--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/memory/space.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,947 @@
+/*
+ * Copyright 1997-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_space.cpp.incl"
+
+HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
+                                                HeapWord* top_obj) {
+  if (top_obj != NULL) {
+    if (_sp->block_is_obj(top_obj)) {
+      if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
+        if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
+          // An arrayOop is starting on the dirty card - since we do exact
+          // store checks for objArrays we are done.
+        } else {
+          // Otherwise, it is possible that the object starting on the dirty
+          // card spans the entire card, and that the store happened on a
+          // later card.  Figure out where the object ends.
+          // Use the block_size() method of the space over which
+          // the iteration is being done.  That space (e.g. CMS) may have
+          // specific requirements on object sizes which will
+          // be reflected in the block_size() method.
+          top = top_obj + oop(top_obj)->size();
+        }
+      }
+    } else {
+      top = top_obj;
+    }
+  } else {
+    assert(top == _sp->end(), "only case where top_obj == NULL");
+  }
+  return top;
+}
+
+void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
+                                            HeapWord* bottom,
+                                            HeapWord* top) {
+  // 1. Blocks may or may not be objects.
+  // 2. Even when a block_is_obj(), it may not entirely
+  //    occupy the block if the block quantum is larger than
+  //    the object size.
+  // We can and should try to optimize by calling the non-MemRegion
+  // version of oop_iterate() for all but the extremal objects
+  // (for which we need to call the MemRegion version of
+  // oop_iterate()) To be done post-beta XXX
+  for (; bottom < top; bottom += _sp->block_size(bottom)) {
+    // As in the case of contiguous space above, we'd like to
+    // just use the value returned by oop_iterate to increment the
+    // current pointer; unfortunately, that won't work in CMS because
+    // we'd need an interface change (it seems) to have the space
+    // "adjust the object size" (for instance pad it up to its
+    // block alignment or minimum block size restrictions. XXX
+    if (_sp->block_is_obj(bottom) &&
+        !_sp->obj_allocated_since_save_marks(oop(bottom))) {
+      oop(bottom)->oop_iterate(_cl, mr);
+    }
+  }
+}
+
+void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
+
+  // Some collectors need to do special things whenever their dirty
+  // cards are processed. For instance, CMS must remember mutator updates
+  // (i.e. dirty cards) so as to re-scan mutated objects.
+  // Such work can be piggy-backed here on dirty card scanning, so as to make
+  // it slightly more efficient than doing a complete non-detructive pre-scan
+  // of the card table.
+  MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
+  if (pCl != NULL) {
+    pCl->do_MemRegion(mr);
+  }
+
+  HeapWord* bottom = mr.start();
+  HeapWord* last = mr.last();
+  HeapWord* top = mr.end();
+  HeapWord* bottom_obj;
+  HeapWord* top_obj;
+
+  assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
+         _precision == CardTableModRefBS::Precise,
+         "Only ones we deal with for now.");
+
+  assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
+         _last_bottom == NULL ||
+         top <= _last_bottom,
+         "Not decreasing");
+  NOT_PRODUCT(_last_bottom = mr.start());
+
+  bottom_obj = _sp->block_start(bottom);
+  top_obj    = _sp->block_start(last);
+
+  assert(bottom_obj <= bottom, "just checking");
+  assert(top_obj    <= top,    "just checking");
+
+  // Given what we think is the top of the memory region and
+  // the start of the object at the top, get the actual
+  // value of the top.
+  top = get_actual_top(top, top_obj);
+
+  // If the previous call did some part of this region, don't redo.
+  if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
+      _min_done != NULL &&
+      _min_done < top) {
+    top = _min_done;
+  }
+
+  // Top may have been reset, and in fact may be below bottom,
+  // e.g. the dirty card region is entirely in a now free object
+  // -- something that could happen with a concurrent sweeper.
