = new_locs_limit;
 188   cs->_frozen = true;
 189   if (!next_cs->is_allocated() && !next_cs->is_frozen()) {
 190     // Give remaining buffer space to the following section.
 191     next_cs->initialize(new_limit, old_limit - new_limit);
 192     next_cs->initialize_shared_locs(new_locs_limit,
 193                                     old_locs_limit - new_locs_limit);
 194   }
 195 }
 196 
 197 void CodeBuffer::set_blob(BufferBlob* blob) {
 198   _blob = blob;
 199   if (blob != NULL) {
 200     address start = blob->content_begin();
 201     address end   = blob->content_end();
 202     // Round up the starting address.
 203     int align = _insts.alignment();
 204     start += (-(intptr_t)start) & (align-1);
 205     _total_start = start;
 206     _total_size  = end - start;
 207   } else {
 208 #ifdef ASSERT
 209     // Clean out dangling pointers.
 210     _total_start    = badAddress;
 211     _consts._start  = _consts._end  = badAddress;
 212     _insts._start   = _insts._end   = badAddress;
 213     _stubs._start   = _stubs._end   = badAddress;
 214 #endif //ASSERT
 215   }
 216 }
 217 
 218 void CodeBuffer::free_blob() {
 219   if (_blob != NULL) {
 220     BufferBlob::free(_blob);
 221     set_blob(NULL);
 222   }
 223 }
 224 
 225 const char* CodeBuffer::code_section_name(int n) {
 226 #ifdef PRODUCT
 227   return NULL;
 228 #else //PRODUCT
 229   switch (n) {
 230   case SECT_CONSTS:            return "consts";
 231   case SECT_INSTS:             return "insts";
 232   case SECT_STUBS:             return "stubs";
 233   default:                     return NULL;
 234   }
 235 #endif //PRODUCT
 236 }
 237 
 238 int CodeBuffer::section_index_of(address addr) const {
 239   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 240     const CodeSection* cs = code_section(n);
 241     if (cs->allocates(addr))  return n;
 242   }
 243   return SECT_NONE;
 244 }
 245 
 246 int CodeBuffer::locator(address addr) const {
 247   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 248     const CodeSection* cs = code_section(n);
 249     if (cs->allocates(addr)) {
 250       return locator(addr - cs->start(), n);
 251     }
 252   }
 253   return -1;
 254 }
 255 
 256 address CodeBuffer::locator_address(int locator) const {
 257   if (locator < 0)  return NULL;
 258   address start = code_section(locator_sect(locator))->start();
 259   return start + locator_pos(locator);
 260 }
 261 
 262 bool CodeBuffer::is_backward_branch(Label& L) {
 263   return L.is_bound() && insts_end() <= locator_address(L.loc());
 264 }
 265 
 266 address CodeBuffer::decode_begin() {
 267   address begin = _insts.start();
 268   if (_decode_begin != NULL && _decode_begin > begin)
 269     begin = _decode_begin;
 270   return begin;
 271 }
 272 
 273 
 274 GrowableArray<int>* CodeBuffer::create_patch_overflow() {
 275   if (_overflow_arena == NULL) {
 276     _overflow_arena = new (mtCode) Arena(mtCode);
 277   }
 278   return new (_overflow_arena) GrowableArray<int>(_overflow_arena, 8, 0, 0);
 279 }
 280 
 281 
 282 // Helper function for managing labels and their target addresses.
 283 // Returns a sensible address, and if it is not the label's final
 284 // address, notes the dependency (at 'branch_pc') on the label.
 285 address CodeSection::target(Label& L, address branch_pc) {
 286   if (L.is_bound()) {
 287     int loc = L.loc();
 288     if (index() == CodeBuffer::locator_sect(loc)) {
 289       return start() + CodeBuffer::locator_pos(loc);
 290     } else {
 291       return outer()->locator_address(loc);
 292     }
 293   } else {
 294     assert(allocates2(branch_pc), "sanity");
 295     address base = start();
 296     int patch_loc = CodeBuffer::locator(branch_pc - base, index());
 297     L.add_patch_at(outer(), patch_loc);
 298 
 299     // Need to return a pc, doesn't matter what it is since it will be
 300     // replaced during resolution later.
 301     // Don't return NULL or badAddress, since branches shouldn't overflow.
 302     // Don't return base either because that could overflow displacements
 303     // for shorter branches.  It will get checked when bound.
 304     return branch_pc;
 305   }
 306 }
 307 
 308 void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {
 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            "code needs relocation information");
 330     // leave behind an indication that we attempted a relocation
 331     DEBUG_ONLY(_locs_start = _locs_limit = (relocInfo*)badAddress);
 332     return;
 333   }
 334 
 335   // Advance the point, noting the offset we'll have to record.
 336   csize_t offset = at - locs_point();
 337   set_locs_point(at);
 338 
 339   // Test for a couple of overflow conditions; maybe expand the buffer.
