LLVM IR extra parameter in every function

[Arpit Aggarwal]

Hi all,
Every function in LLVM-IR of any Go program has an additional parameter as i8* nest.
Can you please tell me what it is and the use of it?

Thanks in advance

Thanks
Arpit

[Andrew Wilkins]

On Wed, 17 May 2017 at 18:38 Arpit Aggarwal <arpit9...@gmail.com> wrote:

Hi all,
Every function in LLVM-IR of any Go program has an additional parameter as i8* nest.
Can you please tell me what it is and the use of it?

The nest parameter is to support closures: the closure is passed in via that nest parameter. Because the caller can't always know whether its callee expects a closure or not, all functions are given a nest parameter.

A function value is represented as two pointers: the function itself, and a pointer to a struct containing closure variables. When making a dynamic function call, the closure struct pointer is passed in via the nest parameter. For a function that doesn't expect a closure, that will be ignored.

Cheers,

Andrew

Thanks in advance

Thanks
Arpit

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[Arpit Aggarwal]

Thanks a lot Andrew.

Regards,
Arpit