+  bottom = MIN2(bottom, top);
+  mr     = MemRegion(bottom, top);
+  assert(bottom <= top &&
+         (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
+          _min_done == NULL ||
+          top <= _min_done),
+         "overlap!");
+
+  // Walk the region if it is not empty; otherwise there is nothing to do.
+  if (!mr.is_empty()) {
+    walk_mem_region(mr, bottom_obj, top);
+  }
+
+  _min_done = bottom;
+}
+
+DirtyCardToOopClosure* Space::new_dcto_cl(OopClosure* cl,
+                                          CardTableModRefBS::PrecisionStyle precision,
+                                          HeapWord* boundary) {
+  return new DirtyCardToOopClosure(this, cl, precision, boundary);
+}
+
+void FilteringClosure::do_oop(oop* p) {
+  do_oop_nv(p);
+}
+
+HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
+                                               HeapWord* top_obj) {
+  if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
+    if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
+      if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
+        // An arrayOop is starting on the dirty card - since we do exact
+        // store checks for objArrays we are done.
+      } else {
+        // Otherwise, it is possible that the object starting on the dirty
+        // card spans the entire card, and that the store happened on a
+        // later card.  Figure out where the object ends.
+        assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
+          "Block size and object size mismatch");
+        top = top_obj + oop(top_obj)->size();
+      }
+    }
+  } else {
+    top = (_sp->toContiguousSpace())->top();
+  }
+  return top;
+}
+
+void Filtering_DCTOC::walk_mem_region(MemRegion mr,
+                                      HeapWord* bottom,
+                                      HeapWord* top) {
+  // Note that this assumption won't hold if we have a concurrent
+  // collector in this space, which may have freed up objects after
+  // they were dirtied and before the stop-the-world GC that is
+  // examining cards here.
+  assert(bottom < top, "ought to be at least one obj on a dirty card.");
+
+  if (_boundary != NULL) {
+    // We have a boundary outside of which we don't want to look
+    // at objects, so create a filtering closure around the
+    // oop closure before walking the region.
+    FilteringClosure filter(_boundary, _cl);
+    walk_mem_region_with_cl(mr, bottom, top, &filter);
+  } else {
+    // No boundary, simply walk the heap with the oop closure.
+    walk_mem_region_with_cl(mr, bottom, top, _cl);
+  }
+
+}
+
+// We must replicate this so that the static type of "FilteringClosure"
+// (see above) is apparent at the oop_iterate calls.
+#define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
+void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr,        \
+                                                   HeapWord* bottom,    \
+                                                   HeapWord* top,       \
+                                                   ClosureType* cl) {   \
+  bottom += oop(bottom)->oop_iterate(cl, mr);                           \
+  if (bottom < top) {                                                   \
+    HeapWord* next_obj = bottom + oop(bottom)->size();                  \
+    while (next_obj < top) {                                            \
+      /* Bottom lies entirely below top, so we can call the */          \
+      /* non-memRegion version of oop_iterate below. */                 \
+      oop(bottom)->oop_iterate(cl);                                     \
+      bottom = next_obj;                                                \
+      next_obj = bottom + oop(bottom)->size();                          \
+    }                                                                   \
+    /* Last object. */                                                  \
+    oop(bottom)->oop_iterate(cl, mr);                                   \
+  }                                                                     \
+}
+
+// (There are only two of these, rather than N, because the split is due
+// only to the introduction of the FilteringClosure, a local part of the
+// impl of this abstraction.)
+ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(OopClosure)
+ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
+
+DirtyCardToOopClosure*
+ContiguousSpace::new_dcto_cl(OopClosure* cl,
+                             CardTableModRefBS::PrecisionStyle precision,
+                             HeapWord* boundary) {
+  return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
+}
+
+void Space::initialize(MemRegion mr, bool clear_space) {
+  HeapWord* bottom = mr.start();
+  HeapWord* end    = mr.end();
+  assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
+         "invalid space boundaries");
+  set_bottom(bottom);
+  set_end(end);
+  if (clear_space) clear();
+}
+
+void Space::clear() {
+  if (ZapUnusedHeapArea) mangle_unused_area();
+}
+
+void ContiguousSpace::initialize(MemRegion mr, bool clear_space)
+{
+  CompactibleSpace::initialize(mr, clear_space);
+  _concurrent_iteration_safe_limit = top();
+}
+
+void ContiguousSpace::clear() {
+  set_top(bottom());
+  set_saved_mark();
+  Space::clear();
+}
+
+bool Space::is_in(const void* p) const {
+  HeapWord* b = block_start(p);
+  return b != NULL && block_is_obj(b);
+}
+
+bool ContiguousSpace::is_in(const void* p) const {
+  return _bottom <= p && p < _top;
+}
+
+bool ContiguousSpace::is_free_block(const HeapWord* p) const {
+  return p >= _top;
+}
+
+void OffsetTableContigSpace::clear() {
+  ContiguousSpace::clear();
+  _offsets.initialize_threshold();
+}
+
+void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
+  Space::set_bottom(new_bottom);
+  _offsets.set_bottom(new_bottom);
+}
+
+void OffsetTableContigSpace::set_end(HeapWord* new_end) {
+  // Space should not advertize an increase in size
+  // until after the underlying offest table has been enlarged.
+  _offsets.resize(pointer_delta(new_end, bottom()));
+  Space::set_end(new_end);
+}
+
+void ContiguousSpace::mangle_unused_area() {
+  // to-space is used for storing marks during mark-sweep
+  mangle_region(MemRegion(top(), end()));
+}
+
+void ContiguousSpace::mangle_region(MemRegion mr) {
+  debug_only(Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord));
+}
+
+void CompactibleSpace::initialize(MemRegion mr, bool clear_space) {
+  Space::initialize(mr, clear_space);
+  _compaction_top = bottom();
+  _next_compaction_space = NULL;
+}
+
+HeapWord* CompactibleSpace::forward(oop q, size_t size,
+                                    CompactPoint* cp, HeapWord* compact_top) {
+  // q is alive
+  // First check if we should switch compaction space
+  assert(this == cp->space, "'this' should be current compaction space.");
+  size_t compaction_max_size = pointer_delta(end(), compact_top);
+  while (size > compaction_max_size) {
+    // switch to next compaction space
+    cp->space->set_compaction_top(compact_top);
+    cp->space = cp->space->next_compaction_space();
+    if (cp->space == NULL) {
+      cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
+      assert(cp->gen != NULL, "compaction must succeed");
+      cp->space = cp->gen->first_compaction_space();
+      assert(cp->space != NULL, "generation must have a first compaction space");
+    }
+    compact_top = cp->space->bottom();
+    cp->space->set_compaction_top(compact_top);
+    cp->threshold = cp->space->initialize_threshold();
+    compaction_max_size = pointer_delta(cp->space->end(), compact_top);
+  }
+
+  // store the forwarding pointer into the mark word
+  if ((HeapWord*)q != compact_top) {
+    q->forward_to(oop(compact_top));
+    assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
+  } else {
+    // if the object isn't moving we can just set the mark to the default
+    // mark and handle it specially later on.
+    q->init_mark();
+    assert(q->forwardee() == NULL, "should be forwarded to NULL");
+  }
+
+  debug_only(MarkSweep::register_live_oop(q, size));
+  compact_top += size;
+
+  // we need to update the offset table so that the beginnings of objects can be
+  // found during scavenge.  Note that we are updating the offset table based on
+  // where the object will be once the compaction phase finishes.
