[cfe-dev] [LLVMdev] ARM failures

[David Blaikie]

On Tue, Jan 8, 2013 at 10:01 AM, David Tweed <David.Tweed at arm.com> wrote:
> | Certainly slow builders are problematic. The phase-based building
> | system David Dean is setting up may help mitigate some of this (it
> | should make better use of the resources we have, as well as allowing
> | us to benefit (in the form of smaller blame lists, though not
> | necessarily lower buildbot result latency) from additional resources
> | by allowing greater parallelism).
>
> There's something I've always meant to ask: when you've got a stable buildot setup (same compiler, etc)
> all the buildbots are still set up to do a configure and "make clean". I can easily understand if there was the possibility that
> any other part of the system might also be being changed you'd want to be sure changes were due to repo changes
> and so do a make clean. But those changes aren't too frequent and you could do manual clean at those times.
>
> So all the make clean appears to be doing is guarding against an error in llvm's build system dependency checking. Is the tiny
> probability of this worth the effect on the build times? (Personally I'd say no, but maybe there's an argument for it I haven't spotted.)

I don't believe so, no, and in fact when I went to setup my own
builders (for the GDB 7.5 test suite - I've got it running on the
public builder, but also my own internal one with a bit more hardware
so I can get results sooner (not ideal - I'd prefer to have things
publically, but I had the hardware lying around so figured I'd use
it)) I tried to do this. I seemed to have trouble with the 'configure'
step invalidating the whole build anyway - I don't want the configure
step to be something someone has to do manually on a new builder, but
I'm not sure how to run it in such a way that it doesn't cause an
otherwise incremental build to become a full rebuild either. Any ideas
would be most welcome.

(I believe Takumi's bots do incremental rebuilds though, so I guess he
has some way of doing that)