Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 1997, 2009, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 # include "incls/_precompiled.incl"

 # include "incls/_codeBuffer.cpp.incl"

 // The structure of a CodeSection:

 //

 //    _start ->           +----------------+

 //                        | machine code...|

 //    _end ->             |----------------|

 //                        |                |

 //                        |    (empty)     |

 //                        |                |

 //                        |                |

 //                        +----------------+

 //    _limit ->           |                |

 //

 //    _locs_start ->      +----------------+

 //                        |reloc records...|

 //                        |----------------|

 //    _locs_end ->        |                |

 //                        |                |

 //                        |    (empty)     |

 //                        |                |

 //                        |                |

 //                        +----------------+

 //    _locs_limit ->      |                |

 // The _end (resp. _limit) pointer refers to the first

 // unused (resp. unallocated) byte.

 // The structure of the CodeBuffer while code is being accumulated:

 //

 //    _total_start ->    \

 //    _insts._start ->              +----------------+

 //                                  |                |

 //                                  |     Code       |

 //                                  |                |

 //    _stubs._start ->              |----------------|

 //                                  |                |

 //                                  |    Stubs       | (also handlers for deopt/exception)

 //                                  |                |

 //    _consts._start ->             |----------------|

 //                                  |                |

 //                                  |   Constants    |

 //                                  |                |

 //                                  +----------------+

 //    + _total_size ->              |                |

 //

 // When the code and relocations are copied to the code cache,

 // the empty parts of each section are removed, and everything

 // is copied into contiguous locations.

 typedef CodeBuffer::csize_t csize_t;  // file-local definition

 // external buffer, in a predefined CodeBlob or other buffer area

 // Important: The code_start must be taken exactly, and not realigned.

 CodeBuffer::CodeBuffer(address code_start, csize_t code_size) {

   assert(code_start != NULL, "sanity");

   initialize_misc("static buffer");

   initialize(code_start, code_size);

   assert(verify_section_allocation(), "initial use of buffer OK");

 }

 void CodeBuffer::initialize(csize_t code_size, csize_t locs_size) {

   // Compute maximal alignment.

   int align = _insts.alignment();

   // Always allow for empty slop around each section.

   int slop = (int) CodeSection::end_slop();

   assert(blob() == NULL, "only once");

   set_blob(BufferBlob::create(_name, code_size + (align+slop) * (SECT_LIMIT+1)));

   if (blob() == NULL) {

     // The assembler constructor will throw a fatal on an empty CodeBuffer.

     return;  // caller must test this

   }

   // Set up various pointers into the blob.

   initialize(_total_start, _total_size);

   assert((uintptr_t)code_begin() % CodeEntryAlignment == 0, "instruction start not code entry aligned");

   pd_initialize();

   if (locs_size != 0) {

     _insts.initialize_locs(locs_size / sizeof(relocInfo));

   }

   assert(verify_section_allocation(), "initial use of blob is OK");

 }

 CodeBuffer::~CodeBuffer() {

   // If we allocate our code buffer from the CodeCache

   // via a BufferBlob, and it's not permanent, then

   // free the BufferBlob.

   // The rest of the memory will be freed when the ResourceObj

   // is released.

   assert(verify_section_allocation(), "final storage configuration still OK");

   for (CodeBuffer* cb = this; cb != NULL; cb = cb->before_expand()) {

     // Previous incarnations of this buffer are held live, so that internal

     // addresses constructed before expansions will not be confused.

     cb->free_blob();

   }

   // free any overflow storage

   delete _overflow_arena;

 #ifdef ASSERT

   // Save allocation type to execute assert in ~ResourceObj()

   // which is called after this destructor.

   ResourceObj::allocation_type at = _default_oop_recorder.get_allocation_type();

   Copy::fill_to_bytes(this, sizeof(*this), badResourceValue);

   ResourceObj::set_allocation_type((address)(&_default_oop_recorder), at);

 #endif

 }

 void CodeBuffer::initialize_oop_recorder(OopRecorder* r) {

   assert(_oop_recorder == &_default_oop_recorder && _default_oop_recorder.is_unused(), "do this once");

   DEBUG_ONLY(_default_oop_recorder.oop_size());  // force unused OR to be frozen

   _oop_recorder = r;

 }

 void CodeBuffer::initialize_section_size(CodeSection* cs, csize_t size) {

   assert(cs != &_insts, "insts is the memory provider, not the consumer");

