505519 - Optimize row iteration in CalcUnpaginagedHeight

Status: NEW

(Core :: Layout: Tables, defect)

Description

[Daniel Holbert [:dholbert]]

Bernd found a performance bug in bug 479166 comment 1, from code inspection.  Quoting his comment:

> The called code at
> http://bonsai.mozilla.org/cvsblame.cgi?file=mozilla/layout/tables/nsTableCellFrame.cpp&rev=3.414&mark=774,775,785-793#763
> 
> looks like a performance penalty. We first look up a the row parent of the
> cell. Its naturally the first row, and then instead of starting the loop there
> we loop over *all* rows till we find the first row that is covered by the cell.

I'm filing this bug about fixing that issue, per bug 479166 comment 3.

Comment 1

[SADINENI RAVI CHANDRA]

i would like to work on this bug ...  so i think its enough if you remove first assignment in the for loop. please correct me if i am wrong . and can you please assign me this bug

Thanks

Comment 2

[Daniel Holbert [:dholbert]]

Thanks!

I believe Bernd's point was that we should start that loop with...
   for (row = rowIndex
...instead of...
   for (row = firstRGInFlow->GetFirstRow()
...because the loop body doesn't do anything until row is >= rowIndex anyway.

(Bernd, correct me if I'm wrong)

Comment 3

[Daniel Holbert [:dholbert]]

Sorry, disregard that last comment; I misread the code & was confusing row & rowX & made no sense.

I believe comment 1 is what Bernd had in mind, but I haven't looked at the code hard enough yet to be sure.

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The bug assignee didn't login in Bugzilla in the last 7 months, so the assignee is being reset.