What complexity have a log(sum) shape?

[Andrei Alexandrescu via Digitalmars-d]

I'm working on the complexity algebra and of course trying to simplify 
my life :o). One good simplification would be to get rid of 
log(polynomial_sum) terms such as:

log(n + m)
log(n^^3 + n1^^2 + n2)

etc.

Do any of these occur in some important algorithms? I couldn't think of 
any nor find any on the various complexity cheat sheets around.


Thanks,

Andrei