turning on link time optimizations (LTO) for 21.04

[Sebastien Bacher]

Hey Matthias,

I see that has been uploaded today [1], isn't it a bit late in the cycle
for such changes? Wouldn't it require a least a ffe?

Cheers,
Sebastien

[1] https://launchpad.net/ubuntu/+source/dpkg/1.20.7.1ubuntu4

Le 29/01/2021 à 13:34, Matthias Klose a écrit :
> Link time optimization (LTO) is a way to run optimizations across multiple
> translation units, enabling more opportunities for optimizations at link time.
> The optimizations allow for faster code and smaller files.
>
> LTO will be turned on for the 64bit architectures (except riscv64) by default
> for 21.04, after glibc 2.33 made it to the release pocket (just for
> disentanglement).
>
> Some upstream projects already turn on LTO by default, or provide configuration
> options to turn it on (like GCC, Python).  Other Linux distributions are already
> released with LTO turned on by default.
>
> If you want to test a package build with LTO turned on, use
>
>     DEB_BUILD_OPTIONS=optimize=+lto dpkg-buildpackage ...
>
> using dpkg 1.20.7.1ubuntu2, currently in hirsute-proposed.
>
> Please make sure to add the 'lto' tag to bug reports when reporting issues about
> LTO.
>
> Details at https://wiki.ubuntu.com/ToolChain/LTO.
> Feedback and improvements for the wiki page are welcome.
>
> Matthias
>
>