diff options
Diffstat (limited to 'library/std/src')
| -rw-r--r-- | library/std/src/alloc.rs | 27 |
1 files changed, 10 insertions, 17 deletions
diff --git a/library/std/src/alloc.rs b/library/std/src/alloc.rs index 37a8f514aa1..74427199346 100644 --- a/library/std/src/alloc.rs +++ b/library/std/src/alloc.rs @@ -181,16 +181,14 @@ unsafe impl AllocRef for System { ); // SAFETY: `new_size` must be non-zero, which is checked in the match expression. + // If `new_size` is zero, then `old_size` has to be zero as well. // Other conditions must be upheld by the caller unsafe { match layout.size() { - old_size if old_size == new_size => { - Ok(NonNull::slice_from_raw_parts(ptr, new_size)) - } 0 => self.alloc(Layout::from_size_align_unchecked(new_size, layout.align())), old_size => { - // `realloc` probably checks for `new_size > size` or something similar. - intrinsics::assume(new_size > old_size); + // `realloc` probably checks for `new_size >= size` or something similar. + intrinsics::assume(new_size >= old_size); let raw_ptr = GlobalAlloc::realloc(&System, ptr.as_ptr(), layout, new_size); let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?; Ok(NonNull::slice_from_raw_parts(ptr, new_size)) @@ -212,16 +210,14 @@ unsafe impl AllocRef for System { ); // SAFETY: `new_size` must be non-zero, which is checked in the match expression. + // If `new_size` is zero, then `old_size` has to be zero as well. // Other conditions must be upheld by the caller unsafe { match layout.size() { - old_size if old_size == new_size => { - Ok(NonNull::slice_from_raw_parts(ptr, new_size)) - } 0 => self.alloc_zeroed(Layout::from_size_align_unchecked(new_size, layout.align())), old_size => { - // `realloc` probably checks for `new_size > size` or something similar. - intrinsics::assume(new_size > old_size); + // `realloc` probably checks for `new_size >= size` or something similar. + intrinsics::assume(new_size >= old_size); let raw_ptr = GlobalAlloc::realloc(&System, ptr.as_ptr(), layout, new_size); raw_ptr.add(old_size).write_bytes(0, new_size - old_size); let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?; @@ -244,11 +240,8 @@ unsafe impl AllocRef for System { "`new_size` must be smaller than or equal to `layout.size()`" ); - let ptr = if new_size == old_size { - ptr - } else if new_size == 0 { - // SAFETY: `layout` is non-zero in size as `old_size` != `new_size` - // Other conditions must be upheld by the caller + let ptr = if new_size == 0 { + // SAFETY: conditions must be upheld by the caller unsafe { self.dealloc(ptr, layout); } @@ -257,8 +250,8 @@ unsafe impl AllocRef for System { // SAFETY: new_size is not zero, // Other conditions must be upheld by the caller let raw_ptr = unsafe { - // `realloc` probably checks for `new_size < old_size` or something similar. - intrinsics::assume(new_size < old_size); + // `realloc` probably checks for `new_size <= old_size` or something similar. + intrinsics::assume(new_size <= old_size); GlobalAlloc::realloc(&System, ptr.as_ptr(), layout, new_size) }; NonNull::new(raw_ptr).ok_or(AllocErr)? |