GFortran testsuite problems with "dg-do compile"

[Brooks Moses]

I just noticed what looks like an anomaly in the gfortran testsuite. 
All of the tests that have "dg-do compile" headers are only being 
compiled once, with an empty "-O" option, rather than iterating over the 
usual list of -O1, -O2, -O3, etc.

(This is, I note, also what's happening with advance_3.f90, which is 
missing a dg-do header altogether.)

Is this the expected/desired behavior for "dg-do compile"?

- Brooks