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Re: Notes from the GROW'10 workshop panel (GCC research opportunities workshop)
Hi,
You know, I'm getting pretty fed up with all this LLVM advocacy on a
GCC list. It's distracting and counter-productive.
It is not as if anything mentioned in this feedback is new and not
already known here on the GCC list. Repeating the long list of known
problems won't help GCC.
Can we now please return to discussions about GCC here? Please?
Ciao!
Steven
On Wed, Apr 14, 2010 at 4:23 PM, Grigori Fursin <gfursin@gmail.com> wrote:
> Hi all,
>
> Dorit and I just got an anonymous ;) feedback about GCC vs LLVM following
> our email about GROW'10 panel questions so we are just forwarding it here
> (non-edited):
>
> The reasons I have seen for using llvm/clang are basically two-fold: gcc is too slow and too
> complicated. (This is true even for a company with significant in-house gcc expertise.) The C
> language parser for llvm (clang) is far faster than the gcc equivalent, easier to modify, and easier
> to build into a separate library. Speed is a major decision for choosing clang/llvm, as OpenCL needs
> to be complied on the fly. The llvm infrastructure is also far easier to manipulate and modify than
> gcc. This is particularly important as implementing OpenCL means building complier backends to
> generate Nvidia's PTX or AMD's IL, adding specific vector extensions, and supporting various
> language intrinsics. I don't know how much of an issue the licensing issues may be. These issues,
> plus significant corporate backing, appear to be really driving llvm in the OpenCL area. My
> impression is that for gcc to be competitive it will have to offer both comparable compilation speed
> and dramatically better code optimizations. Even then, I'm not sure if the difficulty of working
> with it will be considered a good tradeoff for most companies.
>
> Cheers,
> Grigori
>
>
> -----Original Message-----
> From: gcc-owner@gcc.gnu.org [mailto:gcc-owner@gcc.gnu.org] On Behalf Of Dorit Nuzman
> Sent: Sunday, April 11, 2010 2:54 PM
> To: gcc@gcc.gnu.org
> Subject: Notes from the GROW'10 workshop panel (GCC research opportunities workshop)
>
>
> Dear all,
>
> We would like to share notes from the lively panel discussion at
> GROW'10 (GCC Research Opportunities Workshop) that took place at the
> end of January in Pisa, Italy (alongside the HiPEAC conference).
> The main topic of the discussion was:
>
> ? ? ?How to make GCC more attractive to researchers,
> ? ? ?and how GCC can benefit from researchers?
>
> Here is the list of major points and wishes raised by participants:
>
> * Need to encourage cleanup/infrastructure work on GCC and provide
> stable/flexible/extensible APIs (the question is how to encourage such
> infrastructure work...?)
>
> * Encourage people to work on infrastructure and full implementation
> that actually works: Lobby for high quality conferences to reserve a quota
> of the accepted papers to papers that focus on *implementation* work (and
> start with HiPEAC!)
>
> * Follow up to the above: Encourage research that actually works:
> Lobby for conferences to favor research work that is tested on a realistic
> environment (e.g. pass all of SPECcpu...), and that is reproducible.
> Then GCC and the community could immediately benefit from the results and
> not wait for many years before someone decides to reproduce/redo research
> ideas in GCC.
>
> * Get statistics on percentage of papers/projects that use compilers other
> than GCC, and ask them why... (By the way, why was OpenCL implemented only
> on LLVM and not on GCC?)
>
> * Open up GCC to be used as a library by other tools, so that other tools
> could use its analysis facilities. For example, having alias analysis as an
> API rather than a pass that needs to be applied and then collect
> information. Allow developers/tools access those functions outside GCC
> (should be a high-level API).
>
> * Follow up to the above: Need to come up with a common API /
> standardization / common levels of abstractions. Decide on how to
> coordinate efforts and find commonalities.
>
> * Need a simple pass manager that can list all available passes
> and allow any scheduling (providing dependency information).
>
> * Make more visible/accessible guides for building/extending GCC.
>
> * Better advertize Google Summer of Code, and provide more mentoring.
>
> * Send feedback on which plugin events are desired to add to next releases
> of GCC.
>
> * GCC tries to auto-parallelize the programs it compiles. Will GCC itself
> be made more multi-threaded and run faster in a multi-core environment...?
>
>
> We've collected these and other comments/suggestions before/at/after the
> workshop, on the GROW'10 wiki page:
> http://cTuning.org/wiki/index.php/Dissemination:Workshops:GROW10:Panel_Questions
>
>
>
> We hope these notes would help improve GCC and its appeal/usability for
> researches (or at least raise more discussion!)
>
> Yours,
> Grigori Fursin and Dorit Nuzman
> (GROW'10 organizers)
>
>