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

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
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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
>
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