1//! FXSR floating-point context fast save and restore.
2
3#[cfg(test)]
4use stdarch_test::assert_instr;
5
6#[allow(improper_ctypes)]
7extern "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 impl PartialEq<FxsaveArea> for FxsaveArea {
79 fn eq(&self, other: &FxsaveArea) -> bool {
80 for i in 0..self.data.len() {
81 if self.data[i] != other.data[i] {
82 return false;
83 }
84 }
85 true
86 }
87 }
88
89 impl fmt::Debug for FxsaveArea {
90 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
91 write!(f, "[")?;
92 for i in 0..self.data.len() {
93 write!(f, "{}", self.data[i])?;
94 if i != self.data.len() - 1 {
95 write!(f, ", ")?;
96 }
97 }
98 write!(f, "]")
99 }
100 }
101
102 #[simd_test(enable = "fxsr")]
103 #[cfg_attr(miri, ignore)] // Register saving/restoring is not supported in Miri
104 unsafe fn fxsave64() {
105 let mut a = FxsaveArea::new();
106 let mut b = FxsaveArea::new();
107
108 fxsr::_fxsave64(a.ptr());
109 fxsr::_fxrstor64(a.ptr());
110 fxsr::_fxsave64(b.ptr());
111 assert_eq!(a, b);
112 }
113}
114