Compiler Principle and Technology

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Compiler Principle and Technology

• Prof. Dongming LU
• Mar. 11th, 2015

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• Textbook
• COMPILER CONSTRUCTION Principle and Practice
• by Kenneth C. Louden
• (China Machine Press)
• Course Webhttp//netmedia.zju.edu.cn/compiler
• Email ldm_at_cs.zju.edu.cn (Prof. Lu Dongming)

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• Reference books
• 1.Compilers -- Principles, Techniques and
  Tools, (Dragon Book), by Aho, Sethi and Ullman
  (1986)
• 2. Modern Compiler Implementation in Java,
  by Andrew Appel (2002)
• 3. ??????????(?3?),???????,????
• 4. Compiler Design in C, Prentice Hall,
  Allen I. Holub
• 5. ???????,???????,?????
• TA youyou_chen_at_foxmail.com (???)

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Evaluation 1. Homeworks 15     2.
Quizzes 10     3. Mid-Term Exam 20     4.
Final Exams 55
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Content

1. INTRODUCTION
2. SCANNING
3. CONTEXT-FREE GRMMARS AND PARSING
4. TOP-DOWN PARSING
5. BOTTOM-UP PARSING
6. SEMANTIC ANALYSIS
7. RUNTIME ENVIRONMENT
8. CODE GENERATION

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1. INTRODUCTION
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What is a compiler?

• It translates one language to another

extension
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The purpose of this text

• To provide basic knowledge
• To help us understand the design pattern and
  module division methods in software engineering
• A compiler can be regarded as a special
  software.
• To give necessary tools and practical experience
  (In Summer Term)
• A series of simple examples
• TINY, C-Minus

How to translate?
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Main Topics

• 1.1 Why Compilers? A Brief History
• 1.2 Programs Related to Compilers
• 1.3 The Translation Process
• 1.4 Major Data Structures in a Compiler
• 1.5 Other Issues in Compiler Structure
• 1.6 Bootstrapping and Porting

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1.1 Why? A Brief History
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Why Compiler
time consuming and tedious, not easy to understand
Still not easy to write and understand
X2
Mov x, 2
C7 06 0000 0002
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Brief History of Compiler
Theories and algorithmsFA, CFG et al
The Chomsky Hierarchy was also studied
Some tools Yacc, Lex
1954-1957First compiler
1960s 1970s
1970s1990s
The basic of compiler design have not changed much
last 20 years IDE
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1.2 Programs related to Compiler
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Programs related to compiler
Interpreters
Editors
Debuggers
similar to
Compiler
Project managers
Assembler
Linker
Processor
Loader
Preprocessor
Programms above compiler
Programms under compiler
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Interpreters

• Execute the source program immediately rather
  than generating object code
• Examples BASIC, LISP
• Used often in educational or development
  situations
• Speed of execution is slower than compiled code
  by a factor of 10 or more
• Share many of their operations with compilers

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Interpreters VS compilers
compilers
interpreters
interpreter
X86
execute
X86
execute
Basic,Lisp, Php source code
C,C source code
compiler
execute
execute
interpreter
ARM
ARM
execute
execute
MIPS
MIPS
interpreter
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Programs related to compiler
Editors, IDE
Source code
Compiler
Assembly code
Assembler
Object code
Linker
depends on OS and processor
Executable file
Loader
Executable file
Preprocessor
Executable file
Processor
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1.3 The Translation Process
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The Phases of a Compiler
Source code
Scanner
Tokens
Literal Table
Parser
Syntax Tree
Semantics Analyzer
Symbol Table
Annotated Tree
Source Code Optimizer
Error Handler
Intermediate code
Code Generator
Target code
Important data structures
Target Code Optimizer
Target code
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The phases of a compiler

• Six phases
• Scanner
• Parser
• Semantic Analyzer
• Source code optimizer
• Code generator
• Target Code Optimizer

• Three auxiliary components
• Literal table
• Symbol table
• Error Handler

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The Scanner

• Lexical analysis sequences of characters-gttokens
• eg aindex42
• ?id, 1? ?? ?id, 2? ?? ?? ?4?
  ?? ?2?
• a id
• left bracket
• index id
• right bracket
• assignment
• 4 number
• plus sign
• 2 number

