--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/space.inline.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,353 @@
+/*
+ * Copyright (c) 2000, 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_SPACE_INLINE_HPP
+#define SHARE_VM_GC_SHARED_SPACE_INLINE_HPP
+
+#include "gc/serial/markSweep.inline.hpp"
+#include "gc/shared/collectedHeap.hpp"
+#include "gc/shared/generation.hpp"
+#include "gc/shared/space.hpp"
+#include "gc/shared/spaceDecorator.hpp"
+#include "memory/universe.hpp"
+#include "oops/oopsHierarchy.hpp"
+#include "runtime/prefetch.inline.hpp"
+#include "runtime/safepoint.hpp"
+
+inline HeapWord* Space::block_start(const void* p) {
+  return block_start_const(p);
+}
+
+inline HeapWord* OffsetTableContigSpace::allocate(size_t size) {
+  HeapWord* res = ContiguousSpace::allocate(size);
+  if (res != NULL) {
+    _offsets.alloc_block(res, size);
+  }
+  return res;
+}
+
+// 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* OffsetTableContigSpace::par_allocate(size_t size) {
+  MutexLocker x(&_par_alloc_lock);
+  // This ought to be just "allocate", because of the lock above, but that
+  // ContiguousSpace::allocate asserts that either the allocating thread
+  // holds the heap lock or it is the VM thread and we're at a safepoint.
+  // The best I (dld) could figure was to put a field in ContiguousSpace
+  // meaning "locking at safepoint taken care of", and set/reset that
+  // here.  But this will do for now, especially in light of the comment
+  // above.  Perhaps in the future some lock-free manner of keeping the
+  // coordination.
+  HeapWord* res = ContiguousSpace::par_allocate(size);
+  if (res != NULL) {
+    _offsets.alloc_block(res, size);
+  }
+  return res;
+}
+
+inline HeapWord*
+OffsetTableContigSpace::block_start_const(const void* p) const {
+  return _offsets.block_start(p);
+}
+
+size_t CompactibleSpace::obj_size(const HeapWord* addr) const {
+  return oop(addr)->size();
+}
+
+class DeadSpacer : StackObj {
+  size_t _allowed_deadspace_words;
+  bool _active;
+  CompactibleSpace* _space;
+
+public:
+  DeadSpacer(CompactibleSpace* space) : _space(space), _allowed_deadspace_words(0) {
+    size_t ratio = _space->allowed_dead_ratio();
+    _active = ratio > 0;
+
+    if (_active) {
+      assert(!UseG1GC, "G1 should not be using dead space");
+
+      // We allow some amount of garbage towards the bottom of the space, so
+      // we don't start compacting before there is a significant gain to be made.
+      // Occasionally, we want to ensure a full compaction, which is determined
+      // by the MarkSweepAlwaysCompactCount parameter.
+      if ((MarkSweep::total_invocations() % MarkSweepAlwaysCompactCount) != 0) {
+        _allowed_deadspace_words = (space->capacity() * ratio / 100) / HeapWordSize;
+      } else {
+        _active = false;
+      }
+    }
+  }
+
+
+  bool insert_deadspace(HeapWord* dead_start, HeapWord* dead_end) {
+    if (!_active) {
+      return false;
+    }
+
+    size_t dead_length = pointer_delta(dead_end, dead_start);
+    if (_allowed_deadspace_words >= dead_length) {
+      _allowed_deadspace_words -= dead_length;
+      CollectedHeap::fill_with_object(dead_start, dead_length);
+      oop obj = oop(dead_start);
+      obj->set_mark(obj->mark()->set_marked());
+
+      assert(dead_length == (size_t)obj->size(), "bad filler object size");
+      log_develop_trace(gc, compaction)("Inserting object to dead space: " PTR_FORMAT ", " PTR_FORMAT ", " SIZE_FORMAT "b",
+          p2i(dead_start), p2i(dead_end), dead_length * HeapWordSize);
+
+      return true;
+    } else {
+      _active = false;
+      return false;
+    }
+  }
+
+};
+
+template <class SpaceType>
+inline void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp) {
+  // Compute the new addresses for the live objects and store it in the mark
+  // Used by universe::mark_sweep_phase2()
+
+  // We're sure to be here before any objects are compacted into this
+  // space, so this is a good time to initialize this:
+  space->set_compaction_top(space->bottom());
+
+  if (cp->space == NULL) {
+    assert(cp->gen != NULL, "need a generation");
+    assert(cp->threshold == NULL, "just checking");
+    assert(cp->gen->first_compaction_space() == space, "just checking");
+    cp->space = cp->gen->first_compaction_space();
+    cp->threshold = cp->space->initialize_threshold();
+    cp->space->set_compaction_top(cp->space->bottom());
+  }
+
+  HeapWord* compact_top = cp->space->compaction_top(); // This is where we are currently compacting to.
