Bug 115594 – fourthTier: CodeBlock should be RefCounted

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Filip Pizlo]

This will get rid of a bunch of weird ownership rules, and make the implementation of concurrent compilation a heck of a lot easier.

[Geoffrey Garen]

Can we use GC for this instead? Inside the GC heap, it's easier when GC objects point to other GC objects.

[Filip Pizlo]

(In reply to comment #1)
> Can we use GC for this instead? Inside the GC heap, it's easier when GC objects point to other GC objects.

Probably, eventually.  But right now CodeBlock has a weird relationship with the GC - the GC does have a say in when a CodeBlock dies but not in the usual sense of tracing - so we'll have to be careful when we do that.  There's also the issue that how a CodeBlock is traced depends on who owns it (either Executable or the GC itself), so it's not like making it GC'd would simplify its visit methods.

For now, I don't see a clear benefit to making CodeBlock GC'd.  It's true that doing so would mean that Executable would not have to be destructible, but I think that's really the only benefit.

On the other hand, there is a clear benefit to making it ref-counted.

[Filip Pizlo]

Created attachment 201308 [details]
the patch

Not setting r? yet because I'm still running tests.

[Filip Pizlo]

(In reply to comment #3)
> Created an attachment (id=201308) [details]
> the patch
> 
> Not setting r? yet because I'm still running tests.

It's perf neutral.

[Geoffrey Garen]

Comment on attachment 201308 [details]
the patch

r=me

[Filip Pizlo]

Landed in http://trac.webkit.org/changeset/149860