1 //@compile-flags: -Zmiri-symbolic-alignment-check
3 fn test_align_offset() {
4 let d = Box::new([0u32; 4]);
5 // Get u8 pointer to base
6 let raw = d.as_ptr() as *const u8;
8 assert_eq!(raw.align_offset(2), 0);
9 assert_eq!(raw.align_offset(4), 0);
10 assert_eq!(raw.align_offset(8), usize::MAX); // requested alignment higher than allocation alignment
12 assert_eq!(raw.wrapping_offset(1).align_offset(2), 1);
13 assert_eq!(raw.wrapping_offset(1).align_offset(4), 3);
14 assert_eq!(raw.wrapping_offset(1).align_offset(8), usize::MAX); // requested alignment higher than allocation alignment
16 assert_eq!(raw.wrapping_offset(2).align_offset(2), 0);
17 assert_eq!(raw.wrapping_offset(2).align_offset(4), 2);
18 assert_eq!(raw.wrapping_offset(2).align_offset(8), usize::MAX); // requested alignment higher than allocation alignment
23 let d = Box::new([0u32; N]);
24 // Get u8 slice covering the entire thing
25 let s = unsafe { std::slice::from_raw_parts(d.as_ptr() as *const u8, 4 * N) };
29 let (l, m, r) = unsafe { s.align_to::<u32>() };
30 assert_eq!(l.len(), 0);
31 assert_eq!(r.len(), 0);
32 assert_eq!(m.len(), N);
33 assert_eq!(raw, m.as_ptr() as *const u8);
37 let (l, m, r) = unsafe { s[1..].align_to::<u32>() };
38 assert_eq!(l.len(), 3);
39 assert_eq!(m.len(), N - 1);
40 assert_eq!(r.len(), 0);
41 assert_eq!(raw.wrapping_offset(4), m.as_ptr() as *const u8);
45 let (l, m, r) = unsafe { s[..4 * N - 1].align_to::<u32>() };
46 assert_eq!(l.len(), 0);
47 assert_eq!(m.len(), N - 1);
48 assert_eq!(r.len(), 3);
49 assert_eq!(raw, m.as_ptr() as *const u8);
53 let (l, m, r) = unsafe { s[1..4 * N - 1].align_to::<u32>() };
54 assert_eq!(l.len(), 3);
55 assert_eq!(m.len(), N - 2);
56 assert_eq!(r.len(), 3);
57 assert_eq!(raw.wrapping_offset(4), m.as_ptr() as *const u8);
64 let (l, m, r) = unsafe { s.align_to::<Align8>() }; // requested alignment higher than allocation alignment
65 assert_eq!(l.len(), 4 * N);
66 assert_eq!(r.len(), 0);
67 assert_eq!(m.len(), 0);
73 let vec = vec![0x4141414141414141u64; N];
74 let content = unsafe { std::slice::from_raw_parts(vec.as_ptr() as *const u8, 8 * N) };
75 println!("{:?}", std::str::from_utf8(content).unwrap());
81 struct AlignToU64<T>(T);
83 const BYTE_LEN: usize = std::mem::size_of::<[u64; 4]>();
84 type Data = AlignToU64<[u8; BYTE_LEN]>;
86 fn example(data: &Data) {
87 let (head, u64_arrays, tail) = unsafe { data.0.align_to::<[u64; 4]>() };
89 assert!(head.is_empty(), "buffer was not aligned for 64-bit numbers");
90 assert_eq!(u64_arrays.len(), 1, "buffer was not long enough");
91 assert!(tail.is_empty(), "buffer was too long");
93 let u64_array = &u64_arrays[0];
94 let _val = u64_array[0]; // make sure we can actually load this
97 example(&Data::default());