CS453 Lecture Introduction 1

CS453 Compiler Construction

Instructor: Wim Bohm

bohm@cs.colostate.edu

Computer Science Building 470

TA: tba

tba@cs.colostate.edu

URL: http://www.cs.colostate.edu/~cs453

Course Logistics (Highlights, see web page for more detail)Schedule Page and Home/News

Read both of these daily. Lots of reading in the first couple of weeks.

Resources Page

Syllabus and Grading

Professional Conduct

Do your own work.

Act like a professional in the lab.

Participate

Come to class and recitation.

Ask questions and post answers on the RamCT discussion board.

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Plan for Today

Course Logistics (done)

Interpreter and Compiler Structure, or Software Architecture

A scanner/parser/interpreter for a simple expression language What is the difference between a compiler and an interpreter?

Compilers class and reality– Why study compilers?

Overview of Programming Assignments– The MeggyJava compiler we will be building.

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Structure of a Typical Compiler

“sentences”

Synthesis

optimization

code generation

target language

IR

IR code generation

IR

Analysis

character stream

lexical analysis

“words”tokens

semantic analysis

syntactic analysis

AST

annotated AST

interpreter

Expression Language: tokens

Tokens: keyword(s): “print” operators/delimiters: “+”, ”-”, “*”, “;” integer literals: “0”, “1”, “2” ,…,”10”, “11”, … , “100”, …

Symbols (Tokens+optional value) are formed by a scanner performing lexical analysis, while reading from a character stream eg: PRINT token+null, SEMI token+null, NUMBER token + Integer-value

Valid tokens are defined by regular expressions, e.g.:

NUMBER: [0-9]+ CS453 Lecture Introduction 5

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Simple example: Expression Interpreter

character stream (print 2+3*4; …)

lexical analysis

tokens

syntactic analysisplus

calls to evaluate andprint

scanner

parser plusinterpreter

text (14, …)

Expression Language: sentences

Sentences: Program sentences (statements here) are recognized by a parser.

Valid programs are defined by a Grammar:

Program::= stmts

stmts::= stmts stmt | <empty>

stmt::= PRINT exp SEMI

exp::= exp + exp | exp – exp | exp * exp | NUMBER

In our case, the parser evaluates the expressions and prints their

values, i.e. the parser interprets the language

In this week’s recitation you will be exercising with this language, and use tools to generate a scanner and a parser / interpreter

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Why Compilers?

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A LOT OF CONCEPTS, TOOLS, and CODE

Compilers are large and complex software structures In this course you will learn a lot of concepts Regular and Context Free grammars, visitor pattern, architecture In this course you will use A LOT of tools Scanner generators and Parser Generators (recitation this week) Eclipse + version control Makefiles jar files assemblers (Meggy) hardware In this course you will write a lot of code 1000s of lines

Don’t get behind! It will be hard, if not impossible, to catch up.

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Example MeggyJava program

MeggyJava: a Java subset for the Meggy toy we are playing with in this course. Example code:

import meggy.Meggy;

class PA3Flower {public static void main(String[] whatever){

{ // Upper left petal, clockwise Meggy.setPixel( (byte)1, (byte)1, Meggy.Color.WHITE ); Meggy.setPixel( (byte)2, (byte)1, Meggy.Color.WHITE ); … }}

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Structure of the MeggyJava Compiler

“sentences”

SynthesisAnalysis

character stream

lexical analysis

“words”tokens

semantic analysis

syntactic analysis

AST

AST and symbol table

code gen

Atmel assembly code

PA1: Write test cases in C++ and MeggyJava, and Atmel warmupPA2: MeggyJava scanner and setPixelPA3: add exps and control flow (AST)PA4: add methods (symbol table)PA5: add variables and objects

Before Next Time

See schedule.

Read all the pages of the website.

Make sure you can ssh into CS linux machines.

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