Messages in this thread | | | From | Miguel Ojeda <> | Date | Fri, 9 Jul 2021 16:32:27 +0200 | Subject | Re: [PATCH 05/17] rust: add C helpers |
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On Wed, Jul 7, 2021 at 12:19 PM 'Marco Elver' via Clang Built Linux <clang-built-linux@googlegroups.com> wrote: > > What is the story with Rust and LTO? Intuitively, I would expect Rust > code to only perform optimally if the kernel is built with LTO > (currently only supported via Clang).
Cross-language LTO is possible and is used in other major projects. For instance, Firefox seems to use it:
https://bugzilla.mozilla.org/show_bug.cgi?id=1486042
However, we have not taken a look at it yet for the kernel.
> Because if calls to every one of these helpers are real calls, I would > expect performance to be pretty poor. There's probably a reason these > are macros or inlinable functions.
Maybe -- we need to measure.
> I would almost go so far and suggest that CONFIG_RUST be modified as > follows:
Even if the performance was unacceptable, there are other ways than LTO to solve this, such as implementing the equivalent macro/function on Rust's side.
Furthermore, we need to consider GCC too.
Thus I would not be premature in making it depend on LTO.
Cheers, Miguel
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