11/*
2- * Copyright (c) 2018, 2019 , Oracle and/or its affiliates. All rights reserved.
2+ * Copyright (c) 2018, 2021 , Oracle and/or its affiliates. All rights reserved.
33 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
44 *
55 * This code is free software; you can redistribute it and/or modify it
@@ -46,8 +46,6 @@ public class ZPage extends VMObject implements LiveRegionsProvider {
4646 private static CIntegerField seqnumField ;
4747 private static long virtualFieldOffset ;
4848 private static AddressField topField ;
49- private static CIntegerField refcountField ;
50- private static long forwardingFieldOffset ;
5149
5250 static {
5351 VM .registerVMInitializedObserver ((o , d ) -> initialize (VM .getVM ().getTypeDataBase ()));
@@ -60,8 +58,6 @@ static private synchronized void initialize(TypeDataBase db) {
6058 seqnumField = type .getCIntegerField ("_seqnum" );
6159 virtualFieldOffset = type .getField ("_virtual" ).getOffset ();
6260 topField = type .getAddressField ("_top" );
63- refcountField = type .getCIntegerField ("_refcount" );
64- forwardingFieldOffset = type .getField ("_forwarding" ).getOffset ();
6561 }
6662
6763 public ZPage (Address addr ) {
@@ -84,28 +80,8 @@ private Address top() {
8480 return topField .getValue (addr );
8581 }
8682
87- private int refcount () {
88- // refcount is uint32_t so need to be cautious when using this field.
89- return refcountField .getJInt (addr );
90- }
91-
92- private ZForwardingTable forwarding () {
93- return VMObjectFactory .newObject (ZForwardingTable .class , addr .addOffsetTo (forwardingFieldOffset ));
94- }
95-
96- private boolean is_forwarding () {
97- return forwarding ().table () != null ;
98- }
99-
10083 private boolean is_relocatable () {
101- return is_active () && seqnum () < ZGlobals .ZGlobalSeqNum ();
102- }
103-
104- private boolean isPageRelocating () {
105- assert (is_active ());
106- // is_forwarding(): Has a (relocation) forwarding table
107- // is_relocatable(): Has not been freed yet
108- return is_forwarding () && is_relocatable ();
84+ return seqnum () < ZGlobals .ZGlobalSeqNum ();
10985 }
11086
11187 long start () {
@@ -116,31 +92,6 @@ long size() {
11692 return virtual ().end () - virtual ().start ();
11793 }
11894
119- Address forward_object (Address from ) {
120- // Lookup address in forwarding table
121- long from_offset = ZAddress .offset (from );
122- long from_index = (from_offset - start ()) >> object_alignment_shift ();
123- ZForwardingTableEntry entry = forwarding ().find (from_index );
124- assert (!entry .is_empty ());
125- assert (entry .from_index () == from_index );
126-
127- return ZAddress .good (entry .to_offset ());
128- }
129-
130- Address relocate_object (Address from ) {
131- // Lookup address in forwarding table
132- long from_offset = ZAddress .offset (from );
133- long from_index = (from_offset - start ()) >> object_alignment_shift ();
134- ZForwardingTableEntry entry = forwarding ().find (from_index );
135- if (!entry .is_empty () && entry .from_index () == from_index ) {
136- return ZAddress .good (entry .to_offset ());
137- }
138-
139- // There's no relocate operation in the SA.
140- // Mimic object pinning and return the good view of the from object.
141- return ZAddress .good (from );
142- }
143-
14495 long object_alignment_shift () {
14596 if (type () == ZGlobals .ZPageTypeSmall ) {
14697 return ZGlobals .ZObjectAlignmentSmallShift ();
@@ -156,8 +107,10 @@ long objectAlignmentSize() {
156107 return 1 << object_alignment_shift ();
157108 }
158109
159- public boolean is_active () {
160- return refcount () != 0 ;
110+ public boolean isIn (Address addr ) {
111+ long offset = ZAddress .offset (addr );
112+ // FIXME: it does not consider the sign.
113+ return (offset >= start ()) && (offset < top ().asLongValue ());
161114 }
162115
163116 private long getObjectSize (Address good ) {
@@ -173,72 +126,16 @@ private long getObjectSize(Address good) {
173126 return VM .getVM ().alignUp (obj .getObjectSize (), objectAlignmentSize ());
174127 }
175128
176- private void addNotRelocatedRegions (List <MemRegion > regions ) {
177- MemRegion mr = null ;
178-
179- // Some objects have already been forwarded to new locations.
180- long topValue = top ().asLongValue ();
181- for (long offsetValue = start (); offsetValue < topValue ;) {
182- Address from = ZAddress .good (ZUtils .longToAddress (offsetValue ));
183-
184- Address to = relocate_object (from );
185-
186- long byteSize ;
187- try {
188- byteSize = getObjectSize (to );
189- } catch (Exception e ) {
190- // Parsing the ZHeap is inherently unsafe
191- // when classes have been unloaded. Dead objects
192- // might have stale Klass pointers, and there's
193- // no way to get the size of the dead object.
194- //
195- // If possible, run with -XX:-ClassUnloading
196- // to ensure that all Klasses are kept alive.
197- System .err .println ("Unparsable regions found. Skipping: "
198- + from
199- + " "
200- + from .addOffsetTo (topValue - offsetValue ));
201-
202- // Can't proceed further. Just return the collected regions.
203- return ;
204- }
205-
206- if (from .equals (to )) {
207- // Not relocated - add region
208- if (mr == null ) {
209- mr = new MemRegion (from , 0 /* wordSize */ );
210- regions .add (mr );
211- }
212-
213- long wordSize = byteSize / VM .getVM ().getBytesPerWord ();
214- mr .setWordSize (mr .wordSize () + wordSize );
215- } else {
216- // Forwarded somewhere else, split region.
217- mr = null ;
218- }
219-
220- offsetValue += byteSize ;
221- }
222- }
223-
224129 public List <MemRegion > getLiveRegions () {
225- List <MemRegion > res = new ArrayList <>();
226-
227- if (isPageRelocating ()) {
228- addNotRelocatedRegions (res );
229- } else {
230- Address start = ZAddress .good (ZUtils .longToAddress (start ()));
130+ Address start = ZAddress .good (ZUtils .longToAddress (start ()));
231131
232- // Can't convert top() to a "good" address because it might
233- // be at the top of the "offset" range, and therefore also
234- // looks like one of the color bits. Instead use the "good"
235- // address and add the size.
236- long size = top ().asLongValue () - start ();
237- Address end = start .addOffsetTo (size );
238-
239- res .add (new MemRegion (start , end ));
240- }
132+ // Can't convert top() to a "good" address because it might
133+ // be at the top of the "offset" range, and therefore also
134+ // looks like one of the color bits. Instead use the "good"
135+ // address and add the size.
136+ long size = top ().asLongValue () - start ();
137+ Address end = start .addOffsetTo (size );
241138
242- return res ;
139+ return List . of ( new MemRegion ( start , end )) ;
243140 }
244141}
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