src/hotspot/share/asm/codeBuffer.cpp
changeset 47216 71c04702a3d5
parent 46625 edefffab74e2
child 49594 898ef81cbc0e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/asm/codeBuffer.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1252 @@
+/*
+ * Copyright (c) 1997, 2016, 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 "precompiled.hpp"
+#include "asm/codeBuffer.hpp"
+#include "compiler/disassembler.hpp"
+#include "gc/shared/gcLocker.hpp"
+#include "oops/methodData.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/icache.hpp"
+#include "utilities/align.hpp"
+#include "utilities/copy.hpp"
+#include "utilities/xmlstream.hpp"
+
+// 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.
+// Important: The code_start must be taken exactly, and not realigned.
+CodeBuffer::CodeBuffer(CodeBlob* blob) {
+  initialize_misc("static buffer");
+  initialize(blob->content_begin(), blob->content_size());
+  verify_section_allocation();
+}
+
+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)insts_begin() % CodeEntryAlignment == 0, "instruction start not code entry aligned");
+
+  pd_initialize();
+
+  if (locs_size != 0) {
+    _insts.initialize_locs(locs_size / sizeof(relocInfo));
+  }
+
+  verify_section_allocation();
+}
+
+
+CodeBuffer::~CodeBuffer() {
+  verify_section_allocation();
+
+  // 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.
+  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;
+
+  // Claim is that stack allocation ensures resources are cleaned up.
+  // This is resource clean up, let's hope that all were properly copied out.
+  free_strings();
+
+#ifdef ASSERT
+  // Save allocation type to execute assert in ~ResourceObj()
+  // which is called after this destructor.
+  assert(_default_oop_recorder.allocated_on_stack(), "should be embedded object");
+  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.freeze());  // 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");
+  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->content_begin();
+    address end   = blob->content_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;
+    _consts._start  = _consts._end  = badAddress;
+    _insts._start   = _insts._end   = badAddress;
+    _stubs._start   = _stubs._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_CONSTS:            return "consts";
+  case SECT_INSTS:             return "insts";
+  case SECT_STUBS:             return "stubs";
+  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);
+}
+
+bool CodeBuffer::is_backward_branch(Label& L) {
+  return L.is_bound() && insts_end() <= locator_address(L.loc());
+}
+
+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 (mtCode) Arena(mtCode);
+  }
+  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, relocInfo::relocType rtype, int format, jint method_index) {
+  RelocationHolder rh;
+  switch (rtype) {
+    case relocInfo::none: return;
+    case relocInfo::opt_virtual_call_type: {
+      rh = opt_virtual_call_Relocation::spec(method_index);
+      break;
+    }
+    case relocInfo::static_call_type: {
+      rh = static_call_Relocation::spec(method_index);
+      break;
+    }
+    case relocInfo::virtual_call_type: {
+      assert(method_index == 0, "resolved method overriding is not supported");
+      rh = Relocation::spec_simple(rtype);
+      break;
+    }
+    default: {
+      rh = Relocation::spec_simple(rtype);
+      break;
+    }
+  }
+  relocate(at, rh, format);
+}
+
+void CodeSection::relocate(address at, RelocationHolder const& spec, int format) {
+  // Do not relocate in scratch buffers.
+  if (scratch_emit()) { return; }
+  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_content_size() const {
+  csize_t 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
+    size_so_far = cs->align_at_start(size_so_far);
+    size_so_far += cs->size();
+  }
+  return 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_content_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 = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
+    // figure compact layout of each section
+    const CodeSection* cs = code_section(n);
+    csize_t csize = cs->size();
+
+    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_LIMIT - 1)) {
+        // 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_content_size(), "sanity");
+  dest->verify_section_allocation();
+}
+
+// Append an oop reference that keeps the class alive.
+static void append_oop_references(GrowableArray<oop>* oops, Klass* k) {
+  oop cl = k->klass_holder();
+  if (cl != NULL && !oops->contains(cl)) {
+    oops->append(cl);
+  }
+}
+
+void CodeBuffer::finalize_oop_references(const methodHandle& mh) {
+  NoSafepointVerifier nsv;
+
+  GrowableArray<oop> oops;
+
+  // Make sure that immediate metadata records something in the OopRecorder
+  for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
+    // pull code out of each section
+    CodeSection* cs = code_section(n);
+    if (cs->is_empty())  continue;  // skip trivial section
+    RelocIterator iter(cs);
+    while (iter.next()) {
+      if (iter.type() == relocInfo::metadata_type) {
+        metadata_Relocation* md = iter.metadata_reloc();
+        if (md->metadata_is_immediate()) {
+          Metadata* m = md->metadata_value();
+          if (oop_recorder()->is_real(m)) {
+            if (m->is_methodData()) {
+              m = ((MethodData*)m)->method();
+            }
+            if (m->is_method()) {
+              m = ((Method*)m)->method_holder();
+            }
+            if (m->is_klass()) {
+              append_oop_references(&oops, (Klass*)m);
+            } else {
+              // XXX This will currently occur for MDO which don't
+              // have a backpointer.  This has to be fixed later.
