llvm dev - Mar 2014 - [LLVMdev] Contributing the Apple ARM64 compiler backend

On Fri, Mar 28, 2014 at 2:31 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> ----- Original Message -----
> > From: "Tim Northover" <t.p.northover at gmail.com>
> > To: "Renato Golin" <renato.golin at linaro.org>
> > Cc: "LLVM Developers Mailing List" <LLVMdev at
cs.uiuc.edu>
> > Sent: Friday, March 28, 2014 3:47:49 PM
> > Subject: Re: [LLVMdev] Contributing the Apple ARM64 compiler backend
> >
> > Hi Renato,
> > >> 2. Test it. Benchmark it. Explore it. Get data for the
community
> > >> to work with about the state of the back end. ARM has some
> > >> excellent data that will help guide us here.
> > >
> > > Count me in. Would that be a different triple? arm64-linux-gnu?
> >
> > Yep. "--target arm64-linux-gnu" should behave basically the
same as
> > aarch64-linux-gnu, except ending up in the ARM64 backend. Complete
> > with the usual issues of finding your toolchain's includes &
libs;
> > we've not solved that.
>
> Is a different target triple the right thing to do here? I think that
> would introduce a ton of user confusion. How about we keep the target
> triples as they are, and add some other way to choose the desired backend?
>
I share your concern. However, I suspect that a) we will always have at
least an alias as both triples are probably in use at this point, and b) it
won't be the end of the world to have two triples for the same arch long
term. amd64 and x86_64 wasn't the end of the world either. ::shrug::
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On Fri, Mar 28, 2014 at 2:37 PM, Chandler Carruth <chandlerc at
google.com> wrote:
>
> On Fri, Mar 28, 2014 at 2:31 PM, Hal Finkel <hfinkel at anl.gov>
wrote:
>>
>> ----- Original Message -----
>> > From: "Tim Northover" <t.p.northover at gmail.com>
>> > To: "Renato Golin" <renato.golin at linaro.org>
>> > Cc: "LLVM Developers Mailing List" <LLVMdev at
cs.uiuc.edu>
>> > Sent: Friday, March 28, 2014 3:47:49 PM
>> > Subject: Re: [LLVMdev] Contributing the Apple ARM64 compiler
backend
>> >
>> > Hi Renato,
>> > >> 2. Test it. Benchmark it. Explore it. Get data for the
community
>> > >> to work with about the state of the back end. ARM has
some
>> > >> excellent data that will help guide us here.
>> > >
>> > > Count me in. Would that be a different triple?
arm64-linux-gnu?
>> >
>> > Yep. "--target arm64-linux-gnu" should behave basically
the same as
>> > aarch64-linux-gnu, except ending up in the ARM64 backend. Complete
>> > with the usual issues of finding your toolchain's includes
& libs;
>> > we've not solved that.
>>
>> Is a different target triple the right thing to do here? I think that
>> would introduce a ton of user confusion. How about we keep the target
>> triples as they are, and add some other way to choose the desired
backend?
>
>
> I share your concern. However, I suspect that a) we will always have at
> least an alias as both triples are probably in use at this point, and b) it
> won't be the end of the world to have two triples for the same arch
long
> term. amd64 and x86_64 wasn't the end of the world either. ::shrug::
>
I agree here, I'd prefer not to have to switch on and off various backends.

-eric

Maybe we can put some deadlines on merges? E.g. expect two backends to
be merged by 3.5 release?

