Time : 1 Hour Max Marks : 30

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Time : 1 Hour Max Marks : 30"

Transcription

1 Total No. of Questions : 6 P4890 B.E/ Insem.- 74 B.E ( Computer Engg) PRINCIPLES OF MODERN COMPILER DESIGN (2012 Pattern) (Semester I) Time : 1 Hour Max Marks : 30 Q.1 a) Explain need of symbol table with compiler. List different data structures for symbol table. [4] Ans. Symbol table information is used by the analysis and synthesis phases : 1) To verify that used identifiers have been defined (declared) 2) To verify that expressions and assignments are semantically correct type checking 3) To generate intermediate or target code Different data Structures for Symbol Table : 1) Unordered List 2) Ordered List 3) Hash Table 4) Binary Search Tree Q.1 b) What is Garbage Collection [2] Ans. Garbage collection is the systematic recovery of pooled computer storage that is being used by a program when that program no longer needs the storage. There are three main techniques for automatic memory management: reference counting, mark-and-sweep, and copying. Q.1 c) What is LEX? Give format of LEX specification file. [4] Ans. Lex:It is a Scanner Generator that Helps write programs whose control flow is directed by instances of regular expressions in the input stream. Format of LEX specification file :...definitions... %%...rules... %%...code... 1) Definitions section : There are three things that can go in the definitions section:

2 C code Any indented code between %{ and %} is copied to the C file. This is typically used for defining file variables, and for prototypes of routines that are defined in the code segment. A definition is very much like a #define cpp directive. For example letter [a-za-z] digit [0-9] punct [,.:;!?] nonblank [ˆ \t] These definitions can be used in the rules section: one could start a rule {letter}+ {... 2) Rules section The rules section has a number of pattern-action pairs. The patterns are regular expressions. If more than one rule matches the input, the longer match is taken. If two matches are the same length, the earlier one in the list is taken. 3) User code section If the lex program is to be used on its own, this section will contain a main program. If you leave this section empty you will get the default main: int main() { yylex(); return 0; } where yylex is the parser that is built from the rules. OR Q.2) a) Compare single pass and multipass design for compiler[4] Ans. a) 1. A one-pass compiler is a compiler that passes through the source code of each compilation unit only once. A multi-pass compiler is a type of compiler that processes the source code or abstract syntax tree of a program several times.

3 2. A one-pass compilers is faster than multi-pass compilers 3. A one-pass compiler has limited scope of passes but multi-pass compiler has wide scope of passes. 4. Multi-pass compilers are sometimes called wide compilers where as one-pass compiler are sometimes called narrow compiler. 5. Many programming languages cannot be represented with a single pass compilers, for example Pascal can be implemented with a single pass compiler where as languages like Java require a multi-pass compiler. Single Pass Compiler Driver Multi-Pass Compiler Driver Calls calls calls calls Syntactic Analyzer Syntactic Analyzer Contextual Analyzer Code Generator Calls calls i/p o/p i/p o/p i/p o/p Contextual Analyzer Code Generator Source text AST Decorated AST M/c Code Q.2 b) What are lexeme, pattern and token in lexical analysis? [3] Ans b) Token: Token is a sequence of characters that can be treated as a single logical entity. Typical tokens are, 1) Identifiers 2) keywords 3) operators 4) special symbols 5)constants Pattern: A set of strings in the input for which the same token is produced as output. This set of strings is described by a rule called a pattern associated with the token. Lexeme: A lexeme is a sequence of characters in the source program that is matched by the pattern for a token. Q.2 c) Explain static Vs dynamic storage allocation.[3] Ans. c) Static Allocation means, that the memory for your variables is automatically allocated, either on thestack or in other sections of your program. You do not have to reserve extra memory using them, but on the other hand, have also no control over the lifetime of this memory. E.g: a variable in a function, is only there until the function finishes.