+  if (compact_top > cp->threshold)
+    cp->threshold =
+      cp->space->cross_threshold(compact_top - size, compact_top);
+  return compact_top;
+}
+
+
+bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
+                                        HeapWord* q, size_t deadlength) {
+  if (allowed_deadspace_words >= deadlength) {
+    allowed_deadspace_words -= deadlength;
+    oop(q)->set_mark(markOopDesc::prototype()->set_marked());
+    const size_t min_int_array_size = typeArrayOopDesc::header_size(T_INT);
+    if (deadlength >= min_int_array_size) {
+      oop(q)->set_klass(Universe::intArrayKlassObj());
+      typeArrayOop(q)->set_length((int)((deadlength - min_int_array_size)
+                                            * (HeapWordSize/sizeof(jint))));
+    } else {
+      assert((int) deadlength == instanceOopDesc::header_size(),
+             "size for smallest fake dead object doesn't match");
+      oop(q)->set_klass(SystemDictionary::object_klass());
+    }
+    assert((int) deadlength == oop(q)->size(),
+           "make sure size for fake dead object match");
+    // Recall that we required "q == compaction_top".
+    return true;
+  } else {
+    allowed_deadspace_words = 0;
+    return false;
+  }
+}
+
+#define block_is_always_obj(q) true
+#define obj_size(q) oop(q)->size()
+#define adjust_obj_size(s) s
+
+void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
+  SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
+}
+
+// Faster object search.
+void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
+  SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
+}
+
+void Space::adjust_pointers() {
+  // adjust all the interior pointers to point at the new locations of objects
+  // Used by MarkSweep::mark_sweep_phase3()
+
+  // First check to see if there is any work to be done.
+  if (used() == 0) {
+    return;  // Nothing to do.
+  }
+
+  // Otherwise...
+  HeapWord* q = bottom();
+  HeapWord* t = end();
+
+  debug_only(HeapWord* prev_q = NULL);
+  while (q < t) {
+    if (oop(q)->is_gc_marked()) {
+      // q is alive
+
+      debug_only(MarkSweep::track_interior_pointers(oop(q)));
+      // point all the oops to the new location
+      size_t size = oop(q)->adjust_pointers();
+      debug_only(MarkSweep::check_interior_pointers());
+
+      debug_only(prev_q = q);
+      debug_only(MarkSweep::validate_live_oop(oop(q), size));
+
+      q += size;
+    } else {
+      // q is not a live object.  But we're not in a compactible space,
+      // So we don't have live ranges.
+      debug_only(prev_q = q);
+      q += block_size(q);
+      assert(q > prev_q, "we should be moving forward through memory");
+    }
+  }
+  assert(q == t, "just checking");
+}
+
+void CompactibleSpace::adjust_pointers() {
+  // Check first is there is any work to do.
+  if (used() == 0) {
+    return;   // Nothing to do.
+  }
+
+  SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
+}
+
+void CompactibleSpace::compact() {
+  SCAN_AND_COMPACT(obj_size);
+}
+
+void Space::print_short() const { print_short_on(tty); }
+
+void Space::print_short_on(outputStream* st) const {
+  st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
+              (int) ((double) used() * 100 / capacity()));
+}
+
+void Space::print() const { print_on(tty); }
+
+void Space::print_on(outputStream* st) const {
+  print_short_on(st);
+  st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
+                bottom(), end());
+}
+
+void ContiguousSpace::print_on(outputStream* st) const {
+  print_short_on(st);
+  st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
+                bottom(), top(), end());
+}
+
+void OffsetTableContigSpace::print_on(outputStream* st) const {
+  print_short_on(st);
+  st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
+                INTPTR_FORMAT ", " INTPTR_FORMAT ")",
+              bottom(), top(), _offsets.threshold(), end());
+}
+
+void ContiguousSpace::verify(bool allow_dirty) const {
+  HeapWord* p = bottom();
+  HeapWord* t = top();
+  HeapWord* prev_p = NULL;
+  while (p < t) {
+    oop(p)->verify();
+    prev_p = p;
+    p += oop(p)->size();
+  }
+  guarantee(p == top(), "end of last object must match end of space");
+  if (top() != end()) {
+    guarantee(top() == block_start(end()-1) &&
+              top() == block_start(top()),
+              "top should be start of unallocated block, if it exists");
+  }
+}
+
+void Space::oop_iterate(OopClosure* blk) {
+  ObjectToOopClosure blk2(blk);
+  object_iterate(&blk2);
+}
+
+HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) {
+  guarantee(false, "NYI");
+  return bottom();
+}
+
+HeapWord* Space::object_iterate_careful_m(MemRegion mr,
+                                          ObjectClosureCareful* cl) {
+  guarantee(false, "NYI");
+  return bottom();
+}
+
+
+void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
+  assert(!mr.is_empty(), "Should be non-empty");
+  // We use MemRegion(bottom(), end()) rather than used_region() below
+  // because the two are not necessarily equal for some kinds of
+  // spaces, in particular, certain kinds of free list spaces.
