1. Compiler
Lecture 1
CS510

2. E-learning

3. source Lectures Book : “compilers Principles, techniques, & tools”
2nd edition
AHO LAM …
Stanford University PDFs

4. Why Study Compilers? Build a large, ambitious software system.
See theory come to life.
Learn how to build programming languages.
Learn how programming languages work.
Learn tradeoffs in language design.

5. A Short History of Compilers
First, there was nothing.
Then, there was machine code.
Then, there were assembly languages.
Programming expensive; 50% of costs for machines went into programming

6. Definition A compiler is a special form of a translator (Translator)
A translator is a program, or a system, that converts an input text some language to a text in another language, with the same meaning:
Compiler
Interpreter

7. Compiler and Interpreter
The compiler and interpreter are used for converting the high level language to machine language.

8. Interpreter
interpreter just does the same work as of the compiler, but the major variation is that, it converts the high level language into an intermediate code which is executed by the processor.

9. What is a compiler?
A compiler translates (or compiles) a program written in a high-level programming language that is suitable for human programmers into the low-level machine language that is required by computers.
This language can be very different from the machine language that the computer can execute, so some means of bridging the gap is required. This is where the compiler comes in.

11. Interpreter is on-line
Compiler is off-line

12. What Do Compilers Do
A compiler acts as a translator, transforming human-oriented programming languages into computer-oriented machine languages.
Ignore machine-dependent details for programmer
Programming
Language
(Source)
Machine
Language
(Target)
Compiler

13. Compiler
Open slides_01-02-structure-of-a-compiler.pdf

14. The Structure of a Compiler (1)
Any compiler must perform two major tasks
Analysis of the source program
Synthesis of a machine-language program
Compiler
Analysis
Synthesis

15. The Structure of a Compiler (2)
Source
Program
Tokens
Syntactic
Scanner
Parser
Semantic
Routines
Structure
(Character Stream)
Intermediate
Representation
Optimizer
Symbol and
Attribute
Tables
(Used by all Phases of The Compiler)
Code
Generator
Target machine code

16. The Structure of a Compiler (3)
Source
Program
Tokens
Syntactic
Scanner
Parser
Semantic
Routines
Structure
(Character Stream)
Intermediate
Representation
Scanner
The scanner begins the analysis of the source program by reading the input, character by character, and grouping characters into individual words and symbols (tokens)
RE ( Regular expression )
NFA ( Non-deterministic Finite Automata )
DFA ( Deterministic Finite Automata )
LEX
Optimizer
Symbol and
Attribute
Tables
(Used by all
Phases of
The Compiler)
Code
Generator
Target machine code

17. The Structure of a Compiler (4)
Source
Program
Tokens
Syntactic
Scanner
Parser
Semantic
Routines
Structure
(Character Stream)
Intermediate
Representation
Parser
Given a formal syntax specification (typically as a context-free grammar [CFG] ), the parse reads tokens and groups them into units as specified by the productions of the CFG being used.
As syntactic structure is recognized, the parser either calls corresponding semantic routines directly or builds a syntax tree.
CFG ( Context-Free Grammar )
BNF ( Backus-Naur Form )
GAA ( Grammar Analysis Algorithms )
LL, LR, SLR, LALR Parsers
YACC
Optimizer
Symbol and
Attribute
Tables
(Used by all
Phases of
The Compiler)
Code
Generator
Target machine code

18. The Structure of a Compiler (5)
Source
Program
Tokens
Syntactic
Scanner
Parser
Semantic
Routines
Structure
(Character Stream)
Intermediate
Representation
Semantic Routines
Perform two functions
Check the static semantics of each construct
Do the actual translation
The heart of a compiler
Syntax Directed Translation
Semantic Processing Techniques
IR (Intermediate Representation)
Optimizer
Symbol and
Attribute
Tables
(Used by all
Phases of
The Compiler)
Code
Generator
Target machine code

19. The Structure of a Compiler (6)
Source
Program
Tokens
Syntactic
Scanner
Parser
Semantic
Routines
Structure
(Character Stream)
Intermediate
Representation
Optimizer
The IR code generated by the semantic routines is analyzed and transformed into functionally equivalent but improved IR code
This phase can be very complex and slow
Peephole optimization
loop optimization, register allocation, code scheduling
Register and Temporary Management
Peephole Optimization
Optimizer
Symbol and
Attribute
Tables
(Used by all
Phases of
The Compiler)
Code
Generator
Target machine code

20. The Structure of a Compiler (7)
Source
Program
Tokens
Syntactic
Scanner
Parser
Semantic
Routines
Structure
(Character Stream)
Intermediate
Representation
Code Generator
Interpretive Code Generation
Generating Code from Tree/Dag
Grammar-Based Code Generator
Optimizer
Code
Generator
Target machine code

21. The Structure of a Compiler (8)
Code Generator
[Intermediate Code Generator]
Non-optimized Intermediate Code
Scanner [Lexical Analyzer]
Tokens
Code Optimizer
Parser [Syntax Analyzer]
Optimized Intermediate Code
Parse tree
Code Optimizer
Semantic Process [Semantic analyzer]
Target machine code
Abstract Syntax Tree w/ Attributes

22. Programing language basic
Static /Dynamic Distintion
Names, Variables and Identifiers
X.Y is name but x and y are idntifiers
(all identifiers are names but not all names are identifiers )
Variables is particulare location of the store

23. Procedur, Function and Methods
Declaration and definitions
Scopes
Parameter passing

24. Book chapters
Section : 1.2 and 1.6