Chapter 9: Instruction Selection
The LLVM IR used so far still needs to be turned into machine instructions. This is called instruction selection, often abbreviated to ISel. Instruction selection is an important part of the target backend, and LLVM has three different approaches for selecting instructions: the selection DAG, fast instruction selection, and global instruction selection.
In this chapter, you will learn the following topics:
- Understanding the LLVM target backend structure, which introduces you to the task performed by the target backend, and you examine the machine passes to run.
- Using the machine IR (MIR) to test and debug the backend, which helps you to output MIR after a specified pass and run a pass on the MIR file.
- How instruction selection works, in which you learn about the different ways LLVM performs instruction selection.
- Supporting new machine instructions, in which you add a new machine instruction and make it available to the instruction...
