Looks like many x86 cores still do rename MXCSR, though Gracemont notably doesn't: https://chipsandcheese.com/2021/12/21/gracemont-revenge-of-the-atom-cores/ ht

Looks like many x86 cores still do rename MXCSR, though Gracemont notably doesn't: https://chipsandcheese.com/2021/12/21/gracemont-revenge-of-the-atom-cores/ https://chipsandcheese.com/2021/12/21/gracemont-revenge-of-t... Note that you wouldn't necessarily need to do a read-modify-write -- it'd suffice in most cases to just to save the old value and then reset the whole MXCSR for the scope requiring special treatment.