src/hotspot/share/compiler/oopMap.cpp
changeset 47216 71c04702a3d5
parent 46625 edefffab74e2
child 47547 0f7dce1e7690
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/compiler/oopMap.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,831 @@
+/*
+ * Copyright (c) 1998, 2015, 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 "code/codeBlob.hpp"
+#include "code/codeCache.hpp"
+#include "code/nmethod.hpp"
+#include "code/scopeDesc.hpp"
+#include "compiler/oopMap.hpp"
+#include "gc/shared/collectedHeap.hpp"
+#include "memory/allocation.inline.hpp"
+#include "memory/resourceArea.hpp"
+#include "runtime/frame.inline.hpp"
+#include "runtime/signature.hpp"
+#include "utilities/align.hpp"
+#ifdef COMPILER1
+#include "c1/c1_Defs.hpp"
+#endif
+#ifdef COMPILER2
+#include "opto/optoreg.hpp"
+#endif
+#ifdef SPARC
+#include "vmreg_sparc.inline.hpp"
+#endif
+
+// OopMapStream
+
+OopMapStream::OopMapStream(OopMap* oop_map, int oop_types_mask) {
+  _stream = new CompressedReadStream(oop_map->write_stream()->buffer());
+  _mask = oop_types_mask;
+  _size = oop_map->omv_count();
+  _position = 0;
+  _valid_omv = false;
+}
+
+OopMapStream::OopMapStream(const ImmutableOopMap* oop_map, int oop_types_mask) {
+  _stream = new CompressedReadStream(oop_map->data_addr());
+  _mask = oop_types_mask;
+  _size = oop_map->count();
+  _position = 0;
+  _valid_omv = false;
+}
+
+void OopMapStream::find_next() {
+  while(_position++ < _size) {
+    _omv.read_from(_stream);
+    if(((int)_omv.type() & _mask) > 0) {
+      _valid_omv = true;
+      return;
+    }
+  }
+  _valid_omv = false;
+}
+
+
+// OopMap
+
+// frame_size units are stack-slots (4 bytes) NOT intptr_t; we can name odd
+// slots to hold 4-byte values like ints and floats in the LP64 build.
+OopMap::OopMap(int frame_size, int arg_count) {
+  // OopMaps are usually quite so small, so pick a small initial size
+  set_write_stream(new CompressedWriteStream(32));
+  set_omv_count(0);
+
+#ifdef ASSERT
+  _locs_length = VMRegImpl::stack2reg(0)->value() + frame_size + arg_count;
+  _locs_used   = NEW_RESOURCE_ARRAY(OopMapValue::oop_types, _locs_length);
+  for(int i = 0; i < _locs_length; i++) _locs_used[i] = OopMapValue::unused_value;
+#endif
+}
+
+
+OopMap::OopMap(OopMap::DeepCopyToken, OopMap* source) {
+  // This constructor does a deep copy
+  // of the source OopMap.
+  set_write_stream(new CompressedWriteStream(source->omv_count() * 2));
+  set_omv_count(0);
+  set_offset(source->offset());
+
+#ifdef ASSERT
+  _locs_length = source->_locs_length;
+  _locs_used = NEW_RESOURCE_ARRAY(OopMapValue::oop_types, _locs_length);
+  for(int i = 0; i < _locs_length; i++) _locs_used[i] = OopMapValue::unused_value;
+#endif
+
+  // We need to copy the entries too.
+  for (OopMapStream oms(source); !oms.is_done(); oms.next()) {
+    OopMapValue omv = oms.current();
+    omv.write_on(write_stream());
+    increment_count();
+  }
+}
+
+
+OopMap* OopMap::deep_copy() {
+  return new OopMap(_deep_copy_token, this);
+}
+
+void OopMap::copy_data_to(address addr) const {
+  memcpy(addr, write_stream()->buffer(), write_stream()->position());
+}
+
+int OopMap::heap_size() const {
+  int size = sizeof(OopMap);
+  int align = sizeof(void *) - 1;
+  size += write_stream()->position();
+  // Align to a reasonable ending point
+  size = ((size+align) & ~align);
+  return size;
+}
+
+// frame_size units are stack-slots (4 bytes) NOT intptr_t; we can name odd
+// slots to hold 4-byte values like ints and floats in the LP64 build.
