Correct alignment of atomic types and (re)add Atomic{I,U}128

LLVM requires that atomic loads and stores be aligned to at least the size of the type.

src/test/run-pass/atomic-alignment.rs

@@ -0,0 +1,46 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(cfg_target_has_atomic)]
+#![feature(integer_atomics)]
+
+use std::mem::{align_of, size_of};
+use std::sync::atomic::*;
+
+fn main() {
+    #[cfg(target_has_atomic = "8")]
+    assert_eq!(align_of::<AtomicBool>(), size_of::<AtomicBool>());
+    #[cfg(target_has_atomic = "ptr")]
+    assert_eq!(align_of::<AtomicPtr<u8>>(), size_of::<AtomicPtr<u8>>());
+    #[cfg(target_has_atomic = "8")]
+    assert_eq!(align_of::<AtomicU8>(), size_of::<AtomicU8>());
+    #[cfg(target_has_atomic = "8")]
+    assert_eq!(align_of::<AtomicI8>(), size_of::<AtomicI8>());
+    #[cfg(target_has_atomic = "16")]
+    assert_eq!(align_of::<AtomicU16>(), size_of::<AtomicU16>());
+    #[cfg(target_has_atomic = "16")]
+    assert_eq!(align_of::<AtomicI16>(), size_of::<AtomicI16>());
+    #[cfg(target_has_atomic = "32")]
+    assert_eq!(align_of::<AtomicU32>(), size_of::<AtomicU32>());
+    #[cfg(target_has_atomic = "32")]
+    assert_eq!(align_of::<AtomicI32>(), size_of::<AtomicI32>());
+    #[cfg(target_has_atomic = "64")]
+    assert_eq!(align_of::<AtomicU64>(), size_of::<AtomicU64>());
+    #[cfg(target_has_atomic = "64")]
+    assert_eq!(align_of::<AtomicI64>(), size_of::<AtomicI64>());
+    #[cfg(target_has_atomic = "128")]
+    assert_eq!(align_of::<AtomicU128>(), size_of::<AtomicU128>());
+    #[cfg(target_has_atomic = "128")]
+    assert_eq!(align_of::<AtomicI128>(), size_of::<AtomicI128>());
+    #[cfg(target_has_atomic = "ptr")]
+    assert_eq!(align_of::<AtomicUsize>(), size_of::<AtomicUsize>());
+    #[cfg(target_has_atomic = "ptr")]
+    assert_eq!(align_of::<AtomicIsize>(), size_of::<AtomicIsize>());
+}