[lldb-dev] Managing Clang and LLVM dependencies systematically

[Zachary Turner]

One of my posts didn't go through earlier.  It looks like I responded
privately to Siva instead of to the list.

My main issue is that I don't want the canonical way of getting a new
developer started hacking on LLDB to veer either sideways or backwards with
respect to how one gets started on LLVM.  It should either stay the same of
veer towards LLVM, which means CMake and Ninja.

As a result, I wouldn't want this functionality to be hidden behind a
script unless it were also accessible through CMake (similar to how you can
use dotest.py to run the test suite manually, or you can just build the
check-lldb ninja target after generating CMake).

One way to do this in CMake might be to have an LLDB_USE_LKGR_LIBS CMake
variable which defaults to false.  If it's true, it runs this script to set
up the build environment in whatever way is necessary to get these
revisions, and then using ninja works the way it always does, just build
the lldb target and it will automatically use the LKGR targets.

On Wed Nov 19 2014 at 11:09:33 AM Vince Harron <vharron at google.com> wrote:

> We completely agree that there should be a continuous build with
> top-of-everything.
>
> We're looking to *add* a continuous lldb build with the curated versions
> of llvm/clang.  I think this will help lldb developers with the signal to
> noise ratio.  (Separating their breaks from clang/llvm breaks)  I can
> probably get some CPU time for this new build.
>
> Chromium does a similar thing with their multitude of open source
> dependencies.  Siva was explaining to me that there is a engineer
> "gardener" that updates the working versions file daily (we could do
> weekly) by looking for successful "top-of-everything" builds.  The
> "gardener" responsibility is handed off in rotation.
>
> Why don't we do this as a trial.  We will setup the hardware (linux at
> least) and take responsibility for gardening.  We would like our build
> slave to be triggered by the llvm buildbot master.
>
> If there is value in this to the community, we'll expand the gardening
> responsibilities.  We can also update the public lldb build instructions to
> use the curated build script.
>
> Thanks,
>
> Vince
>
>
> On Tue, Nov 18, 2014 at 5:10 PM, Zachary Turner <zturner at google.com>
> wrote:
>
>> Also +1.  I hope to have this going on Windows sometime before the end of
>> the year.  Getting ProcessWindows working at least with minimal
>> functionality is one of the last major hurdles.
>>
>>
>> On Tue Nov 18 2014 at 5:06:22 PM Kate Stone <katherine_stone at apple.com>
>> wrote:
>>
>>> I've made a point of prioritizing getting our tests to run cleanly here,
>>> so it would be a good time for the community to do likewise for other
>>> platforms.  Among other benefits, Improving the signal/noise ratio for test
>>> failures will make the message to LLVM a lot clearer.
>>>
>>> Kate Stone k8stone at apple.com
>>>  Xcode Runtime Analysis Tools
>>>
>>> On Nov 18, 2014, at 4:57 PM, Reid Kleckner <rnk at google.com> wrote:
>>>
>>> On Tue, Nov 18, 2014 at 3:15 PM, <jingham at apple.com> wrote:
>>>
>>>> I actually think it is good that incompatible changes to llvm break the
>>>> lldb build bots right away.  Then they will get fixed in lldb right after
>>>> the change was made when it is clear in people's minds what just went on.
>>>> So I wouldn't want to add any of this sort of machinery to lldb's build
>>>> w.r.t. the build bots.  Now that the build-bots are running regularly, the
>>>> clang folks can also see the breakage right away and just fix it, which
>>>> they often do (thanks for that BTW...)  So if there were a "GOOD_LLVM" it
>>>> should not be used for the build-bots.
>>>>
>>>
>>> +1, LLDB breakages need to be more visible to Clang/LLVM developers.
>>> Currently they are not very visible, mostly for no good reason.
>>>
>>> Stabilizing the LLDB test suite would help, but the bots could probably
>>> be more aggressive about sending IRC or email pings when the build (not
>>> tests) fails, as this is the primary way that LLVM and Clang changes break
>>> LLDB.
>>>
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>>
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>>
>
>
> --
>
> Vince Harron | Technical Lead Manager | vharron at google.com | 858-442-0868
>
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