+void OopMap::set_xxx(VMReg reg, OopMapValue::oop_types x, VMReg optional) {
+
+  assert(reg->value() < _locs_length, "too big reg value for stack size");
+  assert( _locs_used[reg->value()] == OopMapValue::unused_value, "cannot insert twice" );
+  debug_only( _locs_used[reg->value()] = x; )
+
+  OopMapValue o(reg, x);
+
+  if(x == OopMapValue::callee_saved_value) {
+    // This can never be a stack location, so we don't need to transform it.
+    assert(optional->is_reg(), "Trying to callee save a stack location");
+    o.set_content_reg(optional);
+  } else if(x == OopMapValue::derived_oop_value) {
+    o.set_content_reg(optional);
+  }
+
+  o.write_on(write_stream());
+  increment_count();
+}
+
+
+void OopMap::set_oop(VMReg reg) {
+  set_xxx(reg, OopMapValue::oop_value, VMRegImpl::Bad());
+}
+
+
+void OopMap::set_value(VMReg reg) {
+  // At this time, we don't need value entries in our OopMap.
+}
+
+
+void OopMap::set_narrowoop(VMReg reg) {
+  set_xxx(reg, OopMapValue::narrowoop_value, VMRegImpl::Bad());
+}
+
+
+void OopMap::set_callee_saved(VMReg reg, VMReg caller_machine_register ) {
+  set_xxx(reg, OopMapValue::callee_saved_value, caller_machine_register);
+}
+
+
+void OopMap::set_derived_oop(VMReg reg, VMReg derived_from_local_register ) {
+  if( reg == derived_from_local_register ) {
+    // Actually an oop, derived shares storage with base,
+    set_oop(reg);
+  } else {
+    set_xxx(reg, OopMapValue::derived_oop_value, derived_from_local_register);
+  }
+}
+
+// OopMapSet
+
+OopMapSet::OopMapSet() {
+  set_om_size(MinOopMapAllocation);
+  set_om_count(0);
+  OopMap** temp = NEW_RESOURCE_ARRAY(OopMap*, om_size());
+  set_om_data(temp);
+}
+
+
+void OopMapSet::grow_om_data() {
+  int new_size = om_size() * 2;
+  OopMap** new_data = NEW_RESOURCE_ARRAY(OopMap*, new_size);
+  memcpy(new_data,om_data(),om_size() * sizeof(OopMap*));
+  set_om_size(new_size);
+  set_om_data(new_data);
+}
+
+void OopMapSet::add_gc_map(int pc_offset, OopMap *map ) {
+  assert(om_size() != -1,"Cannot grow a fixed OopMapSet");
+
+  if(om_count() >= om_size()) {
+    grow_om_data();
+  }
+  map->set_offset(pc_offset);
+
+#ifdef ASSERT
+  if(om_count() > 0) {
+    OopMap* last = at(om_count()-1);
+    if (last->offset() == map->offset() ) {
+      fatal("OopMap inserted twice");
+    }
+    if(last->offset() > map->offset()) {
+      tty->print_cr( "WARNING, maps not sorted: pc[%d]=%d, pc[%d]=%d",
+                      om_count(),last->offset(),om_count()+1,map->offset());
+    }
+  }
+#endif // ASSERT
+
+  set(om_count(),map);
+  increment_count();
+}
+
+
+int OopMapSet::heap_size() const {
+  // The space we use
+  int size = sizeof(OopMap);
+  int align = sizeof(void *) - 1;
+  size = ((size+align) & ~align);
+  size += om_count() * sizeof(OopMap*);
+
+  // Now add in the space needed for the indivdiual OopMaps
+  for(int i=0; i < om_count(); i++) {
+    size += at(i)->heap_size();
+  }
+  // We don't need to align this, it will be naturally pointer aligned
+  return size;
+}
+
+
+OopMap* OopMapSet::singular_oop_map() {
+  guarantee(om_count() == 1, "Make sure we only have a single gc point");
+  return at(0);
+}
+
+
+OopMap* OopMapSet::find_map_at_offset(int pc_offset) const {
+  int i, len = om_count();
+  assert( len > 0, "must have pointer maps" );
+
+  // Scan through oopmaps. Stop when current offset is either equal or greater
+  // than the one we are looking for.
