[question] Compilation Principle

Preface ：
Author's brief introduction ： Xiao Ming java Asking the way , Focus on the bottom of the computer , Worked as a senior engineer in the back end of a financial company , Be good at high security in the trading field / You can use / Concurrent / Performance design and architecture  
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Introduction to this article ： Part 1 Computer er Computer thinking to master   Reason out , Compilation principle is the process of translating high-level language into assembly language or machine language , In this chapter, we introduce the principle and process of compilation design in detail , And with Graal Compiler certification

One 、 What does the compilation process look like ？

First , Let's take a look at how human translation from English to Chinese is done , We need to find the , The meaning of the word , Analyzing the grammar of this sentence , Finally, translate this sentence into Chinese through semantics , The compilation process of our computer is similar to this process

We think of things like Java、PyThon、Go、C++ Language and so on cannot be operated directly ISA Instruction set （ As mentioned above ） Of , We also need a high-level language compile Into a unified assembly language （ One tool needed is , compiler ）, Then call the assembly code process .

When I Java、Python、C++ Wait for the language , The compiler will pass Analyze morphology , for example if else wait , Construct according to the obtained words and parts of speech AST（AST: Abstract syntax tree (abstract syntax code,AST) Is the tree representation of the abstract syntax structure of the source code ）, The resulting tree is a tree structure in which each node represents a kind of source code , Translate it into... Through semantics IR Language （ For example java Turn into .class Bytecode ）, Finally, analyze and optimize according to the optimization strategy of the compiler （ for example JVM Instruction rearrangement in ） Get the target language

Two 、 Compilation fundamentals

After being familiar with the compilation process, we still need more knowledge points to support , Learn more through a few detailed questions , What are the defined grammars ？ Since we want components AST, We need to define the syntax and word position of each compilation , So the coding information will be defined 、 Encoded word 、 Specify where words appear ; Definition ( distinguish ) What is the word ？ The smallest unit of identification information

For what we need to do （ Compile high-level language into assembly language or machine language ） This process , We can understand that it takes three steps to put the elephant in the refrigerator , Open the refrigerator , Stuffed with elephants , Turn off the fridge.  .

Compilation can also be divided into three steps front end -》 Interlingua -》 Back end , The front end is developed by front-end developers who need to access the current compiler , To adapt to multiple languages , The process is   High level language source code -》 Lexical analysis -》 Syntax analysis -》 artifacts AST The process of -》 To intermediate language , Intermediate language decoupling , The back-end is developed by different back-end developers who need access to the current compiler , To adapt to multiple target machine languages （ISA）, Get the intermediate language -》 Do analysis and optimization , Finally, the target language is generated .

3、 ... and 、 Explain profound theories in simple language  Graal compiler

Understand the principle and process of compilation , We need to know who helped us do so much work , This tool is the compiler , Here we use the author Java Language （ You can also compile scala、python Other languages ） The compiler  Graal Introduce the above principles

Graal compiler Support cross platform based Hot spotJVM Upper intermediate language IR Language —— Bytecode , All kinds of languages （Java、Python、R、JS、C/C++、Scala） Can be in JVM On the implementation , Can enjoy JVM A high performance .GC、 Platform and other features , The picture below is GraalVM Architecture diagram of compiler

1、Truffle Framework：Java's AST Interpreter Framework（Java Of AST Interpreter frame , This thing is a tool for converting various other languages into intermediate languages ）
2、Graal Compiler ：JIT compiler written in Java（ use Java Compiling JIT compiler , It's a JIT Just in time compiler , It has achieved 3）
3、JVM CI (JVM Compiler Interface) Interface for Writing JIT Compiler in Java（JVM Compiler interface , Is an interface specification , Defined JIT Specification of just in time compiler ）
4、Java Hotspot VM（ This is what we commonly call JVM）
5、JIT（ Just in time compiler ）, This implements the front-end and back-end of the compilation principle , Just dynamically compile the language in memory

Graal Is and JDK Together with , As an internal module jdk.internal.vm.compiler in .Graal and JVM It's through JVM CI（JVM Compiler Interface） Come on communicate Of . among JVM CI It is also an internal module in jdk.internal.vm.ci in . Here is a brief introduction to the compiler proof compilation process , And how the compiler should be designed , Later, the author will explain the principle of compiler in detail .

This paper summarizes ： In this chapter, we first translate what we should do in English , Reasoning out , Compilation principle of computer , And the principle and process of compiling design are introduced in detail , Zoe Graal Compiler certification .

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