CHAPTER 1 INTRODUCTION TO COMPILER SUNG-DONG KIM, DEPT. OF COMPUTER ENGINEERING, HANSUNG UNIVERSITY

ABSTRACT  Language Translator: compiler, interpreter  Fundamental Principles of Compilation  Compilation Processes  Compiler Structure  Good Compiler  Portability, Retargetability, Bootstrapping  Short History  Automation Tools  Compiler Theory: Grammar & Automata (2014-1) Compiler 2

1. LANGUAGE TRANSLATOR  Source code/program  Target/object code/program  Language translator Compiler Interpreter Preprocessor Assembler Cross compiler … Language Translator Source Target (2014-1) Compiler 3

1.1 COMPILER  A compiler is a computer program which translates programs written in a particular high-level programming language into executable code for a specific target computer. (2014-1) Compiler 4

1.2 INTERPRETER  Input: executable specification  Output: result of executing the specification (2014-1) Compiler 5 Source Programs Interpreter Results

1.3 HYBRID METHOD  Compile + interpretation  Java (2014-1) Compiler 6 Compiler source code bytecode JVM JIT compiler results native code MACHINE

2. FUNDAMENTAL PRINCIPLES OF COMPILATION  The compiler must preserve the meaning of the program being compiled  The compiler must improve the input program in some discernible way (2014-1) Compiler 7

3. COMPILATION PROCESS (1)  Compiler components (2014-1) Compiler 8

3. COMPILATION PROCESS (2)  Front-end Lexical analysis: token Syntactic analysis(parsing): parse tree Semantic analysis: intermediate code  Back-end Code optimization Target code generation (2014-1) Compiler 9 Source language Target language

4. COMPILER STRUCTURE (2014-1) Compiler 10

어휘 분석 고급 언어 프로그램 기계어 또는 어셈블리어 프로그램 구문 분석 의미 분석 중간 코드 생성 코드 최적화 목적 코드 생성 심벌 테이블 오류 처리 (2014-1) Compiler 11

(2014-1) Compiler 12

(2014-1) Compiler 13

4.1 LEXICAL ANALYSIS  Lexical analyzer(scanner) (2014-1) Compiler 14 ex) if ( a > 10 )... Token : if ( a > 10 )... Token Number :

4.2 SYNTAX ANALYSIS (1)  Syntax analysis, parsing  Syntax analyzer, parser  Function Syntax checking Tree generation (2014-1) Compiler 15

4.2 SYNTAX ANALYSIS (2) (2014-1) Compiler 16 ex) if (a > 10) a = 1; if > = a 10 a 1

4.3 SEMANTIC ANALYSIS  Intermediate code generation  Semantic checking  if (a>10) a = 1.0; when a is integer, semantic error (2014-1) Compiler 17

4.4 CODE OPTIMIZATION (1)  Optional phase  Local optimization Constant folding Eliminating redundant load, store instructions Algebraic simplification Strength reduction (2014-1) Compiler 18

4.4 CODE OPTIMIZATION (2)  Global optimization Flow analysis technique Common sub-expression Moving loop invariants Removing unreachable codes (2014-1) Compiler 19

4.5 TARGET CODE GENERATION  Instruction selection & generation  Instruction scheduling  Register management/allocation  Storage allocation (2014-1) Compiler 20

5. GOOD COMPILER  Correct code generation  Ability of handling of programs of arbitrary size  Compilation speed  Compiler size  User-friendliness: quality of error reporting (2014-1) Compiler 21

6. OTHER ISSUES (1)  Portability The ease with which the compiler itself can be made to run on another machine  Retargetability The ease with which it can be made to generate code for another machine Replace/create back-end (2014-1) Compiler 22

6.1 BOOTSTRAPPING (1)  What language is used to write compiler itself? Implementation (host) language = machine language How the first compilers were written?  Simple case (2014-1) Compiler 23 MACHINE M1 Existing Compiler for language B Compiler for language A Written in language B Running compiler for language A

6.1 BOOTSTRAPPING (2)  More complicated case  T-diagram (2014-1) Compiler 24 MACHINE M1MACHINE M2 Cross compiler Existing Compiler for language B Compiler for language A Written in language B Running compiler for language A ST H

6.1 BOOTSTRAPPING (3)  Combination 1 (2014-1) Compiler 25 ABACBC HHH MACHINE H

6.1 BOOTSTRAPPING (4)  Combination 2 (2014-1) Compiler 26 AABB HH M KK MACHINE H MACHINE M MACHINE K

6.1 BOOTSTRAPPING (5)  Scenario 1 (2014-1) Compiler 27 MACHINE H Existing Compiler for language B Compiler for language A Written in language B Running compiler for language A AAHH BB H HH

6.1 BOOTSTRAPPING (6)  Scenario 2: cross compiler (2014-1) Compiler 28 MACHINE KMACHINE H Existing Compiler for language B Compiler for language A Written in language B Running compiler for language A A A H H BB K K K

6.1 BOOTSTRAPPING (7)  Bootstrapping process “quick and dirty” compiler in assembly language Inefficient and correct code generation Compile “good” compiler by using the “quick and dirty” compiler (2014-1) Compiler 29 AAHH AA H HH Compiler written in its own language A “quick and dirty” compiler written in machine language Running but inefficient compiler

6.1 BOOTSTRAPPING (8) Recompile  final version (2014-1) Compiler 30 AAHH AA H HH Compiler written in its own language A Running but inefficient compiler Final version of the compiler

6.1 BOOTSTRAPPING (9) Advantages Improvement to the source code of the compiler  working compiler Easy porting Porting a compiler written in its own source language (step 1) (2014-1) Compiler 31 AK AA H H AK H Compiler source code retargeted to K Original compiler Cross compiler

6.1 BOOTSTRAPPING (10) Porting a compiler written in its own source language (step 2) (2014-1) Compiler 32 AAKK AA H KK Compiler source code retargeted to K Cross compiler Retargeted compiler

7. SHORT HISTORY  : code generation  : parsing  1975-present: code generation and code optimization Reliability, efficiency, pleasant user interface How to compiler  what to compile (2014-1) Compiler 33

8. AUTOMATION TOOLS  Compiler compiler: compiler generator (2014-1) Compiler 34

8.1 LEXICAL ANALYZER GENERATOR  Ex: LEX (2014-1) Compiler 35

8.2 PARSER GENERATOR  Ex: YACC (2014-1) Compiler 36

(2014-1) Compiler 37

8.3 CODE GENERATION AUTOMATION (2014-1) Compiler 38

9. COMPILER THEORY: GRAMMAR & AUTOMATA (1)  Grammar Noam Chomsky classification Type 3: Regular Grammar (RG) Type 2: Context-Free Grammar (CFG) Type 1: Context-Sensitive Grammar (CSG) Type 0: Unrestricted Grammar (UG) (2014-1) Compiler 39

9. COMPILER THEORY: GRAMMAR & AUTOMATA (2)  RG ⊂ CFG ⊂ CSG ⊂ UG 무제한 문법 문맥 자유 문법 정규 문법 문맥 의존 문법 (2014-1) Compiler 40

9. COMPILER THEORY: GRAMMAR & AUTOMATA (3)  Regular language  Context-free language  Context-sensitive language  Recursively Enumerable Set (2014-1) Compiler 41

9. COMPILER THEORY: GRAMMAR & AUTOMATA (4)  Finite Automata: NFA, DFA  Pushdown Automata  Linear Bounded Automata  Turing Machine (2014-1) Compiler 42

10. OTHERS  Symbol table  Literal table  Error message (2014-1) Compiler 43