src/hotspot/share/gc/g1/heapRegion.inline.hpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2001, 2018, 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.
  *
  */

 #ifndef SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP
 #define SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP

 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
 #include "gc/g1/g1CollectedHeap.inline.hpp"
 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
 #include "gc/g1/heapRegion.hpp"
 #include "gc/shared/space.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/prefetch.inline.hpp"
 #include "utilities/align.hpp"

 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
                                                   size_t desired_word_size,
                                                   size_t* actual_size) {
   HeapWord* obj = top();
   size_t available = pointer_delta(end(), obj);
   size_t want_to_allocate = MIN2(available, desired_word_size);
   if (want_to_allocate >= min_word_size) {
     HeapWord* new_top = obj + want_to_allocate;
     set_top(new_top);
     assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
     *actual_size = want_to_allocate;
     return obj;
   } else {
     return NULL;
   }
 }

 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
                                                       size_t desired_word_size,
                                                       size_t* actual_size) {
   do {
     HeapWord* obj = top();
     size_t available = pointer_delta(end(), obj);
     size_t want_to_allocate = MIN2(available, desired_word_size);
     if (want_to_allocate >= min_word_size) {
       HeapWord* new_top = obj + want_to_allocate;
       HeapWord* result = Atomic::cmpxchg(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");
         *actual_size = want_to_allocate;
         return obj;
       }
     } else {
       return NULL;
     }
   } while (true);
 }

 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
                                              size_t desired_word_size,
                                              size_t* actual_size) {
   HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
   if (res != NULL) {
     _bot_part.alloc_block(res, *actual_size);
   }
   return res;
 }

 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
   size_t temp;
   return allocate(word_size, word_size, &temp);
 }

 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
   size_t temp;
   return par_allocate(word_size, word_size, &temp);
 }

 // Because of the requirement of keeping "_offsets" up to date with the
 // allocations, we sequentialize these with a lock.  Therefore, best if
 // this is used for larger LAB allocations only.
 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
                                                  size_t desired_word_size,
                                                  size_t* actual_size) {
   MutexLocker x(&_par_alloc_lock);
   return allocate(min_word_size, desired_word_size, actual_size);
 }

 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
   return _bot_part.block_start(p);
 }

 inline HeapWord*
 G1ContiguousSpace::block_start_const(const void* p) const {
   return _bot_part.block_start_const(p);
 }

 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
   HeapWord* addr = (HeapWord*) obj;

   assert(addr < top(), "must be");
   assert(!is_closed_archive(),
          "Closed archive regions should not have references into other regions");
   assert(!is_humongous(), "Humongous objects not handled here");
   bool obj_is_dead = is_obj_dead(obj, prev_bitmap);

   if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
     assert(!block_is_obj(addr), "must be");
     *size = block_size_using_bitmap(addr, prev_bitmap);
   } else {
     assert(block_is_obj(addr), "must be");
     *size = obj->size();
   }
   return obj_is_dead;
 }

 inline bool
 HeapRegion::block_is_obj(const HeapWord* p) const {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   if (!this->is_in(p)) {
     assert(is_continues_humongous(), "This case can only happen for humongous regions");
     return (p == humongous_start_region()->bottom());
   }
   if (ClassUnloadingWithConcurrentMark) {
     return !g1h->is_obj_dead(oop(p), this);
   }
   return p < top();
 }

 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
   assert(ClassUnloadingWithConcurrentMark,
          "All blocks should be objects if class unloading isn't used, so this method should not be called. "
          "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
          "addr: " PTR_FORMAT,
          p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));

   // Old regions' dead objects may have dead classes
   // We need to find the next live object using the bitmap
   HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());

   assert(next > addr, "must get the next live object");
   return pointer_delta(next, addr);
 }

 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
   assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
   return !obj_allocated_since_prev_marking(obj) &&
          !prev_bitmap->is_marked((HeapWord*)obj) &&
          !is_open_archive();
 }

 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
   if (addr == top()) {
     return pointer_delta(end(), addr);
   }

   if (block_is_obj(addr)) {
     return oop(addr)->size();
   }

   return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
 }

 inline void HeapRegion::complete_compaction() {
   // Reset space and bot after compaction is complete if needed.
   reset_after_compaction();
   if (used_region().is_empty()) {
     reset_bot();
   }