 340   relocInfo* end = locs_end();
 341   relocInfo* req = end + relocInfo::length_limit;
 342   // Check for (potential) overflow
 343   if (req >= locs_limit() || offset >= relocInfo::offset_limit()) {
 344     req += (uint)offset / (uint)relocInfo::offset_limit();
 345     if (req >= locs_limit()) {
 346       // Allocate or reallocate.
 347       expand_locs(locs_count() + (req - end));
 348       // reload pointer
 349       end = locs_end();
 350     }
 351   }
 352 
 353   // If the offset is giant, emit filler relocs, of type 'none', but
 354   // each carrying the largest possible offset, to advance the locs_point.
 355   while (offset >= relocInfo::offset_limit()) {
 356     assert(end < locs_limit(), "adjust previous paragraph of code");
 357     *end++ = filler_relocInfo();
 358     offset -= filler_relocInfo().addr_offset();
 359   }
 360 
 361   // If it's a simple reloc with no data, we'll just write (rtype | offset).
 362   (*end) = relocInfo(rtype, offset, format);
 363 
 364   // If it has data, insert the prefix, as (data_prefix_tag | data1), data2.
 365   end->initialize(this, reloc);
 366 }
 367 
 368 void CodeSection::initialize_locs(int locs_capacity) {
 369   assert(_locs_start == NULL, "only one locs init step, please");
 370   // Apply a priori lower limits to relocation size:
 371   csize_t min_locs = MAX2(size() / 16, (csize_t)4);
 372   if (locs_capacity < min_locs)  locs_capacity = min_locs;
 373   relocInfo* locs_start = NEW_RESOURCE_ARRAY(relocInfo, locs_capacity);
 374   _locs_start    = locs_start;
 375   _locs_end      = locs_start;
 376   _locs_limit    = locs_start + locs_capacity;
 377   _locs_own      = true;
 378 }
 379 
 380 void CodeSection::initialize_shared_locs(relocInfo* buf, int length) {
 381   assert(_locs_start == NULL, "do this before locs are allocated");
 382   // Internal invariant:  locs buf must be fully aligned.
 383   // See copy_relocations_to() below.
 384   while ((uintptr_t)buf % HeapWordSize != 0 && length > 0) {
 385     ++buf; --length;
 386   }
 387   if (length > 0) {
 388     _locs_start = buf;
 389     _locs_end   = buf;
 390     _locs_limit = buf + length;
 391     _locs_own   = false;
 392   }
 393 }
 394 
 395 void CodeSection::initialize_locs_from(const CodeSection* source_cs) {
 396   int lcount = source_cs->locs_count();
 397   if (lcount != 0) {
 398     initialize_shared_locs(source_cs->locs_start(), lcount);
 399     _locs_end = _locs_limit = _locs_start + lcount;
 400     assert(is_allocated(), "must have copied code already");
 401     set_locs_point(start() + source_cs->locs_point_off());
 402   }
 403   assert(this->locs_count() == source_cs->locs_count(), "sanity");
 404 }
 405 
 406 void CodeSection::expand_locs(int new_capacity) {
 407   if (_locs_start == NULL) {
 408     initialize_locs(new_capacity);
 409     return;
 410   } else {
 411     int old_count    = locs_count();
 412     int old_capacity = locs_capacity();
 413     if (new_capacity < old_capacity * 2)
 414       new_capacity = old_capacity * 2;
 415     relocInfo* locs_start;
 416     if (_locs_own) {
 417       locs_start = REALLOC_RESOURCE_ARRAY(relocInfo, _locs_start, old_capacity, new_capacity);
 418     } else {
 419       locs_start = NEW_RESOURCE_ARRAY(relocInfo, new_capacity);
 420       Copy::conjoint_jbytes(_locs_start, locs_start, old_capacity * sizeof(relocInfo));
 421       _locs_own = true;
 422     }
 423     _locs_start    = locs_start;
 424     _locs_end      = locs_start + old_count;
 425     _locs_limit    = locs_start + new_capacity;
 426   }
 427 }
 428 
 429 
 430 /// Support for emitting the code to its final location.
 431 /// The pattern is the same for all functions.
 432 /// We iterate over all the sections, padding each to alignment.
 433 
 434 csize_t CodeBuffer::total_content_size() const {
 435   csize_t size_so_far = 0;
 436   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 437     const CodeSection* cs = code_section(n);
 438     if (cs->is_empty())  continue;  // skip trivial section
 439     size_so_far = cs->align_at_start(size_so_far);
 440     size_so_far += cs->size();
 441   }
 442   return size_so_far;
 443 }
 444 
 445 void CodeBuffer::compute_final_layout(CodeBuffer* dest) const {
 446   address buf = dest->_total_start;
 447   csize_t buf_offset = 0;
 448   assert(dest->_total_size >= total_content_size(), "must be big enough");
 449 
 450   {
 451     // not sure why this is here, but why not...
