1 files changed, 59 insertions, 0 deletions
diff --git a/tests/ui/simd/repr_packed.rs b/tests/ui/simd/repr_packed.rs
new file mode 100644
index 00000000000..df2d59a58b8
--- /dev/null
+++ b/tests/ui/simd/repr_packed.rs
@@ -0,0 +1,59 @@
+// run-pass
+
+#![feature(repr_simd, platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+#[repr(simd, packed)]
+struct Simd<T, const N: usize>([T; N]);
+
+#[repr(simd)]
+struct FullSimd<T, const N: usize>([T; N]);
+
+fn check_size_align<T, const N: usize>() {
+    use std::mem;
+    assert_eq!(mem::size_of::<Simd<T, N>>(), mem::size_of::<[T; N]>());
+    assert_eq!(mem::size_of::<Simd<T, N>>() % mem::align_of::<Simd<T, N>>(), 0);
+}
+
+fn check_ty<T>() {
+    check_size_align::<T, 1>();
+    check_size_align::<T, 2>();
+    check_size_align::<T, 3>();
+    check_size_align::<T, 4>();
+    check_size_align::<T, 8>();
+    check_size_align::<T, 9>();
+    check_size_align::<T, 15>();
+}
+
+extern "platform-intrinsic" {
+    fn simd_add<T>(a: T, b: T) -> T;
+}
+
+fn main() {
+    check_ty::<u8>();
+    check_ty::<i16>();
+    check_ty::<u32>();
+    check_ty::<i64>();
+    check_ty::<usize>();
+    check_ty::<f32>();
+    check_ty::<f64>();
+
+    unsafe {
+        // powers-of-two have no padding and work as usual
+        let x: Simd<f64, 4> =
+            simd_add(Simd::<f64, 4>([0., 1., 2., 3.]), Simd::<f64, 4>([2., 2., 2., 2.]));
+        assert_eq!(std::mem::transmute::<_, [f64; 4]>(x), [2., 3., 4., 5.]);
+
+        // non-powers-of-two have padding and need to be expanded to full vectors
+        fn load<T, const N: usize>(v: Simd<T, N>) -> FullSimd<T, N> {
+            unsafe {
+                let mut tmp = core::mem::MaybeUninit::<FullSimd<T, N>>::uninit();
+                std::ptr::copy_nonoverlapping(&v as *const _, tmp.as_mut_ptr().cast(), 1);
+                tmp.assume_init()
+            }
+        }
+        let x: FullSimd<f64, 3> =
+            simd_add(load(Simd::<f64, 3>([0., 1., 2.])), load(Simd::<f64, 3>([2., 2., 2.])));
+        assert_eq!(x.0, [2., 3., 4.]);
+    }
+}