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_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
27
28 #include "oops/markWord.hpp"
29 #include "oops/oop.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 class ShenandoahForwarding {
33 public:
34 /* Gets forwardee from the given object. For a self-forwarded object
35 * (evacuation failure), returns the object itself.
36 */
37 static inline oop get_forwardee(oop obj);
38
39 /* Gets forwardee from the given object. Only from mutator thread.
40 * For a self-forwarded object, returns the object itself.
41 */
42 static inline oop get_forwardee_mutator(oop obj);
43
44 /* Returns the raw value from forwardee slot. For a self-forwarded
45 * object, returns the object itself.
46 */
47 static inline oop get_forwardee_raw(oop obj);
48
49 /* Returns the raw value from forwardee slot without any checks.
50 * Used for quick verification. For a self-forwarded object,
51 * returns the object itself.
52 */
53 static inline oop get_forwardee_raw_unchecked(oop obj);
54
55 /**
56 * Returns true if the object is forwarded (including self-forwarded),
57 * false otherwise.
58 */
59 static inline bool is_forwarded(oop obj);
60
61 /**
62 * Returns true iff obj has been self-forwarded (i.e. evacuation has
63 * failed for this object in the current cycle).
64 */
65 static inline bool is_self_forwarded(oop obj);
66
67 /* Tries to atomically update forwardee in $holder object to $update.
68 * Assumes $holder points at itself.
69 * Asserts $holder is in from-space.
70 * Asserts $update is in to-space.
71 *
72 * Returns the new object 'update' upon success, or
73 * the new forwardee that a competing thread installed. If another
74 * thread self-forwarded the object, returns the object itself.
75 */
76 static inline oop try_update_forwardee(oop obj, oop update);
77
78 /* Tries to atomically self-forward obj. Used by the evacuation path
79 * when the copy allocation fails: the failing thread installs the
|
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_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
27
28 #include "oops/markWord.hpp"
29 #include "oops/oop.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 class ShenandoahForwarding {
33 private:
34 static const uintptr_t FWDED_HASH_TRANSITION = 0b111;
35
36 public:
37 /* Gets forwardee from the given object. For a self-forwarded object
38 * (evacuation failure), returns the object itself.
39 */
40 static inline oop get_forwardee(oop obj);
41
42 /* Gets forwardee from the given object. Only from mutator thread.
43 * For a self-forwarded object, returns the object itself.
44 */
45 static inline oop get_forwardee_mutator(oop obj);
46
47 /* Returns the raw value from forwardee slot. For a self-forwarded
48 * object, returns the object itself.
49 */
50 static inline oop get_forwardee_raw(oop obj);
51
52 /* Returns the raw value from forwardee slot without any checks.
53 * Used for quick verification. For a self-forwarded object,
54 * returns the object itself.
55 */
56 static inline oop get_forwardee_raw_unchecked(oop obj);
57
58 /**
59 * Returns true if the object is forwarded (including self-forwarded),
60 * false otherwise.
61 */
62 static inline bool is_forwarded(oop obj);
63 static inline bool is_forwarded(markWord m);
64
65 /**
66 * Returns true iff the mark word's lock bits are marked_value (0b11),
67 * i.e. the upper bits encode a real forwardee pointer. This covers both
68 * normal-forwarded (0b011) and forward-expanded (0b111) states, and
69 * excludes self-forwarded states (0b100, 0b101, 0b110) whose upper bits
70 * still hold the original klass/hash/age metadata.
71 *
72 * Do NOT use markWord::is_marked() for this purpose -- it also returns
73 * true for self-forwarded objects.
74 */
75 static inline bool has_forwardee(markWord m);
76
77 /**
78 * Returns true iff obj has been self-forwarded (i.e. evacuation has
79 * failed for this object in the current cycle).
80 */
81 static inline bool is_self_forwarded(oop obj);
82
83 /* Tries to atomically update forwardee in $holder object to $update.
84 * Assumes $holder points at itself.
85 * Asserts $holder is in from-space.
86 * Asserts $update is in to-space.
87 *
88 * Returns the new object 'update' upon success, or
89 * the new forwardee that a competing thread installed. If another
90 * thread self-forwarded the object, returns the object itself.
91 */
92 static inline oop try_update_forwardee(oop obj, oop update);
93
94 /* Tries to atomically self-forward obj. Used by the evacuation path
95 * when the copy allocation fails: the failing thread installs the
|