Add test.

src/test/ui/simd/issue-105439.rs

@@ -0,0 +1,14 @@
+// This is used to ICE with MIR inlining enabled due to an invalid bitcast.
+// run-pass
+// compile-flags: -O -Zmir-opt-level=3
+#![feature(portable_simd)]
+
+use std::simd::Simd;
+
+fn main() {
+    let a = Simd::from_array([0, 4, 1, 5]);
+    let b = Simd::from_array([2, 6, 3, 7]);
+    let (x, y) = a.deinterleave(b);
+    assert_eq!(x.to_array(), [0, 1, 2, 3]);
+    assert_eq!(y.to_array(), [4, 5, 6, 7]);
+}