[cfe-dev] [LLVMdev] Using CMake/Ninja on buildbots

Tobias Grosser tobias at grosser.es
Wed Feb 6 14:07:39 PST 2013

On 02/06/2013 10:41 PM, Renato Golin wrote:
> Hi all,
> A discussion was being carried on llvmcommits about the extra time for
> cleaning and re-building objects that didn't need to be built on buildbots.
> Since they just update the repository, builds could be a lot faster if
> we let the objects in place. Even faster if we used Ninja with CMake. Is
> there a crucial reason why we're still using autoconf for all builds?
> Some of us acknowledge that sometimes the build gets stuck because of a
> CMake file problem or change that the build can't get around
> automatically. It's probably because of those issues that a "make clean"
> is done on almost all buildbots.

I am running the Polly buildbot which seems to be the only one that uses 
cmake. I have never seen any build being stuck. cmake failures reported 
by the polly bot are normally due to cmake config files that have not 
properly being updated.

> The point is that, for the exception, we're paying it in full, every
> single build. Some of us proposed, then, that we could not have the
> clean phase on buildbots in the first place, and deal with the
> exceptions when they happen. Does that sound terrible to anyone?

I believe the clean phase is mainly to catch buildsystem problems that 
only arise in a clean build. I agree that in a phased build the very 
first build could run without the clean phase to get fast results. For 
not that time critical builds, builds that include the clean phase are 
probablz OK.


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