[llvm-dev] [RFC] Polly Status and Integration

C Bergström via llvm-dev llvm-dev at lists.llvm.org
Wed Sep 13 04:53:53 PDT 2017

On Wed, Sep 13, 2017 at 7:43 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> On 09/13/2017 02:16 AM, C Bergström wrote:
> A completely non-technical point, but what's the current "polly" license?
> Does integrating that code conflict in any way with the work being done to
> relicense llvm?
> Good question. I discussed this explicitly with Tobias, and his general
> feeling is that relicensing isl again would be doable if necessary (we
> already did this once, to an MIT license, in order to enable better LLVM
> integration).
> Does adding polly expose any additional legal risks? Some people from
> Reservoir labs have explicitly stated to me that some of their patents
> target polyhedral optimizations. You should almost certainly review their
> portfolio or contact them.
> If at some point someone wants to add real loop optimizations - will there
> be a conflict?
> Can you define "real loop optimizations"?

I think most readers here will understand what I mean. I can go find
specific chapters of textbooks if it's unclear. Maybe the word "real" could
be replaced with traditional, well tested, industry standard or something
else. (ok I'll stop being snarky)

I really do appreciate your feedback and I do think something beyond just a
soft discussion is required on the IP/license vetting. The relicense
process used before should be substantially similar to the process which
LLVM is going to use. There's a big difference between someone randomly
changing a license header and nobody complaining vs getting explicit and
signed agreements from all copyright holders.

Further, my reading on some of the patents causes significant concerns. (A
point everyone will want to ignore until it's too late). I'm avoiding exact
references, but soon I'll start I'll start listing exact patents if nobody
else cares.
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