+  // We could use the more complicated but more precise:
+  // MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
+  // but the slight imprecision seems acceptable in the assertion check.
+  assert(MemRegion(bottom(), end()).contains(mr),
+         "Should be within used space");
+  HeapWord* prev = cl->previous();   // max address from last time
+  if (prev >= mr.end()) { // nothing to do
+    return;
+  }
+  // This assert will not work when we go from cms space to perm
+  // space, and use same closure. Easy fix deferred for later. XXX YSR
+  // assert(prev == NULL || contains(prev), "Should be within space");
+
+  bool last_was_obj_array = false;
+  HeapWord *blk_start_addr, *region_start_addr;
+  if (prev > mr.start()) {
+    region_start_addr = prev;
+    blk_start_addr    = prev;
+    assert(blk_start_addr == block_start(region_start_addr), "invariant");
+  } else {
+    region_start_addr = mr.start();
+    blk_start_addr    = block_start(region_start_addr);
+  }
+  HeapWord* region_end_addr = mr.end();
+  MemRegion derived_mr(region_start_addr, region_end_addr);
+  while (blk_start_addr < region_end_addr) {
+    const size_t size = block_size(blk_start_addr);
+    if (block_is_obj(blk_start_addr)) {
+      last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
+    } else {
+      last_was_obj_array = false;
+    }
+    blk_start_addr += size;
+  }
+  if (!last_was_obj_array) {
+    assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
+           "Should be within (closed) used space");
+    assert(blk_start_addr > prev, "Invariant");
+    cl->set_previous(blk_start_addr); // min address for next time
+  }
+}
+
+bool Space::obj_is_alive(const HeapWord* p) const {
+  assert (block_is_obj(p), "The address should point to an object");
+  return true;
+}
+
+void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
+  assert(!mr.is_empty(), "Should be non-empty");
+  assert(used_region().contains(mr), "Should be within used space");
+  HeapWord* prev = cl->previous();   // max address from last time
+  if (prev >= mr.end()) { // nothing to do
+    return;
+  }
+  // See comment above (in more general method above) in case you
+  // happen to use this method.
