fxsr.rs - source
Description: Source of the Rust file `library/core/src/../../stdarch/crates/core_arch/src/x86_64/fxsr.rs`.

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core/stdarch/crates/core_arch/src/x86_64/
fxsr.rs

    1//! FXSR floating-point context fast save and restore.
    2
    3#[cfg(test)]
    4use stdarch_test::assert_instr;
    5
    6#[allow(improper_ctypes)]
    7unsafe extern "C" {
    8    #[link_name = "llvm.x86.fxsave64"]
    9    fn fxsave64(p: *mut u8);
    10    #[link_name = "llvm.x86.fxrstor64"]
    11    fn fxrstor64(p: *const u8);
    12}
    13
    14/// Saves the `x87` FPU, `MMX` technology, `XMM`, and `MXCSR` registers to the
    15/// 512-byte-long 16-byte-aligned memory region `mem_addr`.
    16///
    17/// A misaligned destination operand raises a general-protection (#GP) or an
    18/// alignment check exception (#AC).
    19///
    20/// See [`FXSAVE`][fxsave] and [`FXRSTOR`][fxrstor].
    21///
    22/// [fxsave]: http://www.felixcloutier.com/x86/FXSAVE.html
    23/// [fxrstor]: http://www.felixcloutier.com/x86/FXRSTOR.html
    24///
    25/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_fxsave64)
    26#[inline]
    27#[target_feature(enable = "fxsr")]
    28#[cfg_attr(test, assert_instr(fxsave64))]
    29#[stable(feature = "simd_x86", since = "1.27.0")]
    30pub unsafe fn _fxsave64(mem_addr: *mut u8) {
    31    fxsave64(mem_addr)
    32}
    33
    34/// Restores the `XMM`, `MMX`, `MXCSR`, and `x87` FPU registers from the
    35/// 512-byte-long 16-byte-aligned memory region `mem_addr`.
    36///
    37/// The contents of this memory region should have been written to by a
    38/// previous
    39/// `_fxsave` or `_fxsave64` intrinsic.
    40///
    41/// A misaligned destination operand raises a general-protection (#GP) or an
    42/// alignment check exception (#AC).
    43///
    44/// See [`FXSAVE`][fxsave] and [`FXRSTOR`][fxrstor].
    45///
    46/// [fxsave]: http://www.felixcloutier.com/x86/FXSAVE.html
    47/// [fxrstor]: http://www.felixcloutier.com/x86/FXRSTOR.html
    48///
    49/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_fxrstor64)
    50#[inline]
    51#[target_feature(enable = "fxsr")]
    52#[cfg_attr(test, assert_instr(fxrstor64))]
    53#[stable(feature = "simd_x86", since = "1.27.0")]
    54pub unsafe fn _fxrstor64(mem_addr: *const u8) {
    55    fxrstor64(mem_addr)
    56}
    57
    58#[cfg(test)]
    59mod tests {
    60    use crate::core_arch::x86_64::*;
    61    use std::{cmp::PartialEq, fmt};
    62    use stdarch_test::simd_test;
    63
    64    #[repr(align(16))]
    65    struct FxsaveArea {
    66        data: [u8; 512], // 512 bytes
    67    }
    68
    69    impl FxsaveArea {
    70        fn new() -> FxsaveArea {
    71            FxsaveArea { data: [0; 512] }
    72        }
    73        fn ptr(&mut self) -> *mut u8 {
    74            self.data.as_mut_ptr()
    75        }
    76    }
    77
    78    #[simd_test(enable = "fxsr")]
    79    #[cfg_attr(miri, ignore)] // Register saving/restoring is not supported in Miri
    80    unsafe fn test_fxsave64() {
    81        let mut a = FxsaveArea::new();
    82        let mut b = FxsaveArea::new();
    83
    84        fxsr::_fxsave64(a.ptr());
    85        fxsr::_fxrstor64(a.ptr());
    86        fxsr::_fxsave64(b.ptr());
    87    }
    88}