+  for( i = 0; i < len; i++) {
+    if( at(i)->offset() >= pc_offset )
+      break;
+  }
+
+  assert( i < len, "oopmap not found" );
+
+  OopMap* m = at(i);
+  assert( m->offset() == pc_offset, "oopmap not found" );
+  return m;
+}
+
+class DoNothingClosure: public OopClosure {
+ public:
+  void do_oop(oop* p)       {}
+  void do_oop(narrowOop* p) {}
+};
+static DoNothingClosure do_nothing;
+
+static void add_derived_oop(oop* base, oop* derived) {
+#if !defined(TIERED) && !defined(INCLUDE_JVMCI)
+  COMPILER1_PRESENT(ShouldNotReachHere();)
+#endif // !defined(TIERED) && !defined(INCLUDE_JVMCI)
+#if defined(COMPILER2) || INCLUDE_JVMCI
+  DerivedPointerTable::add(derived, base);
+#endif // COMPILER2 || INCLUDE_JVMCI
+}
+
+
+#ifndef PRODUCT
+static void trace_codeblob_maps(const frame *fr, const RegisterMap *reg_map) {
+  // Print oopmap and regmap
+  tty->print_cr("------ ");
+  CodeBlob* cb = fr->cb();
+  const ImmutableOopMapSet* maps = cb->oop_maps();
+  const ImmutableOopMap* map = cb->oop_map_for_return_address(fr->pc());
+  map->print();
+  if( cb->is_nmethod() ) {
+    nmethod* nm = (nmethod*)cb;
+    // native wrappers have no scope data, it is implied
+    if (nm->is_native_method()) {
+      tty->print("bci: 0 (native)");
+    } else {
+      ScopeDesc* scope  = nm->scope_desc_at(fr->pc());
+      tty->print("bci: %d ",scope->bci());
+    }
+  }
+  tty->cr();
+  fr->print_on(tty);
+  tty->print("     ");
+  cb->print_value_on(tty);  tty->cr();
+  reg_map->print();
+  tty->print_cr("------ ");
+
+}
+#endif // PRODUCT
+
+void OopMapSet::oops_do(const frame *fr, const RegisterMap* reg_map, OopClosure* f) {
+  // add derived oops to a table
+  all_do(fr, reg_map, f, add_derived_oop, &do_nothing);
+}
+
+
+void OopMapSet::all_do(const frame *fr, const RegisterMap *reg_map,
+                       OopClosure* oop_fn, void derived_oop_fn(oop*, oop*),
+                       OopClosure* value_fn) {
+  CodeBlob* cb = fr->cb();
+  assert(cb != NULL, "no codeblob");
+
+  NOT_PRODUCT(if (TraceCodeBlobStacks) trace_codeblob_maps(fr, reg_map);)
+
+  const ImmutableOopMapSet* maps = cb->oop_maps();
+  const ImmutableOopMap* map = cb->oop_map_for_return_address(fr->pc());
+  assert(map != NULL, "no ptr map found");
+
+  // handle derived pointers first (otherwise base pointer may be
+  // changed before derived pointer offset has been collected)
+  OopMapValue omv;
+  {
+    OopMapStream oms(map,OopMapValue::derived_oop_value);
+    if (!oms.is_done()) {
+#ifndef TIERED
+      COMPILER1_PRESENT(ShouldNotReachHere();)
+#if INCLUDE_JVMCI
+      if (UseJVMCICompiler) {
+        ShouldNotReachHere();
+      }
+#endif
+#endif // !TIERED
+      // Protect the operation on the derived pointers.  This
+      // protects the addition of derived pointers to the shared
+      // derived pointer table in DerivedPointerTable::add().
