fix opt/8634

[Zdenek Dvorak]

Hello,

> > why not? Is this time critical? Unless it is, I believe a bit slower
> > but easier to understand solution should be preferable.
> 
> Are we to ignore the multitude of complaints concerning increasing
> compile times?

I believe purge_addressof costs us almost nothing (I cannot be sure,
as it has no timevar, but the fact that nobody bothered to add one
tells something); is this really the right place where to attempt to
save?

> The double walk is just gratuitous, and is easily avoided.

Easily? Hmm... yes, right, the solution you propose is doable, but
far from what I would call simple.

Zdenek