?????
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The Parser

• Syntax analysis
• Tokens -gt Parse tree / Syntax tree ( abstract
  syntax tree)

aindex42
The Parse Tree
The Syntax Tree
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The Semantic Analyzer

• The semantics of a program are its meaning,
  including semantics and type checking
• eg aindex42

The Syntax Tree annotated with attributes
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1.4 Other Issues in Compiler Structure
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The Structure of Compiler

• Multiple views from different angles
• Logical Structure
• Physical Structure
• Sequencing of the operations
• A major impact of the structure
• Reliability, efficiency
• Usefulness, maintainability

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Analysis and Synthesis

• The analysis part of the compiler analyzes the
  source program to compute its properties
• Lexical analysis, syntax analysis and semantics
  analysis, as well as optimization
• More mathematical and better understood
• The synthesis part of the compiler produces the
  translated codes
• Code generation, as well as optimization
• More specialized
• The two parts can be changed independently of the
  other

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Front End and Back End
Front end-orient to people depend on the source
language independent of target language
This is important for compiler portability
Back end- orient to computerdepend on the target
language independent of source language
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Passes

• The repetitions to process the entire source
  program before generating code are referred as
  passes.
• A compiler can be one pass or multiple passes
• One pass efficient compilation less efficient
  target code
• -gt space consuming
• Multiple passes efficient target code
  complicated compilation
• -gt time consuming
• Most compilers with optimization use more than
  one pass
• One Pass for scanning and parsing
• One Pass for semantic analysis and source-level
  optimization
• The third Pass for code generation and
  target-level optimization

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Language Definition and compilers

• The lexical and syntactic structure of a
  programming language
• Regular expressions
• Context-free grammar
• The semantics of a programming language in
  English descriptions
• Language reference manual, or language definition.

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Language Definition and compilers

• A language definition and a compiler are often
  developed simultaneously
• The techniques have a major impact on definition
• The definition has a major impact on the
  techniques

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Compiler options and interfaces

• Mechanisms for interfacing with the operation
  system
• Input and output facilities
• Access to the file system of the target machine
• Options to the user for various purposes
• Specification of listing characteristic
• Code optimization options

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Error Handling

• Static (or compile-time) errors must be reported
  by a compiler
• Generate meaningful error messages and resume
  compilation after each error
• Each phase of a compiler needs different kind of
  error handing
• Exception handling
• Generate extra code to perform suitable runtime
  tests to guarantee all such errors to cause an
  appropriate event during execution.

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1.5 Bootstrapping and Porting
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Third Language for Compiler Construction

• Machine language
• Compiler to execute immediately
• Another language with existed compiler on the
  same target machine (First Scenario)
• Compile the new compiler with existing compiler
• Another language with existed compiler on
  different machine (Second Scenario)
• Compilation produce a cross compiler

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T-Diagram Describing Complex Situation

• A compiler written in language H that translates
  language S into language T.
• S T
• H
• T-Diagram can be combined in two basic ways.

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The First T-diagram Combination

• A B B C A C
• H H H
• Two compilers run on the same machine H
• First from A to B
• Second from B to C
• Result from A to C on H

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The Second T-diagram Combination

• A B A B
• H H K K
• M
• Translate implementation language of a compiler
  from H to K
• Use another compiler from H to K

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The First Scenario

• A H A H
• B B H H
• H
• Translate a compiler from A to H written in B
• Use an existing compiler for language B on
  machine H

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The Second Scenario

• A H A H
• B B K K
• K
• Use an existing compiler for language B on
  different machine K
• Result in a cross compiler

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Process of Bootstrapping

• Write a compiler in the same language
• S T
• S
• No compiler for source language yet
• Porting to a new host machine

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The First step in bootstrap

• A H A H
• A A H H
• H
• quick and dirty compiler written in machine
  language H
• Compiler written in its own language A
• Result in running but inefficient compiler

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The Second step in bootstrap

• A H A H
• A A H H
• H
• Running but inefficient compiler
• Compiler written in its own language A
• Result in final version of the compiler

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The step 1 in porting

• A K A K
• A A H H
• H
• Original compiler
• Compiler source code retargeted to K
• Result in Cross Compiler

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The step 2 in porting

• A K A K
• A A K K
• H
• Cross compiler
• Compiler source code retargeted to K
• Result in Retargeted Compiler

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End of Chapter OneThanks

• Mar. 11th, 2015