+      MutexLockerEx x(DerivedPointerTableGC_lock, Mutex::_no_safepoint_check_flag);
+      do {
+        omv = oms.current();
+        oop* loc = fr->oopmapreg_to_location(omv.reg(),reg_map);
+        guarantee(loc != NULL, "missing saved register");
+        oop *derived_loc = loc;
+        oop *base_loc    = fr->oopmapreg_to_location(omv.content_reg(), reg_map);
+        // Ignore NULL oops and decoded NULL narrow oops which
+        // equal to Universe::narrow_oop_base when a narrow oop
+        // implicit null check is used in compiled code.
+        // The narrow_oop_base could be NULL or be the address
+        // of the page below heap depending on compressed oops mode.
+        if (base_loc != NULL && *base_loc != (oop)NULL && !Universe::is_narrow_oop_base(*base_loc)) {
+          derived_oop_fn(base_loc, derived_loc);
+        }
+        oms.next();
+      }  while (!oms.is_done());
+    }
+  }
+
+  // We want coop and oop oop_types
+  int mask = OopMapValue::oop_value | OopMapValue::narrowoop_value;
+  {
+    for (OopMapStream oms(map,mask); !oms.is_done(); oms.next()) {
+      omv = oms.current();
+      oop* loc = fr->oopmapreg_to_location(omv.reg(),reg_map);
+      // It should be an error if no location can be found for a
+      // register mentioned as contained an oop of some kind.  Maybe
+      // this was allowed previously because value_value items might
+      // be missing?
+      guarantee(loc != NULL, "missing saved register");
+      if ( omv.type() == OopMapValue::oop_value ) {
+        oop val = *loc;
+        if (val == (oop)NULL || Universe::is_narrow_oop_base(val)) {
+          // Ignore NULL oops and decoded NULL narrow oops which
+          // equal to Universe::narrow_oop_base when a narrow oop
+          // implicit null check is used in compiled code.
+          // The narrow_oop_base could be NULL or be the address
+          // of the page below heap depending on compressed oops mode.
+          continue;
+        }
+#ifdef ASSERT
+        if ((((uintptr_t)loc & (sizeof(*loc)-1)) != 0) ||
+            !Universe::heap()->is_in_or_null(*loc)) {
+          tty->print_cr("# Found non oop pointer.  Dumping state at failure");
+          // try to dump out some helpful debugging information
+          trace_codeblob_maps(fr, reg_map);
+          omv.print();
+          tty->print_cr("register r");
+          omv.reg()->print();
+          tty->print_cr("loc = %p *loc = %p\n", loc, (address)*loc);
+          // do the real assert.
+          assert(Universe::heap()->is_in_or_null(*loc), "found non oop pointer");
+        }
+#endif // ASSERT
+        oop_fn->do_oop(loc);
+      } else if ( omv.type() == OopMapValue::narrowoop_value ) {
+        narrowOop *nl = (narrowOop*)loc;
+#ifndef VM_LITTLE_ENDIAN
+        VMReg vmReg = omv.reg();
+        // Don't do this on SPARC float registers as they can be individually addressed
+        if (!vmReg->is_stack() SPARC_ONLY(&& !vmReg->is_FloatRegister())) {
+          // compressed oops in registers only take up 4 bytes of an
+          // 8 byte register but they are in the wrong part of the
+          // word so adjust loc to point at the right place.
+          nl = (narrowOop*)((address)nl + 4);
+        }
+#endif
+        oop_fn->do_oop(nl);
+      }
+    }
+  }
+}
+
+
+// Update callee-saved register info for the following frame
+void OopMapSet::update_register_map(const frame *fr, RegisterMap *reg_map) {
+  ResourceMark rm;
+  CodeBlob* cb = fr->cb();
+  assert(cb != NULL, "no codeblob");
+
+  // Any reg might be saved by a safepoint handler (see generate_handler_blob).
