Working with values and instructions
In LLVM, a value is a unique construct – not only does it represent values stored in variables, but it also models a wide range of concepts from constants, global variables, individual instructions, and even basic blocks. In other words, it is one of the foundations of LLVM IR.
The concept of value is especially important for instructions as it directly interacts with values in the IR. Therefore, in this section, we will put them into the same discussion. We are going to see how values work in LLVM IR and how values are associated with instructions. On top of that, we are going to learn how to create and insert new instructions, as well as how to update them.
To learn how to use values in LLVM IR, we must understand the important theory behind this system, which dictates the behavior and the format of LLVM instructions – the Single Static Assignment (SSA) form.
Understanding SSA
SSA is a way of structuring and designing...