 #ifdef ASSERT

   for (int n = (int)SECT_INSTS+1; n < (int)SECT_LIMIT; n++) {

     CodeSection* prevCS = code_section(n);

     if (prevCS == cs)  break;

     assert(!prevCS->is_allocated(), "section allocation must be in reverse order");

   }

 #endif

   csize_t slop = CodeSection::end_slop();  // margin between sections

   int align = cs->alignment();

   assert(is_power_of_2(align), "sanity");

   address start  = _insts._start;

   address limit  = _insts._limit;

   address middle = limit - size;

   middle -= (intptr_t)middle & (align-1);  // align the division point downward

   guarantee(middle - slop > start, "need enough space to divide up");

   _insts._limit = middle - slop;  // subtract desired space, plus slop

   cs->initialize(middle, limit - middle);

   assert(cs->start() == middle, "sanity");

   assert(cs->limit() == limit,  "sanity");

   // give it some relocations to start with, if the main section has them

   if (_insts.has_locs())  cs->initialize_locs(1);

 }

 void CodeBuffer::freeze_section(CodeSection* cs) {

   CodeSection* next_cs = (cs == consts())? NULL: code_section(cs->index()+1);

   csize_t frozen_size = cs->size();

   if (next_cs != NULL) {

     frozen_size = next_cs->align_at_start(frozen_size);

   }

   address old_limit = cs->limit();

   address new_limit = cs->start() + frozen_size;

   relocInfo* old_locs_limit = cs->locs_limit();

   relocInfo* new_locs_limit = cs->locs_end();

   // Patch the limits.

   cs->_limit = new_limit;

   cs->_locs_limit = new_locs_limit;

   cs->_frozen = true;

   if (!next_cs->is_allocated() && !next_cs->is_frozen()) {

     // Give remaining buffer space to the following section.

     next_cs->initialize(new_limit, old_limit - new_limit);

     next_cs->initialize_shared_locs(new_locs_limit,

                                     old_locs_limit - new_locs_limit);

   }

 }

 void CodeBuffer::set_blob(BufferBlob* blob) {

   _blob = blob;

   if (blob != NULL) {

     address start = blob->instructions_begin();

     address end   = blob->instructions_end();

     // Round up the starting address.

     int align = _insts.alignment();

     start += (-(intptr_t)start) & (align-1);

     _total_start = start;

     _total_size  = end - start;

   } else {

     #ifdef ASSERT

     // Clean out dangling pointers.

     _total_start    = badAddress;

     _insts._start   = _insts._end   = badAddress;

     _stubs._start   = _stubs._end   = badAddress;

     _consts._start  = _consts._end  = badAddress;

     #endif //ASSERT

   }

 }

 void CodeBuffer::free_blob() {

   if (_blob != NULL) {

     BufferBlob::free(_blob);

     set_blob(NULL);

   }

 }

 const char* CodeBuffer::code_section_name(int n) {

 #ifdef PRODUCT

   return NULL;

 #else //PRODUCT

   switch (n) {

   case SECT_INSTS:             return "insts";

   case SECT_STUBS:             return "stubs";

   case SECT_CONSTS:            return "consts";

   default:                     return NULL;

   }

 #endif //PRODUCT

 }

 int CodeBuffer::section_index_of(address addr) const {

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     const CodeSection* cs = code_section(n);

     if (cs->allocates(addr))  return n;

   }

   return SECT_NONE;

 }

 int CodeBuffer::locator(address addr) const {

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     const CodeSection* cs = code_section(n);

     if (cs->allocates(addr)) {

       return locator(addr - cs->start(), n);

     }

   }

   return -1;

 }

 address CodeBuffer::locator_address(int locator) const {

   if (locator < 0)  return NULL;

   address start = code_section(locator_sect(locator))->start();

   return start + locator_pos(locator);

 }

 address CodeBuffer::decode_begin() {

   address begin = _insts.start();

   if (_decode_begin != NULL && _decode_begin > begin)

     begin = _decode_begin;

   return begin;

 }

 GrowableArray<int>* CodeBuffer::create_patch_overflow() {

   if (_overflow_arena == NULL) {

     _overflow_arena = new Arena();

   }

   return new (_overflow_arena) GrowableArray<int>(_overflow_arena, 8, 0, 0);

 }

 // Helper function for managing labels and their target addresses.

