[llvm-dev] LLVM Developers Meeting JIT BoF -- Request for Topics of Interest

[Lang Hames via llvm-dev]

Hi Geoff,

I believe clang also defaults to small for ELF / x86-64 (I'd expect it to
be the same as gcc).

RuntimeDyld currently assumes large code model. Testing and support for the
small code model are spotty at best -- it's essentially unsupported.
JITLink *will* support small code model (already does for MachO). The
JITLink ELF/x86-64 implementation isn't quite ready for testing yet, but
I'll make an announcement as soon as it is.

-- Lang.

On Fri, Oct 2, 2020 at 10:02 AM Geoff Levner <glevner at gmail.com> wrote:

>
> On Fri, Oct 2, 2020 at 6:33 PM Lang Hames <lhames at gmail.com> wrote:
>
>> Hi Geoff,
>>
>> I have only encountered one problem. If a static library has not been
>>> compiled with -fPIC and uses symbols from a shared library, LLJIT does not
>>> complain, but the code may crash without warning when it is executed.
>>
>>
>> Was the static library compiled with large code model too?
>>
>
> I don't think so... All libraries are compiled with gcc 6.3.1, and the gcc
> documentation says that the default code model is small. I don't know what
> the default code model is for clang...
>
>
>> I think this is probably a RuntimeDyld bug: It's not great at error
>> reporting. A few people in the community are working on an ELF/x86-64
>> implementation of JITLink at the moment -- Once we have that you should get
>> small code model support and better error handling.
>>
>> -- Lang.
>>
>
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