CS143 Leture01: Overview，Note

The structure of a compiler

1. Lexical Analysis(词法分析)
2. Parsing(预处理)
3. Semantic Analysis(文法分析)
4. Optimization(优化)
5. Code Generation(代码生成)

Lexical Analysis

• Recognize words.

  word is the smallest unit above letters.

• Lexical Analysis divide a string into “words” or “token”

Parsing

Parsing = Diagramming Sentences

Semantic Analysis

To understand the meaning of sentence, but meaning is too hard to a program.

Compilers perform limited semantic analysis to catch inconsistencies.

Optimization

CS243: Program Analysis and Optimization

Code Generation

A translation to another language, and typically produce assembly code.

Intermediate Representations（中间形式，a.k.a. IR）

Many compilers will perform translations between successive intermediate languages（很多编译器翻译时会使用多个中间形式.）

• All but first and last are intermediate representations (IR) internal（内部的） to the compiler.

IRs are useful to hide the lower levels feature from higher levels.

• registers
• memory layout
• raw pointers
• …