C++ how to call IR function

Question

I have a C++ file, which hassome functions, such as:int myMax(int a,int b), and compile it to a llvm IR. Now I want to operate the IR in another C++ file, I don't know how to call the function(such as: myMax)in my C++ file.

Answer 1

You can compile IR to an object file for your platform (using llc). This object file is like any other object file produced by, say, a C++ compiler. So you can call it from your C++ code.

More concretely. You compile a file with int myMax(int a, int b) into some object file, say mymax.o. Your "user" C++ code needs to:

1. See the declaration of myMax by including the appropriate header, or just declaring the function prototype.
2. Link to mymax.o to have the implementation in the final executable.

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Alternatively, you can use the existing JIT capability of LLVM to JIT the IR module in your C++ code and then use getPointerToFunction to access it.