}
/// Checks whether the regions of memory starting at `src` and `dst` of size
-/// `count * size_of::<T>()` overlap.
-fn overlaps<T>(src: *const T, dst: *const T, count: usize) -> bool {
+/// `count * size_of::<T>()` do *not* overlap.
+pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -> bool {
let src_usize = src as usize;
let dst_usize = dst as usize;
let size = mem::size_of::<T>().checked_mul(count).unwrap();
let diff = if src_usize > dst_usize { src_usize - dst_usize } else { dst_usize - src_usize };
- size > diff
+ let overlaps = size > diff;
+ !overlaps
}
/// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
debug_assert!(is_aligned_and_not_null(src), "attempt to copy from unaligned or null pointer");
debug_assert!(is_aligned_and_not_null(dst), "attempt to copy to unaligned or null pointer");
- debug_assert!(!overlaps(src, dst, count), "attempt to copy to overlapping memory");
+ debug_assert!(is_nonoverlapping(src, dst, count), "attempt to copy to overlapping memory");
copy_nonoverlapping(src, dst, count)
}
use crate::cmp::Ordering;
use crate::fmt;
use crate::hash;
-use crate::intrinsics;
+use crate::intrinsics::{self, is_aligned_and_not_null, is_nonoverlapping};
use crate::mem::{self, MaybeUninit};
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
#[stable(feature = "swap_nonoverlapping", since = "1.27.0")]
pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
+ debug_assert!(is_aligned_and_not_null(x), "attempt to swap unaligned or null pointer");
+ debug_assert!(is_aligned_and_not_null(y), "attempt to swap unaligned or null pointer");
+ debug_assert!(is_nonoverlapping(x, y, count), "attempt to swap overlapping memory");
+
let x = x as *mut u8;
let y = y as *mut u8;
let len = mem::size_of::<T>() * count;
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn read<T>(src: *const T) -> T {
+ // `copy_nonoverlapping` takes care of debug_assert.
let mut tmp = MaybeUninit::<T>::uninit();
copy_nonoverlapping(src, tmp.as_mut_ptr(), 1);
tmp.assume_init()
#[inline]
#[stable(feature = "ptr_unaligned", since = "1.17.0")]
pub unsafe fn read_unaligned<T>(src: *const T) -> T {
+ // `copy_nonoverlapping` takes care of debug_assert.
let mut tmp = MaybeUninit::<T>::uninit();
copy_nonoverlapping(src as *const u8, tmp.as_mut_ptr() as *mut u8, mem::size_of::<T>());
tmp.assume_init()
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn write<T>(dst: *mut T, src: T) {
+ debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
intrinsics::move_val_init(&mut *dst, src)
}
#[inline]
#[stable(feature = "ptr_unaligned", since = "1.17.0")]
pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
+ // `copy_nonoverlapping` takes care of debug_assert.
copy_nonoverlapping(&src as *const T as *const u8, dst as *mut u8, mem::size_of::<T>());
mem::forget(src);
}
#[inline]
#[stable(feature = "volatile", since = "1.9.0")]
pub unsafe fn read_volatile<T>(src: *const T) -> T {
+ debug_assert!(is_aligned_and_not_null(src), "attempt to read from unaligned or null pointer");
intrinsics::volatile_load(src)
}
#[inline]
#[stable(feature = "volatile", since = "1.9.0")]
pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
+ debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
intrinsics::volatile_store(dst, src);
}