 452     int alignSize = MAX2((intx) sizeof(jdouble), CodeEntryAlignment);
 453     assert( (dest->_total_start - _insts.start()) % alignSize == 0, "copy must preserve alignment");
 454   }
 455 
 456   const CodeSection* prev_cs      = NULL;
 457   CodeSection*       prev_dest_cs = NULL;
 458 
 459   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 460     // figure compact layout of each section
 461     const CodeSection* cs = code_section(n);
 462     csize_t csize = cs->size();
 463 
 464     CodeSection* dest_cs = dest->code_section(n);
 465     if (!cs->is_empty()) {
 466       // Compute initial padding; assign it to the previous non-empty guy.
 467       // Cf. figure_expanded_capacities.
 468       csize_t padding = cs->align_at_start(buf_offset) - buf_offset;
 469       if (padding != 0) {
 470         buf_offset += padding;
 471         assert(prev_dest_cs != NULL, "sanity");
 472         prev_dest_cs->_limit += padding;
 473       }
 474       #ifdef ASSERT
 475       if (prev_cs != NULL && prev_cs->is_frozen() && n < (SECT_LIMIT - 1)) {
 476         // Make sure the ends still match up.
 477         // This is important because a branch in a frozen section
 478         // might target code in a following section, via a Label,
 479         // and without a relocation record.  See Label::patch_instructions.
 480         address dest_start = buf+buf_offset;
 481         csize_t start2start = cs->start() - prev_cs->start();
 482         csize_t dest_start2start = dest_start - prev_dest_cs->start();
 483         assert(start2start == dest_start2start, "cannot stretch frozen sect");
 484       }
 485       #endif //ASSERT
 486       prev_dest_cs = dest_cs;
 487       prev_cs      = cs;
 488     }
 489 
 490     debug_only(dest_cs->_start = NULL);  // defeat double-initialization assert
 491     dest_cs->initialize(buf+buf_offset, csize);
 492     dest_cs->set_end(buf+buf_offset+csize);
 493     assert(dest_cs->is_allocated(), "must always be allocated");
 494     assert(cs->is_empty() == dest_cs->is_empty(), "sanity");
 495 
 496     buf_offset += csize;
 497   }
 498 
 499   // Done calculating sections; did it come out to the right end?
 500   assert(buf_offset == total_content_size(), "sanity");
 501   dest->verify_section_allocation();
 502 }
 503 
 504 // Append an oop reference that keeps the class alive.
 505 static void append_oop_references(GrowableArray<oop>* oops, Klass* k) {
 506   oop cl = k->klass_holder();
 507   if (cl != NULL && !oops->contains(cl)) {
 508     oops->append(cl);
 509   }
 510 }
 511 
 512 void CodeBuffer::finalize_oop_references(methodHandle mh) {
 513   No_Safepoint_Verifier nsv;
 514 
 515   GrowableArray<oop> oops;
 516 
 517   // Make sure that immediate metadata records something in the OopRecorder
 518   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 519     // pull code out of each section
 520     CodeSection* cs = code_section(n);
 521     if (cs->is_empty())  continue;  // skip trivial section
 522     RelocIterator iter(cs);
 523     while (iter.next()) {
 524       if (iter.type() == relocInfo::metadata_type) {
 525         metadata_Relocation* md = iter.metadata_reloc();
 526         if (md->metadata_is_immediate()) {
 527           Metadata* m = md->metadata_value();
 528           if (oop_recorder()->is_real(m)) {
 529             if (m->is_methodData()) {
 530               m = ((MethodData*)m)->method();
 531             }
 532             if (m->is_method()) {
 533               m = ((Method*)m)->method_holder();
 534             }
 535             if (m->is_klass()) {
 536               append_oop_references(&oops, (Klass*)m);
 537             } else {
 538               // XXX This will currently occur for MDO which don't
 539               // have a backpointer.  This has to be fixed later.
