[llvm-dev] LLJIT vs. thread-local storage

[Praveen Velliengiri via llvm-dev]

Thanks Jameson.

On Sat, 21 Dec 2019 at 02:29, Jameson Nash <vtjnash at gmail.com> wrote:

> I don't think it's especially hard, but just not specifically
> unimplemented because nobody's had a strong need for it. There's probably
> some combinations of code models and machines that does happen to work
> (e.g. emutls+linux+large-code+large-data+no-PIC). Julia has some support
> for thread locals, but as a JIT in control of the language we currently try
> to generate better code than would otherwise happen (often bits of inline
> assembly that's more similar to the initial-exec model than a dynamic
> library would normally be able to use)—but also with more limitations on
> how it may be used and requiring some additional support from the runtime.
>
> On Fri, Dec 20, 2019 at 1:17 PM Praveen Velliengiri <
> praveenvelliengiri at gmail.com> wrote:
>
>> Hi Jameson,
>> Why thread local support is hard to support in JITs? Whether Julia
>> supports Thread locals? If so, it would be very much helpful to know how.
>>
>> Thanks
>>
>> On Fri, 20 Dec 2019 at 23:31, Jameson Nash via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> This had also came up at llvm-devmtg briefly at the JIT roundtable. One
>>> of the collaborators on my project had started a patch years ago to
>>> implement some of it https://reviews.llvm.org/D8815, but then we went a
>>> different direction with TLS in our frontend and it became unnecessary.
>>>
>>> On Fri, Dec 20, 2019 at 12:36 PM David Blaikie via llvm-dev <
>>> llvm-dev at lists.llvm.org> wrote:
>>>
>>>> +Lang for visibility
>>>>
>>>> On Fri, Dec 20, 2019 at 5:09 AM Geoff Levner via llvm-dev <
>>>> llvm-dev at lists.llvm.org> wrote:
>>>>
>>>>> I am in the process of porting our ORC code to ORC v2 and LLJIT. Now
>>>>> that I have worked around a problem getting global constructors to be
>>>>> called, everything seems to work unless a module declares a static
>>>>> thread-local variable. In that case I get a "JIT session error" saying that
>>>>> the symbol __emutls_v.xyz was not found (substitute the mangled
>>>>> variable name for "xyz").
>>>>>
>>>>> Does that mean anything to anybody out there?
>>>>>
>>>>> (I don't know if it's relevant, but we are using LLVM 8, and we are
>>>>> using Clang to compile C++ modules that are all put into a single JITDylib.)
>>>>>
>>>>> Geoff
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> llvm-dev at lists.llvm.org
>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>
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>>
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