   // After a compaction the mark bitmap is invalid, so we must
   // treat all objects as being inside the unmarked area.
   zero_marked_bytes();
   init_top_at_mark_start();

   // Clear unused heap memory in debug builds.
   if (ZapUnusedHeapArea) {
     mangle_unused_area();
   }
 }

 template<typename ApplyToMarkedClosure>
 inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
   HeapWord* limit = scan_limit();
   HeapWord* next_addr = bottom();

   while (next_addr < limit) {
     Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
     // This explicit is_marked check is a way to avoid
     // some extra work done by get_next_marked_addr for
     // the case where next_addr is marked.
     if (bitmap->is_marked(next_addr)) {
       oop current = oop(next_addr);
       next_addr += closure->apply(current);
     } else {
       next_addr = bitmap->get_next_marked_addr(next_addr, limit);
     }
   }

   assert(next_addr == limit, "Should stop the scan at the limit.");
 }

 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
                                                          size_t desired_word_size,
                                                          size_t* actual_word_size) {
   assert(is_young(), "we can only skip BOT updates on young regions");
   return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
 }

 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
   size_t temp;
   return allocate_no_bot_updates(word_size, word_size, &temp);
 }

 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
                                                      size_t desired_word_size,
                                                      size_t* actual_word_size) {
   assert(is_young(), "we can only skip BOT updates on young regions");
   return allocate_impl(min_word_size, desired_word_size, actual_word_size);
 }

 inline void HeapRegion::note_start_of_marking() {
   _next_marked_bytes = 0;
   _next_top_at_mark_start = top();
 }

 inline void HeapRegion::note_end_of_marking() {
   _prev_top_at_mark_start = _next_top_at_mark_start;
   _next_top_at_mark_start = bottom();
   _prev_marked_bytes = _next_marked_bytes;
   _next_marked_bytes = 0;
 }

 inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
   if (is_survivor()) {
     // This is how we always allocate survivors.
     assert(_next_top_at_mark_start == bottom(), "invariant");
   } else {
     if (during_initial_mark) {
       // During initial-mark we'll explicitly mark any objects on old
       // regions that are pointed to by roots. Given that explicit
       // marks only make sense under NTAMS it'd be nice if we could
       // check that condition if we wanted to. Given that we don't
       // know where the top of this region will end up, we simply set
       // NTAMS to the end of the region so all marks will be below
       // NTAMS. We'll set it to the actual top when we retire this region.
       _next_top_at_mark_start = end();
     } else {
       // We could have re-used this old region as to-space over a
       // couple of GCs since the start of the concurrent marking
       // cycle. This means that [bottom,NTAMS) will contain objects
       // copied up to and including initial-mark and [NTAMS, top)
       // will contain objects copied during the concurrent marking cycle.
       assert(top() >= _next_top_at_mark_start, "invariant");
     }
   }
 }

 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
   if (is_survivor()) {
     // This is how we always allocate survivors.
     assert(_next_top_at_mark_start == bottom(), "invariant");
   } else {
     if (during_initial_mark) {
       // See the comment for note_start_of_copying() for the details
       // on this.
       assert(_next_top_at_mark_start == end(), "pre-condition");
       _next_top_at_mark_start = top();
     } else {
       // See the comment for note_start_of_copying() for the details
       // on this.
       assert(top() >= _next_top_at_mark_start, "invariant");
     }
   }
 }

 inline bool HeapRegion::in_collection_set() const {
   return G1CollectedHeap::heap()->is_in_cset(this);
 }

 template <class Closure, bool is_gc_active>
 bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
                                               Closure* cl,
                                               G1CollectedHeap* g1h) {
   assert(is_humongous(), "precondition");
   HeapRegion* sr = humongous_start_region();
   oop obj = oop(sr->bottom());

   // If concurrent and klass_or_null is NULL, then space has been
   // allocated but the object has not yet been published by setting
   // the klass.  That can only happen if the card is stale.  However,
   // we've already set the card clean, so we must return failure,
   // since the allocating thread could have performed a write to the
   // card that might be missed otherwise.
   if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
     return false;
   }

