llvm dev - Oct 2016 - What was the IR made for precisely?

> On Oct 28, 2016, at 1:21 AM, David Chisnall via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> On 28 Oct 2016, at 02:43, ジョウェットジェームス <b3i4zz1gu1 at docomo.ne.jp>
wrote:
>> 
>> I would need to sum up all the rules and ABIs and sizes for all the
targets I need and generate different IR for each, am I correct?
> 
> This is a long-known limitation of LLVM IR and there are a lot of proposals
to fix it.  It would be great if the LLVM Foundation would fund someone to do
the work, as it isn’t a sufficiently high priority for any of the large LLVM
consumers and would make a huge difference to the utility of LLVM for a lot of
people.
It seems to me that it could be a good fit for the scope of a GSoC project.

— 
Mehdi

On 28 Oct 2016, at 09:46, Mehdi Amini <mehdi.amini at apple.com>
wrote:
> 
>> On Oct 28, 2016, at 1:21 AM, David Chisnall via llvm-dev <llvm-dev
at lists.llvm.org> wrote:
>> 
>> On 28 Oct 2016, at 02:43, ジョウェットジェームス <b3i4zz1gu1 at
docomo.ne.jp> wrote:
>>> 
>>> I would need to sum up all the rules and ABIs and sizes for all the
targets I need and generate different IR for each, am I correct?
>> 
>> This is a long-known limitation of LLVM IR and there are a lot of
proposals to fix it.  It would be great if the LLVM Foundation would fund
someone to do the work, as it isn’t a sufficiently high priority for any of the
large LLVM consumers and would make a huge difference to the utility of LLVM for
a lot of people.
> 
> It seems to me that it could be a good fit for the scope of a GSoC project.
I think it would be difficult to do it within the timescale of the GSoC unless
the student was already an experienced LLVM developer.  It would likely involve
designing some good APIs (difficult!), refactoring a bunch of Clang code, and
creating a new LLVM library.  I’ve not seen a GSoC project on this scale succeed
in any of the open source projects that I’ve been involved with.  If we had a
good design doc and a couple of engaged mentors then it might stand a chance.

David

> On Oct 28, 2016, at 1:59 AM, David Chisnall <David.Chisnall at
cl.cam.ac.uk> wrote:
> 
> On 28 Oct 2016, at 09:46, Mehdi Amini <mehdi.amini at apple.com>
wrote:
>> 
>>> On Oct 28, 2016, at 1:21 AM, David Chisnall via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>>> 
>>> On 28 Oct 2016, at 02:43, ジョウェットジェームス <b3i4zz1gu1 at
docomo.ne.jp> wrote:
>>>> 
>>>> I would need to sum up all the rules and ABIs and sizes for all
the targets I need and generate different IR for each, am I correct?
>>> 
>>> This is a long-known limitation of LLVM IR and there are a lot of
proposals to fix it.  It would be great if the LLVM Foundation would fund
someone to do the work, as it isn’t a sufficiently high priority for any of the
large LLVM consumers and would make a huge difference to the utility of LLVM for
a lot of people.
>> 
>> It seems to me that it could be a good fit for the scope of a GSoC
project.
> 
> I think it would be difficult to do it within the timescale of the GSoC
unless the student was already an experienced LLVM developer.  It would likely
involve designing some good APIs (difficult!), refactoring a bunch of Clang
code, and creating a new LLVM library.  I’ve not seen a GSoC project on this
scale succeed in any of the open source projects that I’ve been involved with. 
If we had a good design doc and a couple of engaged mentors then it might stand
a chance.
I agree with all of this, especially we need a well thought proposal and engaged
mentors to conduct this. We could also “staged it” by having intermediate
milestone for the project, and spawn this over multiple GSoC.

— 
Mehdi