[webkit-gtk] FTL-JIT LLVM

[Adrian Perez de Castro]

On Fri, 25 Nov 2016 20:25:54 -0600, Michael Catanzaro <mcatanzaro at igalia.com> wrote:
> On Fri, 2016-11-25 at 23:06 +0100, Manuel Selva wrote:
> > 1- What is the last version of Webkit including a JavaScript engine
> > with 
> > 4 tiers and based on LLVM ?
> 
> There was not actually ever any stable release that used LLVM. The LLVM
> dependency was added during the 2.12 development cycle but removed
> before the 2.12.0 release because the LLVM FTL backend was obsoleted by
> the B3 (bare bones backend) earlier than we expected. B3 handles the
> subset of LLVM intermediate representation needed by JavaScriptCore
> much faster than LLVM can, as LLVM needs more features than
> JavaScriptCore does. (I don't know more than this; you can ask the JSC
> developers on webkit-dev@ if you're interested.)

There's also a nice post in the WebKit blog about the B3 backend:

  https://webkit.org/blog/5852/introducing-the-b3-jit-compiler/

Michael is right, and you should use a released version of WebKitGTK+ (none
of which need LLVM), unless you have a very strong reason to use one of the
development snapshots. And even in that case, you would be probably in a
better spot by making your code work with the most recent stable release
because it contains significant improvements and security fixes.

Regards,


—Adrián