core/stdarch/crates/core_arch/src/x86_64/fxsr.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113
//! FXSR floating-point context fast save and restore.
#[cfg(test)]
use stdarch_test::assert_instr;
#[allow(improper_ctypes)]
extern "C" {
#[link_name = "llvm.x86.fxsave64"]
fn fxsave64(p: *mut u8);
#[link_name = "llvm.x86.fxrstor64"]
fn fxrstor64(p: *const u8);
}
/// Saves the `x87` FPU, `MMX` technology, `XMM`, and `MXCSR` registers to the
/// 512-byte-long 16-byte-aligned memory region `mem_addr`.
///
/// A misaligned destination operand raises a general-protection (#GP) or an
/// alignment check exception (#AC).
///
/// See [`FXSAVE`][fxsave] and [`FXRSTOR`][fxrstor].
///
/// [fxsave]: http://www.felixcloutier.com/x86/FXSAVE.html
/// [fxrstor]: http://www.felixcloutier.com/x86/FXRSTOR.html
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_fxsave64)
#[inline]
#[target_feature(enable = "fxsr")]
#[cfg_attr(test, assert_instr(fxsave64))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _fxsave64(mem_addr: *mut u8) {
fxsave64(mem_addr)
}
/// Restores the `XMM`, `MMX`, `MXCSR`, and `x87` FPU registers from the
/// 512-byte-long 16-byte-aligned memory region `mem_addr`.
///
/// The contents of this memory region should have been written to by a
/// previous
/// `_fxsave` or `_fxsave64` intrinsic.
///
/// A misaligned destination operand raises a general-protection (#GP) or an
/// alignment check exception (#AC).
///
/// See [`FXSAVE`][fxsave] and [`FXRSTOR`][fxrstor].
///
/// [fxsave]: http://www.felixcloutier.com/x86/FXSAVE.html
/// [fxrstor]: http://www.felixcloutier.com/x86/FXRSTOR.html
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_fxrstor64)
#[inline]
#[target_feature(enable = "fxsr")]
#[cfg_attr(test, assert_instr(fxrstor64))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _fxrstor64(mem_addr: *const u8) {
fxrstor64(mem_addr)
}
#[cfg(test)]
mod tests {
use crate::core_arch::x86_64::*;
use std::{cmp::PartialEq, fmt};
use stdarch_test::simd_test;
#[repr(align(16))]
struct FxsaveArea {
data: [u8; 512], // 512 bytes
}
impl FxsaveArea {
fn new() -> FxsaveArea {
FxsaveArea { data: [0; 512] }
}
fn ptr(&mut self) -> *mut u8 {
self.data.as_mut_ptr()
}
}
impl PartialEq<FxsaveArea> for FxsaveArea {
fn eq(&self, other: &FxsaveArea) -> bool {
for i in 0..self.data.len() {
if self.data[i] != other.data[i] {
return false;
}
}
true
}
}
impl fmt::Debug for FxsaveArea {
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, "]")
}
}
#[simd_test(enable = "fxsr")]
#[cfg_attr(miri, ignore)] // Register saving/restoring is not supported in Miri
unsafe fn test_fxsave64() {
let mut a = FxsaveArea::new();
let mut b = FxsaveArea::new();
fxsr::_fxsave64(a.ptr());
fxsr::_fxrstor64(a.ptr());
fxsr::_fxsave64(b.ptr());
assert_eq!(a, b);
}
}