[llvm-dev] How to get the arguments of a function call in LLVM?

Tim Northover via llvm-dev llvm-dev at lists.llvm.org
Wed Apr 19 09:28:03 PDT 2017

On 19 April 2017 at 09:05, Dipanjan Das via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> If I run the pass through `opt`, it produces the following
>     malloc : 0x3df3f40
>     i64 %0
> What does `0x3df3f40` represent?

getArgOperand returns a pointer to a Value object. You're printing
that pointer directly rather than calling its print method to get a
sensible representation.

> Instead of `164` and `512`, why does it produce `i64` and `%0`?

That's because you're iterating through the argument as it exists at
the function's definition/declaration rather than the callsite. You
should be using the CallInst's accessors rather than the Function's if
you want the arguments used for this particular call.



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