--- a/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp Sat Apr 02 05:39:25 2016 +0200
+++ b/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp Fri Apr 01 10:16:31 2016 +0200
@@ -30,7 +30,6 @@
#include "gc/shared/blockOffsetTable.inline.hpp"
#include "gc/shared/collectedHeap.inline.hpp"
#include "gc/shared/genCollectedHeap.hpp"
-#include "gc/shared/liveRange.hpp"
#include "gc/shared/space.inline.hpp"
#include "gc/shared/spaceDecorator.hpp"
#include "memory/allocation.inline.hpp"
--- a/hotspot/src/share/vm/gc/g1/heapRegion.cpp Sat Apr 02 05:39:25 2016 +0200
+++ b/hotspot/src/share/vm/gc/g1/heapRegion.cpp Fri Apr 01 10:16:31 2016 +0200
@@ -34,7 +34,6 @@
#include "gc/g1/heapRegionRemSet.hpp"
#include "gc/g1/heapRegionTracer.hpp"
#include "gc/shared/genOopClosures.inline.hpp"
-#include "gc/shared/liveRange.hpp"
#include "gc/shared/space.inline.hpp"
#include "logging/log.hpp"
#include "memory/iterator.hpp"
--- a/hotspot/src/share/vm/gc/parallel/psMarkSweepDecorator.cpp Sat Apr 02 05:39:25 2016 +0200
+++ b/hotspot/src/share/vm/gc/parallel/psMarkSweepDecorator.cpp Fri Apr 01 10:16:31 2016 +0200
@@ -29,7 +29,6 @@
#include "gc/parallel/psMarkSweep.hpp"
#include "gc/parallel/psMarkSweepDecorator.hpp"
#include "gc/serial/markSweep.inline.hpp"
-#include "gc/shared/liveRange.hpp"
#include "gc/shared/spaceDecorator.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/prefetch.inline.hpp"
@@ -107,9 +106,6 @@
HeapWord* end_of_live= q; /* One byte beyond the last byte of the last
live object. */
HeapWord* first_dead = space()->end(); /* The first dead object. */
- LiveRange* liveRange = NULL; /* The current live range, recorded in the
- first header of preceding free area. */
- _first_dead = first_dead;
const intx interval = PrefetchScanIntervalInBytes;
@@ -231,17 +227,8 @@
}
}
- /* for the previous LiveRange, record the end of the live objects. */
- if (liveRange) {
- liveRange->set_end(q);
- }
-
- /* record the current LiveRange object.
- * liveRange->start() is overlaid on the mark word.
- */
- liveRange = (LiveRange*)q;
- liveRange->set_start(end);
- liveRange->set_end(end);
+ // q is a pointer to a dead object. Use this dead memory to store a pointer to the next live object.
+ (*(HeapWord**)q) = end;
/* see if this is the first dead region. */
if (q < first_dead) {
@@ -254,9 +241,6 @@
}
assert(q == t, "just checking");
- if (liveRange != NULL) {
- liveRange->set_end(q);
- }
_end_of_live = end_of_live;
if (end_of_live < first_dead) {
first_dead = end_of_live;
@@ -307,9 +291,8 @@
if (_first_dead == t) {
q = t;
} else {
- // $$$ This is funky. Using this to read the previously written
- // LiveRange. See also use below.
- q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer();
+ // The first dead object should contain a pointer to the first live object
+ q = *(HeapWord**)_first_dead;
}
}
const intx interval = PrefetchScanIntervalInBytes;
@@ -325,11 +308,11 @@
debug_only(prev_q = q);
q += size;
} else {
- // q is not a live object, so its mark should point at the next
- // live object
debug_only(prev_q = q);
- q = (HeapWord*) oop(q)->mark()->decode_pointer();
- assert(q > prev_q, "we should be moving forward through memory");
+ // The first dead object is no longer an object. At that memory address,
+ // there is a pointer to the first live object that the previous phase found.
+ q = *(HeapWord**)q;
+ assert(q > prev_q, "we should be moving forward through memory, q: " PTR_FORMAT ", prev_q: " PTR_FORMAT, p2i(q), p2i(prev_q));
}
}
--- a/hotspot/src/share/vm/gc/shared/liveRange.hpp Sat Apr 02 05:39:25 2016 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,55 +0,0 @@
-/*
- * Copyright (c) 2001, 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.