+              m->print();
+              ShouldNotReachHere();
+            }
+          }
+        }
+      }
+    }
+  }
+
+  if (!oop_recorder()->is_unused()) {
+    for (int i = 0; i < oop_recorder()->metadata_count(); i++) {
+      Metadata* m = oop_recorder()->metadata_at(i);
+      if (oop_recorder()->is_real(m)) {
+        if (m->is_methodData()) {
+          m = ((MethodData*)m)->method();
+        }
+        if (m->is_method()) {
+          m = ((Method*)m)->method_holder();
+        }
+        if (m->is_klass()) {
+          append_oop_references(&oops, (Klass*)m);
+        } else {
+          m->print();
+          ShouldNotReachHere();
+        }
+      }
+    }
+
+  }
+
+  // Add the class loader of Method* for the nmethod itself
+  append_oop_references(&oops, mh->method_holder());
+
+  // Add any oops that we've found
+  Thread* thread = Thread::current();
+  for (int i = 0; i < oops.length(); i++) {
+    oop_recorder()->find_index((jobject)thread->handle_area()->allocate_handle(oops.at(i)));
+  }
+}
+
+
+
+csize_t CodeBuffer::total_offset_of(const CodeSection* cs) const {
+  csize_t size_so_far = 0;
+  for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
+    const CodeSection* cur_cs = code_section(n);
+    if (!cur_cs->is_empty()) {
+      size_so_far = cur_cs->align_at_start(size_so_far);
+    }
+    if (cur_cs->index() == cs->index()) {
+      return size_so_far;
+    }
+    size_so_far += cur_cs->size();
+  }
+  ShouldNotReachHere();
+  return -1;
+}
+
+csize_t CodeBuffer::total_relocation_size() const {
+  csize_t total = copy_relocations_to(NULL);  // dry run only
+  return (csize_t) align_up(total, HeapWordSize);
+}
+
+csize_t CodeBuffer::copy_relocations_to(address buf, csize_t buf_limit, bool only_inst) const {
+  csize_t buf_offset = 0;
+  csize_t code_end_so_far = 0;
+  csize_t code_point_so_far = 0;
+
+  assert((uintptr_t)buf % HeapWordSize == 0, "buf must be fully aligned");
+  assert(buf_limit % HeapWordSize == 0, "buf must be evenly sized");
+
+  for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
+    if (only_inst && (n != (int)SECT_INSTS)) {
+      // Need only relocation info for code.
+      continue;
+    }
+    // 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(only_inst || code_end_so_far == total_content_size(), "sanity");
+
+  return buf_offset;
+}
+
+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;
+  }
+  // if dest == NULL, this is just the sizing pass
+  //
+  buf_offset = copy_relocations_to(buf, buf_limit, false);
+
+  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);
+  assert(dest_blob->content_size() >= total_content_size(), "good sizing");
+  this->compute_final_layout(&dest);
+
+  // Set beginning of constant table before relocating.
+  dest_blob->set_ctable_begin(dest.consts()->start());
+
+  relocate_code_to(&dest);
+
+  // transfer strings and comments from buffer to blob
+  dest_blob->set_strings(_code_strings);
+
+  // Done moving code bytes; were they the right size?
+  assert((int)align_up(dest.total_content_size(), oopSize) == dest_blob->content_size(), "sanity");
+
+  // Flush generated code
+  ICache::invalidate_range(dest_blob->code_begin(), dest_blob->code_size());
+}
+
+// Move all my code into another code buffer.  Consult applicable
+// relocs to repair embedded addresses.  The layout in the destination
+// CodeBuffer is different to the source CodeBuffer: the destination
+// CodeBuffer gets the final layout (consts, insts, stubs in order of
+// ascending address).
+void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
+  address dest_end = dest->_total_start + dest->_total_size;
+  address dest_filled = NULL;
+  for (int n = (int) SECT_FIRST; 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_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());
+    }
+    // Keep track of the highest filled address
+    dest_filled = MAX2(dest_filled, dest_cs->end() + dest_cs->remaining());
+
+    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);
+  }
+
+  // Do relocation after all sections are copied.
