1 files changed, 112 insertions, 0 deletions
diff --git a/library/stdarch/crates/core_arch/src/x86/fxsr.rs b/library/stdarch/crates/core_arch/src/x86/fxsr.rs
new file mode 100644
index 000000000..8ea1bfab7
--- /dev/null
+++ b/library/stdarch/crates/core_arch/src/x86/fxsr.rs
@@ -0,0 +1,112 @@
+//! FXSR floating-point context fast save and restore.
+
+#[cfg(test)]
+use stdarch_test::assert_instr;
+
+#[allow(improper_ctypes)]
+extern "C" {
+    #[link_name = "llvm.x86.fxsave"]
+    fn fxsave(p: *mut u8);
+    #[link_name = "llvm.x86.fxrstor"]
+    fn fxrstor(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://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_fxsave)
+#[inline]
+#[target_feature(enable = "fxsr")]
+#[cfg_attr(test, assert_instr(fxsave))]
+#[stable(feature = "simd_x86", since = "1.27.0")]
+pub unsafe fn _fxsave(mem_addr: *mut u8) {
+    fxsave(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://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_fxrstor)
+#[inline]
+#[target_feature(enable = "fxsr")]
+#[cfg_attr(test, assert_instr(fxrstor))]
+#[stable(feature = "simd_x86", since = "1.27.0")]
+pub unsafe fn _fxrstor(mem_addr: *const u8) {
+    fxrstor(mem_addr)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::core_arch::x86::*;
+    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 {
+            &mut self.data[0] as *mut _ as *mut u8
+        }
+    }
+
+    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")]
+    unsafe fn fxsave() {
+        let mut a = FxsaveArea::new();
+        let mut b = FxsaveArea::new();
+
+        fxsr::_fxsave(a.ptr());
+        fxsr::_fxrstor(a.ptr());
+        fxsr::_fxsave(b.ptr());
+        assert_eq!(a, b);
+    }
+}