+  assert(prev == NULL || is_in_reserved(prev), "Should be within space");
+
+  bool last_was_obj_array = false;
+  HeapWord *obj_start_addr, *region_start_addr;
+  if (prev > mr.start()) {
+    region_start_addr = prev;
+    obj_start_addr    = prev;
+    assert(obj_start_addr == block_start(region_start_addr), "invariant");
+  } else {
+    region_start_addr = mr.start();
+    obj_start_addr    = block_start(region_start_addr);
+  }
+  HeapWord* region_end_addr = mr.end();
+  MemRegion derived_mr(region_start_addr, region_end_addr);
+  while (obj_start_addr < region_end_addr) {
+    oop obj = oop(obj_start_addr);
+    const size_t size = obj->size();
+    last_was_obj_array = cl->do_object_bm(obj, derived_mr);
+    obj_start_addr += size;
+  }
+  if (!last_was_obj_array) {
+    assert((bottom() <= obj_start_addr)  && (obj_start_addr <= end()),
+           "Should be within (closed) used space");
+    assert(obj_start_addr > prev, "Invariant");
+    cl->set_previous(obj_start_addr); // min address for next time
+  }
+}
+
+#ifndef SERIALGC
+#define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix)         \
+                                                                            \
+  void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
+    HeapWord* obj_addr = mr.start();                                        \
+    HeapWord* t = mr.end();                                                 \
+    while (obj_addr < t) {                                                  \
+      assert(oop(obj_addr)->is_oop(), "Should be an oop");                  \
+      obj_addr += oop(obj_addr)->oop_iterate(blk);                          \
+    }                                                                       \
+  }
+
+  ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
+
+#undef ContigSpace_PAR_OOP_ITERATE_DEFN
+#endif // SERIALGC
+
+void ContiguousSpace::oop_iterate(OopClosure* blk) {
+  if (is_empty()) return;
+  HeapWord* obj_addr = bottom();
+  HeapWord* t = top();
+  // Could call objects iterate, but this is easier.
+  while (obj_addr < t) {
+    obj_addr += oop(obj_addr)->oop_iterate(blk);
+  }
+}
+
+void ContiguousSpace::oop_iterate(MemRegion mr, OopClosure* blk) {
+  if (is_empty()) {
+    return;
+  }
+  MemRegion cur = MemRegion(bottom(), top());
+  mr = mr.intersection(cur);
+  if (mr.is_empty()) {
+    return;
+  }
+  if (mr.equals(cur)) {
+    oop_iterate(blk);
+    return;
+  }
+  assert(mr.end() <= top(), "just took an intersection above");
+  HeapWord* obj_addr = block_start(mr.start());
+  HeapWord* t = mr.end();
+
+  // Handle first object specially.
+  oop obj = oop(obj_addr);
+  SpaceMemRegionOopsIterClosure smr_blk(blk, mr);
+  obj_addr += obj->oop_iterate(&smr_blk);
+  while (obj_addr < t) {
+    oop obj = oop(obj_addr);
+    assert(obj->is_oop(), "expected an oop");
+    obj_addr += obj->size();
+    // If "obj_addr" is not greater than top, then the
+    // entire object "obj" is within the region.
+    if (obj_addr <= t) {
+      obj->oop_iterate(blk);
+    } else {
+      // "obj" extends beyond end of region
+      obj->oop_iterate(&smr_blk);
+      break;
+    }
+  };
+}
+
+void ContiguousSpace::object_iterate(ObjectClosure* blk) {
+  if (is_empty()) return;
+  WaterMark bm = bottom_mark();
+  object_iterate_from(bm, blk);
+}
+
+void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
+  assert(mark.space() == this, "Mark does not match space");
+  HeapWord* p = mark.point();
+  while (p < top()) {
+    blk->do_object(oop(p));
+    p += oop(p)->size();
+  }
+}
+
+HeapWord*
+ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
+  HeapWord * limit = concurrent_iteration_safe_limit();
+  assert(limit <= top(), "sanity check");
+  for (HeapWord* p = bottom(); p < limit;) {
+    size_t size = blk->do_object_careful(oop(p));
+    if (size == 0) {
+      return p;  // failed at p
+    } else {
+      p += size;
+    }
+  }
+  return NULL; // all done
+}
+
+#define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix)  \
+                                                                          \
+void ContiguousSpace::                                                    \
+oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) {            \
+  HeapWord* t;                                                            \
+  HeapWord* p = saved_mark_word();                                        \
+  assert(p != NULL, "expected saved mark");                               \
+                                                                          \
+  const intx interval = PrefetchScanIntervalInBytes;                      \
+  do {                                                                    \
+    t = top();                                                            \
+    while (p < t) {                                                       \
+      Prefetch::write(p, interval);                                       \
+      debug_only(HeapWord* prev = p);                                     \
+      oop m = oop(p);                                                     \
+      p += m->oop_iterate(blk);                                           \
+    }                                                                     \
+  } while (t < top());                                                    \
+                                                                          \
+  set_saved_mark_word(p);                                                 \
+}
+
+ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
+
+#undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
+
+// Very general, slow implementation.
