[LLVMdev] CallInst constructor interface

[Chris Lattner]

On Wed, 24 Aug 2005, Robert L. Bocchino Jr. wrote:
> Inserting a call instruction is a bit of a pain.  The only way I know how to 
> do it is to write a bunch of code like the following:

You're doing two seperate things here: creating a function and inserting a 
call to it.  For the first, check out Module::getOrInsertFunction.

This allows you write something like this:

   // get 'void foo(int)'
   F = M.getOrInsertFunction("foo", Type::VoidTy, Type::IntTy, 0);

To insert a call, you do need a vector if you want to pass more than two 
args.  Up to two can be passed directly in.  You might also find 
make_vector in VectorExtras.h useful, it lets you say stuff like this:

   make_vector(V1, V2, V3, 0)

to create a vector of three things, in-line.

-Chris

>   	std::vector<const Type*> formalArgs;
>   	formalArgs.push_back(arg1->getType());
>   	formalArgs.push_back(arg2->getType());
> 	...
> 	formalArgs.push_back(argn->getType());
> 	std::vector<Value*> args;
> 	args.push_back(arg1);
> 	args.push_back(arg2);
> 	...
> 	args.push_back(argn);
> 	FunctionType *FType = FunctionType::get(RetTy, formalArgs, false);
> 	Module *M = before->getParent()->getParent()->getParent();
> 	Function *F = M->getOrInsertFunction(FName, FType);
> 	CallInst *call = new CallInst(F, args, "func", before);
>
> It seems that for the common case you should just be able to write this:
>
> 	std::vector<Value*> args;
> 	args.push_back(arg1);
> 	args.push_back(arg2);
> 	...
> 	args.push_back(argn);
> 	CallInst *call = new CallInst(RetTy, FName, args, "func", before);
>
> or even (for a small number of arguments)
>
> 	CallInst *call = new CallInst(RetTy, FName, arg1, arg2, ..., argn, 
> "func", before);
>
> All the other stuff can be inferred from these parameters, so the extra 
> rigamarole is redundant.
>
> Does any interface like this exist?  If not, would it be acceptable to add 
> one?  This would make my life easier.
>
> Rob
>
> Robert L. Bocchino Jr.
> Ph.D. Student, Computer Science
> University of Illinois, Urbana-Champaign

-Chris

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