[webkit-dev] JavaScriptCore on Fuchsia

[Adam Barth]

On Tue, Jun 26, 2018 at 2:08 PM Filip Pizlo <fpizlo at apple.com> wrote:
> This looks super interesting!

Thanks.  :)

> I have some questions:
>
> - Does your JSC port enable all of JSC’s optimization features, like the FTL JIT and concurrent GC?

Nope.  I believe we just have the interpreter working.

>         - Is it a goal to enable basically everything we enable, long term?

The Fuchsia project itself doesn't have any particular goals for
JavaScriptCore.  It's possible that our customers who want to use
JavaScriptCore on Fuchsia will have goals for additional functionality
in the future, but assuming we host the code on svn.webkit.org, I
would imagine recommending that those customers interact directly with
the WebKit project.

> - Is this 32-bit, 64-bit, or both?

Fuchsia supports only 64-bit architectures.  We have no interest in
32-bit support in JavaScriptCore.

> - Is this mainly for ARM, x86, some other CPU, or lots of CPUs?

Fuchsia supports x86_64 and aarch64.

> - Do you plan to do significant work on JSC, or do you mainly want to just stay up to date with what we’re doing?

I'd like to foster a healthy dynamic between the WebKit project and
our mutual customers.  It's hard for me to predict to where those
customers will fall on that spectrum, but I would not anticipate the
Fuchsia project itself making significant contributions to JSC.
However, I would anticipate us maintaining the integration between
JavaScriptCore and Fuchsia.

> More thoughts inline:
>
> > On Jun 26, 2018, at 2:00 PM, Adam Barth <abarth at webkit.org> wrote:
> >
> > As part of developing Fuchsia [1] (a new open-source operating
> > system), we ported JavaScriptCore to run on Fuchsia [2].  At the time,
> > our intent was to use this code within the Fuchsia source tree but not
> > to make it available for developers writing applications for Fuchsia.
> > However, recently, we've gotten a number of requests from customers
> > who would like to use JavaScriptCore in their Fuchsia applications.
> >
> > I'd like your advice about the best way to maintain JavaScriptCore
> > support for Fuchsia.  Here are some possibilities I can imagine, but
> > we're open to other possibilities as well:
> >
> > 1. Maintain a fork of JavaScriptCore somewhere on googlesource.com
> > that supports Fuchsia and instruct customers to obtain the Fuchsia
> > port of JavaScriptCore from googlesource.com.
>
> I’d be OK with this.
>
> > 2. Maintain a branch of JavaScriptCore in svn.webkit.org that supports Fuchsia.
>
> In my opinion, SVN branches are not significantly better than (1), and in many ways they are worse.  I wouldn’t advocate for this.

Make sense.

> > 3. Maintain support for JavaScriptCore in the mainline of svn.webkit.org.
>
> I think that I’d be OK with this, too.  This seems better than (1) if you want to stay up-to-date.

Thanks!

Adam


> > For reference, here's the patch we applied to WTF and JavaScriptCore
> > to enable Fuchsia support:
> >
> > https://gist.github.com/abarth/b4fc909d83be5133cd7a5af209757e96
> >
> > This patch is based on webkit at 206446, but we'd obviously rebase the
> > patch onto top-of-tree before contributing it.
> >
> > I'm happy to answer any questions you might have that would help you
> > provide the best advice.  If you would prefer to communicate off-list,
> > I'm happy to do that as well.
> >
> > Thanks in advance,
> > Adam
> >
> > [1] https://fuchsia.googlesource.com/docs/+/master/README.md
> > [2] Actually, if you look at
> > https://fuchsia.googlesource.com/third_party/webkit, you'll see that
> > we've ported WebCore as well, but this email concerns only
> > JavaScriptCore.
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>