   // We have a well-formed humongous object at the start of sr.
   // Only filler objects follow a humongous object in the containing
   // regions, and we can ignore those.  So only process the one
   // humongous object.
   if (!g1h->is_obj_dead(obj, sr)) {
     if (obj->is_objArray() || (sr->bottom() < mr.start())) {
       // objArrays are always marked precisely, so limit processing
       // with mr.  Non-objArrays might be precisely marked, and since
       // it's humongous it's worthwhile avoiding full processing.
       // However, the card could be stale and only cover filler
       // objects.  That should be rare, so not worth checking for;
       // instead let it fall out from the bounded iteration.
       obj->oop_iterate(cl, mr);
     } else {
       // If obj is not an objArray and mr contains the start of the
       // obj, then this could be an imprecise mark, and we need to
       // process the entire object.
       obj->oop_iterate(cl);
     }
   }
   return true;
 }

 template <bool is_gc_active, class Closure>
 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
                                                   Closure* cl) {
   assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   // Special handling for humongous regions.
   if (is_humongous()) {
     return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
   }
   assert(is_old(), "precondition");

   // Because mr has been trimmed to what's been allocated in this
   // region, the parts of the heap that are examined here are always
   // parsable; there's no need to use klass_or_null to detect
   // in-progress allocation.

   // Cache the boundaries of the memory region in some const locals
   HeapWord* const start = mr.start();
   HeapWord* const end = mr.end();

   // Find the obj that extends onto mr.start().
   // Update BOT as needed while finding start of (possibly dead)
   // object containing the start of the region.
   HeapWord* cur = block_start(start);

 #ifdef ASSERT
   {
     assert(cur <= start,
            "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
     HeapWord* next = cur + block_size(cur);
     assert(start < next,
            "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
   }
 #endif

   const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
   do {
     oop obj = oop(cur);
     assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
     assert(obj->klass_or_null() != NULL,
            "Unparsable heap at " PTR_FORMAT, p2i(cur));

     size_t size;
     bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);

     cur += size;
     if (!is_dead) {
       // Process live object's references.

       // Non-objArrays are usually marked imprecise at the object
       // start, in which case we need to iterate over them in full.
       // objArrays are precisely marked, but can still be iterated
       // over in full if completely covered.
       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
         obj->oop_iterate(cl);
       } else {
         obj->oop_iterate(cl, mr);
       }
     }
   } while (cur < end);

   return true;
 }

 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP
	/*
	* Copyright (c) 2001, 2018, 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.
	*
	*/

	#ifndef SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP
	#define SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP

	#include "gc/g1/g1BlockOffsetTable.inline.hpp"
	#include "gc/g1/g1CollectedHeap.inline.hpp"
	#include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
	#include "gc/g1/heapRegion.hpp"
	#include "gc/shared/space.hpp"
	#include "oops/oop.inline.hpp"
	#include "runtime/atomic.hpp"
	#include "runtime/prefetch.inline.hpp"
	#include "utilities/align.hpp"

	inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_size) {
	HeapWord* obj = top();
	size_t available = pointer_delta(end(), obj);
	size_t want_to_allocate = MIN2(available, desired_word_size);
	if (want_to_allocate >= min_word_size) {
	HeapWord* new_top = obj + want_to_allocate;
	set_top(new_top);
	assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
	*actual_size = want_to_allocate;
	return obj;
	} else {
	return NULL;
	}
	}

	inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_size) {
	do {
	HeapWord* obj = top();
	size_t available = pointer_delta(end(), obj);
	size_t want_to_allocate = MIN2(available, desired_word_size);
	if (want_to_allocate >= min_word_size) {
	HeapWord* new_top = obj + want_to_allocate;
	HeapWord* result = Atomic::cmpxchg(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");
	*actual_size = want_to_allocate;
	return obj;
	}
	} else {
	return NULL;
	}
	} while (true);
	}

	inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_size) {
	HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
	if (res != NULL) {
	_bot_part.alloc_block(res, *actual_size);
	}
	return res;
	}

	inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
	size_t temp;
	return allocate(word_size, word_size, &temp);
	}

	inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
	size_t temp;
	return par_allocate(word_size, word_size, &temp);
	}

