Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Rerevert "Remove checked_add in Layout::repeat" #69743

Closed
wants to merge 1 commit into from
Closed

Rerevert "Remove checked_add in Layout::repeat" #69743

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 9 additions & 2 deletions src/libcore/alloc.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -235,11 +235,18 @@ impl Layout {
#[unstable(feature = "alloc_layout_extra", issue = "55724")]
#[inline]
pub fn repeat(&self, n: usize) -> Result<(Self, usize), LayoutErr> {
// This cannot overflow. Quoting from the invariant of Layout:
// `padded_size` cannot overflow. Quoting from the invariant of Layout:
// > `size`, when rounded up to the nearest multiple of `align`,
// > must not overflow (i.e., the rounded value must be less than
// > `usize::MAX`)
let padded_size = self.size() + self.padding_needed_for(self.align());
//
// However, replacing this line with an `unchecked_add` or a regular `+`
// operator caused a noticeable slowdown, see #69710.
let padded_size = self
.size()
.checked_add(self.padding_needed_for(self.align()))
.ok_or(LayoutErr { private: () })?;

let alloc_size = padded_size.checked_mul(n).ok_or(LayoutErr { private: () })?;

unsafe {
Expand Down