+  // This is necessary if the code uses constants in stubs, which are
+  // relocated when the corresponding instruction in the code (e.g., a
+  // call) is relocated. Stubs are placed behind the main code
+  // section, so that section has to be copied before relocating.
+  for (int n = (int) SECT_FIRST; 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);
+    { // 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);
+      }
+    }
+  }
+
+  if (dest->blob() == NULL && dest_filled != NULL) {
+    // Destination is a final resting place, not just another buffer.
+    // Normalize uninitialized bytes in the final padding.
+    Copy::fill_to_bytes(dest_filled, dest_end - dest_filled,
+                        Assembler::code_fill_byte());
+
+  }
+}
+
+csize_t CodeBuffer::figure_expanded_capacities(CodeSection* which_cs,
+                                               csize_t amount,
+                                               csize_t* new_capacity) {
+  csize_t new_total_cap = 0;
+
+  for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
+    const CodeSection* sect = code_section(n);
+
+    if (!sect->is_empty()) {
+      // Compute initial padding; assign it to the previous section,
+      // even if it's empty (e.g. consts section can be empty).
+      // 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(n - 1 >= SECT_FIRST, "sanity");
+        new_capacity[n - 1] += padding;
+      }
+    }
+
+    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];
+  memset(new_capacity, 0, sizeof(csize_t) * 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_FIRST; 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());
+    }
+  }
+
+  // Needs to be initialized when calling fix_relocation_after_move.
+  cb.blob()->set_ctable_begin(cb.consts()->start());
+
+  // 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.
+  verify_section_allocation();
+
+#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");
+  // 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);
+}
+
+void CodeBuffer::verify_section_allocation() {
+  address tstart = _total_start;
+  if (tstart == badAddress)  return;  // smashed by set_blob(NULL)
+  address tend   = tstart + _total_size;
+  if (_blob != NULL) {
+
+    guarantee(tstart >= _blob->content_begin(), "sanity");
+    guarantee(tend   <= _blob->content_end(),   "sanity");
+  }
+  // Verify disjointness.
+  for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
+    CodeSection* sect = code_section(n);
+    if (!sect->is_allocated() || sect->is_empty())  continue;
+    guarantee((intptr_t)sect->start() % sect->alignment() == 0
+           || sect->is_empty() || _blob == NULL,
+           "start is aligned");
+    for (int m = (int) SECT_FIRST; m < (int) SECT_LIMIT; m++) {
+      CodeSection* other = code_section(m);
+      if (!other->is_allocated() || other == sect)  continue;
+      guarantee(!other->contains(sect->start()    ), "sanity");
+      // limit is an exclusive address and can be the start of another
+      // section.
+      guarantee(!other->contains(sect->limit() - 1), "sanity");
+    }
+    guarantee(sect->end() <= tend, "sanity");
+    guarantee(sect->end() <= sect->limit(), "sanity");
+  }
+}
+
+void CodeBuffer::log_section_sizes(const char* name) {
+  if (xtty != NULL) {
+    ttyLocker ttyl;
+    // log info about buffer usage
+    xtty->print_cr("<blob name='%s' size='%d'>", name, _total_size);
+    for (int n = (int) CodeBuffer::SECT_FIRST; n < (int) CodeBuffer::SECT_LIMIT; n++) {
+      CodeSection* sect = code_section(n);
+      if (!sect->is_allocated() || sect->is_empty())  continue;
+      xtty->print_cr("<sect index='%d' size='" SIZE_FORMAT "' free='" SIZE_FORMAT "'/>",
+                     n, sect->limit() - sect->start(), sect->limit() - sect->end());
+    }
+    xtty->print_cr("</blob>");
+  }
+}
+
+#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(INTPTR_FORMAT ": ", p2i(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) {
+  _code_strings.add_comment(offset, comment);
+}
+
+const char* CodeBuffer::code_string(const char* str) {
+  return _code_strings.add_string(str);
+}
+
+class CodeString: public CHeapObj<mtCode> {
+ private:
+  friend class CodeStrings;
+  const char * _string;
+  CodeString*  _next;
+  intptr_t     _offset;
+
+  ~CodeString() {
+    assert(_next == NULL, "wrong interface for freeing list");
+    os::free((void*)_string);
+  }
+
+  bool is_comment() const { return _offset >= 0; }
+
+ public:
+  CodeString(const char * string, intptr_t offset = -1)
+    : _next(NULL), _offset(offset) {
+    _string = os::strdup(string, mtCode);
+  }
+
+  const char * string() const { return _string; }
+  intptr_t     offset() const { assert(_offset >= 0, "offset for non comment?"); return _offset;  }
+  CodeString* next()    const { return _next; }
+
+  void set_next(CodeString* next) { _next = next; }
+
+  CodeString* first_comment() {
+    if (is_comment()) {
+      return this;
+    } else {
+      return next_comment();
+    }
+  }
+  CodeString* next_comment() const {
+    CodeString* s = _next;
+    while (s != NULL && !s->is_comment()) {
+      s = s->_next;
+    }
+    return s;
+  }
+};
+
+CodeString* CodeStrings::find(intptr_t offset) const {
+  CodeString* a = _strings->first_comment();
+  while (a != NULL && a->offset() != offset) {
+    a = a->next_comment();
+  }
+  return a;
+}
+
+// Convenience for add_comment.