 540               m->print();
 541               ShouldNotReachHere();
 542             }
 543           }
 544         }
 545       }
 546     }
 547   }
 548 
 549   if (!oop_recorder()->is_unused()) {
 550     for (int i = 0; i < oop_recorder()->metadata_count(); i++) {
 551       Metadata* m = oop_recorder()->metadata_at(i);
 552       if (oop_recorder()->is_real(m)) {
 553         if (m->is_methodData()) {
 554           m = ((MethodData*)m)->method();
 555         }
 556         if (m->is_method()) {
 557           m = ((Method*)m)->method_holder();
 558         }
 559         if (m->is_klass()) {
 560           append_oop_references(&oops, (Klass*)m);
 561         } else {
 562           m->print();
 563           ShouldNotReachHere();
 564         }
 565       }
 566     }
 567 
 568   }
 569 
 570   // Add the class loader of Method* for the nmethod itself
 571   append_oop_references(&oops, mh->method_holder());
 572 
 573   // Add any oops that we've found
 574   Thread* thread = Thread::current();
 575   for (int i = 0; i < oops.length(); i++) {
 576     oop_recorder()->find_index((jobject)thread->handle_area()->allocate_handle(oops.at(i)));
 577   }
 578 }
 579 
 580 
 581 
 582 csize_t CodeBuffer::total_offset_of(CodeSection* cs) const {
 583   csize_t size_so_far = 0;
 584   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 585     const CodeSection* cur_cs = code_section(n);
 586     if (!cur_cs->is_empty()) {
 587       size_so_far = cur_cs->align_at_start(size_so_far);
 588     }
 589     if (cur_cs->index() == cs->index()) {
 590       return size_so_far;
 591     }
 592     size_so_far += cur_cs->size();
 593   }
 594   ShouldNotReachHere();
 595   return -1;
 596 }
 597 
 598 csize_t CodeBuffer::total_relocation_size() const {
 599   csize_t lsize = copy_relocations_to(NULL);  // dry run only
 600   csize_t csize = total_content_size();
 601   csize_t total = RelocIterator::locs_and_index_size(csize, lsize);
 602   return (csize_t) align_size_up(total, HeapWordSize);
 603 }
 604 
 605 csize_t CodeBuffer::copy_relocations_to(CodeBlob* dest) const {
 606   address buf = NULL;
 607   csize_t buf_offset = 0;
 608   csize_t buf_limit = 0;
 609   if (dest != NULL) {
 610     buf = (address)dest->relocation_begin();
 611     buf_limit = (address)dest->relocation_end() - buf;
 612     assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");
 613     assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");
 614   }
 615   // if dest == NULL, this is just the sizing pass
 616 
 617   csize_t code_end_so_far = 0;
 618   csize_t code_point_so_far = 0;
 619   for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
 620     // pull relocs out of each section
 621     const CodeSection* cs = code_section(n);
 622     assert(!(cs->is_empty() && cs->locs_count() > 0), "sanity");
 623     if (cs->is_empty())  continue;  // skip trivial section
 624     relocInfo* lstart = cs->locs_start();
 625     relocInfo* lend   = cs->locs_end();
 626     csize_t    lsize  = (csize_t)( (address)lend - (address)lstart );
 627     csize_t    csize  = cs->size();
 628     code_end_so_far = cs->align_at_start(code_end_so_far);
 629 
 630     if (lsize > 0) {
 631       // Figure out how to advance the combined relocation point
 632       // first to the beginning of this section.
 633       // We'll insert one or more filler relocs to span that gap.
 634       // (Don't bother to improve this by editing the first reloc's offset.)
 635       csize_t new_code_point = code_end_so_far;
 636       for (csize_t jump;
 637            code_point_so_far < new_code_point;
 638            code_point_so_far += jump) {
 639         jump = new_code_point - code_point_so_far;
 640         relocInfo filler = filler_relocInfo();
 641         if (jump >= filler.addr_offset()) {
 642           jump = filler.addr_offset();
 643         } else {  // else shrink the filler to fit
 644           filler = relocInfo(relocInfo::none, jump);
 645         }
 646         if (buf != NULL) {
 647           assert(buf_offset + (csize_t)sizeof(filler) <= buf_limit, "filler in bounds");
 648           *(relocInfo*)(buf+buf_offset) = filler;
 649         }
 650         buf_offset += sizeof(filler);
 651       }
 652 
 653       // Update code point and end to skip past this section:
 654       csize_t last_code_point = code_end_so_far + cs->locs_point_off();
 655       assert(code_point_so_far <= last_code_point, "sanity");
 656       code_point_so_far = last_code_point; // advance past this guy's relocs
 657     }
 658     code_end_so_far += csize;  // advance past this guy's instructions too
 659 
 660     // Done with filler; emit the real relocations:
 661     if (buf != NULL && lsize != 0) {
 662       assert(buf_offset + lsize <= buf_limit, "target in bounds");
 663       assert((uintptr_t)lstart % HeapWordSize == 0, "sane start");
 664       if (buf_offset % HeapWordSize == 0) {
 665         // Use wordwise copies if possible:
 666         Copy::disjoint_words((HeapWord*)lstart,
 667                              (HeapWord*)(buf+buf_offset),
 668                              (lsize + HeapWordSize-1) / HeapWordSize);
 669       } else {
 670         Copy::conjoint_jbytes(lstart, buf+buf_offset, lsize);
 671       }
 672     }
 673     buf_offset += lsize;
 674   }
 675 
 676   // Align end of relocation info in target.
 677   while (buf_offset % HeapWordSize != 0) {
 678     if (buf != NULL) {
 679       relocInfo padding = relocInfo(relocInfo::none, 0);
 680       assert(buf_offset + (csize_t)sizeof(padding) <= buf_limit, "padding in bounds");
 681       *(relocInfo*)(buf+buf_offset) = padding;
 682     }
 683     buf_offset += sizeof(relocInfo);
 684   }
 685 
 686   assert(code_end_so_far == total_content_size(), "sanity");
 687 
 688   // Account for index:
 689   if (buf != NULL) {
 690     RelocIterator::create_index(dest->relocation_begin(),
 691                                 buf_offset / sizeof(relocInfo),
 692                                 dest->relocation_end());
 693   }
 694 
 695   return buf_offset;
 696 }
 697 
 698 void CodeBuffer::copy_code_to(CodeBlob* dest_blob) {
 699 #ifndef PRODUCT
 700   if (PrintNMethods && (WizardMode || Verbose)) {
 701     tty->print("done with CodeBuffer:");
 702     ((CodeBuffer*)this)->print();
 703   }
 704 #endif //PRODUCT
 705 
 706   CodeBuffer dest(dest_blob);
 707   assert(dest_blob->content_size() >= total_content_size(), "good sizing");
 708   this->compute_final_layout(&dest);
 709   relocate_code_to(&dest);
 710 
 711   // transfer strings and comments from buffer to blob
 712   dest_blob->set_strings(_code_strings);
 713 
 714   // Done moving code bytes; were they the right size?
