# 1.27.0[−][src]Function core::arch::x86_64::_xsaveopt

    pub unsafe fn _xsaveopt(mem_addr: *mut u8, save_mask: u64)

This is supported on x86-64 and target feature `xsave,xsaveopt` only.

Performs a full or partial save of the enabled processor states to memory at `mem_addr`.

State is saved based on bits `[62:0]` in `save_mask` and `XCR0`. `mem_addr` must be aligned on a 64-byte boundary. The hardware may optimize the manner in which data is saved. The performance of this instruction will be equal to or better than using the `XSAVE` instruction.

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