[llvmlinux] What's the status of llvm linux for X86_64?

Behan Webster behanw at converseincode.com
Mon Apr 29 18:00:29 UTC 2013


On 13-04-29 01:53 PM, Marcelo Sousa wrote:
> Hi again,
>
>
> On Mon, Apr 29, 2013 at 6:49 PM, Behan Webster 
> <behanw at converseincode.com <mailto:behanw at converseincode.com>> wrote:
>
>     On 13-04-29 12:16 PM, Marcelo Sousa wrote:
>
>         Hello all,
>
>         Can someone elaborate on what's the status of the project for
>         X86_64?
>
>     It builds, boots and works in our limited testing so far.
>
>
>         I'm interested in applying my static analysis tools that I
>         developed for LLVM IR to the Linux Kernel.
>
>     Sounds great!
>
>
>         However, it's clear that clang is not there yet to cope with
>         Kernel code.
>
>     It's not that simple. The kernel code does a number of things
>     which are very gcc-ish and in some cases break the C standards. We
>     largely patch around those problems. The work is upstreaming fixes
>     to the kernel, or upstreaming code to LLVM to add compatibility.
>     This is ongoing work.
>
>
> Where can I read more about which things the kernel is doing that are 
> sketchy in this context?
There is no one good place to look; things change too fast. The website 
is the most up-to-date written resource (though it is a little behind). 
The patches are even more up-to-date. The meetings are the best place to 
find out about these topics.

>
>         Are you applying patches at which level: clang, Kernel or both?
>
>     Both code bases. We have a few more things we want to upstream to
>     Clang/LLVM, but it will mostly work fine for clang 3.3 when
>     released. There is a lot more to upstream to the kernel still
>     (mostly because without a clang which works, upstreaming code to
>     the kernel which they can't test is a non-starter)
>
>
> Can you elaborate on which changes to what? Is this documented 
> somewhere? I need to do some sanity check there to praise soundness of 
> my tools.
My appologies, but the best place to see what needs changing is to look 
at the patches (we are still working on commenting them better). We'll 
be discussing a lot more about this at this week's meeting.

>         Some weeks ago I was able to generate LLVM IR for vexpress,
>         but I need a more functional infrastructure that can work for
>         x86 and several version of the Kernel. Is this at all possible
>         at the moment?
>
>     Give x86_64 a try.
>
>     Try building it in our build system. It is the easiest way to work
>     with all of these updates (and the easiest to try new code we add).
>
>
>         I'm willing to spend time coding and fixing issues, so please
>         feel free to point me around. Furthermore, when will you have
>         the next meeting?
>
>     The meetings are scheduled with doodle polls then announced on
>     this mailing list. You should have seen the latest meeting listed
>     here this past Friday. Here it is again for your convenience: :)
>
>     Thursday, May 2 at 3pm UTC (11AM EST) on Google Hangouts. Make
>     sure you circle me on G+ so I can add you to the call.
>
>     We hope to see you there!
>
>
> See you there!
Excellent!

Behan

-- 
Behan Webster
behanw at converseincode.com

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