Dense array capacity used to be stored in dslots[-1], but it recently got moved to an fslot. But dslots[-1] is still allocated, eg. in growDenseArrayElements(), shrinkDenseArrayElements(). I think/hope this is now unnecessary. Assuming that's correct, we can change ARRAY_CAPACITY_MIN from 7 to 8, and change ensureDenseArrayElements() to use the sequence 8, 16, 32, ... instead of 7, 15, 31, ..., and any other required clean-up.

Bug 584917 has details on this -- Brian made the fix there as part of right-sizing fslots, and found some trace test jitstats dependencies that led to false positives. He fixed the test(s), IIRC. /be

I should be careful with verb tense -- bug 584917 is not yet fixed, there's just a patch. I need to land bug 558451's monster queue (early next week) on tm. /be

So dslots[-1] will be disappearing altogether? Hooray! I'll leave this bug open and dependent on bug 584917 just in case that doesn't entirely fix the matter.

The object size calculation from bug 584175 will require an update when this is landed (assuming 584175 lands first.)

Can this be closed out?