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    //! `i586`'s `xsave` and `xsaveopt` target feature intrinsics
    #![allow(clippy::module_name_repetitions)]

    #[cfg(test)]
    use stdsimd_test::assert_instr;

    #[allow(improper_ctypes)]
    extern "C" {
        #[link_name = "llvm.x86.xsave"]
        fn xsave(p: *mut u8, hi: u32, lo: u32) -> ();
        #[link_name = "llvm.x86.xrstor"]
        fn xrstor(p: *const u8, hi: u32, lo: u32) -> ();
        #[link_name = "llvm.x86.xsetbv"]
        fn xsetbv(v: u32, hi: u32, lo: u32) -> ();
        #[link_name = "llvm.x86.xsaveopt"]
        fn xsaveopt(p: *mut u8, hi: u32, lo: u32) -> ();
        #[link_name = "llvm.x86.xsavec"]
        fn xsavec(p: *mut u8, hi: u32, lo: u32) -> ();
        #[link_name = "llvm.x86.xsaves"]
        fn xsaves(p: *mut u8, hi: u32, lo: u32) -> ();
        #[link_name = "llvm.x86.xrstors"]
        fn xrstors(p: *const u8, hi: u32, lo: u32) -> ();
    }

    /// 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 format of the XSAVE area is detailed in Section 13.4, “XSAVE Area,” of
    /// Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xsave)
    #[inline]
    #[target_feature(enable = "xsave")]
    #[cfg_attr(test, assert_instr(xsave))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xsave(mem_addr: *mut u8, save_mask: u64) {
        xsave(mem_addr, (save_mask >> 32) as u32, save_mask as u32);
    }

    /// Performs a full or partial restore of the enabled processor states using
    /// the state information stored in memory at `mem_addr`.
    ///
    /// State is restored based on bits `[62:0]` in `rs_mask`, `XCR0`, and
    /// `mem_addr.HEADER.XSTATE_BV`. `mem_addr` must be aligned on a 64-byte
    /// boundary.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xrstor)
    #[inline]
    #[target_feature(enable = "xsave")]
    #[cfg_attr(test, assert_instr(xrstor))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xrstor(mem_addr: *const u8, rs_mask: u64) {
        xrstor(mem_addr, (rs_mask >> 32) as u32, rs_mask as u32);
    }

    /// `XFEATURE_ENABLED_MASK` for `XCR`
    ///
    /// This intrinsic maps to `XSETBV` instruction.
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub const _XCR_XFEATURE_ENABLED_MASK: u32 = 0;

    /// Copies 64-bits from `val` to the extended control register (`XCR`) specified
    /// by `a`.
    ///
    /// Currently only `XFEATURE_ENABLED_MASK` `XCR` is supported.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xsetbv)
    #[inline]
    #[target_feature(enable = "xsave")]
    #[cfg_attr(test, assert_instr(xsetbv))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xsetbv(a: u32, val: u64) {
        xsetbv(a, (val >> 32) as u32, val as u32);
    }

    /// Reads the contents of the extended control register `XCR`
    /// specified in `xcr_no`.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xgetbv)
    #[inline]
    #[target_feature(enable = "xsave")]
    #[cfg_attr(test, assert_instr(xgetbv))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xgetbv(xcr_no: u32) -> u64 {
        let eax: u32;
        let edx: u32;
        asm!("xgetbv" : "={eax}"(eax), "={edx}"(edx) : "{ecx}"(xcr_no));
        ((edx as u64) << 32) | (eax as u64)
    }

    /// 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.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xsaveopt)
    #[inline]
    #[target_feature(enable = "xsave,xsaveopt")]
    #[cfg_attr(test, assert_instr(xsaveopt))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xsaveopt(mem_addr: *mut u8, save_mask: u64) {
        xsaveopt(mem_addr, (save_mask >> 32) as u32, save_mask as u32);
    }

    /// Performs a full or partial save of the enabled processor states to memory
    /// at `mem_addr`.
    ///
    /// `xsavec` differs from `xsave` in that it uses compaction and that it may
    /// use init optimization. State is saved based on bits `[62:0]` in `save_mask`
    /// and `XCR0`. `mem_addr` must be aligned on a 64-byte boundary.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xsavec)
    #[inline]
    #[target_feature(enable = "xsave,xsavec")]
    #[cfg_attr(test, assert_instr(xsavec))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xsavec(mem_addr: *mut u8, save_mask: u64) {
        xsavec(mem_addr, (save_mask >> 32) as u32, save_mask as u32);
    }

    /// Performs a full or partial save of the enabled processor states to memory at
    /// `mem_addr`
    ///
    /// `xsaves` differs from xsave in that it can save state components
    /// corresponding to bits set in `IA32_XSS` `MSR` and that it may use the
    /// modified optimization. State is saved based on bits `[62:0]` in `save_mask`
    /// and `XCR0`. `mem_addr` must be aligned on a 64-byte boundary.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xsaves)
    #[inline]
    #[target_feature(enable = "xsave,xsaves")]
    #[cfg_attr(test, assert_instr(xsaves))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xsaves(mem_addr: *mut u8, save_mask: u64) {
        xsaves(mem_addr, (save_mask >> 32) as u32, save_mask as u32);
    }

