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Gaier, Bjoern via llvm-dev

2020-Jan-07 14:13 UTC

[llvm-dev] Moving to ORCv2 - Where are my global constructors and destructors? + More information

Sorry for the spam, but I made some progress with my issue and wanted to share
what I found out.

I tried the following line before adding my module to the LLJIT:
“this->mainModule->getFunction("_GLOBAL__sub_I_VectorBIOS.cpp")->isDiscardableIfUnused();”
This actually returned true
So I tried the following line:
“this->mainModule->getFunction("_GLOBAL__sub_I_VectorBIOS.cpp")->setLinkage(llvm::GlobalValue::ExternalLinkage);”
Now I was able to find the function and execute the global constructor. For a
workaround this works for me.
However, running LLJITs ‘runConstructors’ does still not work, they are still
empty.


From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of Gaier,
Bjoern via llvm-dev
Sent: 06 January 2020 15:02
To: David Blaikie <dblaikie at gmail.com>; Lang Hames <lhames at
gmail.com>
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] Moving to ORCv2 - Where are my global constructors and
destructors?

Is there a code example or maybe a documentation about this subject? Sadly it is
an important part of my project to get the addresses of the constructors and
destructors.
I really ran out of ideas though, every time when I try to look them up, they
seem to be gone already .w.

From: David Blaikie <dblaikie at gmail.com<mailto:dblaikie at
gmail.com>>
Sent: 19 December 2019 20:52
To: Gaier, Bjoern <Bjoern.Gaier at horiba.com<mailto:Bjoern.Gaier at
horiba.com>>; Lang Hames <lhames at gmail.com<mailto:lhames at
gmail.com>>
Cc: llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
Subject: Re: [llvm-dev] Moving to ORCv2 - Where are my global constructors and
destructors?

+Lang Hames<mailto:lhames at gmail.com> owner/author of the ORC JIT
(though I think he's out of office at the moment, so replies from him might
be delayed).

I believe there's a way to wire up the global ctors, but I don't know
the details unfortunately - perhaps someone else will chime in if/before Lang
gets a chance.

On Thu, Dec 19, 2019 at 5:53 AM Gaier, Bjoern via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:
Heyho,

Recently I tried out the ORCv2 JIT, especially the LLJIT. I gotta say, that I
really like the new interface and the way you use it! However there is one thing
I’m missing. I wrote a small bit code file, which should force having a global
constructor.

int wuff();

__declspec(noinline) int miau()
{
       printf("Huhuhu");
       return wuff();
}

const int x = miau();

When I parse this IR file in my JIT and go through the ‘globals()’ of the
llvm::Module, then I will encounter a symbol with the following name:
“_GLOBAL__sub_I_VectorBIOS.cpp” where VectorBIOS.cpp was the name of the source
file I compiled to the bit code.

I then wanted to get the address of that symbol - from the MCJIT times I
remember, that those functions are the global constructors, but when calling
lookup on that name, I was not able to find the symbol.
So I tried a different way:
llvm::GlobalVariable *var =
module->getNamedGlobal("llvm.global_ctors");
if(var)
{
       llvm::ConstantArray *InitList =
(llvm::ConstantArray*)var->getInitializer();
       for(unsigned int n = 0; n < InitList->getNumOperands(); n++)
       {
             llvm::ConstantStruct *CS =
(llvm::ConstantStruct*)InitList->getOperand(n);
             if(!CS)
             {
                    continue;
             }

             llvm::Constant *FP = CS->getOperand(1);
             if(FP->isNullValue())
                    continue;

             llvm::ConstantExpr *CE = (llvm::ConstantExpr*)FP;
             if(CE->isCast())
             {
                    FP = CE->getOperand(0);
             }

             ((llvm::Function*)FP)->getName();
       }
}
I then printed the name of the llvm::Function but it was exactly the name I
expected “_GLOBAL__sub_I_VectorBIOS.cpp”. This code was executed before I added
module to the JIT.
For various reasons I wanted to store the address to the constructor – so I
don’t want to call the LLJIT runConstructor – simply because I want to execute
those functions later, when the LLJIT does not exist anymore.

I hope someone can help me with this…

Kind Greetings
Björn
Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, USt.ID-Nr.
DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert Plank, Markus
Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima. Junichi Tajika
_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, USt.ID-Nr.
DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert Plank, Markus
Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima. Junichi Tajika
Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, USt.ID-Nr.
DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert Plank, Markus
Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima. Junichi Tajika
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Lang Hames via llvm-dev

2020-Jan-17 02:49 UTC

head link

[llvm-dev] Moving to ORCv2 - Where are my global constructors and destructors? + More information

HI Bjoern,

Thanks for your patience — It’s going to take some time for me to get through
all the emails that built up while I was away last month.

I’m glad you found a workaround for your issue, and thanks for pointing out the
runConstructors problem. I’m working on a big update to the static
initializers/deinitializers problem which I hope to land in the next week or so.
Hopefully that will address this issue.

— Lang.

Sent from my iPad
> On Jan 7, 2020, at 6:13 AM, Gaier, Bjoern <Bjoern.Gaier at
horiba.com> wrote:
> 
> 
> Sorry for the spam, but I made some progress with my issue and wanted to
share what I found out.
>  
> I tried the following line before adding my module to the LLJIT:
>
“this->mainModule->getFunction("_GLOBAL__sub_I_VectorBIOS.cpp")->isDiscardableIfUnused();”
This actually returned true
> So I tried the following line:
>
“this->mainModule->getFunction("_GLOBAL__sub_I_VectorBIOS.cpp")->setLinkage(llvm::GlobalValue::ExternalLinkage);”
> Now I was able to find the function and execute the global constructor. For
a workaround this works for me.
> However, running LLJITs ‘runConstructors’ does still not work, they are
still empty.
>  
>  
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of
Gaier, Bjoern via llvm-dev
> Sent: 06 January 2020 15:02
> To: David Blaikie <dblaikie at gmail.com>; Lang Hames <lhames at
gmail.com>
> Cc: llvm-dev at lists.llvm.org
> Subject: Re: [llvm-dev] Moving to ORCv2 - Where are my global constructors
and destructors?
>  
> Is there a code example or maybe a documentation about this subject? Sadly
it is an important part of my project to get the addresses of the constructors
and destructors.
> I really ran out of ideas though, every time when I try to look them up,
they seem to be gone already .w.
>  
> From: David Blaikie <dblaikie at gmail.com> 
> Sent: 19 December 2019 20:52
> To: Gaier, Bjoern <Bjoern.Gaier at horiba.com>; Lang Hames <lhames
at gmail.com>
> Cc: llvm-dev at lists.llvm.org
> Subject: Re: [llvm-dev] Moving to ORCv2 - Where are my global constructors
and destructors?
>  
> +Lang Hames owner/author of the ORC JIT (though I think he's out of
office at the moment, so replies from him might be delayed).
> 
> I believe there's a way to wire up the global ctors, but I don't
know the details unfortunately - perhaps someone else will chime in if/before
Lang gets a chance.
>  
> On Thu, Dec 19, 2019 at 5:53 AM Gaier, Bjoern via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> Heyho,
>  
> Recently I tried out the ORCv2 JIT, especially the LLJIT. I gotta say, that
I really like the new interface and the way you use it! However there is one
thing I’m missing. I wrote a small bit code file, which should force having a
global constructor.
>  
> int wuff();
>  
> __declspec(noinline) int miau()
> {
>        printf("Huhuhu");
>        return wuff();
> }
>  
> const int x = miau();
>  
> When I parse this IR file in my JIT and go through the ‘globals()’ of the
llvm::Module, then I will encounter a symbol with the following name:
> “_GLOBAL__sub_I_VectorBIOS.cpp” where VectorBIOS.cpp was the name of the
source file I compiled to the bit code.
>  
> I then wanted to get the address of that symbol - from the MCJIT times I
remember, that those functions are the global constructors, but when calling
lookup on that name, I was not able to find the symbol.
> So I tried a different way:
> llvm::GlobalVariable *var =
module->getNamedGlobal("llvm.global_ctors");
> if(var)
> {
>        llvm::ConstantArray *InitList =
(llvm::ConstantArray*)var->getInitializer();
>        for(unsigned int n = 0; n < InitList->getNumOperands(); n++)
>        {
>              llvm::ConstantStruct *CS =
(llvm::ConstantStruct*)InitList->getOperand(n);
>              if(!CS)
>              {
>                     continue;
>              }
>  
>              llvm::Constant *FP = CS->getOperand(1);
>              if(FP->isNullValue())
>                     continue;
>  
>              llvm::ConstantExpr *CE = (llvm::ConstantExpr*)FP;
>              if(CE->isCast())
>              {
>                     FP = CE->getOperand(0);
>              }
>  
>              ((llvm::Function*)FP)->getName();
>        }
> }
> I then printed the name of the llvm::Function but it was exactly the name I
expected “_GLOBAL__sub_I_VectorBIOS.cpp”. This code was executed before I added
module to the JIT.
> For various reasons I wanted to store the address to the constructor – so I
don’t want to call the LLJIT runConstructor – simply because I want to execute
those functions later, when the LLJIT does not exist anymore.
>  
> I hope someone can help me with this…
>  
> Kind Greetings
> Björn
> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima. Junichi
Tajika
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima. Junichi
Tajika
> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima. Junichi
Tajika-------------- next part --------------
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llvm dev - Jan 2020 - Moving to ORCv2 - Where are my global constructors and destructors? + More information

[llvm-dev] Moving to ORCv2 - Where are my global constructors and destructors? + More information

[llvm-dev] Moving to ORCv2 - Where are my global constructors and destructors? + More information