add SIMD intrinsic distr

Author: TheIronBorn

src/distributions/integer.rs

@@ -12,6 +12,10 @@ use {Rng};
 use distributions::{Distribution, Standard};
 #[cfg(feature="simd_support")]
 use packed_simd::*;
+#[cfg(all(target_arch = "x86", feature="nightly"))]
+use core::arch::x86::*;
+#[cfg(all(target_arch = "x86_64", feature="nightly"))]
+use core::arch::x86_64::*;
 
 impl Distribution<u8> for Standard {
     #[inline]
@@ -86,6 +90,15 @@ impl_int_from_uint! { isize, usize }
 
 #[cfg(feature="simd_support")]
 macro_rules! simd_impl {
+    ($(($intrinsic:ident, $vec:ty),)+) => {$(
+        impl Distribution<$intrinsic> for Standard {
+            #[inline]
+            fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> $intrinsic {
+                $intrinsic::from_bits(rng.gen::<$vec>())
+            }
+        }
+    )+};
+
     ($bits:expr,) => {};
     ($bits:expr, $ty:ty, $($ty_more:ty,)*) => {
         simd_impl!($bits, $($ty_more,)*);
@@ -102,7 +115,7 @@ macro_rules! simd_impl {
                 vec.to_le()
             }
         }
-    }
+    };
 }
 
 #[cfg(feature="simd_support")]
@@ -117,6 +130,8 @@ simd_impl!(128, u8x16, i8x16, u16x8, i16x8, u32x4, i32x4, u64x2, i64x2,);
 simd_impl!(256, u8x32, i8x32, u16x16, i16x16, u32x8, i32x8, u64x4, i64x4,);
 #[cfg(feature="simd_support")]
 simd_impl!(512, u8x64, i8x64, u16x32, i16x32, u32x16, i32x16, u64x8, i64x8,);
+#[cfg(all(feature="simd_support", feature="nightly", any(target_arch="x86", target_arch="x86_64")))]
+simd_impl!((__m64, u8x8), (__m128i, u8x16), (__m256i, u8x32),);
 
 #[cfg(test)]
 mod tests {