llvm dev - Dec 2020 - Inserting a function with arguments to appendToGlobalCtors

You probably need to create a function that takes no arguments - and have
that function then create the arguments and call the
functions-taking-arguments you want to run as global ctors. Add the outer
no-argument-taking-function to the global ctors list.

On Mon, Dec 21, 2020 at 5:28 PM Mohannad Ismail via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> I want to insert a function call that executes first. I figured the way to
> do this is to insert to the global constructors with appendToGlobalCtors()
> in this way:
>
> LLVMContext &C = M.getContext();
> Function* FInit = Function::Create(FunctionType::get(Type::getVoidTy(C),
false), GlobalValue::ExternalLinkage, INITMEMORY, &M);
> appendToGlobalCtors(M, FInit, 0);
>
> This works well if the function has no arguments. But what if the function
> I need to insert has arguments that I would like to specify? How do I
> create the function to insert into the global constructors? The function I
> have returns void. I already know how to use the IRBuilder to create a
> function call. But the builder takes the arguments in the
> builder.CreateCall(Func, FuncArgs). In general, I need to execute a bunch
> of function calls first when I am able to obtain their parameters in the
> program.
>
> Hope I was clear enough. Let me know if this needs more clarification.
> Thanks!
>
>
> Best regards,
>
> Mohannad Ismail
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20201221/6dfe72a9/attachment.html>

Hi David,

Thank you for your fast reply.

That's a good idea. But the arguments I need are obtained from the IR, or
in more accurately, from the static analysis I do on the IR. I can't
get these arguments externally. Are you proposing I create the function
within the pass? How do I do that?

On Mon, Dec 21, 2020 at 8:40 PM David Blaikie <dblaikie at gmail.com>
wrote:
> You probably need to create a function that takes no arguments - and have
> that function then create the arguments and call the
> functions-taking-arguments you want to run as global ctors. Add the outer
> no-argument-taking-function to the global ctors list.
>
> On Mon, Dec 21, 2020 at 5:28 PM Mohannad Ismail via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> I want to insert a function call that executes first. I figured the way
>> to do this is to insert to the global constructors with
>> appendToGlobalCtors() in this way:
>>
>> LLVMContext &C = M.getContext();
>> Function* FInit =
Function::Create(FunctionType::get(Type::getVoidTy(C), false),
GlobalValue::ExternalLinkage, INITMEMORY, &M);
>> appendToGlobalCtors(M, FInit, 0);
>>
>> This works well if the function has no arguments. But what if the
>> function I need to insert has arguments that I would like to specify?
How
>> do I create the function to insert into the global constructors? The
>> function I have returns void. I already know how to use the IRBuilder
to
>> create a function call. But the builder takes the arguments in the
>> builder.CreateCall(Func, FuncArgs). In general, I need to execute a
bunch
>> of function calls first when I am able to obtain their parameters in
the
>> program.
>>
>> Hope I was clear enough. Let me know if this needs more clarification.
>> Thanks!
>>
>>
>> Best regards,
>>
>> Mohannad Ismail
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20201221/719c33f6/attachment.html>