Fedora 33 LTO Support Is Now In Good Shape For Faster, Smaller Packages

[phoronix]

Phoronix: Fedora 33 LTO Support Is Now In Good Shape For Faster, Smaller Packages

Fedora's plans to make use of link-time optimizations (LTO) by default with the GCC compiler when building Fedora 33 packages is looking like it will successfully pan out...

http://www.phoronix.com/scan.php?page=news_item&px=Fedora-33-LTO-August-Status

[Danny3]

It would be great if Ubuntu would do the same.

[treba]

I hope they figure out https://bugzilla.redhat.com/show_bug.cgi?id=1849165 in time - building FF with both LTO and PGO was quite a win when it worked AFAIK.

[Mario Junior]

Waiting for BTRFS customization on the installer.

[CommunityMember]

"Faster, smaller"? Not always (to either; another "your mileage WILL vary" case), but on average this will be a win.

And it has (as was sort of expected) resulted in a couple of new bugs being identified against GCC, which will help not only Fedora in the future (allowing some of the remaining packages that are currently exempted to be built LTO), but the GCC project itself which helps others.

[CommunityMember]

It would be great if Ubuntu would do the same.

I fully expect LTO will be the new normal for most distros at some point now that SUSE Tumbleweed and Fedora have moved there for the majority of packages and are pushing for the fixes for the remaining (packages and GCC, as appropriate). Clearly those using Ubuntu should start asking their Canonical TME about whether it is currently in plan for 22.04, and which interim release might include the changes (21.xx?).

[CommunityMember]

I hope they figure out https://bugzilla.redhat.com/show_bug.cgi?id=1849165 in time - building FF with both LTO and PGO was quite a win when it worked AFAIK.

If the GCC bug is not resolved soon-ish, a proposed fallback is to move to using LLVM, which will get one the equivalent improvements (and, as I recall, Mozilla is using LLVM for their nightly Firefox builds, so it is expected to just build).

[Tvashtar]

Mozilla is using Clang/LLVM for ALL their builds, for quite a some time already. You can check it in their builds by going to about:buildconfig.
And they're both LTO and PGO

[You-]

Mozilla is using Clang/LLVM for ALL their builds, for quite a some time already. You can check it in their builds by going to about:buildconfig.
And they're both LTO and PGO

Yes, but it would be bad news for Fedora to follow suit - we need GCC to remain competitive or the leading platform because the licence means it will always be available, which is a pretty important thing.

(There is a reason Apple spent $$$ getting LLVM into shape after GCC moved to GPL V3.)

[FPScholten]

Most code builds fine with -flto, but whenever I compile FFMPEG with -flto the build fails. Builds just fine without -flto