[LLVMdev] How to know the size of a 'long'?

[Duncan Sands]

Hi Paul,

> AFAIK, if I want to call an external C function from IR code, I need to use Function::Create() to create a Function whose signature matches the external C function, then call ExecutionEngine::addGlobalMapping() to "bind" the LLVM Function to the external C function (right?).
>
> Assuming that's correct, if the external C function is declared:
>
> 	void foo(long);
>
> how can I know whether to call Type::getInt32Ty() or Type::getInt64Ty() when creating the argument types vector that will be passed to Function::Create()?  I.e., how do I know how big a C 'long' is on a given platform?

if you are willing to assume that the size of long is the same as the size of a
pointer then you can use getIntPtrType from TargetData.

Ciao, Duncan.