You're correct. If you have:

  public int someField;
 
  public void inc() {
    someField += 1;
  }

that still compiles down to:

  GETFIELD [someField]
  ICONST_1
  IADD
  PUTFIELD [somefield]

whether 'someField' is volatile or not. The volatile just affects the load/store semantics of the GETFIELD/PUTFIELD ops. For atomic increment you have to go through something like AtomicInteger that will internally use an Unsafe instance to ensure it emits a platform-specific atomic increment instruction.