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

Developing a sanitizer

A sanitizer is a kind of technique that checks certain runtime properties of the code (probe) that's inserted by the compiler. People usually use a sanitizer to ensure program correctness or enforce security policies. To give you an idea of how a sanitizer works, let's use one of the most popular sanitizers in Clang as an example – the address sanitizer.

An example of using an address sanitizer

Let's assume we have some simple C code, such as the following:

int main(int argc, char **argv) {
  int buffer[3];
  for (int i = 1; i < argc; ++i)
    buffer[i-1] = atoi(argv[i]);
  for (int i = 1; i < argc; ++i)
    printf("%d ", buffer[i-1]);
  printf("\n");
  return 0;
}

The preceding code converted the command-line arguments into integers and stored them in a buffer of size 3. Then, we printed them out.

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