llvm dev - Jul 2016 - [RFC] Make Lanai backend non-experimental

> On Jul 19, 2016, at 12:57 PM, Pete Cooper via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi Renato
>> On Jul 19, 2016, at 9:42 AM, Renato Golin via llvm-dev <llvm-dev at
lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>> 
>> A few basic rules to get accepted are if:
>> * the target exists and can be easily purchased / emulated for
>> investigating problems,
>> * there are official documents / specs published by the project /
>> company that maintains the targets,
>> * there is a reasonable community maintaining the rest of the system
>> (firmware, OS, other tools, etc),
>> * enough people commit themselves to maintain the LLVM back-end to
>> avoid bit-rot,
>> * the back-end is free of contentious features that would mean
>> breaking every other target.
> This is an excellent list.  We should probably have something like it in
the docs if we don’t already.
Agree with Pete.

I’d add (because the community will have to maintain it somehow):
- good code quality and documentation
- good testing (small tests, documented, with good coverage).

— 
Mehdi

> 
> I have no problem with Lanai in LLVM (non-experimentally) if it meets most
of these criteria to some degree.  Obviously that doesn’t mean every target in
LLVM needs to have detailed microarchitecture documents, but a basic ISA should
be publicly available.  Personally I also think the ability to at least simulate
the code is very important too.
> 
> I tried googling it but mostly found news reports about the existence of
the backend, not documentation or anything else.
> 
> I think the Lanai community have done an excellent job meeting the last 2
points.  However, I’d really appreciate more information on the first 3.  I
think meeting each of them (even minimally) is important to leave experimental
status.
> 
> Thanks,
> Pete
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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Hey,

That sounds good. We are:
* Open-sourcing functional simulator to verify execution;
* Publishing ISA spec document that could serve as official reference
- the previously published documentation is out-of-date;

I've created a patch (https://reviews.llvm.org/D22530) that adds Lanai
as one of the default targets.

Thanks,

Jacques

On Tue, Jul 19, 2016 at 11:59 PM, Mehdi Amini via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> On Jul 19, 2016, at 12:57 PM, Pete Cooper via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>
> Hi Renato
>
> On Jul 19, 2016, at 9:42 AM, Renato Golin via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>
> A few basic rules to get accepted are if:
> * the target exists and can be easily purchased / emulated for
> investigating problems,
> * there are official documents / specs published by the project /
> company that maintains the targets,
> * there is a reasonable community maintaining the rest of the system
> (firmware, OS, other tools, etc),
> * enough people commit themselves to maintain the LLVM back-end to
> avoid bit-rot,
> * the back-end is free of contentious features that would mean
> breaking every other target.
>
> This is an excellent list.  We should probably have something like it in
the
> docs if we don’t already.
>
>
> Agree with Pete.
>
> I’d add (because the community will have to maintain it somehow):
> - good code quality and documentation
> - good testing (small tests, documented, with good coverage).
>
> —
> Mehdi
>
>
>
> I have no problem with Lanai in LLVM (non-experimentally) if it meets most
> of these criteria to some degree.  Obviously that doesn’t mean every target
> in LLVM needs to have detailed microarchitecture documents, but a basic ISA
> should be publicly available.  Personally I also think the ability to at
> least simulate the code is very important too.
>
> I tried googling it but mostly found news reports about the existence of
the
> backend, not documentation or anything else.
>
> I think the Lanai community have done an excellent job meeting the last 2
> points.  However, I’d really appreciate more information on the first 3.  I
> think meeting each of them (even minimally) is important to leave
> experimental status.
>
> Thanks,
> Pete
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

On 25 July 2016 at 12:16, Jacques Pienaar <jpienaar at google.com>
wrote:
> That sounds good. We are:
> * Open-sourcing functional simulator to verify execution;
> * Publishing ISA spec document that could serve as official reference
Hi Jacques,

Thanks for the effort! What's the time frame for this?

Pete's point is an important one, and I think this could be an
important example on how we keep back-ends in or out.

It seems you guys are doing the right thing, but it would be good if
you could do that first, so that we can use Lanai as an example to all
future targets.

Following this thread, I'm adding a new section to the developer's
policy to outline the criteria for new targets:

https://reviews.llvm.org/D22753

cheers,
--renato

> On Jul 25, 2016, at 4:16 AM, Jacques Pienaar <jpienaar at google.com>
wrote:
> 
> Hey,
> 
> That sounds good. We are:
> * Open-sourcing functional simulator to verify execution;
> * Publishing ISA spec document that could serve as official reference
> - the previously published documentation is out-of-date;
Thanks Jacques.  Thats great!  I look forward to trying it out.

Cheers,
Pete
> 
> I've created a patch (https://reviews.llvm.org/D22530) that adds Lanai
> as one of the default targets.
> 
> Thanks,
> 
> Jacques
> 
> On Tue, Jul 19, 2016 at 11:59 PM, Mehdi Amini via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> 
>> On Jul 19, 2016, at 12:57 PM, Pete Cooper via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>> 
>> Hi Renato
>> 
>> On Jul 19, 2016, at 9:42 AM, Renato Golin via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>> 
>> A few basic rules to get accepted are if:
>> * the target exists and can be easily purchased / emulated for
>> investigating problems,
>> * there are official documents / specs published by the project /
>> company that maintains the targets,
>> * there is a reasonable community maintaining the rest of the system
>> (firmware, OS, other tools, etc),
>> * enough people commit themselves to maintain the LLVM back-end to
>> avoid bit-rot,
>> * the back-end is free of contentious features that would mean
>> breaking every other target.
>> 
>> This is an excellent list.  We should probably have something like it
in the
>> docs if we don’t already.
>> 
>> 
>> Agree with Pete.
>> 
>> I’d add (because the community will have to maintain it somehow):
>> - good code quality and documentation
>> - good testing (small tests, documented, with good coverage).
>> 
>> —
>> Mehdi
>> 
>> 
>> 
>> I have no problem with Lanai in LLVM (non-experimentally) if it meets
most
>> of these criteria to some degree.  Obviously that doesn’t mean every
target
>> in LLVM needs to have detailed microarchitecture documents, but a basic
ISA
>> should be publicly available.  Personally I also think the ability to
at
>> least simulate the code is very important too.
>> 
>> I tried googling it but mostly found news reports about the existence
of the
>> backend, not documentation or anything else.
>> 
>> I think the Lanai community have done an excellent job meeting the last
2
>> points.  However, I’d really appreciate more information on the first
3.  I
>> think meeting each of them (even minimally) is important to leave
>> experimental status.
>> 
>> Thanks,
>> Pete
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>> 
>> 
>> 
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>