disable a test that currently fails on big-endian

Author: RalfJung

src/tools/miri/tests/pass/portable-simd.rs

@@ -268,11 +268,15 @@ fn simd_mask() {
     }
 
     // This used to cause an ICE. It exercises simd_select_bitmask with an array as input.
-    let bitmask = u8x4::from_array([0b00001101, 0, 0, 0]);
-    assert_eq!(
-        mask32x4::from_bitmask_vector(bitmask),
-        mask32x4::from_array([true, false, true, true]),
-    );
+    if cfg!(target_endian = "little") {
+        // FIXME this test currently fails on big-endian:
+        // <https://github.com/rust-lang/portable-simd/issues/379>
+        let bitmask = u8x4::from_array([0b00001101, 0, 0, 0]);
+        assert_eq!(
+            mask32x4::from_bitmask_vector(bitmask),
+            mask32x4::from_array([true, false, true, true]),
+        );
+    }
     let bitmask = u8x8::from_array([0b01000101, 0, 0, 0, 0, 0, 0, 0]);
     assert_eq!(
         mask32x8::from_bitmask_vector(bitmask),