+CodeString* CodeStrings::find_last(intptr_t offset) const {
+  CodeString* a = find(offset);
+  if (a != NULL) {
+    CodeString* c = NULL;
+    while (((c = a->next_comment()) != NULL) && (c->offset() == offset)) {
+      a = c;
+    }
+  }
+  return a;
+}
+
+void CodeStrings::add_comment(intptr_t offset, const char * comment) {
+  check_valid();
+  CodeString* c      = new CodeString(comment, offset);
+  CodeString* inspos = (_strings == NULL) ? NULL : find_last(offset);
+
+  if (inspos) {
+    // insert after already existing comments with same offset
+    c->set_next(inspos->next());
+    inspos->set_next(c);
+  } else {
+    // no comments with such offset, yet. Insert before anything else.
+    c->set_next(_strings);
+    _strings = c;
+  }
+}
+
+void CodeStrings::assign(CodeStrings& other) {
+  other.check_valid();
+  assert(is_null(), "Cannot assign onto non-empty CodeStrings");
+  _strings = other._strings;
+#ifdef ASSERT
+  _defunct = false;
+#endif
+  other.set_null_and_invalidate();
+}
+
+// Deep copy of CodeStrings for consistent memory management.
+// Only used for actual disassembly so this is cheaper than reference counting
+// for the "normal" fastdebug case.
+void CodeStrings::copy(CodeStrings& other) {
+  other.check_valid();
+  check_valid();
+  assert(is_null(), "Cannot copy onto non-empty CodeStrings");
+  CodeString* n = other._strings;
+  CodeString** ps = &_strings;
+  while (n != NULL) {
+    *ps = new CodeString(n->string(),n->offset());
+    ps = &((*ps)->_next);
+    n = n->next();
+  }
+}
+
+const char* CodeStrings::_prefix = " ;; ";  // default: can be changed via set_prefix
+
+void CodeStrings::print_block_comment(outputStream* stream, intptr_t offset) const {
+    check_valid();
+    if (_strings != NULL) {
+    CodeString* c = find(offset);
+    while (c && c->offset() == offset) {
+      stream->bol();
+      stream->print("%s", _prefix);
+      // Don't interpret as format strings since it could contain %
+      stream->print_raw_cr(c->string());
+      c = c->next_comment();
+    }
+  }
+}
+
+// Also sets isNull()
+void CodeStrings::free() {
+  CodeString* n = _strings;
+  while (n) {
+    // unlink the node from the list saving a pointer to the next
+    CodeString* p = n->next();
+    n->set_next(NULL);
+    delete n;
+    n = p;
+  }
+  set_null_and_invalidate();
+}
+
+const char* CodeStrings::add_string(const char * string) {
+  check_valid();
+  CodeString* s = new CodeString(string);
+  s->set_next(_strings);
+  _strings = s;
+  assert(s->string() != NULL, "should have a string");
+  return s->string();
+}
+
+void CodeBuffer::decode() {
+  ttyLocker ttyl;
+  Disassembler::decode(decode_begin(), insts_end());
+  _decode_begin = insts_end();
+}
+
+
+void CodeBuffer::skip_decode() {
+  _decode_begin = insts_end();
+}
+
+
+void CodeBuffer::decode_all() {
+  ttyLocker ttyl;
+  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, p2i(start()), p2i(end()), p2i(limit()), size(), capacity(),
+                is_frozen()? " [frozen]": "");
+  tty->print_cr(" %7s.locs = " PTR_FORMAT " : " PTR_FORMAT " : " PTR_FORMAT " (%d of %d) point=%d",
+                name, p2i(locs_start()), p2i(locs_end()), p2i(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