On Sat, Mar 29, 2014 at 1:37 AM, Chandler Carruth <chandlerc at
google.com> wrote:
>
> On Fri, Mar 28, 2014 at 2:31 PM, Hal Finkel <hfinkel at anl.gov>
wrote:
>>
>> ----- Original Message -----
>> > From: "Tim Northover" <t.p.northover at gmail.com>
>> > To: "Renato Golin" <renato.golin at linaro.org>
>> > Cc: "LLVM Developers Mailing List" <LLVMdev at
cs.uiuc.edu>
>> > Sent: Friday, March 28, 2014 3:47:49 PM
>> > Subject: Re: [LLVMdev] Contributing the Apple ARM64 compiler
backend
>> >
>> > Hi Renato,
>> > >> 2. Test it. Benchmark it. Explore it. Get data for the
community
>> > >> to work with about the state of the back end. ARM has
some
>> > >> excellent data that will help guide us here.
>> > >
>> > > Count me in. Would that be a different triple?
arm64-linux-gnu?
>> >
>> > Yep. "--target arm64-linux-gnu" should behave basically
the same as
>> > aarch64-linux-gnu, except ending up in the ARM64 backend. Complete
>> > with the usual issues of finding your toolchain's includes
& libs;
>> > we've not solved that.
>>
>> Is a different target triple the right thing to do here? I think that
>> would introduce a ton of user confusion. How about we keep the target
>> triples as they are, and add some other way to choose the desired
backend?
>
>
> I share your concern. However, I suspect that a) we will always have at
> least an alias as both triples are probably in use at this point, and b) it
> won't be the end of the world to have two triples for the same arch
long
> term. amd64 and x86_64 wasn't the end of the world either. ::shrug::
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>


-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

On 28 March 2014 21:58, Anton Korobeynikov <anton at korobeynikov.info>
wrote:
> Maybe we can put some deadlines on merges? E.g. expect two backends to
> be merged by 3.5 release?
I think this is a bit too optimistic...

At least the PCS and toolchain kludge detection needs updating, which
is not much. But testing it will be tough without public facing
buildbots, and with scarce availability of v8 hardware.

cheers,
--renato

On Mar 28, 2014, at 2:58 PM, Anton Korobeynikov <anton at
korobeynikov.info> wrote:
> Maybe we can put some deadlines on merges? E.g. expect two backends to
> be merged by 3.5 release?
I don't think this will be feasible.  We want the "right" thing to
happen, adding schedule pressure runs counter to that goal.

-Chris

I would like having this by the 3.5 release. :-)

-bw

On Mar 28, 2014, at 2:58 PM, Anton Korobeynikov <anton at
korobeynikov.info> wrote:
> Maybe we can put some deadlines on merges? E.g. expect two backends to
> be merged by 3.5 release?
> 
> On Sat, Mar 29, 2014 at 1:37 AM, Chandler Carruth <chandlerc at
google.com> wrote:
>> 
>> On Fri, Mar 28, 2014 at 2:31 PM, Hal Finkel <hfinkel at anl.gov>
wrote:
>>> 
>>> ----- Original Message -----
>>>> From: "Tim Northover" <t.p.northover at
gmail.com>
>>>> To: "Renato Golin" <renato.golin at linaro.org>
>>>> Cc: "LLVM Developers Mailing List" <LLVMdev at
cs.uiuc.edu>
>>>> Sent: Friday, March 28, 2014 3:47:49 PM
>>>> Subject: Re: [LLVMdev] Contributing the Apple ARM64 compiler
backend
>>>> 
>>>> Hi Renato,
>>>>>> 2. Test it. Benchmark it. Explore it. Get data for the
community
>>>>>> to work with about the state of the back end. ARM has
some
>>>>>> excellent data that will help guide us here.
>>>>> 
>>>>> Count me in. Would that be a different triple?
arm64-linux-gnu?
>>>> 
>>>> Yep. "--target arm64-linux-gnu" should behave
basically the same as
>>>> aarch64-linux-gnu, except ending up in the ARM64 backend.
Complete
>>>> with the usual issues of finding your toolchain's includes
& libs;
>>>> we've not solved that.
>>> 
>>> Is a different target triple the right thing to do here? I think
that
>>> would introduce a ton of user confusion. How about we keep the
target
>>> triples as they are, and add some other way to choose the desired
backend?
>> 
>> 
>> I share your concern. However, I suspect that a) we will always have at
>> least an alias as both triples are probably in use at this point, and
b) it
>> won't be the end of the world to have two triples for the same arch
long
>> term. amd64 and x86_64 wasn't the end of the world either.
::shrug::
>> 
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>> 
> 
> 
> 
> -- 
> With best regards, Anton Korobeynikov
> Faculty of Mathematics and Mechanics, Saint Petersburg State University
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev