The interpreter tool (lli) implements an LLVM bitcode interpreter and JIT compiler as well by using the LLVM execution engines studied in this chapter. Let's consider the source file, sum-main.c:

#include <stdio.h>

int sum(int a, int b) {
  return a + b;
}

int main() {
  printf("sum: %d\n", sum(2, 3) + sum(3, 4));
  return 0;
}

The lli tool is capable of running bitcode files when a main function is provided. Generate the sum-main.bc bitcode file by using clang:

$ clang -emit-llvm -c sum-main.c -o sum-main.bc

Now, run the bitcode through lli by using the old JIT compilation engine:

$ lli sum-main.bc 
sum: 12 

Alternatively, use the MCJIT engine:

$ lli -use-mcjit sum-main.bc 
sum: 12

There is also a flag to use the interpreter, which is usually much slower:

$ lli -force-interpreter sum-main.bc
sum:12

The llvm...