This will allow us to implement butterfly objects.
Created attachment 153360 [details] it starts
Created attachment 153386 [details] more
Created attachment 153409 [details] it does more things than before And now, it can even reallocate storage.
I initially wanted to reverse both the direction of storage and the direction of PropertyOffsets in one patch, 'cause that seemed more sensible. But when it came to debugging (both performance and soundness), I found that the fact that I had conflated these two changes made life totally miserable. I'm now making only one of the changes (direction of storage) and making it so that if you have to do an out-of-line uncached access, there's some negation that needs to happen. We can make the other change later if we feel like it.
Created attachment 153679 [details] almost done Backing up, and putting up for EWS though I suspect the results won't be pretty.
Zoltan: this might require some ARM changes because our compact offset patching (for get_by_id) may want to patch in a negative offset. Note that the patch doesn't yet have the right 32-bit code, so it doesn't make sense to start porting yet. But I figured I'd give you a heads up.
Created attachment 153912 [details] the patch
Comment on attachment 153912 [details] the patch r=me
Landed in http://trac.webkit.org/changeset/123417
> Zoltan: this might require some ARM changes because our compact offset patching (for get_by_id) may want to patch in a negative offset. Note that the patch doesn't yet have the right 32-bit code, so it doesn't make sense to start porting yet. But I figured I'd give you a heads up. Thanks, I will fix it soon.
Landed windows build fix in http://trac.webkit.org/changeset/123503