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Learn LLVM 12

You're reading from   Learn LLVM 12 A beginner's guide to learning LLVM compiler tools and core libraries with C++

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Product type Paperback
Published in May 2021
Publisher Packt
ISBN-13 9781839213502
Length 392 pages
Edition 1st Edition
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Author (1):
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Kai Nacke Kai Nacke
Author Profile Icon Kai Nacke
Kai Nacke
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Table of Contents (17) Chapters Close

Preface 1. Section 1 – The Basics of Compiler Construction with LLVM
2. Chapter 1: Installing LLVM FREE CHAPTER 3. Chapter 2: Touring the LLVM Source 4. Chapter 3: The Structure of a Compiler 5. Section 2 – From Source to Machine Code Generation
6. Chapter 4: Turning the Source File into an Abstract Syntax Tree 7. Chapter 5: Basics of IR Code Generation 8. Chapter 6: IR Generation for High-Level Language Constructs 9. Chapter 7: Advanced IR Generation 10. Chapter 8: Optimizing IR 11. Section 3 –Taking LLVM to the Next Level
12. Chapter 9: Instruction Selection 13. Chapter 10: JIT Compilation 14. Chapter 11: Debugging Using LLVM Tools 15. Chapter 12: Create Your Own Backend 16. Other Books You May Enjoy

Utilizing a JIT compiler for code evaluation

Compiler writers make a great effort to produce optimal code. A simple, yet effective, optimization is to replace an arithmetic operation on two constants by the result value of this operation. To be able to perform the computation, an interpreter for constant expressions is embedded. And to arrive at the same result, the interpreter has to implement the same rules as the generated machine code! Of course, this can be the source of subtle errors.

A different approach would be to compile the constant expression to IR using the same code generations methods, and then have JIT compile and execute the IR. This idea can even be taken a step further. In mathematics, a function always produces the same result for the same input. For functions in computer languages, this is not true. A good example is the rand() function, which returns a random value for each call. A function in computer languages, which has the same characteristic as a function...

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