+  assert( reg_map->_update_for_id == NULL || fr->is_older(reg_map->_update_for_id),
+         "already updated this map; do not 'update' it twice!" );
+  debug_only(reg_map->_update_for_id = fr->id());
+
+  // Check if caller must update oop argument
+  assert((reg_map->include_argument_oops() ||
+          !cb->caller_must_gc_arguments(reg_map->thread())),
+         "include_argument_oops should already be set");
+
+  // Scan through oopmap and find location of all callee-saved registers
+  // (we do not do update in place, since info could be overwritten)
+
+  address pc = fr->pc();
+  const ImmutableOopMap* map  = cb->oop_map_for_return_address(pc);
+  assert(map != NULL, "no ptr map found");
+  DEBUG_ONLY(int nof_callee = 0;)
+
+  for (OopMapStream oms(map, OopMapValue::callee_saved_value); !oms.is_done(); oms.next()) {
+    OopMapValue omv = oms.current();
+    VMReg reg = omv.content_reg();
+    oop* loc = fr->oopmapreg_to_location(omv.reg(), reg_map);
+    reg_map->set_location(reg, (address) loc);
+    DEBUG_ONLY(nof_callee++;)
+  }
+
+  // Check that runtime stubs save all callee-saved registers
+#ifdef COMPILER2
+  assert(cb->is_compiled_by_c1() || cb->is_compiled_by_jvmci() || !cb->is_runtime_stub() ||
+         (nof_callee >= SAVED_ON_ENTRY_REG_COUNT || nof_callee >= C_SAVED_ON_ENTRY_REG_COUNT),
+         "must save all");
+#endif // COMPILER2
+}
+
+//=============================================================================
+// Non-Product code
+
+#ifndef PRODUCT
+
+bool ImmutableOopMap::has_derived_pointer() const {
+#if !defined(TIERED) && !defined(INCLUDE_JVMCI)
+  COMPILER1_PRESENT(return false);
+#endif // !TIERED
+#if defined(COMPILER2) || INCLUDE_JVMCI
+  OopMapStream oms(this,OopMapValue::derived_oop_value);
+  return oms.is_done();
+#else
+  return false;
+#endif // COMPILER2 || INCLUDE_JVMCI
+}
+
+#endif //PRODUCT
+
+// Printing code is present in product build for -XX:+PrintAssembly.
+
+static
+void print_register_type(OopMapValue::oop_types x, VMReg optional,
+                         outputStream* st) {
+  switch( x ) {
+  case OopMapValue::oop_value:
+    st->print("Oop");
+    break;
+  case OopMapValue::narrowoop_value:
+    st->print("NarrowOop");
+    break;
+  case OopMapValue::callee_saved_value:
+    st->print("Callers_");
+    optional->print_on(st);
+    break;
+  case OopMapValue::derived_oop_value:
+    st->print("Derived_oop_");
+    optional->print_on(st);
+    break;
+  default:
+    ShouldNotReachHere();
+  }
+}
+
+void OopMapValue::print_on(outputStream* st) const {
+  reg()->print_on(st);
+  st->print("=");
+  print_register_type(type(),content_reg(),st);
+  st->print(" ");
+}
+
+void ImmutableOopMap::print_on(outputStream* st) const {
+  OopMapValue omv;
+  st->print("ImmutableOopMap{");
+  for(OopMapStream oms(this); !oms.is_done(); oms.next()) {
+    omv = oms.current();
+    omv.print_on(st);
+  }
+  st->print("}");
+}
+
+void OopMap::print_on(outputStream* st) const {
+  OopMapValue omv;
+  st->print("OopMap{");
+  for(OopMapStream oms((OopMap*)this); !oms.is_done(); oms.next()) {
+    omv = oms.current();
+    omv.print_on(st);
+  }
+  st->print("off=%d}", (int) offset());
+}
+
+void ImmutableOopMapSet::print_on(outputStream* st) const {
+  const ImmutableOopMap* last = NULL;
+  for (int i = 0; i < _count; ++i) {
+    const ImmutableOopMapPair* pair = pair_at(i);
+    const ImmutableOopMap* map = pair->get_from(this);
+    if (map != last) {
+      st->cr();
+      map->print_on(st);
