llvm dev - Jun 2014 - [LLVMdev] Is there any tool can generate MIPS ELF file?

Thank you very much for your information and documents!

Why Imagination Technologies do not offer the latest MIPS ABI document
download link just like the ISA docs? If they thought no much people
interested in that doc, they had to make greate effort on compiler
like GCC,LLVM by themself,then why GCC disagree with some MIPS ABI, it
should be freely designed by MIPS ABI designer and compiler backend
target implementation. Do I miss something?

-- 
Best Regards,
Yu Rong Tan

On Mon, Jun 16, 2014 at 5:30 PM, Matheus Almeida
<Matheus.Almeida at imgtec.com> wrote:
> Could you be more specific about what ABIs are you after ? The reason
I'm asking is that there are several ABIs available for Mips and only a few
of them are supported by LLVM (o32, n32 and n64). There are several ABIs defined
by GNU with very little documentation that describes them (EABI is one example).
>
> We are aware that the available documentation and GCC disagree sometimes
and given that GCC is the de-facto standard, LLVM tries to follow GCC's
behaviour as close as possible.
>
> As far as I know there isn't any link from Imagination
Technologies' website that I can point you to w.r.t ABIs but there's
documentation out there like:
> https://dmz-portal.mips.com/mw/images/f/fe/MD00305-2B-ABIDESC-SPC-01.03.pdf
// This is probably the best document as it compares the 3 most important ABIs.
Note that it's an old document and needs some refactoring given that the
implementation in GCC sometimes differs from the documentation.
> http://math-atlas.sourceforge.net/devel/assembly/mipsabi32.pdf // O32
> ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/MIPS-N32-ABI-Handbook.pdf
//n32
>
> Regards,
> Matheus
>

> Why Imagination Technologies do not offer the latest MIPS ABI document
download link just like the ISA docs?
It's something we're considering to do and the documents should be
available at some point in the [hopefully] not too distant future.
> then why GCC disagree with some MIPS ABI, it should be freely designed by
MIPS ABI designer and compiler backend target implementation.
I don't have a very good explanation to this question. The ABIs were
implemented a long time ago and I can only guess at this point but I'd say
that there were some misinterpretations of the spec and given the popularity of
GCC, the implementation became the new standard and it's something that LLVM
needs to cope with.

Regards,
Matheus

-----Original Message-----
From: Nancy [mailto:nancydreaming at gmail.com] 
Sent: 17 June 2014 13:56
To: Matheus Almeida
Cc: LLVM Developers Mailing List
Subject: Re: [LLVMdev] Is there any tool can generate MIPS ELF file?

Thank you very much for your information and documents!

Why Imagination Technologies do not offer the latest MIPS ABI document download
link just like the ISA docs? If they thought no much people interested in that
doc, they had to make greate effort on compiler like GCC,LLVM by themself,then
why GCC disagree with some MIPS ABI, it should be freely designed by MIPS ABI
designer and compiler backend target implementation. Do I miss something?

--
Best Regards,
Yu Rong Tan

On Mon, Jun 16, 2014 at 5:30 PM, Matheus Almeida <Matheus.Almeida at
imgtec.com> wrote:
> Could you be more specific about what ABIs are you after ? The reason
I'm asking is that there are several ABIs available for Mips and only a few
of them are supported by LLVM (o32, n32 and n64). There are several ABIs defined
by GNU with very little documentation that describes them (EABI is one example).
>
> We are aware that the available documentation and GCC disagree sometimes
and given that GCC is the de-facto standard, LLVM tries to follow GCC's
behaviour as close as possible.
>
> As far as I know there isn't any link from Imagination
Technologies' website that I can point you to w.r.t ABIs but there's
documentation out there like:
> https://dmz-portal.mips.com/mw/images/f/fe/MD00305-2B-ABIDESC-SPC-01.03.pdf
// This is probably the best document as it compares the 3 most important ABIs.
Note that it's an old document and needs some refactoring given that the
implementation in GCC sometimes differs from the documentation.
> http://math-atlas.sourceforge.net/devel/assembly/mipsabi32.pdf // O32 
> ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/MIPS-N32-ABI-Handbook.
> pdf //n32
>
> Regards,
> Matheus
>

On Wed, Jun 18, 2014 at 2:03 AM, Matheus Almeida
<Matheus.Almeida at imgtec.com> wrote:
>> Why Imagination Technologies do not offer the latest MIPS ABI document
download link just like the ISA docs?
> It's something we're considering to do and the documents should be
available at some point in the [hopefully] not too distant future.
>
>> then why GCC disagree with some MIPS ABI, it should be freely designed
by MIPS ABI designer and compiler backend target implementation.
> I don't have a very good explanation to this question. The ABIs were
implemented a long time ago and I can only guess at this point but I'd say
that there were some misinterpretations of the spec and given the popularity of
GCC, the implementation became the new standard and it's something that LLVM
needs to cope with.
>
There are a lot of MIPS ABIs.

o32, n32, n64 - These came from the SGI world for IRIX originally, but
were also adopted for linux and used in gcc for both.
o64 - Invented at Cygnus for 64-bit processors
eabi - Different one invented at Cygnus
meabi - Invented with MIPS and Cygnus (and possibly others) in the
late 90s as a new embedded abi.
And there's been at least one or two other ABIs since - I'm pretty
sure Imagination Technologies working up a new abi right now.

-eric
> Regards,
> Matheus
>
> -----Original Message-----
> From: Nancy [mailto:nancydreaming at gmail.com]
> Sent: 17 June 2014 13:56
> To: Matheus Almeida
> Cc: LLVM Developers Mailing List
> Subject: Re: [LLVMdev] Is there any tool can generate MIPS ELF file?
>
> Thank you very much for your information and documents!
>
> Why Imagination Technologies do not offer the latest MIPS ABI document
download link just like the ISA docs? If they thought no much people interested
in that doc, they had to make greate effort on compiler like GCC,LLVM by
themself,then why GCC disagree with some MIPS ABI, it should be freely designed
by MIPS ABI designer and compiler backend target implementation. Do I miss
something?
>
> --
> Best Regards,
> Yu Rong Tan
>
> On Mon, Jun 16, 2014 at 5:30 PM, Matheus Almeida <Matheus.Almeida at
imgtec.com> wrote:
>> Could you be more specific about what ABIs are you after ? The reason
I'm asking is that there are several ABIs available for Mips and only a few
of them are supported by LLVM (o32, n32 and n64). There are several ABIs defined
by GNU with very little documentation that describes them (EABI is one example).
>>
>> We are aware that the available documentation and GCC disagree
sometimes and given that GCC is the de-facto standard, LLVM tries to follow
GCC's behaviour as close as possible.
>>
>> As far as I know there isn't any link from Imagination
Technologies' website that I can point you to w.r.t ABIs but there's
documentation out there like:
>>
https://dmz-portal.mips.com/mw/images/f/fe/MD00305-2B-ABIDESC-SPC-01.03.pdf   //
This is probably the best document as it compares the 3 most important ABIs.
Note that it's an old document and needs some refactoring given that the
implementation in GCC sometimes differs from the documentation.
>> http://math-atlas.sourceforge.net/devel/assembly/mipsabi32.pdf // O32
>> ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/MIPS-N32-ABI-Handbook.
>> pdf //n32
>>
>> Regards,
>> Matheus
>>
>
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