Allow raw pointers in SIMD types

compiler/rustc_middle/src/ty/sty.rs

@@ -1890,7 +1890,10 @@ impl<'tcx> TyS<'tcx> {
 
     #[inline]
     pub fn is_machine(&self) -> bool {
-        matches!(self.kind(), Int(..) | Uint(..) | Float(..))
+        // Yes, RawPtr is a "machine" type for these purposes.
+        // LLVM uses a vector-of-pointers model for scatter/gather ops,
+        // which typically use a base pointer and vector of signed integers.
+        matches!(self.kind(), Int(..) | Uint(..) | Float(..) | RawPtr(..))
     }
 
     #[inline]

src/test/ui/simd/issue-85915-simd-ptrs.rs

@@ -0,0 +1,67 @@
+// run-pass
+// ignore-emscripten
+
+// Short form of the generic gather/scatter tests,
+// verifying simd([*const T; N]) and simd([*mut T; N]) pass typeck and work.
+#![feature(repr_simd, platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+#[repr(simd)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+struct cptrx4<T>([*const T; 4]);
+
+#[repr(simd)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+struct mptrx4<T>([*mut T; 4]);
+
+#[repr(simd)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+struct f32x4([f32; 4]);
+
+#[repr(simd)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+struct i32x4([i32; 4]);
+
+extern "platform-intrinsic" {
+    fn simd_gather<T, U, V>(x: T, y: U, z: V) -> T;
+    fn simd_scatter<T, U, V>(x: T, y: U, z: V) -> ();
+}
+
+fn main() {
+    let mut x = [0_f32, 1., 2., 3., 4., 5., 6., 7.];
+
+    let default = f32x4([-3_f32, -3., -3., -3.]);
+    let s_strided = f32x4([0_f32, 2., -3., 6.]);
+    let mask = i32x4([-1_i32, -1, 0, -1]);
+
+    // reading from *const
+    unsafe {
+        let pointer = &x as *const f32;
+        let pointers =  cptrx4([
+            pointer.offset(0) as *const f32,
+            pointer.offset(2),
+            pointer.offset(4),
+            pointer.offset(6)
+        ]);
+
+        let r_strided = simd_gather(default, pointers, mask);
+
+        assert_eq!(r_strided, s_strided);
+    }
+
+    // writing to *mut
+    unsafe {
+        let pointer = &mut x as *mut f32;
+        let pointers = mptrx4([
+            pointer.offset(0) as *mut f32,
+            pointer.offset(2),
+            pointer.offset(4),
+            pointer.offset(6)
+        ]);
+
+        let values = f32x4([42_f32, 43_f32, 44_f32, 45_f32]);
+        simd_scatter(values, pointers, mask);
+
+        assert_eq!(x, [42., 1., 43., 3., 4., 5., 45., 7.]);
+    }
+}