Allow isize/usize in simd_cast

Author: calebzulawski

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -1715,14 +1715,26 @@ unsupported {} from `{}` with element `{}` of size `{}` to `{}`"#,
         let (in_style, in_width) = match in_elem.kind() {
             // vectors of pointer-sized integers should've been
             // disallowed before here, so this unwrap is safe.
-            ty::Int(i) => (Style::Int(true), i.bit_width().unwrap()),
-            ty::Uint(u) => (Style::Int(false), u.bit_width().unwrap()),
+            ty::Int(i) => (
+                Style::Int(true),
+                i.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
+            ty::Uint(u) => (
+                Style::Int(false),
+                u.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
             ty::Float(f) => (Style::Float, f.bit_width()),
             _ => (Style::Unsupported, 0),
         };
         let (out_style, out_width) = match out_elem.kind() {
-            ty::Int(i) => (Style::Int(true), i.bit_width().unwrap()),
-            ty::Uint(u) => (Style::Int(false), u.bit_width().unwrap()),
+            ty::Int(i) => (
+                Style::Int(true),
+                i.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
+            ty::Uint(u) => (
+                Style::Int(false),
+                u.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
             ty::Float(f) => (Style::Float, f.bit_width()),
             _ => (Style::Unsupported, 0),
         };

src/test/ui/simd/intrinsic/generic-cast-pointer-width.rs

@@ -0,0 +1,21 @@
+// run-pass
+#![feature(repr_simd, platform_intrinsics)]
+
+extern "platform-intrinsic" {
+    fn simd_cast<T, U>(x: T) -> U;
+}
+
+#[derive(Copy, Clone)]
+#[repr(simd)]
+struct V<T>([T; 4]);
+
+fn main() {
+    let u = V::<usize>([0, 1, 2, 3]);
+    let uu32: V<u32> = unsafe { simd_cast(u) };
+    let ui64: V<i64> = unsafe { simd_cast(u) };
+
+    for (u, (uu32, ui64)) in u.0.iter().zip(uu32.0.iter().zip(ui64.0.iter())) {
+        assert_eq!(*u as u32, *uu32);
+        assert_eq!(*u as i64, *ui64);
+    }
+}