5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 //
26 // Free block maintenance for Concurrent Mark Sweep Generation
27 //
28 // The main data structure for free blocks are
29 // . an indexed array of small free blocks, and
30 // . a dictionary of large free blocks
31 //
32
33 // No virtuals in FreeChunk (don't want any vtables).
34
35 // A FreeChunk is merely a chunk that can be in a doubly linked list
36 // and has a size field. NOTE: FreeChunks are distinguished from allocated
37 // objects in two ways (by the sweeper), depending on whether the VM is 32 or
38 // 64 bits.
39 // In 32 bits or 64 bits without CompressedOops, the second word (prev) has the
40 // LSB set to indicate a free chunk; allocated objects' klass() pointers
41 // don't have their LSB set. The corresponding bit in the CMSBitMap is
42 // set when the chunk is allocated. There are also blocks that "look free"
43 // but are not part of the free list and should not be coalesced into larger
44 // free blocks. These free blocks have their two LSB's set.
124 set_mark(markOopDesc::prototype());
125 }
126 #endif
127 assert(!isFree(), "Error");
128 }
129
130 // Return the address past the end of this chunk
131 HeapWord* end() const { return ((HeapWord*) this) + size(); }
132
133 // debugging
134 void verify() const PRODUCT_RETURN;
135 void verifyList() const PRODUCT_RETURN;
136 void mangleAllocated(size_t size) PRODUCT_RETURN;
137 void mangleFreed(size_t size) PRODUCT_RETURN;
138
139 void print_on(outputStream* st);
140 };
141
142 extern size_t MinChunkSize;
143
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5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_FREECHUNK_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_FREECHUNK_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/markOop.hpp"
31 #include "runtime/mutex.hpp"
32 #include "utilities/debug.hpp"
33 #include "utilities/globalDefinitions.hpp"
34 #include "utilities/ostream.hpp"
35
36 //
37 // Free block maintenance for Concurrent Mark Sweep Generation
38 //
39 // The main data structure for free blocks are
40 // . an indexed array of small free blocks, and
41 // . a dictionary of large free blocks
42 //
43
44 // No virtuals in FreeChunk (don't want any vtables).
45
46 // A FreeChunk is merely a chunk that can be in a doubly linked list
47 // and has a size field. NOTE: FreeChunks are distinguished from allocated
48 // objects in two ways (by the sweeper), depending on whether the VM is 32 or
49 // 64 bits.
50 // In 32 bits or 64 bits without CompressedOops, the second word (prev) has the
51 // LSB set to indicate a free chunk; allocated objects' klass() pointers
52 // don't have their LSB set. The corresponding bit in the CMSBitMap is
53 // set when the chunk is allocated. There are also blocks that "look free"
54 // but are not part of the free list and should not be coalesced into larger
55 // free blocks. These free blocks have their two LSB's set.
135 set_mark(markOopDesc::prototype());
136 }
137 #endif
138 assert(!isFree(), "Error");
139 }
140
141 // Return the address past the end of this chunk
142 HeapWord* end() const { return ((HeapWord*) this) + size(); }
143
144 // debugging
145 void verify() const PRODUCT_RETURN;
146 void verifyList() const PRODUCT_RETURN;
147 void mangleAllocated(size_t size) PRODUCT_RETURN;
148 void mangleFreed(size_t size) PRODUCT_RETURN;
149
150 void print_on(outputStream* st);
151 };
152
153 extern size_t MinChunkSize;
154
155
156 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_FREECHUNK_HPP
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