 // Returns a sensible address, and if it is not the label's final

 // address, notes the dependency (at 'branch_pc') on the label.

 address CodeSection::target(Label& L, address branch_pc) {

   if (L.is_bound()) {

     int loc = L.loc();

     if (index() == CodeBuffer::locator_sect(loc)) {

       return start() + CodeBuffer::locator_pos(loc);

     } else {

       return outer()->locator_address(loc);

     }

   } else {

     assert(allocates2(branch_pc), "sanity");

     address base = start();

     int patch_loc = CodeBuffer::locator(branch_pc - base, index());

     L.add_patch_at(outer(), patch_loc);

     // Need to return a pc, doesn't matter what it is since it will be

     // replaced during resolution later.

     // Don't return NULL or badAddress, since branches shouldn't overflow.

     // Don't return base either because that could overflow displacements

     // for shorter branches.  It will get checked when bound.

     return branch_pc;

   }

 }

 void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {

   Relocation* reloc = spec.reloc();

   relocInfo::relocType rtype = (relocInfo::relocType) reloc->type();

   if (rtype == relocInfo::none)  return;

   // The assertion below has been adjusted, to also work for

   // relocation for fixup.  Sometimes we want to put relocation

   // information for the next instruction, since it will be patched

   // with a call.

   assert(start() <= at && at <= end()+1,

          "cannot relocate data outside code boundaries");

   if (!has_locs()) {

     // no space for relocation information provided => code cannot be

     // relocated.  Make sure that relocate is only called with rtypes

     // that can be ignored for this kind of code.

     assert(rtype == relocInfo::none              ||

            rtype == relocInfo::runtime_call_type ||

            rtype == relocInfo::internal_word_type||

            rtype == relocInfo::section_word_type ||

            rtype == relocInfo::external_word_type,

            "code needs relocation information");

     // leave behind an indication that we attempted a relocation

     DEBUG_ONLY(_locs_start = _locs_limit = (relocInfo*)badAddress);

     return;

   }

   // Advance the point, noting the offset we'll have to record.

   csize_t offset = at - locs_point();

   set_locs_point(at);

   // Test for a couple of overflow conditions; maybe expand the buffer.

   relocInfo* end = locs_end();

   relocInfo* req = end + relocInfo::length_limit;

   // Check for (potential) overflow

   if (req >= locs_limit() || offset >= relocInfo::offset_limit()) {

     req += (uint)offset / (uint)relocInfo::offset_limit();

     if (req >= locs_limit()) {

       // Allocate or reallocate.

       expand_locs(locs_count() + (req - end));

       // reload pointer

       end = locs_end();

     }

   }

   // If the offset is giant, emit filler relocs, of type 'none', but

   // each carrying the largest possible offset, to advance the locs_point.

   while (offset >= relocInfo::offset_limit()) {

     assert(end < locs_limit(), "adjust previous paragraph of code");

     *end++ = filler_relocInfo();

     offset -= filler_relocInfo().addr_offset();

   }

   // If it's a simple reloc with no data, we'll just write (rtype | offset).

   (*end) = relocInfo(rtype, offset, format);

   // If it has data, insert the prefix, as (data_prefix_tag | data1), data2.

   end->initialize(this, reloc);

 }

 void CodeSection::initialize_locs(int locs_capacity) {

   assert(_locs_start == NULL, "only one locs init step, please");

   // Apply a priori lower limits to relocation size:

   csize_t min_locs = MAX2(size() / 16, (csize_t)4);

   if (locs_capacity < min_locs)  locs_capacity = min_locs;

   relocInfo* locs_start = NEW_RESOURCE_ARRAY(relocInfo, locs_capacity);

   _locs_start    = locs_start;

   _locs_end      = locs_start;

   _locs_limit    = locs_start + locs_capacity;

   _locs_own      = true;

 }

 void CodeSection::initialize_shared_locs(relocInfo* buf, int length) {

   assert(_locs_start == NULL, "do this before locs are allocated");

   // Internal invariant:  locs buf must be fully aligned.

