Fix passing and returning vector types

Author: bjorn3

example/std_example.rs

@@ -1,4 +1,4 @@
-#![feature(core_intrinsics, generators, generator_trait, is_sorted)]
+#![feature(core_intrinsics, generators, generator_trait, is_sorted, repr_simd)]
 
 #[cfg(target_arch = "x86_64")]
 use std::arch::x86_64::*;
@@ -153,12 +153,20 @@ fn main() {
 
         enum Never {}
     }
+
+    foo(I64X2(0, 0));
 }
 
 fn panic(_: u128) {
     panic!();
 }
 
+#[repr(simd)]
+struct I64X2(i64, i64);
+
+#[allow(improper_ctypes_definitions)]
+extern "C" fn foo(_a: I64X2) {}
+
 #[cfg(target_arch = "x86_64")]
 #[target_feature(enable = "sse2")]
 unsafe fn test_simd() {

src/value_and_place.rs

@@ -165,6 +165,9 @@ impl<'tcx> CValue<'tcx> {
             CValueInner::ByRef(ptr, None) => {
                 let clif_ty = match layout.abi {
                     Abi::Scalar(scalar) => scalar_to_clif_type(fx.tcx, scalar),
+                    Abi::Vector { element, count } => scalar_to_clif_type(fx.tcx, element)
+                        .by(u32::try_from(count).unwrap())
+                        .unwrap(),
                     _ => unreachable!("{:?}", layout.ty),
                 };
                 let mut flags = MemFlags::new();