llvm dev - Apr 2016 - Add Call instruction in IR for a non-existing function

Hello everyone,
I am trying to add checkpoints to my IR code. In order to do that I need to
add this instruction:
call void @m5_checkpoint(i64 0, i64 0)
to some of the basic blocks in my benchmark.
m5_checkpoint is a function defined for checkpointing in another simulator
and is not included in my benchmark source code. So I need to create this
instruction and I couldn't figure out how to do this by reading the manual.
I will appreciate if anyone can help me .
Regards,
Fami
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On Tue, Apr 05, 2016 at 04:28:18PM -0400, fateme Hoseini via llvm-dev
wrote:
> Hello everyone,
> I am trying to add checkpoints to my IR code. In order to do that I need to
> add this instruction:
> call void @m5_checkpoint(i64 0, i64 0)
> to some of the basic blocks in my benchmark.
> m5_checkpoint is a function defined for checkpointing in another simulator
> and is not included in my benchmark source code. So I need to create this
> instruction and I couldn't figure out how to do this by reading the
manual.
> I will appreciate if anyone can help me .
> Regards,
> Fami
Hi Fami,

you need to declare your function as an external global Symbol in order
to use it (you will still need to provide the symbol at linktime
though).

One way to do this is to call the module method getOrInsertFunction
after creating the correct Functiontype:

    auto *FT = llvm::FunctionType::get(...);
    M.getOrInsertFunction("m5_checkpoint", FT)

hope it helps,

Serge

Hi,

I think it's called getOrInsertFunction() in module class, with reference
from:

http://llvm.org/releases/2.6/docs/tutorial/JITTutorial1.html

Also, when you encounter questions for LLVM C++ APIs in the future, you can
write desired output code and use llc to generate proper C++API code, which
I think is a very neat feature of LLVM.

e.g.
clang -c -emit-llvm your_desired_output.c
llc -march=cpp your_desired_output.bc

Hope this helps.
Regards,
Kevin


On Tue, Apr 5, 2016 at 3:28 PM fateme Hoseini via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hello everyone,
> I am trying to add checkpoints to my IR code. In order to do that I need
> to add this instruction:
> call void @m5_checkpoint(i64 0, i64 0)
> to some of the basic blocks in my benchmark.
> m5_checkpoint is a function defined for checkpointing in another simulator
> and is not included in my benchmark source code. So I need to create this
> instruction and I couldn't figure out how to do this by reading the
manual.
> I will appreciate if anyone can help me .
> Regards,
> Fami
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Thank you all.
Kevin,
I didn't get your point. Do you mean to change the bc file and them create
C++ out of it?
Regards,
Fami

On Tue, Apr 5, 2016 at 4:48 PM, Kevin Hu <hxy9243 at gmail.com> wrote:
> Hi,
>
> I think it's called getOrInsertFunction() in module class, with
reference
> from:
>
> http://llvm.org/releases/2.6/docs/tutorial/JITTutorial1.html
>
> Also, when you encounter questions for LLVM C++ APIs in the future, you
> can write desired output code and use llc to generate proper C++API code,
> which I think is a very neat feature of LLVM.
>
> e.g.
> clang -c -emit-llvm your_desired_output.c
> llc -march=cpp your_desired_output.bc
>
> Hope this helps.
> Regards,
> Kevin
>
>
> On Tue, Apr 5, 2016 at 3:28 PM fateme Hoseini via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hello everyone,
>> I am trying to add checkpoints to my IR code. In order to do that I
need
>> to add this instruction:
>> call void @m5_checkpoint(i64 0, i64 0)
>> to some of the basic blocks in my benchmark.
>> m5_checkpoint is a function defined for checkpointing in another
>> simulator and is not included in my benchmark source code. So I need to
>> create this instruction and I couldn't figure out how to do this by
reading
>> the manual. I will appreciate if anyone can help me .
>> Regards,
>> Fami
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
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