4 void func() { } int i; /* `i` only exists during `func` */ Dynamic memory allocation is a bit different. Allocation of memory at the time of execution (run time) is known as dynamic memory allocation. Here we can control the exact size and the lifetime of these memory locations. Static Allocation Memory is allocated before the execution of the program begins. (During Compilation) Dynamic Allocation Memory is allocated during the execution of the program. No memory allocation or deallocation actions are performed during Execution. Memory Bindings are established and destroyed during the Execution. Variables remain permanently allocated. Allocated only when program unit is active. Implemented using stacks and heaps. Implemented using data segments. Pointer is needed to accessing variables. No need of Dynamically allocated pointers. Faster execution than Dynamic. Slower execution than static. More memory Space required. Less Memory space required. Q.3 a) What are problems/ issues associated with top-down parser. [2] Ans a) Problems with the Top-Down Parser 1. Only judges grammaticality. 2. Stops when it finds a single derivation.

5 3. No semantic knowledge employed. 4. No way to rank the derivations. 5. Problems with left-recursive rules. 6. Problems with ungrammatical sentences. Q.3 b) What is type checking [2] Ans b) Type checking is a program analysis that verifies something about the types that are used in the program. Type checker verifies that the type of a construct (constant, variable, array, list, object) matches what is expected in its usage context. E.g.,Java's % (modulo) operator expects two integers, so 3%4.5 is a type error. Q.3 c) Generate LR(1) parsing table for following grammar : [6] S -> BB B-> cb B-> d Ans. c) Augment the grammar : I : S ->.S, $ Now, produce LR(1) set of items Closure(I) : Io : S ->.S, $ S->.BB, $ goto(i2, B) I5 : S-> BB., $ B->.cB, c d goto(i2, c) I6 : B-> c.b, $ B->.d, c d B->.cB, $ B->.d, $ goto(io, S) I1 : S -> S., $ goto(i2, d) I7 : B-> d., $ goto(io, B) I2 : S -> B.B, $ goto(i3, B) I8 : B-> cb., c d B->.cB, $ goto(i3, c) : I3 B->.d, $ goto(i3, d) : I3 goto(i6, B) I9 : B-> cb., $ goto(io, c) I3 : B-> c.b, c d goto(i6, c) : I6 B->.cB, c d goto(i6,d) : I7 B->.d, c d goto(io, d) I4 : B-> d., c d

6 Parsing Table Action Action Goto States c d $ S B 0 S3 S accept 2 S6 S7 5 3 S3 S4 8 4 R3 R3 5 R1 6 S6 S7 9 7 R3 8 R2 R2 9 R2 OR Q.4 a) Explain in brief: Recursive Descent parser [2] Ans a) A recursive descent parser is a kind of top-down parser built from a set of mutually recursive procedures (or a non-recursive equivalent) where each such procedure usually implements one of the productions of the grammar. Or Recursive descent parsing associates a procedure with each nonterminal in the grammar, it may require backtracking of the input string. Q.4 b) Differentiate between syntax and semantic analysis by giving example [2] Ans b) Syntax is about the structure or the grammar of the language. They are rules that define whether or not the sentence is properly constructed. Here are some C language syntax rules: separate statements with a semi-colon enclose the conditional expression of an IF statement inside parentheses group multiple statements into a single statement by enclosing in curly braces data types and variables must be declared before the first executable statement (this feature has been dropped in C99. C99 and latter allow mixed type declarations.) Semantics is about the meaning of the sentence. For example: x++; // increment foo(xyz, --b, &qrs); // call foo Consider the ++ operator in the first statement. First of all, is it even valid to attempt this?

7 If x is a float data type, this statement has no meaning (according to the C language rules) and thus it is an error even though the statement is syntactically correct. If x is a pointer to some data type, the meaning of the statement is to "add sizeof(some data type) to the value at address x and store the result into the location at address x". If x is a scalar, the meaning of the statement is "add one to the value at address x and store the result into the location at address x". Q.4 c) Check if the following grammar is LL(1) [6] S-> ictss a S -> es Ɛ C -> b Ans c) Grammar is not left recursive and also need not be left factored. Now, computing FIRST and FOLLOW sets. FIRST(S) = { i, a} FOLLOW(S) = { e, $} FISRT (S ) = {e, Ɛ} FOLLOW(S ) = { e, $} FIRST ( C) = {b} FOLLOW(C ) = {t } Parsing Table construction T i t a e b $ NT S S->iCtSS S->a S S ->es S -> Ɛ C C->b S ->Ɛ As there are no conflicts in the table and grammar is not left recursive, we can say that the grammar is LL(1).

