# _xsaveopt64()

Saves the states of x87 FPU, MMX, XMM, YMM, and MXCSR registers to memory, optimizing the save operation if possible.

## Syntax

extern void _xsaveopt64(void *mem, unsigned __int64 save_mask);

## Arguments

mem

  A memory reference to `FXSAVE` area. The 512-bytes memory addressed by the reference must be 16-bytes aligned.

save_mask

  A bit mask specifying the extended states to be saved.

## Description

Saves the states of x87 FPU, MMX, XMM, YMM, and MXCSR registers to memory, optimizing the save operation if possible. This intrinsic maps to XSAVEOPT64 instruction.

Parent topic: Intrinsics for Saving and Restoring the Extended Processor States