+
+  DeadSpacer dead_spacer(space);
+
+  HeapWord*  end_of_live = space->bottom();  // One byte beyond the last byte of the last live object.
+  HeapWord*  first_dead = NULL; // The first dead object.
+
+  const intx interval = PrefetchScanIntervalInBytes;
+
+  HeapWord* cur_obj = space->bottom();
+  HeapWord* scan_limit = space->scan_limit();
+
+  while (cur_obj < scan_limit) {
+    assert(!space->scanned_block_is_obj(cur_obj) ||
+           oop(cur_obj)->mark()->is_marked() || oop(cur_obj)->mark()->is_unlocked() ||
+           oop(cur_obj)->mark()->has_bias_pattern(),
+           "these are the only valid states during a mark sweep");
+    if (space->scanned_block_is_obj(cur_obj) && oop(cur_obj)->is_gc_marked()) {
+      // prefetch beyond cur_obj
+      Prefetch::write(cur_obj, interval);
+      size_t size = space->scanned_block_size(cur_obj);
+      compact_top = cp->space->forward(oop(cur_obj), size, cp, compact_top);
+      cur_obj += size;
+      end_of_live = cur_obj;
+    } else {
+      // run over all the contiguous dead objects
+      HeapWord* end = cur_obj;
+      do {
+        // prefetch beyond end
+        Prefetch::write(end, interval);
+        end += space->scanned_block_size(end);
+      } while (end < scan_limit && (!space->scanned_block_is_obj(end) || !oop(end)->is_gc_marked()));
+
+      // see if we might want to pretend this object is alive so that
+      // we don't have to compact quite as often.
+      if (cur_obj == compact_top && dead_spacer.insert_deadspace(cur_obj, end)) {
+        oop obj = oop(cur_obj);
+        compact_top = cp->space->forward(obj, obj->size(), cp, compact_top);
+        end_of_live = end;
+      } else {
+        // otherwise, it really is a free region.
+
+        // cur_obj is a pointer to a dead object. Use this dead memory to store a pointer to the next live object.
+        *(HeapWord**)cur_obj = end;
+
+        // see if this is the first dead region.
+        if (first_dead == NULL) {
+          first_dead = cur_obj;
+        }
+      }
+
+      // move on to the next object
+      cur_obj = end;
+    }
+  }
+
+  assert(cur_obj == scan_limit, "just checking");
+  space->_end_of_live = end_of_live;
+  if (first_dead != NULL) {
+    space->_first_dead = first_dead;
+  } else {
+    space->_first_dead = end_of_live;
+  }
+
+  // save the compaction_top of the compaction space.
+  cp->space->set_compaction_top(compact_top);
+}
+
+template <class SpaceType>
+inline void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space) {
+  // adjust all the interior pointers to point at the new locations of objects
+  // Used by MarkSweep::mark_sweep_phase3()
+
+  HeapWord* cur_obj = space->bottom();
+  HeapWord* const end_of_live = space->_end_of_live;  // Established by "scan_and_forward".
+  HeapWord* const first_dead = space->_first_dead;    // Established by "scan_and_forward".
+
+  assert(first_dead <= end_of_live, "Stands to reason, no?");
+
+  const intx interval = PrefetchScanIntervalInBytes;
+
+  debug_only(HeapWord* prev_obj = NULL);
+  while (cur_obj < end_of_live) {
+    Prefetch::write(cur_obj, interval);
+    if (cur_obj < first_dead || oop(cur_obj)->is_gc_marked()) {
+      // cur_obj is alive
+      // point all the oops to the new location
+      size_t size = MarkSweep::adjust_pointers(oop(cur_obj));
+      size = space->adjust_obj_size(size);
+      debug_only(prev_obj = cur_obj);
+      cur_obj += size;
+    } else {
+      debug_only(prev_obj = cur_obj);
+      // cur_obj is not a live object, instead it points at the next live object
+      cur_obj = *(HeapWord**)cur_obj;
+      assert(cur_obj > prev_obj, "we should be moving forward through memory, cur_obj: " PTR_FORMAT ", prev_obj: " PTR_FORMAT, p2i(cur_obj), p2i(prev_obj));
+    }
+  }
+
+  assert(cur_obj == end_of_live, "just checking");
+}
+
+#ifdef ASSERT
+template <class SpaceType>
+inline void CompactibleSpace::verify_up_to_first_dead(SpaceType* space) {
+  HeapWord* cur_obj = space->bottom();
+
+  if (cur_obj < space->_end_of_live && space->_first_dead > cur_obj && !oop(cur_obj)->is_gc_marked()) {
+     // we have a chunk of the space which hasn't moved and we've reinitialized
+     // the mark word during the previous pass, so we can't use is_gc_marked for
+     // the traversal.
