src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp

*** 63,73 ****
    // save unlocked object header into the displaced header location on the stack
    movptr(Address(disp_hdr, 0), hdr);
    // test if object header is still the same (i.e. unlocked), and if so, store the
    // displaced header address in the object header - if it is not the same, get the
    // object header instead
!   if (os::is_MP()) MacroAssembler::lock(); // must be immediately before cmpxchg!
    cmpxchgptr(disp_hdr, Address(obj, hdr_offset));
    // if the object header was the same, we're done
    if (PrintBiasedLockingStatistics) {
      cond_inc32(Assembler::equal,
                 ExternalAddress((address)BiasedLocking::fast_path_entry_count_addr()));
--- 63,73 ----
    // save unlocked object header into the displaced header location on the stack
    movptr(Address(disp_hdr, 0), hdr);
    // test if object header is still the same (i.e. unlocked), and if so, store the
    // displaced header address in the object header - if it is not the same, get the
    // object header instead
!   MacroAssembler::lock(); // must be immediately before cmpxchg!
    cmpxchgptr(disp_hdr, Address(obj, hdr_offset));
    // if the object header was the same, we're done
    if (PrintBiasedLockingStatistics) {
      cond_inc32(Assembler::equal,
                 ExternalAddress((address)BiasedLocking::fast_path_entry_count_addr()));
*** 124,134 ****
    }
    verify_oop(obj);
    // test if object header is pointing to the displaced header, and if so, restore
    // the displaced header in the object - if the object header is not pointing to
    // the displaced header, get the object header instead
!   if (os::is_MP()) MacroAssembler::lock(); // must be immediately before cmpxchg!
    cmpxchgptr(hdr, Address(obj, hdr_offset));
    // if the object header was not pointing to the displaced header,
    // we do unlocking via runtime call
    jcc(Assembler::notEqual, slow_case);
    // done
--- 124,134 ----
    }
    verify_oop(obj);
    // test if object header is pointing to the displaced header, and if so, restore
    // the displaced header in the object - if the object header is not pointing to
    // the displaced header, get the object header instead
!   MacroAssembler::lock(); // must be immediately before cmpxchg!
    cmpxchgptr(hdr, Address(obj, hdr_offset));
    // if the object header was not pointing to the displaced header,
    // we do unlocking via runtime call
    jcc(Assembler::notEqual, slow_case);
    // done