   // See copy_relocations_to() below.

   while ((uintptr_t)buf % HeapWordSize != 0 && length > 0) {

     ++buf; --length;

   }

   if (length > 0) {

     _locs_start = buf;

     _locs_end   = buf;

     _locs_limit = buf + length;

     _locs_own   = false;

   }

 }

 void CodeSection::initialize_locs_from(const CodeSection* source_cs) {

   int lcount = source_cs->locs_count();

   if (lcount != 0) {

     initialize_shared_locs(source_cs->locs_start(), lcount);

     _locs_end = _locs_limit = _locs_start + lcount;

     assert(is_allocated(), "must have copied code already");

     set_locs_point(start() + source_cs->locs_point_off());

   }

   assert(this->locs_count() == source_cs->locs_count(), "sanity");

 }

 void CodeSection::expand_locs(int new_capacity) {

   if (_locs_start == NULL) {

     initialize_locs(new_capacity);

     return;

   } else {

     int old_count    = locs_count();

     int old_capacity = locs_capacity();

     if (new_capacity < old_capacity * 2)

       new_capacity = old_capacity * 2;

     relocInfo* locs_start;

     if (_locs_own) {

       locs_start = REALLOC_RESOURCE_ARRAY(relocInfo, _locs_start, old_capacity, new_capacity);

     } else {

       locs_start = NEW_RESOURCE_ARRAY(relocInfo, new_capacity);

       Copy::conjoint_jbytes(_locs_start, locs_start, old_capacity * sizeof(relocInfo));

       _locs_own = true;

     }

     _locs_start    = locs_start;

     _locs_end      = locs_start + old_count;

     _locs_limit    = locs_start + new_capacity;

   }

 }

 /// Support for emitting the code to its final location.

 /// The pattern is the same for all functions.

 /// We iterate over all the sections, padding each to alignment.

 csize_t CodeBuffer::total_code_size() const {

   csize_t code_size_so_far = 0;

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     const CodeSection* cs = code_section(n);

     if (cs->is_empty())  continue;  // skip trivial section

     code_size_so_far = cs->align_at_start(code_size_so_far);

     code_size_so_far += cs->size();

   }

   return code_size_so_far;

 }

 void CodeBuffer::compute_final_layout(CodeBuffer* dest) const {

   address buf = dest->_total_start;

   csize_t buf_offset = 0;

   assert(dest->_total_size >= total_code_size(), "must be big enough");

   {

     // not sure why this is here, but why not...

     int alignSize = MAX2((intx) sizeof(jdouble), CodeEntryAlignment);

     assert( (dest->_total_start - _insts.start()) % alignSize == 0, "copy must preserve alignment");

   }

   const CodeSection* prev_cs      = NULL;

   CodeSection*       prev_dest_cs = NULL;

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     // figure compact layout of each section

     const CodeSection* cs = code_section(n);

     address cstart = cs->start();

     address cend   = cs->end();

     csize_t csize  = cend - cstart;

     CodeSection* dest_cs = dest->code_section(n);

     if (!cs->is_empty()) {

       // Compute initial padding; assign it to the previous non-empty guy.

       // Cf. figure_expanded_capacities.

       csize_t padding = cs->align_at_start(buf_offset) - buf_offset;

       if (padding != 0) {

         buf_offset += padding;

         assert(prev_dest_cs != NULL, "sanity");

         prev_dest_cs->_limit += padding;

       }

       #ifdef ASSERT

       if (prev_cs != NULL && prev_cs->is_frozen() && n < SECT_CONSTS) {

         // Make sure the ends still match up.

         // This is important because a branch in a frozen section

         // might target code in a following section, via a Label,

         // and without a relocation record.  See Label::patch_instructions.

         address dest_start = buf+buf_offset;

         csize_t start2start = cs->start() - prev_cs->start();

         csize_t dest_start2start = dest_start - prev_dest_cs->start();

         assert(start2start == dest_start2start, "cannot stretch frozen sect");

       }

       #endif //ASSERT

       prev_dest_cs = dest_cs;

       prev_cs      = cs;

     }

     debug_only(dest_cs->_start = NULL);  // defeat double-initialization assert

     dest_cs->initialize(buf+buf_offset, csize);

     dest_cs->set_end(buf+buf_offset+csize);

     assert(dest_cs->is_allocated(), "must always be allocated");

     assert(cs->is_empty() == dest_cs->is_empty(), "sanity");

     buf_offset += csize;

   }

   // Done calculating sections; did it come out to the right end?

   assert(buf_offset == total_code_size(), "sanity");

   assert(dest->verify_section_allocation(), "final configuration works");

 }

 csize_t CodeBuffer::total_offset_of(address addr) const {

   csize_t code_size_so_far = 0;

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     const CodeSection* cs = code_section(n);

     if (!cs->is_empty()) {

       code_size_so_far = cs->align_at_start(code_size_so_far);

     }

     if (cs->contains2(addr)) {

       return code_size_so_far + (addr - cs->start());