 715   assert(round_to(dest.total_content_size(), oopSize) == dest_blob->content_size(), "sanity");
 716 
 717   // Flush generated code
 718   ICache::invalidate_range(dest_blob->code_begin(), dest_blob->code_size());
 719 }
 720 
 721 // Move all my code into another code buffer.  Consult applicable
 722 // relocs to repair embedded addresses.  The layout in the destination
 723 // CodeBuffer is different to the source CodeBuffer: the destination
 724 // CodeBuffer gets the final layout (consts, insts, stubs in order of
 725 // ascending address).
 726 void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
 727   address dest_end = dest->_total_start + dest->_total_size;
 728   address dest_filled = NULL;
 729   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 730     // pull code out of each section
 731     const CodeSection* cs = code_section(n);
 732     if (cs->is_empty())  continue;  // skip trivial section
 733     CodeSection* dest_cs = dest->code_section(n);
 734     assert(cs->size() == dest_cs->size(), "sanity");
 735     csize_t usize = dest_cs->size();
 736     csize_t wsize = align_size_up(usize, HeapWordSize);
 737     assert(dest_cs->start() + wsize <= dest_end, "no overflow");
 738     // Copy the code as aligned machine words.
 739     // This may also include an uninitialized partial word at the end.
 740     Copy::disjoint_words((HeapWord*)cs->start(),
 741                          (HeapWord*)dest_cs->start(),
 742                          wsize / HeapWordSize);
 743 
 744     if (dest->blob() == NULL) {
 745       // Destination is a final resting place, not just another buffer.
 746       // Normalize uninitialized bytes in the final padding.
 747       Copy::fill_to_bytes(dest_cs->end(), dest_cs->remaining(),
 748                           Assembler::code_fill_byte());
 749     }
 750     // Keep track of the highest filled address
 751     dest_filled = MAX2(dest_filled, dest_cs->end() + dest_cs->remaining());
 752 
 753     assert(cs->locs_start() != (relocInfo*)badAddress,
 754            "this section carries no reloc storage, but reloc was attempted");
 755 
 756     // Make the new code copy use the old copy's relocations:
 757     dest_cs->initialize_locs_from(cs);
 758   }
 759 
 760   // Do relocation after all sections are copied.
 761   // This is necessary if the code uses constants in stubs, which are
 762   // relocated when the corresponding instruction in the code (e.g., a
 763   // call) is relocated. Stubs are placed behind the main code
 764   // section, so that section has to be copied before relocating.
 765   for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
 766     // pull code out of each section
 767     const CodeSection* cs = code_section(n);
 768     if (cs->is_empty()) continue;  // skip trivial section
 769     CodeSection* dest_cs = dest->code_section(n);
 770     { // Repair the pc relative information in the code after the move
 771       RelocIterator iter(dest_cs);
 772       while (iter.next()) {
 773         iter.reloc()->fix_relocation_after_move(this, dest);
 774       }
 775     }
 776   }
 777 
 778   if (dest->blob() == NULL && dest_filled != NULL) {
 779     // Destination is a final resting place, not just another buffer.
 780     // Normalize uninitialized bytes in the final padding.
 781     Copy::fill_to_bytes(dest_filled, dest_end - dest_filled,
 782                         Assembler::code_fill_byte());
 783 
 784   }
 785 }
 786 
 787 csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,
 788                                                csize_t amount,
 789                                                csize_t* new_capacity) {
 790   csize_t new_total_cap = 0;
 791 
 792   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 793     const CodeSection* sect = code_section(n);
 794 
 795     if (!sect->is_empty()) {
 796       // Compute initial padding; assign it to the previous section,
 797       // even if it's empty (e.g. consts section can be empty).
 798       // Cf. compute_final_layout
 799       csize_t padding = sect->align_at_start(new_total_cap) - new_total_cap;
 800       if (padding != 0) {
 801         new_total_cap += padding;
 802         assert(n - 1 >= SECT_FIRST, "sanity");
 803         new_capacity[n - 1] += padding;
 804       }
 805     }
 806 
 807     csize_t exp = sect->size();  // 100% increase
 808     if ((uint)exp < 4*K)  exp = 4*K;       // minimum initial increase
 809     if (sect == which_cs) {
 810       if (exp < amount)  exp = amount;
 811       if (StressCodeBuffers)  exp = amount;  // expand only slightly
 812     } else if (n == SECT_INSTS) {
 813       // scale down inst increases to a more modest 25%
 814       exp = 4*K + ((exp - 4*K) >> 2);
 815       if (StressCodeBuffers)  exp = amount / 2;  // expand only slightly
 816     } else if (sect->is_empty()) {
 817       // do not grow an empty secondary section
 818       exp = 0;
 819     }
 820     // Allow for inter-section slop:
 821     exp += CodeSection::end_slop();
 822     csize_t new_cap = sect->size() + exp;
 823     if (new_cap < sect->capacity()) {
 824       // No need to expand after all.
 825       new_cap = sect->capacity();
 826     }
 827     new_capacity[n] = new_cap;
 828     new_total_cap += new_cap;
 829   }
 830 
 831   return new_total_cap;
 832 }
 833 
 834 void CodeBuffer::expand(CodeSection* which_cs, csize_t amount) {
 835 #ifndef PRODUCT
 836   if (PrintNMethods && (WizardMode || Verbose)) {
 837     tty->print("expanding CodeBuffer:");
 838     this->print();
 839   }
 840 
 841   if (StressCodeBuffers && blob() != NULL) {
 842     static int expand_count = 0;
 843     if (expand_count >= 0)  expand_count += 1;
 844     if (expand_count > 100 && is_power_of_2(expand_count)) {
 845       tty->print_cr("StressCodeBuffers: have expanded %d times", expand_count);
 846       // simulate an occasional allocation failure:
 847       free_blob();
 848     }
 849   }
 850 #endif //PRODUCT
 851 
 852   // Resizing must be allowed
 853   {
 854     if (blob() == NULL)  return;  // caller must check for blob == NULL
 855     for (int n = 0; n < (int)SECT_LIMIT; n++) {
 856       guarantee(!code_section(n)->is_frozen(), "resizing not allowed when frozen");
 857     }
 858   }
 859 
 860   // Figure new capacity for each section.
 861   csize_t new_capacity[SECT_LIMIT];
 862   csize_t new_total_cap
 863     = figure_expanded_capacities(which_cs, amount, new_capacity);
 864 
 865   // Create a new (temporary) code buffer to hold all the new data
 866   CodeBuffer cb(name(), new_total_cap, 0);
 867   if (cb.blob() == NULL) {
 868     // Failed to allocate in code cache.
 869     free_blob();
 870     return;
 871   }
 872 
 873   // Create an old code buffer to remember which addresses used to go where.
 874   // This will be useful when we do final assembly into the code cache,
 875   // because we will need to know how to warp any internal address that
 876   // has been created at any time in this CodeBuffer's past.
 877   CodeBuffer* bxp = new CodeBuffer(_total_start, _total_size);
 878   bxp->take_over_code_from(this);  // remember the old undersized blob
 879   DEBUG_ONLY(this->_blob = NULL);  // silence a later assert
 880   bxp->_before_expand = this->_before_expand;
 881   this->_before_expand = bxp;
 882 
 883   // Give each section its required (expanded) capacity.
 884   for (int n = (int)SECT_LIMIT-1; n >= SECT_FIRST; n--) {
 885     CodeSection* cb_sect   = cb.code_section(n);
 886     CodeSection* this_sect = code_section(n);
 887     if (new_capacity[n] == 0)  continue;  // already nulled out
 888     if (n != SECT_INSTS) {
 889       cb.initialize_section_size(cb_sect, new_capacity[n]);
 890     }
 891     assert(cb_sect->capacity() >= new_capacity[n], "big enough");
 892     address cb_start = cb_sect->start();
 893     cb_sect->set_end(cb_start + this_sect->size());
 894     if (this_sect->mark() == NULL) {
 895       cb_sect->clear_mark();
 896     } else {
 897       cb_sect->set_mark(cb_start + this_sect->mark_off());
 898     }
 899   }
 900 
 901   // Move all the code and relocations to the new blob:
 902   relocate_code_to(&cb);
 903 
 904   // Copy the temporary code buffer into the current code buffer.
 905   // Basically, do {*this = cb}, except for some control information.
 906   this->take_over_code_from(&cb);
 907   cb.set_blob(NULL);
 908 
 909   // Zap the old code buffer contents, to avoid mistakenly using them.
 910   debug_only(Copy::fill_to_bytes(bxp->_total_start, bxp->_total_size,
 911                                  badCodeHeapFreeVal));
 912 
 913   _decode_begin = NULL;  // sanity
 914 
 915   // Make certain that the new sections are all snugly inside the new blob.
 916   verify_section_allocation();
 917 
 918 #ifndef PRODUCT
 919   if (PrintNMethods && (WizardMode || Verbose)) {
 920     tty->print("expanded CodeBuffer:");
 921     this->print();
 922   }
 923 #endif //PRODUCT
 924 }
 925 
 926 void CodeBuffer::take_over_code_from(CodeBuffer* cb) {
 927   // Must already have disposed of the old blob somehow.
 928   assert(blob() == NULL, "must be empty");
 929   // Take the new blob away from cb.
 930   set_blob(cb->blob());
 931   // Take over all the section pointers.
