[llvm-dev] [RFC] Lanai backend

[Hal Finkel via llvm-dev]

----- Original Message -----
> From: "Hal Finkel via llvm-dev" <llvm-dev at lists.llvm.org>
> To: "C Bergström" <cbergstrom at pathscale.com>
> Cc: "llvm-dev" <llvm-dev at lists.llvm.org>
> Sent: Tuesday, February 9, 2016 6:11:14 PM
> Subject: Re: [llvm-dev] [RFC] Lanai backend
> 
> ----- Original Message -----
> > From: "C Bergström via llvm-dev" <llvm-dev at lists.llvm.org>
> > To: "Jacques Pienaar" <jpienaar at google.com>
> > Cc: "llvm-dev" <llvm-dev at lists.llvm.org>
> > Sent: Tuesday, February 9, 2016 4:53:14 PM
> > Subject: Re: [llvm-dev] [RFC] Lanai backend
> > 
> > On Wed, Feb 10, 2016 at 5:39 AM, Jacques Pienaar via llvm-dev
> > <llvm-dev at lists.llvm.org> wrote:
> > > The ISA & encoding is documented in the comments and diagrams of
> > > lib/Target/Lanai/LanaiInstrFormats.td. If that makes sense I'll
> > > add
> > > a link
> > > to this tablegen in docs/CompilerWriterInfo.rst.
> > 
> > Some driveby comments -
> > 
> > If the processor isn't encumbered and by this I mean any company
> > could
> > in theory make a "Lanai compatible" processor, then I personally
> > would
> > be supportive or middle path. If on the other hand the processor is
> > highly proprietary or encumbered (patents?) then I'd more in the
> > middle or slightly against.
> 
> This is an important point.
> 
> Whether or not the ISA is encumbered in the sense you mentioned does
> not affect my view on whether it should be accepted upstream or not,
> however, given the potential for such a backend to serve educational
> purposes, I think it is important that Google make the relevant
> legal status of the ISA clear.

To be clear, I don't think that clarifying their feelings on independent ISA implementations should be a prerequisite to upstreaming their backend. However, such a clarification certainly affects the educational value of the backend. Given that the ISA seems simple enough to be valuable in a classroom setting, such a clarification would seem practically useful.

 -Hal

> 
>  -Hal
> 
> > 
> > I can't always agree with all @google people and or their
> > comments/attitudes, but in general @google has built up quite a bit
> > of
> > positive "karma", at least from my outside perspective. (I suspect
> > others probably see and may feel this way as well)
> > 
> > To compare against AMDGPU isn't really fair. AMDGPU may have
> > "limited
> > use" as pointed out, but the niche community that does in fact use
> > it
> > and care about it has high impact. The hardware is also publicly
> > available. /* In theory nothing gets in the way of AMD GPU's
> > gaining
> > greater market adoption - I blame marketing more than technology
> > since
> > they are strong on the current gen consoles */
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> > 
> 
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory