[webkit-dev] Bit fields cause Purify to report UMRs

David Hyatt hyatt at apple.com
Wed May 2 17:44:18 PDT 2007

This seems like a pretty sad technical limitation of Purify.

On May 2, 2007, at 5:31 PM, Anyang Ren wrote:

> There are so many UMRs that I am forced to ignroe all UMRs.
> This is bad.  I am wondering if you'd consider not using bit fields
> so that these UMRs can be eliminated.  You can either just make
> them regular fields, which take more space,

I think it would be reasonable to eliminate bit fields in any place  
where they aren't genuinely saving us space.  (There are cases of bit  
field overuse in the tree right now where there aren't enough unique  
bits to really save space.)

However we have used bit fields in many cases (especially in the  
RenderTree) to get a very significant memory savings, so it's  
obviously no good to eliminate those bitfields.

> or implement the bit
> fields by hand.

I don't think it's worth complicating our use of bit fields just to  
work around a flaw in one particular tool.

Have you considered running a script over the source code to  
eliminate the bit fields and then just pass that altered source code  
to Purify?


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