[LLVMdev] [cfe-dev] [PATCH] triples for baremetal

[Renato Golin]

Hi Jonathan,

The main issue with your patch is that it can change user expected
behaviour, and I can't tell you what is the expected behaviour in
Darwin or BSD. If people usually use "unknown" in triples, this will
break their builds. If not, this could break the build of someone who
does.

My advice is to create a "default" mechanism for the affected targets,
something that maps "unknwon" to "whatever" (usually "none" but could
be "linux" or "win" depending on the rest of the triple). To do that,
you'll have to learn what is the expected default on each.

You could just completely ignore the expectation and just commit your
patch as it is, but only with agreement from the rest of the community
(Darwin, x86-Linux and FreeBSD). On ARM+Linux, "unknown" is basically
the same as "none", aka "bare-metal". But I can't tell you on anything
else. So, while I don't mind the change, people might do.

cheers,
--renato

On 19 June 2014 14:52, Jonathan Roelofs <jonathan at codesourcery.com> wrote:
> [+llvm-commits, +cfe-commits] (forgot to add them too)
>
>
>
> -------- Original Message --------
> Subject: [cfe-dev] [PATCH] triples for baremetal
> Date: Thu, 19 Jun 2014 07:43:44 -0600
> From: Jonathan Roelofs <jonathan at codesourcery.com>
> To: Eric Christopher <echristo at gmail.com>
> CC: Clang Commits <cfe-commits at cs.uiuc.edu>, Phoebe Buckheister
> <llvm at quasiparticle.net>, "cfe-dev at cs.uiuc.edu" <cfe-dev at cs.uiuc.edu>,
> "llvmdev at cs.uiuc.edu" <llvmdev at cs.uiuc.edu>
>
> Eric,
>
> Attached are patches for llvm and clang that implement this.
>
> I've made 'none' a component that must be added explicitly (i.e. don't turn
> arm-eabi into arm--none-eabi, but rather turn it into arm--unknown-eabi) to
> try
> to reduce surprises. It also keeps the normalization logic a bit simpler
> than it
> would otherwise have to be.
>
> SPIR triples were one place where I was uncertain... I'm not sure if they'd
> prefer to use 'none' or rather just omit that part of the triple. So on
> those,
> I've left them to use Triple::UnknownOS.
>
>
> Cheers,
> Jon
>
> On 6/17/14, 11:11 AM, Eric Christopher wrote:
>>
>> Agreed.
>>
>> -eric
>>
>> On Tue, Jun 17, 2014 at 9:54 AM, Jonathan Roelofs
>> <jonathan at codesourcery.com> wrote:
>>>
>>> [+llvmdev, -llvm-dev]
>>>
>>> (Oopsies, llvmdev doesn't have a hyphen in it like all the others do)
>>>
>>>
>>> On 6/17/14, 10:45 AM, Jonathan Roelofs wrote:
>>>>
>>>>
>>>> [+llvm-dev, cfe-dev]
>>>>
>>>> Was "Re: [PATCH] ARM: allow inline atomics on Cortex M"
>>>>
>>>> On 6/17/14, 10:42 AM, Jonathan Roelofs wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 6/17/14, 9:35 AM, Renato Golin wrote:
>>>>>>
>>>>>>
>>>>>> On 17 June 2014 16:29, Jonathan Roelofs <jonathan at codesourcery.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>> Attached is what I now think the patch ought to be.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Does unknownOS *always* mean bare-metal?
>>>>>
>>>>>
>>>>> I'm not sure. It might be a good time to fork this thread, and start
>>>>> another
>>>>> about triples for bare-metal...
>>>>
>>>>
>>>>
>>>> Personally, I think we ought to add a 'None' entry to the OSType enum
>>>> specifically for baremetal, and then map triples like arm-none-eabi and
>>>> arm--eabi to it (but not arm-foobar-eabi, for example).
>>>>
>>>> Thoughts?
>>>>
>>>> Jon
>>>>
>>>>>>
>>>>>> --renato
>>>>>>
>>>>>
>>>>
>>>
>>> --
>>> Jon Roelofs
>>> jonathan at codesourcery.com
>>> CodeSourcery / Mentor Embedded
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
> --
> Jon Roelofs
> jonathan at codesourcery.com
> CodeSourcery / Mentor Embedded
>
>
> --
> Jon Roelofs
> jonathan at codesourcery.com
> CodeSourcery / Mentor Embedded
>
>
>
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