 932   for (int n = 0; n < (int)SECT_LIMIT; n++) {
 933     CodeSection* cb_sect   = cb->code_section(n);
 934     CodeSection* this_sect = code_section(n);
 935     this_sect->take_over_code_from(cb_sect);
 936   }
 937   _overflow_arena = cb->_overflow_arena;
 938   // Make sure the old cb won't try to use it or free it.
 939   DEBUG_ONLY(cb->_blob = (BufferBlob*)badAddress);
 940 }
 941 
 942 void CodeBuffer::verify_section_allocation() {
 943   address tstart = _total_start;
 944   if (tstart == badAddress)  return;  // smashed by set_blob(NULL)
 945   address tend   = tstart + _total_size;
 946   if (_blob != NULL) {
 947 
 948     guarantee(tstart >= _blob->content_begin(), "sanity");
 949     guarantee(tend   <= _blob->content_end(),   "sanity");
 950   }
 951   // Verify disjointness.
 952   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
 953     CodeSection* sect = code_section(n);
 954     if (!sect->is_allocated() || sect->is_empty())  continue;
 955     guarantee((intptr_t)sect->start() % sect->alignment() == 0
 956            || sect->is_empty() || _blob == NULL,
 957            "start is aligned");
 958     for (int m = (int) SECT_FIRST; m < (int) SECT_LIMIT; m++) {
 959       CodeSection* other = code_section(m);
 960       if (!other->is_allocated() || other == sect)  continue;
 961       guarantee(!other->contains(sect->start()    ), "sanity");
 962       // limit is an exclusive address and can be the start of another
 963       // section.
 964       guarantee(!other->contains(sect->limit() - 1), "sanity");
 965     }
 966     guarantee(sect->end() <= tend, "sanity");
 967     guarantee(sect->end() <= sect->limit(), "sanity");
 968   }
 969 }
 970 
 971 void CodeBuffer::log_section_sizes(const char* name) {
 972   if (xtty != NULL) {
 973     ttyLocker ttyl;
 974     // log info about buffer usage
 975     xtty->print_cr("<blob name='%s' size='%d'>", name, _total_size);
 976     for (int n = (int) CodeBuffer::SECT_FIRST; n < (int) CodeBuffer::SECT_LIMIT; n++) {
 977       CodeSection* sect = code_section(n);
 978       if (!sect->is_allocated() || sect->is_empty())  continue;
 979       xtty->print_cr("<sect index='%d' size='" SIZE_FORMAT "' free='" SIZE_FORMAT "'/>",
 980                      n, sect->limit() - sect->start(), sect->limit() - sect->end());
 981     }
 982     xtty->print_cr("</blob>");
 983   }
 984 }
 985 
 986 #ifndef PRODUCT
 987 
 988 void CodeSection::dump() {
 989   address ptr = start();
 990   for (csize_t step; ptr < end(); ptr += step) {
 991     step = end() - ptr;
 992     if (step > jintSize * 4)  step = jintSize * 4;
 993     tty->print(INTPTR_FORMAT ": ", p2i(ptr));
 994     while (step > 0) {
 995       tty->print(" " PTR32_FORMAT, *(jint*)ptr);
 996       ptr += jintSize;
 997     }
 998     tty->cr();
 999   }
1000 }
1001 
1002 
1003 void CodeSection::decode() {
1004   Disassembler::decode(start(), end());
1005 }
1006 
1007 
1008 void CodeBuffer::block_comment(intptr_t offset, const char * comment) {
1009   _code_strings.add_comment(offset, comment);
1010 }
1011 
1012 const char* CodeBuffer::code_string(const char* str) {
1013   return _code_strings.add_string(str);
1014 }
1015 
1016 class CodeString: public CHeapObj<mtCode> {
1017  private:
1018   friend class CodeStrings;
1019   const char * _string;
1020   CodeString*  _next;
1021   intptr_t     _offset;
1022 
1023   ~CodeString() {
1024     assert(_next == NULL, "wrong interface for freeing list");
1025     os::free((void*)_string);
1026   }
1027 
1028   bool is_comment() const { return _offset >= 0; }
1029 
1030  public:
1031   CodeString(const char * string, intptr_t offset = -1)
1032     : _next(NULL), _offset(offset) {
1033     _string = os::strdup(string, mtCode);
1034   }
1035 
1036   const char * string() const { return _string; }
1037   intptr_t     offset() const { assert(_offset >= 0, "offset for non comment?"); return _offset;  }
1038   CodeString* next()    const { return _next; }
1039 
1040   void set_next(CodeString* next) { _next = next; }
1041 
1042   CodeString* first_comment() {
1043     if (is_comment()) {
1044       return this;
1045     } else {
1046       return next_comment();
1047     }
1048   }
1049   CodeString* next_comment() const {
1050     CodeString* s = _next;
1051     while (s != NULL && !s->is_comment()) {
1052       s = s->_next;
1053     }
1054     return s;
1055   }
1056 };
1057 
1058 CodeString* CodeStrings::find(intptr_t offset) const {
1059   CodeString* a = _strings->first_comment();
1060   while (a != NULL && a->offset() != offset) {
1061     a = a->next_comment();
1062   }
1063   return a;
1064 }
1065 
1066 // Convenience for add_comment.
