[webkit-gtk] FTL plans for 2.12

[Michael Catanzaro]

On Tue, 2016-02-02 at 07:59 +0100, Carlos Garcia Campos wrote:
> At the beginning of this release cycle we enabled FTL using LLVM with
> the idea of finally having FTL support since 2.12. At the same time
> Apple JSC developers were working on a new backend for FTL, B3 to
> replace the LLVM. This has many advantages, but from the maintenance
> point of view it means we don't need to depend on LLVM anymore (note
> that we don't just link to LLVM, we have a shared library linking to
> LLVM that JSC loads with dlopen at runtime only when needed). 
> I think most of the distros have already prepared their packages for
> the LLVM machinery.

As far as I know, only Fedora and openSUSE have. No other distros even
look at our unstable releases.

> My proposal is to try with c):
> 
>  1. Switch to B3 in trunk ASAP.
>  2. Set up a bot that runs Octane, Speedometer, JetStream and Kraken
> in
> a real browser.
>  3. Make an unstable release with B3 right before branching.
>  4.a If the release is super unstable, branch for 2.12 and disable
> FTL
> in the branch.
>  4.b If the release works reasonable well, branch for 2.12 and keep
> merging B3 fixes and improvements in the branch.
>  5. Right before the hard code freeze we have the last opportunity to
> keep B3 or disable FTL in case of 4.b, but hopefully we don't need to
> wait until the very last moment to decide.
> 
> So yes, I'm discarding any option to keep LLVM.

I like this plan.

I don't think it's a priority to have B3 FTL in 2.12, but it's quite
nice to have.

I don't want to release with LLVM FTL.

Michael