i </em>only if RFBM[<em>i</em>] = 1 and XINUSE[<em>i</em>] = 1.<sup>1 </sup>(XINUSE is a bitmap by which the processor tracks the status of various state components. See Section 13.6, “Processor Tracking of XSAVEManaged State.”) Even if both bits are 1, XSAVEOPT may optimize and not save state component <em>i </em>if (1) state component <em>i </em>has not been modified since the last execution of XRSTOR or XRSTORS; and (2) this execution of XSAVES corresponds to that last execution of XRSTOR or XRSTORS 