llvm dev - Apr 2020 - C++ JIT Compiler with LLVM on Windows 10 - part 5

Hello LLVM developers!

So, I'm continuing my journey with my toy C++ JIT compiler implementation,
and I wrote another article on the issues/solutions I've been working on in
the past few days, mainly:

- Precompiled header handling,
- Emulated TLS desactivation,
- Globals construction & destruction,
- C++ exceptions handling,
- Multi modules linking,

=> In case this could be helpful to anyone, you will find this article
here:
http://wiki.nervtech.org/doku.php?id=blog:2020:0425_jit_compiler_part5_improvements

And of course, if you have any questions for me, just let me know.

Meanwhile, happy hacking everyone ;-)!

Best regards,
Manu.
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+Lang for LLVM Orc things

On Mon, Apr 27, 2020 at 3:34 AM Emmanuel Roche via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hello LLVM developers!
>
> So, I'm continuing my journey with my toy C++ JIT compiler
implementation,
> and I wrote another article on the issues/solutions I've been working
on in
> the past few days, mainly:
>
> - Precompiled header handling,
> - Emulated TLS desactivation,
> - Globals construction & destruction,
> - C++ exceptions handling,
> - Multi modules linking,
>
> => In case this could be helpful to anyone, you will find this article
> here:
>
http://wiki.nervtech.org/doku.php?id=blog:2020:0425_jit_compiler_part5_improvements
>
> And of course, if you have any questions for me, just let me know.
>
> Meanwhile, happy hacking everyone ;-)!
>
> Best regards,
> Manu.
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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I was just reading the blog post -- very cool!

Regarding Globals construction & destruction: There definitely has been a
lot of churn in that area. There will probably be more before  LLVM 11 is
released, but I can see light at the end of the tunnel. I think the Right
Way to run initializers in a JITDylib is to treat it as equivalent to a
dlopen operation (with extra allowances for the fact that new initializers
can be added to a JITDylib at runtime). This is what the LLJIT::initialize
method is doing. Now we just need to generalize it to support
out-of-process JITs. That will at least require a new remote-target
abstraction, and an RPC implementation for testing in-tree.

Regarding emulated TLS deactivation: I've never looking into how/whether
this works on Windows. If it doesn't make sense to have it on by default
there we can change the default for Windows targets.

Regarding merging of multiple modules:

"But of course this would not work because as soon as I try to load the
second script, I get a duplicate symbol error from LLVM (and this
completely makes sense):

[ERROR]: LLVM error: Duplicate definition of symbol '??_7success at
lest@@6B@'"

I think that anything that llvm-link can merge should, in theory, be safe
to add to the JIT. This actually sounds like a bug. Are you able to share
the full modules that you were merging?

Regards,
Lang.


On Mon, Apr 27, 2020 at 11:11 AM David Blaikie <dblaikie at gmail.com>
wrote:
> +Lang for LLVM Orc things
>
> On Mon, Apr 27, 2020 at 3:34 AM Emmanuel Roche via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hello LLVM developers!
>>
>> So, I'm continuing my journey with my toy C++ JIT compiler
>> implementation, and I wrote another article on the issues/solutions
I've
>> been working on in the past few days, mainly:
>>
>> - Precompiled header handling,
>> - Emulated TLS desactivation,
>> - Globals construction & destruction,
>> - C++ exceptions handling,
>> - Multi modules linking,
>>
>> => In case this could be helpful to anyone, you will find this
article
>> here:
>>
http://wiki.nervtech.org/doku.php?id=blog:2020:0425_jit_compiler_part5_improvements
>>
>> And of course, if you have any questions for me, just let me know.
>>
>> Meanwhile, happy hacking everyone ;-)!
>>
>> Best regards,
>> Manu.
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
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