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src/hotspot/share/oops/objLayout.cpp

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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 #include "oops/markWord.hpp"
26 #include "oops/objLayout.hpp"
27 #include "runtime/globals.hpp"
28 #include "utilities/debug.hpp"
29 
30 ObjLayout::Mode ObjLayout::_klass_mode = ObjLayout::Undefined;
31 int ObjLayout::_oop_base_offset_in_bytes = 0;
32 bool ObjLayout::_oop_has_klass_gap = false;
33 
34 void ObjLayout::initialize() {
35 #ifdef _LP64
36   assert(_klass_mode == Undefined, "ObjLayout initialized twice");
37   if (UseCompactObjectHeaders) {
38     _klass_mode = Compact;
39     _oop_base_offset_in_bytes = sizeof(markWord);
40     _oop_has_klass_gap = false;
41   } else if (UseCompressedClassPointers) {
42     _klass_mode = Compressed;
43     _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(narrowKlass);
44     _oop_has_klass_gap = true;
45   } else {
46     _klass_mode = Uncompressed;
47     _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(Klass*);
48     _oop_has_klass_gap = false;
49   }
50 #else
51   assert(_klass_mode == Undefined, "ObjLayout initialized twice");
52   assert(!UseCompactObjectHeaders, "COH unsupported on 32-bit");
53   // We support +-UseCompressedClassPointers on 32-bit, but the layout
54   // is exactly the same as it was with uncompressed klass pointers
55   _klass_mode = UseCompressedClassPointers ? Compressed : Uncompressed;
56   _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(Klass*);
57   _oop_has_klass_gap = false;
58 #endif
59 }

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 #include "oops/markWord.hpp"
26 #include "oops/objLayout.hpp"
27 #include "runtime/globals.hpp"
28 #include "utilities/debug.hpp"
29 
30 ObjLayout::Mode ObjLayout::_klass_mode = ObjLayout::Undefined;
31 int ObjLayout::_oop_base_offset_in_bytes = 0;
32 bool ObjLayout::_oop_has_klass_gap = false;
33 
34 void ObjLayout::initialize() {
35 #ifdef _LP64
36   assert(_klass_mode == Undefined, "ObjLayout initialized twice");
37   if (UseCompactObjectHeaders) {
38     _klass_mode = Compact;
39     _oop_base_offset_in_bytes = sizeof(uint32_t);
40     _oop_has_klass_gap = true;
41   } else if (UseCompressedClassPointers) {
42     _klass_mode = Compressed;
43     _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(narrowKlass);
44     _oop_has_klass_gap = true;
45   } else {
46     _klass_mode = Uncompressed;
47     _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(Klass*);
48     _oop_has_klass_gap = false;
49   }
50 #else
51   assert(_klass_mode == Undefined, "ObjLayout initialized twice");
52   assert(!UseCompactObjectHeaders, "COH unsupported on 32-bit");
53   // We support +-UseCompressedClassPointers on 32-bit, but the layout
54   // is exactly the same as it was with uncompressed klass pointers
55   _klass_mode = UseCompressedClassPointers ? Compressed : Uncompressed;
56   _oop_base_offset_in_bytes = sizeof(markWord) + sizeof(Klass*);
57   _oop_has_klass_gap = false;
58 #endif
59 }
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