	// Because of the requirement of keeping "_offsets" up to date with the
	// allocations, we sequentialize these with a lock. Therefore, best if
	// this is used for larger LAB allocations only.
	inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_size) {
	MutexLocker x(&_par_alloc_lock);
	return allocate(min_word_size, desired_word_size, actual_size);
	}

	inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
	return _bot_part.block_start(p);
	}

	inline HeapWord*
	G1ContiguousSpace::block_start_const(const void* p) const {
	return _bot_part.block_start_const(p);
	}

	inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
	HeapWord* addr = (HeapWord*) obj;

	assert(addr < top(), "must be");
	assert(!is_closed_archive(),
	"Closed archive regions should not have references into other regions");
	assert(!is_humongous(), "Humongous objects not handled here");
	bool obj_is_dead = is_obj_dead(obj, prev_bitmap);

	if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
	assert(!block_is_obj(addr), "must be");
	*size = block_size_using_bitmap(addr, prev_bitmap);
	} else {
	assert(block_is_obj(addr), "must be");
	*size = obj->size();
	}
	return obj_is_dead;
	}

	inline bool
	HeapRegion::block_is_obj(const HeapWord* p) const {
	G1CollectedHeap* g1h = G1CollectedHeap::heap();

	if (!this->is_in(p)) {
	assert(is_continues_humongous(), "This case can only happen for humongous regions");
	return (p == humongous_start_region()->bottom());
	}
	if (ClassUnloadingWithConcurrentMark) {
	return !g1h->is_obj_dead(oop(p), this);
	}
	return p < top();
	}

	inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
	assert(ClassUnloadingWithConcurrentMark,
	"All blocks should be objects if class unloading isn't used, so this method should not be called. "
	"HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
	"addr: " PTR_FORMAT,
	p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));

	// Old regions' dead objects may have dead classes
	// We need to find the next live object using the bitmap
	HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());

	assert(next > addr, "must get the next live object");
	return pointer_delta(next, addr);
	}

	inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
	assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
	return !obj_allocated_since_prev_marking(obj) &&
	!prev_bitmap->is_marked((HeapWord*)obj) &&
	!is_open_archive();
	}

	inline size_t HeapRegion::block_size(const HeapWord *addr) const {
	if (addr == top()) {
	return pointer_delta(end(), addr);
	}

	if (block_is_obj(addr)) {
	return oop(addr)->size();
	}

	return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
	}

	inline void HeapRegion::complete_compaction() {
	// Reset space and bot after compaction is complete if needed.
	reset_after_compaction();
	if (used_region().is_empty()) {
	reset_bot();
	}

	// After a compaction the mark bitmap is invalid, so we must
	// treat all objects as being inside the unmarked area.
	zero_marked_bytes();
	init_top_at_mark_start();

	// Clear unused heap memory in debug builds.
	if (ZapUnusedHeapArea) {
	mangle_unused_area();
	}
	}

	template<typename ApplyToMarkedClosure>
	inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
	HeapWord* limit = scan_limit();
	HeapWord* next_addr = bottom();

	while (next_addr < limit) {
	Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
	// This explicit is_marked check is a way to avoid
	// some extra work done by get_next_marked_addr for
	// the case where next_addr is marked.
	if (bitmap->is_marked(next_addr)) {
	oop current = oop(next_addr);
	next_addr += closure->apply(current);
	} else {
	next_addr = bitmap->get_next_marked_addr(next_addr, limit);
	}
	}

	assert(next_addr == limit, "Should stop the scan at the limit.");
	}

	inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_word_size) {
	assert(is_young(), "we can only skip BOT updates on young regions");
	return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
	}

	inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
	size_t temp;
	return allocate_no_bot_updates(word_size, word_size, &temp);
	}

	inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
	size_t desired_word_size,
	size_t* actual_word_size) {
	assert(is_young(), "we can only skip BOT updates on young regions");
	return allocate_impl(min_word_size, desired_word_size, actual_word_size);
	}

	inline void HeapRegion::note_start_of_marking() {
	_next_marked_bytes = 0;
	_next_top_at_mark_start = top();
	}

	inline void HeapRegion::note_end_of_marking() {
	_prev_top_at_mark_start = _next_top_at_mark_start;
	_next_top_at_mark_start = bottom();
	_prev_marked_bytes = _next_marked_bytes;
	_next_marked_bytes = 0;
	}

	inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
	if (is_survivor()) {
	// This is how we always allocate survivors.
	assert(_next_top_at_mark_start == bottom(), "invariant");
	} else {
	if (during_initial_mark) {
	// During initial-mark we'll explicitly mark any objects on old
	// regions that are pointed to by roots. Given that explicit
	// marks only make sense under NTAMS it'd be nice if we could
	// check that condition if we wanted to. Given that we don't
	// know where the top of this region will end up, we simply set
	// NTAMS to the end of the region so all marks will be below
	// NTAMS. We'll set it to the actual top when we retire this region.
	_next_top_at_mark_start = end();
	} else {
	// We could have re-used this old region as to-space over a
	// couple of GCs since the start of the concurrent marking
	// cycle. This means that [bottom,NTAMS) will contain objects
	// copied up to and including initial-mark and [NTAMS, top)
	// will contain objects copied during the concurrent marking cycle.
	assert(top() >= _next_top_at_mark_start, "invariant");
	}
	}
	}

	inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
	if (is_survivor()) {
	// This is how we always allocate survivors.
	assert(_next_top_at_mark_start == bottom(), "invariant");
	} else {
	if (during_initial_mark) {
	// See the comment for note_start_of_copying() for the details
	// on this.
	assert(_next_top_at_mark_start == end(), "pre-condition");
	_next_top_at_mark_start = top();
	} else {
	// See the comment for note_start_of_copying() for the details
	// on this.
	assert(top() >= _next_top_at_mark_start, "invariant");
	}
	}
	}

	inline bool HeapRegion::in_collection_set() const {
	return G1CollectedHeap::heap()->is_in_cset(this);
	}

	template <class Closure, bool is_gc_active>
	bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
	Closure* cl,
	G1CollectedHeap* g1h) {
	assert(is_humongous(), "precondition");
	HeapRegion* sr = humongous_start_region();
	oop obj = oop(sr->bottom());

	// If concurrent and klass_or_null is NULL, then space has been
	// allocated but the object has not yet been published by setting
	// the klass. That can only happen if the card is stale. However,
	// we've already set the card clean, so we must return failure,
	// since the allocating thread could have performed a write to the
	// card that might be missed otherwise.
	if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
	return false;
	}

	// We have a well-formed humongous object at the start of sr.
	// Only filler objects follow a humongous object in the containing
	// regions, and we can ignore those. So only process the one
	// humongous object.
	if (!g1h->is_obj_dead(obj, sr)) {
	if (obj->is_objArray() \|\| (sr->bottom() < mr.start())) {
	// objArrays are always marked precisely, so limit processing
	// with mr. Non-objArrays might be precisely marked, and since
	// it's humongous it's worthwhile avoiding full processing.
	// However, the card could be stale and only cover filler
	// objects. That should be rare, so not worth checking for;
	// instead let it fall out from the bounded iteration.
	obj->oop_iterate(cl, mr);
	} else {
	// If obj is not an objArray and mr contains the start of the
	// obj, then this could be an imprecise mark, and we need to
	// process the entire object.
	obj->oop_iterate(cl);
	}
	}
	return true;
	}

	template <bool is_gc_active, class Closure>
	bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
	Closure* cl) {
	assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
	G1CollectedHeap* g1h = G1CollectedHeap::heap();

	// Special handling for humongous regions.
	if (is_humongous()) {
	return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
	}
	assert(is_old(), "precondition");

	// Because mr has been trimmed to what's been allocated in this
	// region, the parts of the heap that are examined here are always
	// parsable; there's no need to use klass_or_null to detect
	// in-progress allocation.

	// Cache the boundaries of the memory region in some const locals
	HeapWord* const start = mr.start();
	HeapWord* const end = mr.end();

	// Find the obj that extends onto mr.start().
	// Update BOT as needed while finding start of (possibly dead)
	// object containing the start of the region.
	HeapWord* cur = block_start(start);

	#ifdef ASSERT
	{
	assert(cur <= start,
	"cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
	HeapWord* next = cur + block_size(cur);
	assert(start < next,
	"start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
	}
	#endif

	const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
	do {
	oop obj = oop(cur);
	assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
	assert(obj->klass_or_null() != NULL,
	"Unparsable heap at " PTR_FORMAT, p2i(cur));

	size_t size;
	bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);

	cur += size;
	if (!is_dead) {
	// Process live object's references.

	// Non-objArrays are usually marked imprecise at the object
	// start, in which case we need to iterate over them in full.
	// objArrays are precisely marked, but can still be iterated
	// over in full if completely covered.
	if (!obj->is_objArray() \|\| (((HeapWord*)obj) >= start && cur <= end)) {
	obj->oop_iterate(cl);
	} else {
	obj->oop_iterate(cl, mr);
	}
	}
	} while (cur < end);

	return true;
	}

	#endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP