1365   }

  1365   }

  1366 

  1366 

  1367   // On MP platform loads could return 'stale' values in some cases.

  1367   // On MP platform loads could return 'stale' values in some cases.

  1368   // That is acceptable since either CAS or slow case path is taken in the worst case.

  1368   // That is acceptable since either CAS or slow case path is taken in the worst case.

  1369 

  1369 

  1371   cmp(tmp_reg, markWord::biased_lock_pattern);

  1371   cmp(tmp_reg, markWord::biased_lock_pattern);

  1372 

  1372 

  1373   b(cas_label, ne);

  1373   b(cas_label, ne);

  1374 

  1374 

  1375   // The bias pattern is present in the object's header. Need to check

  1375   // The bias pattern is present in the object's header. Need to check

  1399   // header.

  1399   // header.

  1400 

  1400 

  1401   // If the low three bits in the xor result aren't clear, that means

  1401   // If the low three bits in the xor result aren't clear, that means

  1402   // the prototype header is no longer biased and we have to revoke

  1402   // the prototype header is no longer biased and we have to revoke

  1403   // the bias on this object.

  1403   // the bias on this object.

  1405   b(try_revoke_bias, ne);

  1405   b(try_revoke_bias, ne);

  1406 

  1406 

  1407   // Biasing is still enabled for this data type. See whether the

  1407   // Biasing is still enabled for this data type. See whether the

  1408   // epoch of the current bias is still valid, meaning that the epoch

  1408   // epoch of the current bias is still valid, meaning that the epoch

  1409   // bits of the mark word are equal to the epoch bits of the

  1409   // bits of the mark word are equal to the epoch bits of the

  1411   // only change at a safepoint.) If not, attempt to rebias the object

  1411   // only change at a safepoint.) If not, attempt to rebias the object

  1412   // toward the current thread. Note that we must be absolutely sure

  1412   // toward the current thread. Note that we must be absolutely sure

  1413   // that the current epoch is invalid in order to do this because

  1413   // that the current epoch is invalid in order to do this because

  1414   // otherwise the manipulations it performs on the mark word are

  1414   // otherwise the manipulations it performs on the mark word are

  1415   // illegal.

  1415   // illegal.

  1417   b(try_rebias, ne);

  1417   b(try_rebias, ne);

  1418 

  1418 

  1419   // tmp_reg has the age, epoch and pattern bits cleared

  1419   // tmp_reg has the age, epoch and pattern bits cleared

  1420   // The remaining (owner) bits are (Thread ^ current_owner)

  1420   // The remaining (owner) bits are (Thread ^ current_owner)

  1421 

  1421 

  1517   // a higher level. Second, if the bias was revoked while we held the

  1517   // a higher level. Second, if the bias was revoked while we held the

  1518   // lock, the object could not be rebiased toward another thread, so

  1518   // lock, the object could not be rebiased toward another thread, so

  1519   // the bias bit would be clear.

  1519   // the bias bit would be clear.

  1520   ldr(tmp_reg, Address(obj_reg, oopDesc::mark_offset_in_bytes()));

  1520   ldr(tmp_reg, Address(obj_reg, oopDesc::mark_offset_in_bytes()));

  1521 

  1521 

  1523   cmp(tmp_reg, markWord::biased_lock_pattern);

  1523   cmp(tmp_reg, markWord::biased_lock_pattern);

  1524   b(done, eq);

  1524   b(done, eq);

  1525 }

  1525 }

  1526 

  1526 

  1527 

  1527