1801268 - Clang should be built with ThinLTO

Status: RESOLVED FIXED

(Firefox Build System :: Toolchains, enhancement)

Description

[[:sergesanspaille]]

If we build our core compiler with LTO in addition to the existing PGO step, it should run faster, which in turn should make fx builds faster.

Comment 1

[[:sergesanspaille]]

Attachment: Bug 1801268 - enable lto-built clang

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Firefox Build System::Toolchains' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:sergesanspaille, could you have a look please?
If you still have some work to do, you can add an action "Plan Changes" in Phabricator.
For more information, please visit auto_nag documentation.

Comment 4

[[:sergesanspaille]]

This should be ok to land now that lld usage has reached a decent state.

Comment 5

[[:sergesanspaille]]

edit: there was some warnings in the build logs that hints at using llvm-ar instead of ar when linking with lto, /me checks this.

Comment 6

[Mike Hommey [:glandium]]

(In reply to [:sergesanspaille] from comment #5)

edit: there was some warnings in the build logs that hints at using llvm-ar instead of ar when linking with lto, /me checks this.

where did that lead?

Comment 7

[[:sergesanspaille]]

I ended up forcing usage of llvm-ar, llvm-ranlib (from teh same toolchain as clang), and that worked nice.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/db348b7063d4
enable lto-built clang r=firefox-build-system-reviewers,glandium

Comment 9

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/db348b7063d4