Endian-dependent type-punning from vectors to tuples and arrays

crates/coresimd/tests/endian_tests.rs

@@ -24,13 +24,12 @@ fn endian_bitcasts() {
         8, 9, 10, 11, 12, 13, 14, 15,
     );
     let t: i16x8 = unsafe { mem::transmute(x) };
-    if cfg!(target_endian = "little") {
-        let t_el = i16x8::new(256, 770, 1284, 1798, 2312, 2826, 3340, 3854);
-        assert_eq!(t, t_el);
-    } else if cfg!(target_endian = "big") {
-        let t_be = i16x8::new(1, 515, 1029, 1543, 2057, 2571, 3085, 3599);
-        assert_eq!(t, t_be);
-    }
+    let e: i16x8 = if cfg!(target_endian = "little") {
+        i16x8::new(256, 770, 1284, 1798, 2312, 2826, 3340, 3854)
+    } else {
+        i16x8::new(1, 515, 1029, 1543, 2057, 2571, 3085, 3599)
+    };
+    assert_eq!(t, e);
 }
 
 #[test]
@@ -61,13 +60,12 @@ fn endian_load_and_stores() {
         slice::from_raw_parts_mut(&mut y as *mut _ as *mut i8, 16)
     });
 
-    if cfg!(target_endian = "little") {
-        let e: [i16; 8] = [256, 770, 1284, 1798, 2312, 2826, 3340, 3854];
-        assert_eq!(y, e);
-    } else if cfg!(target_endian = "big") {
-        let e: [i16; 8] = [1, 515, 1029, 1543, 2057, 2571, 3085, 3599];
-        assert_eq!(y, e);
-    }
+    let e: [i16; 8] = if cfg!(target_endian = "little") {
+        [256, 770, 1284, 1798, 2312, 2826, 3340, 3854]
+    } else {
+        [1, 515, 1029, 1543, 2057, 2571, 3085, 3599]
+    };
+    assert_eq!(y, e);
 
     let z = i8x16::load_unaligned(unsafe {
         slice::from_raw_parts(&y as *const _ as *const i8, 16)
@@ -124,6 +122,24 @@ fn endian_array_union() {
     );
     let z = unsafe { B { data: y }.vec };
     assert_eq!(z, e);
+
+    union C {
+        data: [i16; 8],
+        vec: i8x16,
+    }
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    let x = i8x16::new(
+        0, 1, 2, 3, 4, 5, 6, 7,
+        8, 9, 10, 11, 12, 13, 14, 15,
+    );
+    let x: [i16; 8] = unsafe { C { vec: x }.data };
+
+    let e: [i16; 8] = if cfg!(target_endian = "little") {
+        [256, 770, 1284, 1798, 2312, 2826, 3340, 3854]
+    } else {
+        [1, 515, 1029, 1543, 2057, 2571, 3085, 3599]
+    };
+    assert_eq!(x, e);
 }
 
 #[test]
@@ -192,4 +208,71 @@ fn endian_tuple_access() {
         7, 6, 5, 4, 3, 2, 1, 0
     );
     assert_eq!(e, z);
+
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    type I16x8T = (i16, i16, i16, i16, i16, i16, i16, i16);
+    union C {
+        data: I16x8T,
+        vec: i8x16,
+    }
+
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    let x = i8x16::new(
+        0, 1, 2, 3, 4, 5, 6, 7,
+        8, 9, 10, 11, 12, 13, 14, 15,
+    );
+    let x: I16x8T = unsafe { C { vec: x }.data };
+
+    let e: [i16; 8] = if cfg!(target_endian = "little") {
+        [256, 770, 1284, 1798, 2312, 2826, 3340, 3854]
+    } else {
+        [1, 515, 1029, 1543, 2057, 2571, 3085, 3599]
+    };
+    assert_eq!(x.0, e[0]);
+    assert_eq!(x.1, e[1]);
+    assert_eq!(x.2, e[2]);
+    assert_eq!(x.3, e[3]);
+    assert_eq!(x.4, e[4]);
+    assert_eq!(x.5, e[5]);
+    assert_eq!(x.6, e[6]);
+    assert_eq!(x.7, e[7]);
+
+    // Without repr(C) this produces total garbage.
+    // FIXME: investigate more, this is maybe due to
+    // to tuple field reordering to minimize padding.
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    #[repr(C)]
+    #[derive(Copy ,Clone)]
+    pub struct Tup(pub i8, pub i8, pub i16, pub i8, pub i8, pub i16,
+                   pub i8, pub i8, pub i16, pub i8, pub i8, pub i16);
+
+    union D {
+        data: Tup,
+        vec: i8x16,
+    }
+
+    #[cfg_attr(rustfmt, rustfmt_skip)]
+    let x = i8x16::new(
+        0, 1, 2, 3, 4, 5, 6, 7,
+        8, 9, 10, 11, 12, 13, 14, 15,
+    );
+    let x: Tup = unsafe { D { vec: x }.data };
+
+    let e: [i16; 12] = if cfg!(target_endian = "little") {
+        [0, 1, 770, 4, 5, 1798, 8, 9, 2826, 12, 13, 3854]
+    } else {
+        [0, 1, 515, 4, 5, 1543, 8, 9, 2571, 12, 13, 3599]
+    };
+    assert_eq!(x.0 as i16, e[0]);
+    assert_eq!(x.1 as i16, e[1]);
+    assert_eq!(x.2 as i16, e[2]);
+    assert_eq!(x.3 as i16, e[3]);
+    assert_eq!(x.4 as i16, e[4]);
+    assert_eq!(x.5 as i16, e[5]);
+    assert_eq!(x.6 as i16, e[6]);
+    assert_eq!(x.7 as i16, e[7]);
+    assert_eq!(x.8 as i16, e[8]);
+    assert_eq!(x.9 as i16, e[9]);
+    assert_eq!(x.10 as i16, e[10]);
+    assert_eq!(x.11 as i16, e[11]);
 }