8 Q.5 a) Explain advantages of intermediate code[2] Ans a) Advantages of intermediate code. 1. Target code can be generated to any machine just by attaching new machine as the back end. This is called retargeting. b. It is possible to apply machine independent code optimization. This helps in faster generation of code. Q.5 b) Compare quadruple, triple and indirect triple[4] Ans b) 1. Quadruples- Quadruples consists of four fields in the record structure. One field to store operator op, two fields to store operands or arguments arg1and arg2 and one field to store result res. res = arg1 op arg2 Example: a = b + c b is represented as arg1, c is represented as arg2, + as op and a as res. a = -b * d + c + (-b) * d Three address code for the above statement is as follows t1 = - b t2 = t1 * d t3 = t2 + c t4 = - b t5 = t4 * d t6 = t3 + t5 a = t6 Quadruples for the above example is as follows Op Arg1 Arg2 Res - B T1 * T1 D T2 + T2 C T3 - B T4 * T4 D T5 + T3 T5 T6 = T6 a 2. Triples Triples uses only three fields in the record structure. One field for operator, two fields for operands named as arg1 and arg2. Value of temporary

9 variable can be accessed by the position of the statement the computes it and not by location as in quadruples. Triples for the above example is as follows StmtNo Op Arg1 Arg2 0 - B 1 * D C B 4 * D = A 5 3. Indirect Triples Indirect Triples Indirect triples are used to achieve indirection in listing of pointers. That is, it uses pointers to triples than listing of triples themselves. Stmt No (0) (10) (1) (11) (2) (12) (3) (13) (4) (14) (5) (15) (6) (16) StmtNo Op Arg1 Arg B 11 * D C B 14 * D = A 5 Both indirect triples and quadruples give almost performance with respect to space and reordering code. However indirect triples can be space saving if temporary variables are reused. Q.5 c) Generate intermediate code for the following statement [4] a= b + c; (Specify syntax directed translation) Ans. c) S id:= E S.Code := E.Code gen(id.place = E.place) E E + E E.place := newtemp( ), E.Code =E1.Code E2.Code gen(e.place = E1.place + E2.place) E E * E E.place = newtemp( ), E.Code := E1.Code E2.Code gen(e.place = E1.place * E2.place)

10 E -E E (E1) E.place = newtemp( ), E.Code := E1.Code gen (E.place = uni E1.place) E.place = E1.place, E.Code = E1.Code E id E.place = id.place, E.Code := Three-address code statements for the above expression will be as follows t1 = b t2 = c t3 = t1 +t2 a = t3 OR Q.6 a) Explain need for intermediate code [2] Ans a) If a compiler translates the source language to its target machine language without having the option for generating intermediate code, then for each new machine, a full native compiler is required. Intermediate code eliminates the need of a new full compiler for every unique machine by keeping the analysis portion same for all the compilers. The second part of compiler, synthesis, is changed according to the target machine. It becomes easier to apply the source code modifications to improve code performance by applying code optimization techniques on the intermediate code. Q.6 b) Define L-attributed grammar [2] Ans b) L-attributed grammars are a special type of attribute grammars. They allow the attributes to be evaluated in one depth-first left-to-right traversal of the abstract syntax tree. As a result, attribute evaluation in L-attributed grammars can be incorporated conveniently in top-down parsing. A syntax-directed definition is L-attributed if each inherited attribute of Xj on the right side of A X1 X2 Xn depends only on 1.the attributes of the symbols X1, X2,, Xj-1 2.the inherited attributes of A Every S-attributed syntax-directed definition is also L-attributed.

11 Q.6 c) Generate intermediate code for the following statement [4] Ans c) p<q or a>b (Specify syntax directed translation) Control-Flow Translation of Boolean Expressions SDD for Boolean Expressions is shown below. Production E E1 or E2 E E1 and E2 E-> not E1 Semantic Rules { Eplace := newtemp; E.place := E1.place OR E2.place } { Eplace := newtemp; E.place := E1.place AND E2.place } { Eplace := newtemp; E.place := NOT E1.place } E-> (E1) E.place:= E1.place; } E->id1 relop id2 {E.place := newtemp; gen( if id1.place RELOP id2.place goto stmt +3 ); gen(e.place :=0); gen( goto stmt+2); gen(e.place :=1); } E->true E->false { Eplace := newtemp; gen(e.place := 1 ); } { Eplace := newtemp; gen(e.place := 0 ); } 100: if p<q goto : t1 = 0 102: goto : t1 = 1 104: if a>b goto : t2 = 0 106: goto : t2 =1 108:

CMPSC 160 Translation of Programming Languages. Three-Address Code

CMPSC 160 Translation of Programming Languages. Three-Address Code CMPSC 160 Translation of Programming Languages Lectures 16: Code Generation: Three- Address Code Three-Address Code Each instruction can have at most three operands Each operand corresponds to a memory

More information

Alternatives for semantic processing

Alternatives for semantic processing Semantic Processing Copyright c 2000 by Antony L. Hosking. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies

More information

Dixita Kagathara Page 1

Dixita Kagathara Page 1 2014 Sem-VII Intermediate Code Generation 1) What is intermediate code? Intermediate code is: The output of the parser and the input to the Code Generator. Relatively machine-independent: allows the compiler

More information

Context-free grammars

Context-free grammars Context-free grammars Section 4.2 Formal way of specifying rules about the structure/syntax of a program terminals - tokens non-terminals - represent higher-level structures of a program start symbol,

More information

Semantic Analysis computes additional information related to the meaning of the program once the syntactic structure is known.

Semantic Analysis computes additional information related to the meaning of the program once the syntactic structure is known. SEMANTIC ANALYSIS: Semantic Analysis computes additional information related to the meaning of the program once the syntactic structure is known. Parsing only verifies that the program consists of tokens

More information

LECTURE 3. Compiler Phases

LECTURE 3. Compiler Phases LECTURE 3 Compiler Phases COMPILER PHASES Compilation of a program proceeds through a fixed series of phases. Each phase uses an (intermediate) form of the program produced by an earlier phase. Subsequent

More information

Intermediate Code Generation

Intermediate Code Generation Intermediate Code Generation Rupesh Nasre. CS3300 Compiler Design IIT Madras Aug 2015 Character stream Lexical Analyzer Machine-Independent Code Optimizer F r o n t e n d Token stream Syntax Analyzer Syntax

More information

PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILERS

PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILERS Objective PRINCIPLES OF COMPILER DESIGN UNIT I INTRODUCTION TO COMPILERS Explain what is meant by compiler. Explain how the compiler works. Describe various analysis of the source program. Describe the

More information

CS606- compiler instruction Solved MCQS From Midterm Papers

CS606- compiler instruction Solved MCQS From Midterm Papers CS606- compiler instruction Solved MCQS From Midterm Papers March 06,2014 MC100401285 Moaaz.pk@gmail.com Mc100401285@gmail.com PSMD01 Final Term MCQ s and Quizzes CS606- compiler instruction If X is a

More information

Anatomy of a Compiler. Overview of Semantic Analysis. The Compiler So Far. Why a Separate Semantic Analysis?

Anatomy of a Compiler. Overview of Semantic Analysis. The Compiler So Far. Why a Separate Semantic Analysis? Anatomy of a Compiler Program (character stream) Lexical Analyzer (Scanner) Syntax Analyzer (Parser) Semantic Analysis Parse Tree Intermediate Code Generator Intermediate Code Optimizer Code Generator

More information

Introduction to Syntax Analysis Recursive-Descent Parsing

Introduction to Syntax Analysis Recursive-Descent Parsing Introduction to Syntax Analysis Recursive-Descent Parsing CS F331 Programming Languages CSCE A331 Programming Language Concepts Lecture Slides Friday, February 10, 2017 Glenn G. Chappell Department of

More information

EDAN65: Compilers, Lecture 06 A LR parsing. Görel Hedin Revised:

EDAN65: Compilers, Lecture 06 A LR parsing. Görel Hedin Revised: EDAN65: Compilers, Lecture 06 A LR parsing Görel Hedin Revised: 2017-09-11 This lecture Regular expressions Context-free grammar Attribute grammar Lexical analyzer (scanner) Syntactic analyzer (parser)

More information

Syntax-Directed Translation

Syntax-Directed Translation Syntax-Directed Translation ALSU Textbook Chapter 5.1 5.4, 4.8, 4.9 Tsan-sheng Hsu tshsu@iis.sinica.edu.tw http://www.iis.sinica.edu.tw/~tshsu 1 What is syntax-directed translation? Definition: The compilation

More information

Writing Evaluators MIF08. Laure Gonnord

Writing Evaluators MIF08. Laure Gonnord Writing Evaluators MIF08 Laure Gonnord Laure.Gonnord@univ-lyon1.fr Evaluators, what for? Outline 1 Evaluators, what for? 2 Implementation Laure Gonnord (Lyon1/FST) Writing Evaluators 2 / 21 Evaluators,

More information

TDDD55- Compilers and Interpreters Lesson 3

TDDD55- Compilers and Interpreters Lesson 3 TDDD55- Compilers and Interpreters Lesson 3 Zeinab Ganjei (zeinab.ganjei@liu.se) Department of Computer and Information Science Linköping University 1. Grammars and Top-Down Parsing Some grammar rules

More information

11. a b c d e. 12. a b c d e. 13. a b c d e. 14. a b c d e. 15. a b c d e

11. a b c d e. 12. a b c d e. 13. a b c d e. 14. a b c d e. 15. a b c d e CS-3160 Concepts of Programming Languages Spring 2015 EXAM #1 (Chapters 1-6) Name: SCORES MC: /75 PROB #1: /15 PROB #2: /10 TOTAL: /100 Multiple Choice Responses Each multiple choice question in the separate

More information

COMP455: COMPILER AND LANGUAGE DESIGN. Dr. Alaa Aljanaby University of Nizwa Spring 2013

COMP455: COMPILER AND LANGUAGE DESIGN. Dr. Alaa Aljanaby University of Nizwa Spring 2013 COMP455: COMPILER AND LANGUAGE DESIGN Dr. Alaa Aljanaby University of Nizwa Spring 2013 Chapter 1: Introduction Compilers draw together all of the theory and techniques that you ve learned about in most

More information

Answer: Early binding generally leads to greater efficiency (compilation approach) Late binding general leads to greater flexibility

Answer: Early binding generally leads to greater efficiency (compilation approach) Late binding general leads to greater flexibility Quiz Review Q1. What is the advantage of binding things as early as possible? Is there any advantage to delaying binding? Answer: Early binding generally leads to greater efficiency (compilation approach)

More information

The Decaf Language. 1 Lexical considerations

The Decaf Language. 1 Lexical considerations The Decaf Language In this course, we will write a compiler for a simple object-oriented programming language called Decaf. Decaf is a strongly-typed, object-oriented language with support for inheritance

More information

COMPILERS AND INTERPRETERS Lesson 4 TDDD16

COMPILERS AND INTERPRETERS Lesson 4 TDDD16 COMPILERS AND INTERPRETERS Lesson 4 TDDD16 Kristian Stavåker (kristian.stavaker@liu.se) Department of Computer and Information Science Linköping University TODAY Introduction to the Bison parser generator

More information

JavaCC Parser. The Compilation Task. Automated? JavaCC Parser

JavaCC Parser. The Compilation Task. Automated? JavaCC Parser JavaCC Parser The Compilation Task Input character stream Lexer stream Parser Abstract Syntax Tree Analyser Annotated AST Code Generator Code CC&P 2003 1 CC&P 2003 2 Automated? JavaCC Parser The initial

More information

Formal Languages and Compilers Lecture X Intermediate Code Generation

Formal Languages and Compilers Lecture X Intermediate Code Generation Formal Languages and Compilers Lecture X Intermediate Code Generation Free University of Bozen-Bolzano Faculty of Computer Science POS Building, Room: 2.03 artale@inf.unibz.it http://www.inf.unibz.it/

More information

Chapter 6 Intermediate Code Generation

Chapter 6 Intermediate Code Generation Chapter 6 Intermediate Code Generation Outline Variants of Syntax Trees Three-address code Types and declarations Translation of expressions Type checking Control flow Backpatching Introduction Intermediate

More information

Context-sensitive analysis. Semantic Processing. Alternatives for semantic processing. Context-sensitive analysis

Context-sensitive analysis. Semantic Processing. Alternatives for semantic processing. Context-sensitive analysis Semantic Processing The compilation process is driven by the syntactic structure of the program as discovered by the parser Semantic routines: interpret meaning of the program based on its syntactic structure