     }

     code_size_so_far += cs->size();

   }

 #ifndef PRODUCT

   tty->print_cr("Dangling address " PTR_FORMAT " in:", addr);

   ((CodeBuffer*)this)->print();

 #endif

   ShouldNotReachHere();

   return -1;

 }

 csize_t CodeBuffer::total_relocation_size() const {

   csize_t lsize = copy_relocations_to(NULL);  // dry run only

   csize_t csize = total_code_size();

   csize_t total = RelocIterator::locs_and_index_size(csize, lsize);

   return (csize_t) align_size_up(total, HeapWordSize);

 }

 csize_t CodeBuffer::copy_relocations_to(CodeBlob* dest) const {

   address buf = NULL;

   csize_t buf_offset = 0;

   csize_t buf_limit = 0;

   if (dest != NULL) {

     buf = (address)dest->relocation_begin();

     buf_limit = (address)dest->relocation_end() - buf;

     assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");

     assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");

   }

   // if dest == NULL, this is just the sizing pass

   csize_t code_end_so_far = 0;

   csize_t code_point_so_far = 0;

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     // pull relocs out of each section

     const CodeSection* cs = code_section(n);

     assert(!(cs->is_empty() && cs->locs_count() > 0), "sanity");

     if (cs->is_empty())  continue;  // skip trivial section

     relocInfo* lstart = cs->locs_start();

     relocInfo* lend   = cs->locs_end();

     csize_t    lsize  = (csize_t)( (address)lend - (address)lstart );

     csize_t    csize  = cs->size();

     code_end_so_far = cs->align_at_start(code_end_so_far);

     if (lsize > 0) {

       // Figure out how to advance the combined relocation point

       // first to the beginning of this section.

       // We'll insert one or more filler relocs to span that gap.

       // (Don't bother to improve this by editing the first reloc's offset.)

       csize_t new_code_point = code_end_so_far;

       for (csize_t jump;

            code_point_so_far < new_code_point;

            code_point_so_far += jump) {

         jump = new_code_point - code_point_so_far;

         relocInfo filler = filler_relocInfo();

         if (jump >= filler.addr_offset()) {

           jump = filler.addr_offset();

         } else {  // else shrink the filler to fit

           filler = relocInfo(relocInfo::none, jump);

         }

         if (buf != NULL) {

           assert(buf_offset + (csize_t)sizeof(filler) <= buf_limit, "filler in bounds");

           *(relocInfo*)(buf+buf_offset) = filler;

         }

         buf_offset += sizeof(filler);

       }

       // Update code point and end to skip past this section:

       csize_t last_code_point = code_end_so_far + cs->locs_point_off();

       assert(code_point_so_far <= last_code_point, "sanity");

       code_point_so_far = last_code_point; // advance past this guy's relocs

     }

     code_end_so_far += csize;  // advance past this guy's instructions too

     // Done with filler; emit the real relocations:

     if (buf != NULL && lsize != 0) {

       assert(buf_offset + lsize <= buf_limit, "target in bounds");

       assert((uintptr_t)lstart % HeapWordSize == 0, "sane start");

       if (buf_offset % HeapWordSize == 0) {

         // Use wordwise copies if possible:

         Copy::disjoint_words((HeapWord*)lstart,

                              (HeapWord*)(buf+buf_offset),

                              (lsize + HeapWordSize-1) / HeapWordSize);

       } else {

         Copy::conjoint_jbytes(lstart, buf+buf_offset, lsize);

       }

     }

     buf_offset += lsize;

   }

   // Align end of relocation info in target.

   while (buf_offset % HeapWordSize != 0) {

     if (buf != NULL) {

       relocInfo padding = relocInfo(relocInfo::none, 0);

       assert(buf_offset + (csize_t)sizeof(padding) <= buf_limit, "padding in bounds");

       *(relocInfo*)(buf+buf_offset) = padding;

     }

     buf_offset += sizeof(relocInfo);

   }

   assert(code_end_so_far == total_code_size(), "sanity");

   // Account for index:

   if (buf != NULL) {

     RelocIterator::create_index(dest->relocation_begin(),

                                 buf_offset / sizeof(relocInfo),

                                 dest->relocation_end());

   }

   return buf_offset;

 }

 void CodeBuffer::copy_code_to(CodeBlob* dest_blob) {

 #ifndef PRODUCT

   if (PrintNMethods && (WizardMode || Verbose)) {

     tty->print("done with CodeBuffer:");

