256937 - Use state bits to avoid property lookups for Overflow properties

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Robert O'Callahan (:roc) (email my personal email if necessary)]

The patch in bug 253977 caused a Tp regression, I suspect because it started
calling GetOverflowLines in a few places that we didn't before.

I'm going to attach a patch that uses frame state bits to record the presence of
the Overflow(Lines/OutOfFlows/Placeholders) properties. This should make the
lookup case where no property is present extremely fast. Even if it turns out
not to ameliorate the Tp hit in bug 253977, it's probably still worth it for
columns where we use these properties a lot.

Comment 1

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: fix

As described.

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 157018 [details] [diff] [review]
fix

Use state bits to speed up GetOverflowLines/OutOfFlows/Placeholders in the
common case where there is no property set.

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

checked in.

Comment 4

[Robert Kaiser]

brad tinderbox shows a significant increase in leaks and refcnt leaks for the
time window where this and bug 256932 were checked in.
I don't know anything about those changes, but one of those two checkins looks
to have caused those leaks...

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I'm pretty confident that the leaks are due to bug 256932, not this bug.

Comment 6

[Boris Zbarsky [:bzbarsky]]

Could this patch have caused bug 266454?