LLVM Cookbook

Linking LLVM bitcode

In this section, you will link previously generated .bc files to get one single bitcode file containing all the needed references.

Getting ready

To link the .bc files, you need the llvm-link tool.

How to do it...

Do the following steps:

1. To show the working of llvm-link, first write two codes in different files, where one makes a reference to the other:

   $ cat test1.c
   int func(int a) {
   a = a*2;
   return a;
   }
   $ cat test2.c
   #include<stdio.h>
   extern int func(int a);
   int main() {
   int num = 5;
   num = func(num);
   printf("number is %d\n", num);
   return num;
   }
   

2. Using the following formats to convert this C code to bitstream file format, first convert to .ll files, then from .ll files to .bc files:

   $ clang -emit-llvm -S test1.c -o test1.ll
   $ clang ...