     ((CodeBuffer*)this)->print();

   }

 #endif //PRODUCT

   CodeBuffer dest(dest_blob->instructions_begin(),

                   dest_blob->instructions_size());

   assert(dest_blob->instructions_size() >= total_code_size(), "good sizing");

   this->compute_final_layout(&dest);

   relocate_code_to(&dest);

   // transfer comments from buffer to blob

   dest_blob->set_comments(_comments);

   // Done moving code bytes; were they the right size?

   assert(round_to(dest.total_code_size(), oopSize) == dest_blob->instructions_size(), "sanity");

   // Flush generated code

   ICache::invalidate_range(dest_blob->instructions_begin(),

                            dest_blob->instructions_size());

 }

 // Move all my code into another code buffer.

 // Consult applicable relocs to repair embedded addresses.

 void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {

   DEBUG_ONLY(address dest_end = dest->_total_start + dest->_total_size);

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     // pull code out of each section

     const CodeSection* cs = code_section(n);

     if (cs->is_empty())  continue;  // skip trivial section

     CodeSection* dest_cs = dest->code_section(n);

     assert(cs->size() == dest_cs->size(), "sanity");

     csize_t usize = dest_cs->size();

     csize_t wsize = align_size_up(usize, HeapWordSize);

     assert(dest_cs->start() + wsize <= dest_end, "no overflow");

     // Copy the code as aligned machine words.

     // This may also include an uninitialized partial word at the end.

     Copy::disjoint_words((HeapWord*)cs->start(),

                          (HeapWord*)dest_cs->start(),

                          wsize / HeapWordSize);

     if (dest->blob() == NULL) {

       // Destination is a final resting place, not just another buffer.

       // Normalize uninitialized bytes in the final padding.

       Copy::fill_to_bytes(dest_cs->end(), dest_cs->remaining(),

                           Assembler::code_fill_byte());

     }

     assert(cs->locs_start() != (relocInfo*)badAddress,

            "this section carries no reloc storage, but reloc was attempted");

     // Make the new code copy use the old copy's relocations:

     dest_cs->initialize_locs_from(cs);

     { // Repair the pc relative information in the code after the move

       RelocIterator iter(dest_cs);

       while (iter.next()) {

         iter.reloc()->fix_relocation_after_move(this, dest);

       }

     }

   }

 }

 csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,

                                                csize_t amount,

                                                csize_t* new_capacity) {

   csize_t new_total_cap = 0;

   int prev_n = -1;

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     const CodeSection* sect = code_section(n);

     if (!sect->is_empty()) {

       // Compute initial padding; assign it to the previous non-empty guy.

       // Cf. compute_final_layout.

       csize_t padding = sect->align_at_start(new_total_cap) - new_total_cap;

       if (padding != 0) {

         new_total_cap += padding;

         assert(prev_n >= 0, "sanity");

         new_capacity[prev_n] += padding;

       }

       prev_n = n;

     }

     csize_t exp = sect->size();  // 100% increase

     if ((uint)exp < 4*K)  exp = 4*K;       // minimum initial increase

     if (sect == which_cs) {

       if (exp < amount)  exp = amount;

       if (StressCodeBuffers)  exp = amount;  // expand only slightly

     } else if (n == SECT_INSTS) {

       // scale down inst increases to a more modest 25%

       exp = 4*K + ((exp - 4*K) >> 2);

       if (StressCodeBuffers)  exp = amount / 2;  // expand only slightly

     } else if (sect->is_empty()) {

       // do not grow an empty secondary section

       exp = 0;

     }

     // Allow for inter-section slop:

     exp += CodeSection::end_slop();

     csize_t new_cap = sect->size() + exp;

     if (new_cap < sect->capacity()) {

       // No need to expand after all.

       new_cap = sect->capacity();

     }

     new_capacity[n] = new_cap;

     new_total_cap += new_cap;

   }

   return new_total_cap;

 }

 void CodeBuffer::expand(CodeSection* which_cs, csize_t amount) {

 #ifndef PRODUCT

   if (PrintNMethods && (WizardMode || Verbose)) {

     tty->print("expanding CodeBuffer:");

     this->print();

   }

   if (StressCodeBuffers && blob() != NULL) {

     static int expand_count = 0;

     if (expand_count >= 0)  expand_count += 1;

     if (expand_count > 100 && is_power_of_2(expand_count)) {

       tty->print_cr("StressCodeBuffers: have expanded %d times", expand_count);

