929546 - Rekey InitialShapeTable for moving metadata object pointer

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Steve Fink [:sfink] [:s:]]

Bug 929151 disables ggc whenever the metadata hook is set. If this feature ends up getting used, it would be much better to leave ggc enabled and rekey instead.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: bug929546-rekey-initial-shape-table

Rather than iterating through all the initial shape tables per bug 953188, here's a patch which adds a storebuffer entry to rekey the entries if necessary.

From running our tests I found that any of the proto, metadata and parent pointers can be in the nursery.

Comment 2

[Terrence Cole [:terrence]]

Comment on attachment 8355554 [details] [diff] [review]
bug929546-rekey-initial-shape-table

Review of attachment 8355554 [details] [diff] [review]:
-----------------------------------------------------------------

Great work! That's much better than the hack I had in mind. r=me

::: js/src/vm/Shape.h
@@ +1463,5 @@
>          {}
> +
> +#ifdef JSGC_GENERATIONAL
> +        /*
> +         * For use by generational GC post barriers.  Look up an entry whose

One space between sentences.

Comment 4

[Jon Coppeard (:jonco)]

Attachment: bug929546-dont-mark-initial-shapes

I always fall foul of the single space rule :)

Looking at the code again I discovered that we already mark all initial shape table entries on minor GC.  With the patch above, we can remove this.

Comment 5

[Terrence Cole [:terrence]]

(In reply to Jon Coppeard (:jonco) from comment #4)
> Created attachment 8355856 [details] [diff] [review]
> bug929546-dont-mark-initial-shapes
> 
> I always fall foul of the single space rule :)
> 
> Looking at the code again I discovered that we already mark all initial
> shape table entries on minor GC.  With the patch above, we can remove this.

Makes sense; I thought it was pretty odd that we weren't hitting this all the time.

Comment 6

[Terrence Cole [:terrence]]

Comment on attachment 8355856 [details] [diff] [review]
bug929546-dont-mark-initial-shapes

Review of attachment 8355856 [details] [diff] [review]:
-----------------------------------------------------------------

r=me

Comment 7

[Jon Coppeard (:jonco)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/34a1652e8f52
https://hg.mozilla.org/integration/mozilla-inbound/rev/224f3b70841f

Comment 8

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/34a1652e8f52
https://hg.mozilla.org/mozilla-central/rev/224f3b70841f