More information

TDDD55 - Compilers and Interpreters Lesson 3

TDDD55 - Compilers and Interpreters Lesson 3 TDDD55 - Compilers and Interpreters Lesson 3 November 22 2011 Kristian Stavåker (kristian.stavaker@liu.se) Department of Computer and Information Science Linköping University LESSON SCHEDULE November 1,

More information

Type Checking. Chapter 6, Section 6.3, 6.5

Type Checking. Chapter 6, Section 6.3, 6.5 Type Checking Chapter 6, Section 6.3, 6.5 Inside the Compiler: Front End Lexical analyzer (aka scanner) Converts ASCII or Unicode to a stream of tokens Syntax analyzer (aka parser) Creates a parse tree

More information

Intermediate Code Generation

Intermediate Code Generation Intermediate Code Generation 1 Intermediate Code Generation Translating source program into an intermediate language" Simple CPU Independent, yet, close in spirit to machine language Benefits Retargeting

More information

Semantic Analysis. Outline. The role of semantic analysis in a compiler. Scope. Types. Where we are. The Compiler Front-End

Semantic Analysis. Outline. The role of semantic analysis in a compiler. Scope. Types. Where we are. The Compiler Front-End Outline Semantic Analysis The role of semantic analysis in a compiler A laundry list of tasks Scope Static vs. Dynamic scoping Implementation: symbol tables Types Static analyses that detect type errors

More information

Compilers. Compiler Construction Tutorial The Front-end

Compilers. Compiler Construction Tutorial The Front-end Compilers Compiler Construction Tutorial The Front-end Salahaddin University College of Engineering Software Engineering Department 2011-2012 Amanj Sherwany http://www.amanj.me/wiki/doku.php?id=teaching:su:compilers

More information

Principles of Programming Languages COMP251: Syntax and Grammars

Principles of Programming Languages COMP251: Syntax and Grammars Principles of Programming Languages COMP251: Syntax and Grammars Prof. Dekai Wu Department of Computer Science and Engineering The Hong Kong University of Science and Technology Hong Kong, China Fall 2007

More information

Building Compilers with Phoenix

Building Compilers with Phoenix Building Compilers with Phoenix Parser Generators: ANTLR History of ANTLR ANother Tool for Language Recognition Terence Parr's dissertation: Obtaining Practical Variants of LL(k) and LR(k) for k > 1 PCCTS:

More information

Decaf Language Reference

Decaf Language Reference Decaf Language Reference Mike Lam, James Madison University Fall 2016 1 Introduction Decaf is an imperative language similar to Java or C, but is greatly simplified compared to those languages. It will

More information

Lexical analysis. Syntactical analysis. Semantical analysis. Intermediate code generation. Optimization. Code generation. Target specific optimization

Lexical analysis. Syntactical analysis. Semantical analysis. Intermediate code generation. Optimization. Code generation. Target specific optimization Second round: the scanner Lexical analysis Syntactical analysis Semantical analysis Intermediate code generation Optimization Code generation Target specific optimization Lexical analysis (Chapter 3) Why

More information

THEORY OF COMPILATION

THEORY OF COMPILATION Lecture 09 IR (ackpatching) THEORY OF COMPILATION Eran Yahav www.cs.technion.ac.il/~yahave/tocs2011/compilers-lec09.pptx Reference: Dragon 6.2,6.3,6.4,6.6 1 Recap Lexical analysis regular expressions identify

More information

Programming Languages Third Edition. Chapter 7 Basic Semantics

Programming Languages Third Edition. Chapter 7 Basic Semantics Programming Languages Third Edition Chapter 7 Basic Semantics Objectives Understand attributes, binding, and semantic functions Understand declarations, blocks, and scope Learn how to construct a symbol

More information

Context-Free Grammar. Concepts Introduced in Chapter 2. Parse Trees. Example Grammar and Derivation

Context-Free Grammar. Concepts Introduced in Chapter 2. Parse Trees. Example Grammar and Derivation Concepts Introduced in Chapter 2 A more detailed overview of the compilation process. Parsing Scanning Semantic Analysis Syntax-Directed Translation Intermediate Code Generation Context-Free Grammar A

More information

The compilation process is driven by the syntactic structure of the program as discovered by the parser

The compilation process is driven by the syntactic structure of the program as discovered by the parser Semantic Analysis The compilation process is driven by the syntactic structure of the program as discovered by the parser Semantic routines: interpret meaning of the program based on its syntactic structure