       // simulate an occasional allocation failure:

       free_blob();

     }

   }

 #endif //PRODUCT

   // Resizing must be allowed

   {

     if (blob() == NULL)  return;  // caller must check for blob == NULL

     for (int n = 0; n < (int)SECT_LIMIT; n++) {

       guarantee(!code_section(n)->is_frozen(), "resizing not allowed when frozen");

     }

   }

   // Figure new capacity for each section.

   csize_t new_capacity[SECT_LIMIT];

   csize_t new_total_cap

     = figure_expanded_capacities(which_cs, amount, new_capacity);

   // Create a new (temporary) code buffer to hold all the new data

   CodeBuffer cb(name(), new_total_cap, 0);

   if (cb.blob() == NULL) {

     // Failed to allocate in code cache.

     free_blob();

     return;

   }

   // Create an old code buffer to remember which addresses used to go where.

   // This will be useful when we do final assembly into the code cache,

   // because we will need to know how to warp any internal address that

   // has been created at any time in this CodeBuffer's past.

   CodeBuffer* bxp = new CodeBuffer(_total_start, _total_size);

   bxp->take_over_code_from(this);  // remember the old undersized blob

   DEBUG_ONLY(this->_blob = NULL);  // silence a later assert

   bxp->_before_expand = this->_before_expand;

   this->_before_expand = bxp;

   // Give each section its required (expanded) capacity.

   for (int n = (int)SECT_LIMIT-1; n >= SECT_INSTS; n--) {

     CodeSection* cb_sect   = cb.code_section(n);

     CodeSection* this_sect = code_section(n);

     if (new_capacity[n] == 0)  continue;  // already nulled out

     if (n > SECT_INSTS) {

       cb.initialize_section_size(cb_sect, new_capacity[n]);

     }

     assert(cb_sect->capacity() >= new_capacity[n], "big enough");

     address cb_start = cb_sect->start();

     cb_sect->set_end(cb_start + this_sect->size());

     if (this_sect->mark() == NULL) {

       cb_sect->clear_mark();

     } else {

       cb_sect->set_mark(cb_start + this_sect->mark_off());

     }

   }

   // Move all the code and relocations to the new blob:

   relocate_code_to(&cb);

   // Copy the temporary code buffer into the current code buffer.

   // Basically, do {*this = cb}, except for some control information.

   this->take_over_code_from(&cb);

   cb.set_blob(NULL);

   // Zap the old code buffer contents, to avoid mistakenly using them.

   debug_only(Copy::fill_to_bytes(bxp->_total_start, bxp->_total_size,

                                  badCodeHeapFreeVal));

   _decode_begin = NULL;  // sanity

   // Make certain that the new sections are all snugly inside the new blob.

   assert(verify_section_allocation(), "expanded allocation is ship-shape");

 #ifndef PRODUCT

   if (PrintNMethods && (WizardMode || Verbose)) {

     tty->print("expanded CodeBuffer:");

     this->print();

   }

 #endif //PRODUCT

 }

 void CodeBuffer::take_over_code_from(CodeBuffer* cb) {

   // Must already have disposed of the old blob somehow.

   assert(blob() == NULL, "must be empty");

 #ifdef ASSERT

 #endif

   // Take the new blob away from cb.

   set_blob(cb->blob());

   // Take over all the section pointers.

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     CodeSection* cb_sect   = cb->code_section(n);

     CodeSection* this_sect = code_section(n);

     this_sect->take_over_code_from(cb_sect);

   }

   _overflow_arena = cb->_overflow_arena;

   // Make sure the old cb won't try to use it or free it.

   DEBUG_ONLY(cb->_blob = (BufferBlob*)badAddress);

 }

 #ifdef ASSERT

 bool CodeBuffer::verify_section_allocation() {

   address tstart = _total_start;

   if (tstart == badAddress)  return true;  // smashed by set_blob(NULL)

   address tend   = tstart + _total_size;

   if (_blob != NULL) {

     assert(tstart >= _blob->instructions_begin(), "sanity");

     assert(tend   <= _blob->instructions_end(),   "sanity");

   }

   address tcheck = tstart;  // advancing pointer to verify disjointness

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     CodeSection* sect = code_section(n);

     if (!sect->is_allocated())  continue;

     assert(sect->start() >= tcheck, "sanity");

     tcheck = sect->start();

     assert((intptr_t)tcheck % sect->alignment() == 0

            || sect->is_empty() || _blob == NULL,

            "start is aligned");

     assert(sect->end()   >= tcheck, "sanity");

     assert(sect->end()   <= tend,   "sanity");