1067 CodeString* CodeStrings::find_last(intptr_t offset) const {
1068   CodeString* a = find(offset);
1069   if (a != NULL) {
1070     CodeString* c = NULL;
1071     while (((c = a->next_comment()) != NULL) && (c->offset() == offset)) {
1072       a = c;
1073     }
1074   }
1075   return a;
1076 }
1077 
1078 void CodeStrings::add_comment(intptr_t offset, const char * comment) {
1079   check_valid();
1080   CodeString* c      = new CodeString(comment, offset);
1081   CodeString* inspos = (_strings == NULL) ? NULL : find_last(offset);
1082 
1083   if (inspos) {
1084     // insert after already existing comments with same offset
1085     c->set_next(inspos->next());
1086     inspos->set_next(c);
1087   } else {
1088     // no comments with such offset, yet. Insert before anything else.
1089     c->set_next(_strings);
1090     _strings = c;
1091   }
1092 }
1093 
1094 void CodeStrings::assign(CodeStrings& other) {
1095   other.check_valid();
1096   // Cannot do following because CodeStrings constructor is not alway run!
1097   assert(is_null(), "Cannot assign onto non-empty CodeStrings");
1098   _strings = other._strings;
1099   other.set_null_and_invalidate();
1100 }
1101 
1102 // Deep copy of CodeStrings for consistent memory management.
1103 // Only used for actual disassembly so this is cheaper than reference counting
1104 // for the "normal" fastdebug case.
1105 void CodeStrings::copy(CodeStrings& other) {
1106   other.check_valid();
1107   check_valid();
1108   assert(is_null(), "Cannot copy onto non-empty CodeStrings");
1109   CodeString* n = other._strings;
1110   CodeString** ps = &_strings;
1111   while (n != NULL) {
1112     *ps = new CodeString(n->string(),n->offset());
1113     ps = &((*ps)->_next);
1114     n = n->next();
1115   }
1116 }
1117 
1118 void CodeStrings::print_block_comment(outputStream* stream, intptr_t offset) const {
1119     check_valid();
1120     if (_strings != NULL) {
1121     CodeString* c = find(offset);
1122     while (c && c->offset() == offset) {
1123       stream->bol();
1124       stream->print("  ;; ");
1125       stream->print_cr("%s", c->string());
1126       c = c->next_comment();
1127     }
1128   }
1129 }
1130 
1131 // Also sets isNull()
1132 void CodeStrings::free() {
1133   CodeString* n = _strings;
1134   while (n) {
1135     // unlink the node from the list saving a pointer to the next
1136     CodeString* p = n->next();
1137     n->set_next(NULL);
1138     delete n;
1139     n = p;
1140   }
1141   set_null_and_invalidate();
1142 }
1143 
1144 const char* CodeStrings::add_string(const char * string) {
1145   check_valid();
1146   CodeString* s = new CodeString(string);
1147   s->set_next(_strings);
1148   _strings = s;
1149   assert(s->string() != NULL, "should have a string");
1150   return s->string();
1151 }
1152 
1153 void CodeBuffer::decode() {
1154   ttyLocker ttyl;
1155   Disassembler::decode(decode_begin(), insts_end());
1156   _decode_begin = insts_end();
1157 }
1158 
1159 
1160 void CodeBuffer::skip_decode() {
1161   _decode_begin = insts_end();
1162 }
1163 
1164 
1165 void CodeBuffer::decode_all() {
1166   ttyLocker ttyl;
1167   for (int n = 0; n < (int)SECT_LIMIT; n++) {
1168     // dump contents of each section
1169     CodeSection* cs = code_section(n);
1170     tty->print_cr("! %s:", code_section_name(n));
1171     if (cs != consts())
1172       cs->decode();
1173     else
1174       cs->dump();
1175   }
1176 }
1177 
1178 
1179 void CodeSection::print(const char* name) {
1180   csize_t locs_size = locs_end() - locs_start();
1181   tty->print_cr(" %7s.code = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d)%s",
1182                 name, p2i(start()), p2i(end()), p2i(limit()), size(), capacity(),
1183                 is_frozen()? " [frozen]": "");
1184   tty->print_cr(" %7s.locs = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d) point=%d",
1185                 name, p2i(locs_start()), p2i(locs_end()), p2i(locs_limit()), locs_size, locs_capacity(), locs_point_off());
1186   if (PrintRelocations) {
1187     RelocIterator iter(this);
1188     iter.print();
1189   }
1190 }
1191 
1192 void CodeBuffer::print() {
1193   if (this == NULL) {
1194     tty->print_cr("NULL CodeBuffer pointer");
1195     return;
1196   }
1197 
1198   tty->print_cr("CodeBuffer:");
1199   for (int n = 0; n < (int)SECT_LIMIT; n++) {
1200     // print each section
1201     CodeSection* cs = code_section(n);
1202     cs->print(code_section_name(n));
1203   }
1204 }
1205 
1206 #endif // PRODUCT