    /// Performs a full or partial restore of the enabled processor states using the
    /// state information stored in memory at `mem_addr`.
    ///
    /// `xrstors` differs from `xrstor` in that it can restore state components
    /// corresponding to bits set in the `IA32_XSS` `MSR`; `xrstors` cannot restore
    /// from an `xsave` area in which the extended region is in the standard form.
    /// State is restored based on bits `[62:0]` in `rs_mask`, `XCR0`, and
    /// `mem_addr.HEADER.XSTATE_BV`. `mem_addr` must be aligned on a 64-byte
    /// boundary.
    ///
    /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_xrstors)
    #[inline]
    #[target_feature(enable = "xsave,xsaves")]
    #[cfg_attr(test, assert_instr(xrstors))]
    #[stable(feature = "simd_x86", since = "1.27.0")]
    pub unsafe fn _xrstors(mem_addr: *const u8, rs_mask: u64) {
        xrstors(mem_addr, (rs_mask >> 32) as u32, rs_mask as u32);
    }

    #[cfg(test)]
    mod tests {
        use std::{fmt, prelude::v1::*};

        use crate::core_arch::x86::*;
        use stdsimd_test::simd_test;

        #[repr(align(64))]
        struct XsaveArea {
            // max size for 256-bit registers is 800 bytes:
            // see https://software.intel.com/en-us/node/682996
            // max size for 512-bit registers is 2560 bytes:
            // FIXME: add source
            data: [u8; 2560],
        }

        impl XsaveArea {
            fn new() -> XsaveArea {
                XsaveArea { data: [0; 2560] }
            }
            fn ptr(&mut self) -> *mut u8 {
                &mut self.data[0] as *mut _ as *mut u8
            }
        }

        impl PartialEq<XsaveArea> for XsaveArea {
            fn eq(&self, other: &XsaveArea) -> bool {
                for i in 0..self.data.len() {
                    if self.data[i] != other.data[i] {
                        return false;
                    }
                }
                true
            }
        }

        impl fmt::Debug for XsaveArea {
            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                write!(f, "[")?;
                for i in 0..self.data.len() {
                    write!(f, "{}", self.data[i])?;
                    if i != self.data.len() - 1 {
                        write!(f, ", ")?;
                    }
                }
                write!(f, "]")
            }
        }

        // FIXME: https://github.com/rust-lang-nursery/stdsimd/issues/209
        /*
        #[simd_test(enable = "xsave")]
        unsafe fn xsave() {
            let m = 0xFFFFFFFFFFFFFFFF_u64; //< all registers
            let mut a = XsaveArea::new();
            let mut b = XsaveArea::new();

            _xsave(a.ptr(), m);
            _xrstor(a.ptr(), m);
            _xsave(b.ptr(), m);
            assert_eq!(a, b);
        }
        */

        #[simd_test(enable = "xsave")]
        unsafe fn xgetbv_xsetbv() {
            let xcr_n: u32 = _XCR_XFEATURE_ENABLED_MASK;

            let xcr: u64 = _xgetbv(xcr_n);
            // FIXME: XSETBV is a privileged instruction we should only test this
            // when running in privileged mode:
            //
            // _xsetbv(xcr_n, xcr);
            let xcr_cpy: u64 = _xgetbv(xcr_n);
            assert_eq!(xcr, xcr_cpy);
        }

        // FIXME: https://github.com/rust-lang-nursery/stdsimd/issues/209
        /*
        #[simd_test(enable = "xsave,xsaveopt")]
        unsafe fn xsaveopt() {
            let m = 0xFFFFFFFFFFFFFFFF_u64; //< all registers
            let mut a = XsaveArea::new();
            let mut b = XsaveArea::new();

            _xsaveopt(a.ptr(), m);
            _xrstor(a.ptr(), m);
            _xsaveopt(b.ptr(), m);
            assert_eq!(a, b);
        }
        */

        // FIXME: this looks like a bug in Intel's SDE:
        #[cfg(not(stdsimd_intel_sde))]
        #[simd_test(enable = "xsave,xsavec")]
        unsafe fn xsavec() {
            let m = 0xFFFFFFFFFFFFFFFF_u64; //< all registers
            let mut a = XsaveArea::new();
            let mut b = XsaveArea::new();

            _xsavec(a.ptr(), m);
            _xrstor(a.ptr(), m);
            _xsavec(b.ptr(), m);
            assert_eq!(a, b);
        }

        // FIXME: https://github.com/rust-lang-nursery/stdsimd/issues/209
        /*
        #[simd_test(enable = "xsave,xsaves")]
        unsafe fn xsaves() {
            let m = 0xFFFFFFFFFFFFFFFF_u64; //< all registers
            let mut a = XsaveArea::new();
            let mut b = XsaveArea::new();

            _xsaves(a.ptr(), m);
            _xrstors(a.ptr(), m);
            _xsaves(b.ptr(), m);
            assert_eq!(a, b);
        }
        */
    }

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