+      st->print("pc offsets: ");
+    }
+    last = map;
+    st->print("%d ", pair->pc_offset());
+  }
+}
+
+void OopMapSet::print_on(outputStream* st) const {
+  int i, len = om_count();
+
+  st->print_cr("OopMapSet contains %d OopMaps\n",len);
+
+  for( i = 0; i < len; i++) {
+    OopMap* m = at(i);
+    st->print_cr("#%d ",i);
+    m->print_on(st);
+    st->cr();
+  }
+}
+
+bool OopMap::equals(const OopMap* other) const {
+  if (other->_omv_count != _omv_count) {
+    return false;
+  }
+  if (other->write_stream()->position() != write_stream()->position()) {
+    return false;
+  }
+  if (memcmp(other->write_stream()->buffer(), write_stream()->buffer(), write_stream()->position()) != 0) {
+    return false;
+  }
+  return true;
+}
+
+const ImmutableOopMap* ImmutableOopMapSet::find_map_at_offset(int pc_offset) const {
+  ImmutableOopMapPair* pairs = get_pairs();
+  ImmutableOopMapPair* last = NULL;
+
+  for (int i = 0; i < _count; ++i) {
+    if (pairs[i].pc_offset() >= pc_offset) {
+      last = &pairs[i];
+      break;
+    }
+  }
+
+  assert(last->pc_offset() == pc_offset, "oopmap not found");
+  return last->get_from(this);
+}
+
+const ImmutableOopMap* ImmutableOopMapPair::get_from(const ImmutableOopMapSet* set) const {
+  return set->oopmap_at_offset(_oopmap_offset);
+}
+
+ImmutableOopMap::ImmutableOopMap(const OopMap* oopmap) : _count(oopmap->count()) {
+  address addr = data_addr();
+  oopmap->copy_data_to(addr);
+}
+
+#ifdef ASSERT
+int ImmutableOopMap::nr_of_bytes() const {
+  OopMapStream oms(this);
+
+  while (!oms.is_done()) {
+    oms.next();
+  }
+  return sizeof(ImmutableOopMap) + oms.stream_position();
+}
+#endif
+
+ImmutableOopMapBuilder::ImmutableOopMapBuilder(const OopMapSet* set) : _set(set), _new_set(NULL), _empty(NULL), _last(NULL), _empty_offset(-1), _last_offset(-1), _offset(0), _required(-1) {
+  _mapping = NEW_RESOURCE_ARRAY(Mapping, _set->size());
+}
+
+int ImmutableOopMapBuilder::size_for(const OopMap* map) const {
+  return align_up((int)sizeof(ImmutableOopMap) + map->data_size(), 8);
+}
+
+int ImmutableOopMapBuilder::heap_size() {
+  int base = sizeof(ImmutableOopMapSet);
+  base = align_up(base, 8);
+
+  // all of ours pc / offset pairs
+  int pairs = _set->size() * sizeof(ImmutableOopMapPair);
+  pairs = align_up(pairs, 8);
+
+  for (int i = 0; i < _set->size(); ++i) {
+    int size = 0;
+    OopMap* map = _set->at(i);
+
+    if (is_empty(map)) {
+      /* only keep a single empty map in the set */
+      if (has_empty()) {
+        _mapping[i].set(Mapping::OOPMAP_EMPTY, _empty_offset, 0, map, _empty);
+      } else {
+        _empty_offset = _offset;
+        _empty = map;
+        size = size_for(map);
+        _mapping[i].set(Mapping::OOPMAP_NEW, _offset, size, map);
+      }
+    } else if (is_last_duplicate(map)) {
+      /* if this entry is identical to the previous one, just point it there */
+      _mapping[i].set(Mapping::OOPMAP_DUPLICATE, _last_offset, 0, map, _last);
+    } else {
+      /* not empty, not an identical copy of the previous entry */
+      size = size_for(map);
+      _mapping[i].set(Mapping::OOPMAP_NEW, _offset, size, map);
+      _last_offset = _offset;
+      _last = map;
+    }
+
+    assert(_mapping[i]._map == map, "check");
+    _offset += size;
+  }
+
+  int total = base + pairs + _offset;
+  DEBUG_ONLY(total += 8);
+  _required = total;
+  return total;
+}
+
+void ImmutableOopMapBuilder::fill_pair(ImmutableOopMapPair* pair, const OopMap* map, int offset, const ImmutableOopMapSet* set) {
