request for timings - makedepend

[Mark Mitchell]

I don't think this has to be perfect to be a big win over what we've got.

The worst slowdown anybody is reporting with Zack's simple-minded 
approach is on the order of a minute.  That's on slow machines, where a 
GCC bootstrap will take hours.  So, I'm not worried about the time *at 
all*.  I'd be very happy to pay the cost to avoid having to keep 
dependencies up to date.

I'm not worried about the case where the header files are renamed 
screwing things up.  That's rare.  And there's a workaround: touch the 
header, and then rebuild the dependencies.  If we can fix this, great, 
but if we can't, I don't see it as a showstopper.

We do need a story for generated headers.  I'd be happy with explicit 
dependencies in the Makefiles indicating what source files depend on 
what generated headers.  We'd still be able to get rid of 99% of the 
dependencies in our Makefiles, and avoid most of the cases where 
something either (a) fails to get rebuilt, or (b) gets rebuilt too often.

My two cents,

-- 
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304