Book Image

LLVM Techniques, Tips, and Best Practices Clang and Middle-End Libraries

By : Min-Yih Hsu
Book Image

LLVM Techniques, Tips, and Best Practices Clang and Middle-End Libraries

By: Min-Yih Hsu

Overview of this book

Every programmer or engineer, at some point in their career, works with compilers to optimize their applications. Compilers convert a high-level programming language into low-level machine-executable code. LLVM provides the infrastructure, reusable libraries, and tools needed for developers to build their own compilers. With LLVM’s extensive set of tooling, you can effectively generate code for different backends as well as optimize them. In this book, you’ll explore the LLVM compiler infrastructure and understand how to use it to solve different problems. You’ll start by looking at the structure and design philosophy of important components of LLVM and gradually move on to using Clang libraries to build tools that help you analyze high-level source code. As you advance, the book will show you how to process LLVM IR – a powerful way to transform and optimize the source program for various purposes. Equipped with this knowledge, you’ll be able to leverage LLVM and Clang to create a wide range of useful programming language tools, including compilers, interpreters, IDEs, and source code analyzers. By the end of this LLVM book, you’ll have developed the skills to create powerful tools using the LLVM framework to overcome different real-world challenges.
Table of Contents (18 chapters)
1
Section 1: Build System and LLVM-Specific Tooling
6
Section 2: Frontend Development
11
Section 3: "Middle-End" Development

Collecting statistics

As mentioned in the previous section, a compiler is a complex piece of software. Collecting statistical numbers—for example, the number of basic blocks processed by a specific optimization—is one of the easiest and most efficient ways to get a quick portrait on the runtime behaviors of a compiler.

There are several ways to collect statistics in LLVM. In this section, we are going to learn three of the most common and useful options for doing this, and these methods are outlined here:

  • Using the Statistic class
  • Using an optimization remark
  • Adding time measurements

The first option is a general utility that collects statistics via simple counters; the second option is specifically designed to profile compiler optimizations; and the last option is used for collecting timing information in the compiler.

Let's start with the first one.

Using the Statistic class

In this section, we are going to demonstrate new features...