+  assert(offset < set->nr_of_bytes(), "check");
+  new ((address) pair) ImmutableOopMapPair(map->offset(), offset);
+}
+
+int ImmutableOopMapBuilder::fill_map(ImmutableOopMapPair* pair, const OopMap* map, int offset, const ImmutableOopMapSet* set) {
+  fill_pair(pair, map, offset, set);
+  address addr = (address) pair->get_from(_new_set); // location of the ImmutableOopMap
+
+  new (addr) ImmutableOopMap(map);
+  return size_for(map);
+}
+
+void ImmutableOopMapBuilder::fill(ImmutableOopMapSet* set, int sz) {
+  ImmutableOopMapPair* pairs = set->get_pairs();
+
+  for (int i = 0; i < set->count(); ++i) {
+    const OopMap* map = _mapping[i]._map;
+    ImmutableOopMapPair* pair = NULL;
+    int size = 0;
+
+    if (_mapping[i]._kind == Mapping::OOPMAP_NEW) {
+      size = fill_map(&pairs[i], map, _mapping[i]._offset, set);
+    } else if (_mapping[i]._kind == Mapping::OOPMAP_DUPLICATE || _mapping[i]._kind == Mapping::OOPMAP_EMPTY) {
+      fill_pair(&pairs[i], map, _mapping[i]._offset, set);
+    }
+
+    const ImmutableOopMap* nv = set->find_map_at_offset(map->offset());
+    assert(memcmp(map->data(), nv->data_addr(), map->data_size()) == 0, "check identity");
+  }
+}
+
+#ifdef ASSERT
+void ImmutableOopMapBuilder::verify(address buffer, int size, const ImmutableOopMapSet* set) {
+  for (int i = 0; i < 8; ++i) {
+    assert(buffer[size - 8 + i] == (unsigned char) 0xff, "overwritten memory check");
+  }
+
+  for (int i = 0; i < set->count(); ++i) {
+    const ImmutableOopMapPair* pair = set->pair_at(i);
+    assert(pair->oopmap_offset() < set->nr_of_bytes(), "check size");
+    const ImmutableOopMap* map = pair->get_from(set);
+    int nr_of_bytes = map->nr_of_bytes();
+    assert(pair->oopmap_offset() + nr_of_bytes <= set->nr_of_bytes(), "check size + size");
+  }
+}
+#endif
+
+ImmutableOopMapSet* ImmutableOopMapBuilder::generate_into(address buffer) {
+  DEBUG_ONLY(memset(&buffer[_required-8], 0xff, 8));
+
+  _new_set = new (buffer) ImmutableOopMapSet(_set, _required);
+  fill(_new_set, _required);
+
+  DEBUG_ONLY(verify(buffer, _required, _new_set));
+
+  return _new_set;
+}
+
+ImmutableOopMapSet* ImmutableOopMapBuilder::build() {
+  _required = heap_size();
+
+  // We need to allocate a chunk big enough to hold the ImmutableOopMapSet and all of its ImmutableOopMaps
+  address buffer = (address) NEW_C_HEAP_ARRAY(unsigned char, _required, mtCode);
+  return generate_into(buffer);
+}
+
+ImmutableOopMapSet* ImmutableOopMapSet::build_from(const OopMapSet* oopmap_set) {
+  ResourceMark mark;
+  ImmutableOopMapBuilder builder(oopmap_set);
+  return builder.build();
+}
+
+
+//------------------------------DerivedPointerTable---------------------------
+
+#if defined(COMPILER2) || INCLUDE_JVMCI
+
+class DerivedPointerEntry : public CHeapObj<mtCompiler> {
+ private:
+  oop*     _location; // Location of derived pointer (also pointing to the base)
+  intptr_t _offset;   // Offset from base pointer
+ public:
+  DerivedPointerEntry(oop* location, intptr_t offset) { _location = location; _offset = offset; }
+  oop* location()    { return _location; }
+  intptr_t  offset() { return _offset; }
+};
+
+
+GrowableArray<DerivedPointerEntry*>* DerivedPointerTable::_list = NULL;
+bool DerivedPointerTable::_active = false;
+
+
+void DerivedPointerTable::clear() {
+  // The first time, we create the list.  Otherwise it should be
+  // empty.  If not, then we have probably forgotton to call
+  // update_pointers after last GC/Scavenge.
+  assert (!_active, "should not be active");
+  assert(_list == NULL || _list->length() == 0, "table not empty");
+  if (_list == NULL) {
+    _list = new (ResourceObj::C_HEAP, mtCompiler) GrowableArray<DerivedPointerEntry*>(10, true); // Allocated on C heap
+  }
+  _active = true;
+}
+
+
+// Returns value of location as an int
+intptr_t value_of_loc(oop *pointer) { return cast_from_oop<intptr_t>((*pointer)); }
+
+
+void DerivedPointerTable::add(oop *derived_loc, oop *base_loc) {
+  assert(Universe::heap()->is_in_or_null(*base_loc), "not an oop");
+  assert(derived_loc != base_loc, "Base and derived in same location");
+  if (_active) {
+    assert(*derived_loc != (oop)base_loc, "location already added");
+    assert(_list != NULL, "list must exist");
+    intptr_t offset = value_of_loc(derived_loc) - value_of_loc(base_loc);
+    // This assert is invalid because derived pointers can be
+    // arbitrarily far away from their base.
+    // assert(offset >= -1000000, "wrong derived pointer info");
+
+    if (TraceDerivedPointers) {
+      tty->print_cr(
+        "Add derived pointer@" INTPTR_FORMAT
+        " - Derived: " INTPTR_FORMAT
+        " Base: " INTPTR_FORMAT " (@" INTPTR_FORMAT ") (Offset: " INTX_FORMAT ")",
+        p2i(derived_loc), p2i((address)*derived_loc), p2i((address)*base_loc), p2i(base_loc), offset
+      );
+    }
+    // Set derived oop location to point to base.
+    *derived_loc = (oop)base_loc;
+    assert_lock_strong(DerivedPointerTableGC_lock);
+    DerivedPointerEntry *entry = new DerivedPointerEntry(derived_loc, offset);
+    _list->append(entry);
+  }
+}
+
+
+void DerivedPointerTable::update_pointers() {
+  assert(_list != NULL, "list must exist");
+  for(int i = 0; i < _list->length(); i++) {
+    DerivedPointerEntry* entry = _list->at(i);
+    oop* derived_loc = entry->location();
+    intptr_t offset  = entry->offset();
+    // The derived oop was setup to point to location of base
+    oop  base        = **(oop**)derived_loc;
+    assert(Universe::heap()->is_in_or_null(base), "must be an oop");
+
+    *derived_loc = (oop)(((address)base) + offset);
+    assert(value_of_loc(derived_loc) - value_of_loc(&base) == offset, "sanity check");
+
+    if (TraceDerivedPointers) {
+      tty->print_cr("Updating derived pointer@" INTPTR_FORMAT
+                    " - Derived: " INTPTR_FORMAT "  Base: " INTPTR_FORMAT " (Offset: " INTX_FORMAT ")",
+          p2i(derived_loc), p2i((address)*derived_loc), p2i((address)base), offset);
+    }
+
+    // Delete entry
+    delete entry;
+    _list->at_put(i, NULL);
+  }
+  // Clear list, so it is ready for next traversal (this is an invariant)
+  if (TraceDerivedPointers && !_list->is_empty()) {
+    tty->print_cr("--------------------------");
+  }
+  _list->clear();
+  _active = false;
+}
+
+#endif // COMPILER2 || INCLUDE_JVMCI