   }

   return true;

 }

 #endif //ASSERT

 #ifndef PRODUCT

 void CodeSection::dump() {

   address ptr = start();

   for (csize_t step; ptr < end(); ptr += step) {

     step = end() - ptr;

     if (step > jintSize * 4)  step = jintSize * 4;

     tty->print(PTR_FORMAT ": ", ptr);

     while (step > 0) {

       tty->print(" " PTR32_FORMAT, *(jint*)ptr);

       ptr += jintSize;

     }

     tty->cr();

   }

 }

 void CodeSection::decode() {

   Disassembler::decode(start(), end());

 }

 void CodeBuffer::block_comment(intptr_t offset, const char * comment) {

   _comments.add_comment(offset, comment);

 }

 class CodeComment: public CHeapObj {

  private:

   friend class CodeComments;

   intptr_t     _offset;

   const char * _comment;

   CodeComment* _next;

   ~CodeComment() {

     assert(_next == NULL, "wrong interface for freeing list");

     os::free((void*)_comment);

   }

  public:

   CodeComment(intptr_t offset, const char * comment) {

     _offset = offset;

     _comment = os::strdup(comment);

     _next = NULL;

   }

   intptr_t     offset()  const { return _offset;  }

   const char * comment() const { return _comment; }

   CodeComment* next()          { return _next; }

   void set_next(CodeComment* next) { _next = next; }

   CodeComment* find(intptr_t offset) {

     CodeComment* a = this;

     while (a != NULL && a->_offset != offset) {

       a = a->_next;

     }

     return a;

   }

 };

 void CodeComments::add_comment(intptr_t offset, const char * comment) {

   CodeComment* c = new CodeComment(offset, comment);

   CodeComment* insert = NULL;

   if (_comments != NULL) {

     CodeComment* c = _comments->find(offset);

     insert = c;

     while (c && c->offset() == offset) {

       insert = c;

       c = c->next();

     }

   }

   if (insert) {

     // insert after comments with same offset

     c->set_next(insert->next());

     insert->set_next(c);

   } else {

     c->set_next(_comments);

     _comments = c;

   }

 }

 void CodeComments::assign(CodeComments& other) {

   assert(_comments == NULL, "don't overwrite old value");

   _comments = other._comments;

 }

 void CodeComments::print_block_comment(outputStream* stream, intptr_t offset) {

   if (_comments != NULL) {

     CodeComment* c = _comments->find(offset);

     while (c && c->offset() == offset) {

       stream->bol();

       stream->print("  ;; ");

       stream->print_cr(c->comment());

       c = c->next();

     }

   }

 }

 void CodeComments::free() {

   CodeComment* n = _comments;

   while (n) {

     // unlink the node from the list saving a pointer to the next

     CodeComment* p = n->_next;

     n->_next = NULL;

     delete n;

     n = p;

   }

   _comments = NULL;

 }

 void CodeBuffer::decode() {

   Disassembler::decode(decode_begin(), code_end());

   _decode_begin = code_end();

 }

 void CodeBuffer::skip_decode() {

   _decode_begin = code_end();

 }

 void CodeBuffer::decode_all() {

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     // dump contents of each section

     CodeSection* cs = code_section(n);

     tty->print_cr("! %s:", code_section_name(n));

     if (cs != consts())

       cs->decode();

     else

       cs->dump();

   }

 }

 void CodeSection::print(const char* name) {

   csize_t locs_size = locs_end() - locs_start();

   tty->print_cr(" %7s.code = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d)%s",

                 name, start(), end(), limit(), size(), capacity(),

                 is_frozen()? " [frozen]": "");

   tty->print_cr(" %7s.locs = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d) point=%d",

                 name, locs_start(), locs_end(), locs_limit(), locs_size, locs_capacity(), locs_point_off());

   if (PrintRelocations) {

     RelocIterator iter(this);

     iter.print();

   }

 }

 void CodeBuffer::print() {

   if (this == NULL) {

     tty->print_cr("NULL CodeBuffer pointer");

     return;

   }

   tty->print_cr("CodeBuffer:");

   for (int n = 0; n < (int)SECT_LIMIT; n++) {

     // print each section

     CodeSection* cs = code_section(n);

     cs->print(code_section_name(n));

   }

 }

 #endif // PRODUCT