Principles of compiler design

MODULE CODE:055CS603

MODULE NAME: PRINCIPLES OF COMPILER DESIGN

PRESENTED BY:A.ALMA CANDIDA , B.Sc .,MCA.,

April 10, 2023 A.Alma Candida B.Sc.,MCA., DMI St.Eugene University

TOPICS TO BE COVERED

• DEFINITION OF COMPLIER• LANGUAGE PROCESSING SYSTEMS• PHASES OF COMPILER


COMPILER

• Translates one language to another language.

• Role - report any errors in the source program.


CompilerSourceProgram

TargetProgram

Interpreter

• Which convert from one language to another.• Convert line by line.• Error will be displayed at the time of

conversion.


Language Processing Systems

Preprocessor CompilerAssemblerLinkerLoader


Steps for Language Processing System


Pre Processor

• modules are stored in separate files.• source program is collected by a separate

program.


Compiler

• Source program is fed to a compiler. • Output- assembly-language program .• Assembly language is easier to produce as

output.• easier to debug.


Assembler

• Assembly language into relocatable machine code.

• Large programs are compiled into small modules.

• The relocatable machine code have to be linked together with other relocatable object files and library files .

• This code actually runs on the machine.


Linker

• Resolves external memory addresses,• The code in one file may refer to a location

in another file.


Loader

• Puts together all of the executable object files into memory for execution.


Phases Of Compiler

• There are six different phases available in the compiler

Lexical Analysis Syntax AnalysisSemantic AnalysisIntermediate Code GenerationCode OptimizationCode Generation


Symbol-Table Management

• Data structure containing a record for each variable name, with fields for the attributes of the name.

• Designed to allow the compiler• Find the record for each name quickly and to

store or retrieve data from that record quickly.


Lexical Analysis

• This is also called as Scanning.• It collects sequences of characters into

meaningful units called tokens.• The text is read and divided into tokens.Lexemes• Reads the stream of characters • Groups the characters into meaningful

sequences called lexemes. • The output will be in the form of tokens.


Lexical Analysis (cont..)

• General Form: (token-name, attribute-value)token-name -> an abstract symbol attribute-value-> entry in the symbol table

for this token.


Example of Lexical Analysisposition = initial + rate * 60

<id,1><=> <id,2><+><id,3><*><60>• Position - mapped into a token (id, 1)–id ->identifier and 1 points to the symbol- table• Assignment symbol = mapped into the token (=). • Initial - mapped into the token (id, 2), • + - mapped into the token (+). • Rate mapped into the token (id, 3)• * mapped into the token (*) . • 60 mapped into the token (60)


Syntax Analysis

• This is also called as Parsing.• Arrange tokens form of Tree called Syntax

Tree.• Interior node ->operation • Child node ->Arguments of the operations.• Output -> Tree.


Syntax Analysis(cont..)• Consider the example

• position = initial + rate * 60 • The Syntax tree is in the form of



Semantic Analysis

• Convert from one data type to another.• Example:

• position=initial + rate*60– position, initial, and rate have been declared to be

floating-point numbers, and that the lexeme 60 by itself forms an integer.

– the integer may be converted into a floating-point number.

– the output -> has an extra node for the operator inttofloat, which explicitly converts its integer argument into a floating-point number.


Intermediate Code Generation

• translated to a simple machine-independent intermediate language.

• Convert into low level language• The output -> three-address code sequence.• Example:• tl = inttofloat (60)• t2 = id3 * tl • t3 = id2 + t2 • id1 = t3


Code Optimization

• Attempts to improve the intermediate code so that better target code will result.

• Its is in the form of shorter sequence.

•t1=id3*60.0•id1=id2+t1


CODE GENERATION• Input an intermediate representation of the source

program and maps it into the target language. • Target language is machine code, registers or memory

locations are selected for each of the variables used by the program.

• Registers R1 and R2, the intermediate translated into the machine code

LDF R2, id3 MULF R2, R2, #60.0 LDF Rl, id2 ADDF Rl, Rl, R2 STF idl, Rl


PHASES OF THE COMPILER



Principles of compiler design

Technology

alma candida

dmi st

language program

module code

assembler assembly language

example position

token id

output tree