llvm dev - Dec 2016 - LLD status update and performance chart

Hal Finkel <hfinkel at anl.gov> writes:
>> Why? What is wrong with setting priorities and observing that what
>> library support we already have has had a disproportional cost?
>
> Can you please elaborate on this disproportional cost? I think it is really
important to be specific about these kinds of things for the benefit of all
potential contributors.
Yes. Getting the early shutdown code was way more work than it would
have been if this was just a program. The code is also quite ugly.

It also prevents us from sharing error handling functions with the COFF
linker.

So, please, I *BEG YOU*, let us write a linker. Once we have a
workning, production qualitity linker we can setup a performance
tracking bot and evaluate each librification change for its cost in
performance and code quality. We are just not there yet and not in a
position to take those patches.

Cheers,
Rafael

----- Original Message -----
> From: "Rafael Avila de Espindola" <rafael.espindola at
gmail.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: "llvm-dev" <llvm-dev at lists.llvm.org>, "Mehdi
Amini" <mehdi.amini at apple.com>
> Sent: Tuesday, December 13, 2016 12:09:00 PM
> Subject: Re: [llvm-dev] LLD status update and performance chart
> 
> Hal Finkel <hfinkel at anl.gov> writes:
> >> Why? What is wrong with setting priorities and observing that what
> >> library support we already have has had a disproportional cost?
> >
> > Can you please elaborate on this disproportional cost? I think it
> > is really important to be specific about these kinds of things for
> > the benefit of all potential contributors.
> 
> Yes. Getting the early shutdown code was way more work than it would
> have been if this was just a program. The code is also quite ugly.
This is general issue across LLVM's codebase. Is there some reason this is
worse in lld than anywhere else in the project?
> 
> It also prevents us from sharing error handling functions with the
> COFF
> linker.
Is this a technical problem is just a lack of needed refactoring?

Thanks again,
Hal
> 
> So, please, I *BEG YOU*, let us write a linker. Once we have a
> workning, production qualitity linker we can setup a performance
> tracking bot and evaluate each librification change for its cost in
> performance and code quality. We are just not there yet and not in a
> position to take those patches.
> 
> Cheers,
> Rafael
> 
-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory

Hal Finkel <hfinkel at anl.gov> writes:
>> Yes. Getting the early shutdown code was way more work than it would
>> have been if this was just a program. The code is also quite ugly.
>
> This is general issue across LLVM's codebase. Is there some reason this
is worse in lld than anywhere else in the project?
It is not worse in ELF than in other libraries (LLVM or not), but it
could be simpler if lld was really just a program like the others in
tools.
>> It also prevents us from sharing error handling functions with the
>> COFF
>> linker.
>
> Is this a technical problem is just a lack of needed refactoring?
Because the COFF ones can just exit as fortunately the COFF linker is
actually just a linker.

Cheers,
Rafael