[llvm-dev] How to create an alloca variable of type i64 in LLVM IR?

[Don Hinton via llvm-dev]

If you want the value, you'll need to load it first, e.g., by using
CreateLoad...

hth...
don

On Tue, Oct 10, 2017 at 9:07 PM, Dipanjan Das via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

>
> To create a stack based (local) 64 bit integer in LLVM IR, I used:
> Value *var = builder.CreateAlloca(Type::getInt64Ty(Ctx));
>
> I wish to pass this variable to a function "void foo(unsigned long)". I
> created the signature of function foo() as follows:
> Constant *func = M->getOrInsertFunction("foo", Type::getVoidTy(Ctx),Type::getInt64Ty(Ctx),
> NULL);
>
> To pass the newly created variable var to foo():
> Value *args[] = {var};
> builder.CreateCall(func, args);
>
> However, LLVM backend throws assertion error: "Calling a function with a
> bad signature!"
>
> If I print the types of the following:
> errs() << *Type::getInt64Ty(Ctx) << ", " << *var->getType();
>
> I can see first one is i64 and second one is i64*; hence the
> incompatibility. How can I create an alloca variable of type i64?
>
> --
>
> Thanks & Regards,
> Dipanjan
>
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>
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