+     HeapWord* prev_obj = NULL;
+
+     while (cur_obj < space->_first_dead) {
+       size_t size = space->obj_size(cur_obj);
+       assert(!oop(cur_obj)->is_gc_marked(), "should be unmarked (special dense prefix handling)");
+       prev_obj = cur_obj;
+       cur_obj += size;
+     }
+  }
+}
+#endif
+
+template <class SpaceType>
+inline void CompactibleSpace::clear_empty_region(SpaceType* space) {
+  // Let's remember if we were empty before we did the compaction.
+  bool was_empty = space->used_region().is_empty();
+  // Reset space after compaction is complete
+  space->reset_after_compaction();
+  // We do this clear, below, since it has overloaded meanings for some
+  // space subtypes.  For example, OffsetTableContigSpace's that were
+  // compacted into will have had their offset table thresholds updated
+  // continuously, but those that weren't need to have their thresholds
+  // re-initialized.  Also mangles unused area for debugging.
+  if (space->used_region().is_empty()) {
+    if (!was_empty) space->clear(SpaceDecorator::Mangle);
+  } else {
+    if (ZapUnusedHeapArea) space->mangle_unused_area();
+  }
+}
+
+template <class SpaceType>
+inline void CompactibleSpace::scan_and_compact(SpaceType* space) {
+  // Copy all live objects to their new location
+  // Used by MarkSweep::mark_sweep_phase4()
+
+  verify_up_to_first_dead(space);
+
+  HeapWord* const bottom = space->bottom();
+  HeapWord* const end_of_live = space->_end_of_live;
+
+  assert(space->_first_dead <= end_of_live, "Invariant. _first_dead: " PTR_FORMAT " <= end_of_live: " PTR_FORMAT, p2i(space->_first_dead), p2i(end_of_live));
+  if (space->_first_dead == end_of_live && (bottom == end_of_live || !oop(bottom)->is_gc_marked())) {
+    // Nothing to compact. The space is either empty or all live object should be left in place.
+    clear_empty_region(space);
+    return;
+  }
+
+  const intx scan_interval = PrefetchScanIntervalInBytes;
+  const intx copy_interval = PrefetchCopyIntervalInBytes;
+
+  assert(bottom < end_of_live, "bottom: " PTR_FORMAT " should be < end_of_live: " PTR_FORMAT, p2i(bottom), p2i(end_of_live));
+  HeapWord* cur_obj = bottom;
+  if (space->_first_dead > cur_obj && !oop(cur_obj)->is_gc_marked()) {
+    // All object before _first_dead can be skipped. They should not be moved.
+    // A pointer to the first live object is stored at the memory location for _first_dead.
+    cur_obj = *(HeapWord**)(space->_first_dead);
+  }
+
+  debug_only(HeapWord* prev_obj = NULL);
+  while (cur_obj < end_of_live) {
+    if (!oop(cur_obj)->is_gc_marked()) {
+      debug_only(prev_obj = cur_obj);
+      // The first word of the dead object contains a pointer to the next live object or end of space.
+      cur_obj = *(HeapWord**)cur_obj;
+      assert(cur_obj > prev_obj, "we should be moving forward through memory");
+    } else {
+      // prefetch beyond q
+      Prefetch::read(cur_obj, scan_interval);
+
+      // size and destination
+      size_t size = space->obj_size(cur_obj);
+      HeapWord* compaction_top = (HeapWord*)oop(cur_obj)->forwardee();
+
+      // prefetch beyond compaction_top
+      Prefetch::write(compaction_top, copy_interval);
+
+      // copy object and reinit its mark
+      assert(cur_obj != compaction_top, "everything in this pass should be moving");
+      Copy::aligned_conjoint_words(cur_obj, compaction_top, size);
+      oop(compaction_top)->init_mark();
+      assert(oop(compaction_top)->klass() != NULL, "should have a class");
+
+      debug_only(prev_obj = cur_obj);
+      cur_obj += size;
+    }
+  }
+
+  clear_empty_region(space);
+}
+
+size_t ContiguousSpace::scanned_block_size(const HeapWord* addr) const {
+  return oop(addr)->size();
+}
+
+#endif // SHARE_VM_GC_SHARED_SPACE_INLINE_HPP