+HeapWord* ContiguousSpace::block_start(const void* p) const {
+  assert(MemRegion(bottom(), end()).contains(p), "p not in space");
+  if (p >= top()) {
+    return top();
+  } else {
+    HeapWord* last = bottom();
+    HeapWord* cur = last;
+    while (cur <= p) {
+      last = cur;
+      cur += oop(cur)->size();
+    }
+    assert(oop(last)->is_oop(), "Should be an object start");
+    return last;
+  }
+}
+
+size_t ContiguousSpace::block_size(const HeapWord* p) const {
+  assert(MemRegion(bottom(), end()).contains(p), "p not in space");
+  HeapWord* current_top = top();
+  assert(p <= current_top, "p is not a block start");
+  assert(p == current_top || oop(p)->is_oop(), "p is not a block start");
+  if (p < current_top)
+    return oop(p)->size();
+  else {
+    assert(p == current_top, "just checking");
+    return pointer_delta(end(), (HeapWord*) p);
+  }
+}
+
+// This version requires locking.
+inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
+                                                HeapWord* const end_value) {
+  assert(Heap_lock->owned_by_self() ||
+         (SafepointSynchronize::is_at_safepoint() &&
+          Thread::current()->is_VM_thread()),
+         "not locked");
+  HeapWord* obj = top();
+  if (pointer_delta(end_value, obj) >= size) {
+    HeapWord* new_top = obj + size;
+    set_top(new_top);
+    assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
+    return obj;
+  } else {
+    return NULL;
+  }
+}
+
+// This version is lock-free.
+inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
+                                                    HeapWord* const end_value) {
+  do {
+    HeapWord* obj = top();
+    if (pointer_delta(end_value, obj) >= size) {
+      HeapWord* new_top = obj + size;
+      HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
+      // result can be one of two:
+      //  the old top value: the exchange succeeded
+      //  otherwise: the new value of the top is returned.
+      if (result == obj) {
+        assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
+        return obj;
+      }
+    } else {
+      return NULL;
+    }
+  } while (true);
+}
+
+// Requires locking.
+HeapWord* ContiguousSpace::allocate(size_t size) {
+  return allocate_impl(size, end());
+}
+
+// Lock-free.
+HeapWord* ContiguousSpace::par_allocate(size_t size) {
+  return par_allocate_impl(size, end());
+}
+
+void ContiguousSpace::allocate_temporary_filler(int factor) {
+  // allocate temporary type array decreasing free size with factor 'factor'
+  assert(factor >= 0, "just checking");
+  size_t size = pointer_delta(end(), top());
+
+  // if space is full, return
+  if (size == 0) return;
+
+  if (factor > 0) {
+    size -= size/factor;
+  }
+  size = align_object_size(size);
+
+  const size_t min_int_array_size = typeArrayOopDesc::header_size(T_INT);
+  if (size >= min_int_array_size) {
+    size_t length = (size - min_int_array_size) * (HeapWordSize / sizeof(jint));
+    // allocate uninitialized int array
+    typeArrayOop t = (typeArrayOop) allocate(size);
+    assert(t != NULL, "allocation should succeed");
+    t->set_mark(markOopDesc::prototype());
+    t->set_klass(Universe::intArrayKlassObj());
+    t->set_length((int)length);
+  } else {
+    assert((int) size == instanceOopDesc::header_size(),
+           "size for smallest fake object doesn't match");
+    instanceOop obj = (instanceOop) allocate(size);
+    obj->set_mark(markOopDesc::prototype());
+    obj->set_klass(SystemDictionary::object_klass());
+  }
+}
+
+void EdenSpace::clear() {
+  ContiguousSpace::clear();
+  set_soft_end(end());
+}
+
+// Requires locking.
+HeapWord* EdenSpace::allocate(size_t size) {
+  return allocate_impl(size, soft_end());
+}
+
+// Lock-free.
+HeapWord* EdenSpace::par_allocate(size_t size) {
+  return par_allocate_impl(size, soft_end());
+}
+
+HeapWord* ConcEdenSpace::par_allocate(size_t size)
+{
+  do {
+    // The invariant is top() should be read before end() because
+    // top() can't be greater than end(), so if an update of _soft_end
+    // occurs between 'end_val = end();' and 'top_val = top();' top()
+    // also can grow up to the new end() and the condition
+    // 'top_val > end_val' is true. To ensure the loading order
+    // OrderAccess::loadload() is required after top() read.
+    HeapWord* obj = top();
+    OrderAccess::loadload();
+    if (pointer_delta(*soft_end_addr(), obj) >= size) {
+      HeapWord* new_top = obj + size;
+      HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
+      // result can be one of two:
+      //  the old top value: the exchange succeeded
+      //  otherwise: the new value of the top is returned.
+      if (result == obj) {
+        assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
+        return obj;
+      }
+    } else {
+      return NULL;
+    }
+  } while (true);
+}
+
+
+HeapWord* OffsetTableContigSpace::initialize_threshold() {
+  return _offsets.initialize_threshold();
+}
+
+HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
+  _offsets.alloc_block(start, end);
+  return _offsets.threshold();
+}
+
+OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
+                                               MemRegion mr) :
+  _offsets(sharedOffsetArray, mr),
+  _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
+{
+  _offsets.set_contig_space(this);
+  initialize(mr, true);
+}
+
+
+class VerifyOldOopClosure : public OopClosure {
+ public:
+  oop the_obj;
+  bool allow_dirty;
+  void do_oop(oop* p) {
+    the_obj->verify_old_oop(p, allow_dirty);
+  }
+};
+
+#define OBJ_SAMPLE_INTERVAL 0
+#define BLOCK_SAMPLE_INTERVAL 100
+
+void OffsetTableContigSpace::verify(bool allow_dirty) const {
+  HeapWord* p = bottom();
+  HeapWord* prev_p = NULL;
+  VerifyOldOopClosure blk;      // Does this do anything?
+  blk.allow_dirty = allow_dirty;
+  int objs = 0;
+  int blocks = 0;
+
+  if (VerifyObjectStartArray) {
+    _offsets.verify();
+  }
+
+  while (p < top()) {
+    size_t size = oop(p)->size();
+    // For a sampling of objects in the space, find it using the
+    // block offset table.
+    if (blocks == BLOCK_SAMPLE_INTERVAL) {
+      guarantee(p == block_start(p + (size/2)), "check offset computation");
+      blocks = 0;
+    } else {
+      blocks++;
+    }
+
+    if (objs == OBJ_SAMPLE_INTERVAL) {
+      oop(p)->verify();
+      blk.the_obj = oop(p);
+      oop(p)->oop_iterate(&blk);
+      objs = 0;
+    } else {
+      objs++;
+    }
+    prev_p = p;
+    p += size;
+  }
+  guarantee(p == top(), "end of last object must match end of space");
+}
+
+void OffsetTableContigSpace::serialize_block_offset_array_offsets(
+                                                      SerializeOopClosure* soc) {
+  _offsets.serialize(soc);
+}
+
+
+int TenuredSpace::allowed_dead_ratio() const {
+  return MarkSweepDeadRatio;
+}
+
+
+int ContigPermSpace::allowed_dead_ratio() const {
+  return PermMarkSweepDeadRatio;
+}