- *
- */
-
-#ifndef SHARE_VM_GC_SHARED_LIVERANGE_HPP
-#define SHARE_VM_GC_SHARED_LIVERANGE_HPP
-
-#include "memory/memRegion.hpp"
-#include "utilities/copy.hpp"
-
-// This is a shared helper class used during phase 3 and 4 to move all the objects
-// Dead regions in a Space are linked together to keep track of the live regions
-// so that the live data can be traversed quickly without having to look at each
-// object.
-
-class LiveRange: public MemRegion {
-public:
- LiveRange(HeapWord* bottom, HeapWord* top): MemRegion(bottom, top) {}
-
- void set_end(HeapWord* e) {
- assert(e >= start(), "should be a non-zero range");
- MemRegion::set_end(e);
- }
- void set_word_size(size_t ws) {
- MemRegion::set_word_size(ws);
- }
-
- LiveRange * next() { return (LiveRange *) end(); }
-
- void move_to(HeapWord* destination) {
- Copy::aligned_conjoint_words(start(), destination, word_size());
- }
-};
-
-#endif // SHARE_VM_GC_SHARED_LIVERANGE_HPP
--- a/hotspot/src/share/vm/gc/shared/space.cpp Sat Apr 02 05:39:25 2016 +0200
+++ b/hotspot/src/share/vm/gc/shared/space.cpp Fri Apr 01 10:16:31 2016 +0200
@@ -30,7 +30,6 @@
#include "gc/shared/collectedHeap.inline.hpp"
#include "gc/shared/genCollectedHeap.hpp"
#include "gc/shared/genOopClosures.inline.hpp"
-#include "gc/shared/liveRange.hpp"
#include "gc/shared/space.hpp"
#include "gc/shared/space.inline.hpp"
#include "gc/shared/spaceDecorator.hpp"
--- a/hotspot/src/share/vm/gc/shared/space.inline.hpp Sat Apr 02 05:39:25 2016 +0200
+++ b/hotspot/src/share/vm/gc/shared/space.inline.hpp Fri Apr 01 10:16:31 2016 +0200
@@ -28,7 +28,6 @@
#include "gc/serial/markSweep.inline.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/generation.hpp"
-#include "gc/shared/liveRange.hpp"
#include "gc/shared/space.hpp"
#include "gc/shared/spaceDecorator.hpp"
#include "memory/universe.hpp"
@@ -117,9 +116,6 @@
HeapWord* end_of_live= q; // One byte beyond the last byte of the last
// live object.
HeapWord* first_dead = space->end(); // The first dead object.
- LiveRange* liveRange = NULL; // The current live range, recorded in the
- // first header of preceding free area.
- space->_first_dead = first_dead;
const intx interval = PrefetchScanIntervalInBytes;
@@ -158,16 +154,8 @@
// otherwise, it really is a free region.
- // for the previous LiveRange, record the end of the live objects.
- if (liveRange) {
- liveRange->set_end(q);
- }
-
- // record the current LiveRange object.
- // liveRange->start() is overlaid on the mark word.
- liveRange = (LiveRange*)q;
- liveRange->set_start(end);
- liveRange->set_end(end);
+ // q is a pointer to a dead object. Use this dead memory to store a pointer to the next live object.
+ (*(HeapWord**)q) = end;
// see if this is the first dead region.
if (q < first_dead) {
@@ -180,9 +168,6 @@
}
assert(q == t, "just checking");
- if (liveRange != NULL) {
- liveRange->set_end(q);
- }
space->_end_of_live = end_of_live;
if (end_of_live < first_dead) {
first_dead = end_of_live;
@@ -227,9 +212,9 @@
if (space->_first_dead == t) {
q = t;
} else {
- // $$$ This is funky. Using this to read the previously written
- // LiveRange. See also use below.
- q = (HeapWord*)oop(space->_first_dead)->mark()->decode_pointer();
+ // The first dead object is no longer an object. At that memory address,
+ // there is a pointer to the first live object that the previous phase found.
+ q = *((HeapWord**)(space->_first_dead));
}
}
@@ -247,11 +232,10 @@
debug_only(prev_q = q);
q += size;
} else {
- // q is not a live object, so its mark should point at the next
- // live object
debug_only(prev_q = q);
- q = (HeapWord*) oop(q)->mark()->decode_pointer();
- assert(q > prev_q, "we should be moving forward through memory");
+ // q is not a live object, instead it points at the next live object
+ q = *(HeapWord**)q;
+ assert(q > prev_q, "we should be moving forward through memory, q: " PTR_FORMAT ", prev_q: " PTR_FORMAT, p2i(q), p2i(prev_q));
}
}