Overview
Overview
70%lab 30%final exam
what is a compiler
把一种高级语言转换成另一种高级语言，比如C->Rust 称为transpiler
先把代码转换成bytecode，再放到对应的virtual machine上执行
interpreter不将一种高级语言转换成另一种语言，而是直接在源语言中解释状态
linker链接
compiler组成
- Front End
- Lexical Analysis 词法分析器
- Syntax Analysis 语法
- Semantic Analysis 语义
- IR(Intermediate Representation 中间表示)
- Optimiser
- IR
- Back End
- Register Allocation
- Instruction Selection
- Instruction Scheduling
Lexical Analysis -> Syntax Analysis -> Semantic Analysis
Front End: Lexical Analysis
Find lexemes according to patterns, and create tokens
- Lexeme a character string
- Pattern regular expression(lexical errors if no patterns matched)
- Token <token-class, attribute> attribute distinguishes tokens in the same class
Front End: Syntax Analysis
Create the (abstract ) syntax tree (AST)生成语法树
Front End: Semantic Analysis
Passing syntax analysis does not mean the program is valid
Semantic analysis checks correct meaning and decorates AST
Front End Generation
Middle End: Optimizations
可以优化代码
Back End: Instruction Selection
Translate IR to machine code