More information

UNIT -2 LEXICAL ANALYSIS

UNIT -2 LEXICAL ANALYSIS OVER VIEW OF LEXICAL ANALYSIS UNIT -2 LEXICAL ANALYSIS o To identify the tokens we need some method of describing the possible tokens that can appear in the input stream. For this purpose we introduce

More information

4. An interpreter is a program that

4. An interpreter is a program that 1. In an aboslute loading scheme, which loader function is accomplished by programmer? A. Allocation B. LInking C. Reallocation D. both (A) and (B) 2. A compiler program written in a high level language

More information

UNIT -1 1.1 OVERVIEW OF LANGUAGE PROCESSING SYSTEM 1.2 Preprocessor A preprocessor produce input to compilers. They may perform the following functions. 1. Macro processing: A preprocessor may allow a

More information

Syntax Analysis/Parsing. Context-free grammars (CFG s) Context-free grammars vs. Regular Expressions. BNF description of PL/0 syntax

Syntax Analysis/Parsing. Context-free grammars (CFG s) Context-free grammars vs. Regular Expressions. BNF description of PL/0 syntax Susan Eggers 1 CSE 401 Syntax Analysis/Parsing Context-free grammars (CFG s) Purpose: determine if tokens have the right form for the language (right syntactic structure) stream of tokens abstract syntax

More information

Introduction to Compiler Construction

Introduction to Compiler Construction Introduction to Compiler Construction ASU Textbook Chapter 1 Tsan-sheng Hsu tshsu@iis.sinica.edu.tw http://www.iis.sinica.edu.tw/~tshsu 1 What is a compiler? Definitions: A recognizer. A translator. source

More information

Syntactic Analysis. The Big Picture Again. Grammar. ICS312 Machine-Level and Systems Programming

Syntactic Analysis. The Big Picture Again. Grammar. ICS312 Machine-Level and Systems Programming The Big Picture Again Syntactic Analysis source code Scanner Parser Opt1 Opt2... Optn Instruction Selection Register Allocation Instruction Scheduling machine code ICS312 Machine-Level and Systems Programming

More information

EDAN65: Compilers, Lecture 04 Grammar transformations: Eliminating ambiguities, adapting to LL parsing. Görel Hedin Revised:

EDAN65: Compilers, Lecture 04 Grammar transformations: Eliminating ambiguities, adapting to LL parsing. Görel Hedin Revised: EDAN65: Compilers, Lecture 04 Grammar transformations: Eliminating ambiguities, adapting to LL parsing Görel Hedin Revised: 2017-09-04 This lecture Regular expressions Context-free grammar Attribute grammar

More information

KINGS COLLEGE OF ENGINEERING DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING ACADEMIC YEAR / EVEN SEMESTER

KINGS COLLEGE OF ENGINEERING DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING ACADEMIC YEAR / EVEN SEMESTER KINGS COLLEGE OF ENGINEERING PUNALKULAM DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING ACADEMIC YEAR 2010-2011 / EVEN SEMESTER SUBJECT CODE\SUBJECT NAME: CS1352 \ PRINCIPLES OF COMPILER DESIGN QUESTION BANK

More information

MIDTERM EXAM (Solutions)

MIDTERM EXAM (Solutions) MIDTERM EXAM (Solutions) Total Score: 100, Max. Score: 83, Min. Score: 26, Avg. Score: 57.3 1. (10 pts.) List all major categories of programming languages, outline their definitive characteristics and

More information

Syntax Intro and Overview. Syntax

Syntax Intro and Overview. Syntax Syntax Intro and Overview CS331 Syntax Syntax defines what is grammatically valid in a programming language Set of grammatical rules E.g. in English, a sentence cannot begin with a period Must be formal

More information

Principles of Compiler Design

Principles of Compiler Design Principles of Compiler Design Intermediate Representation Compiler Lexical Analysis Syntax Analysis Semantic Analysis Source Program Token stream Abstract Syntax tree Unambiguous Program representation

More information

Today's Topics. CISC 458 Winter J.R. Cordy

Today's Topics. CISC 458 Winter J.R. Cordy Today's Topics Last Time Semantics - the meaning of program structures Stack model of expression evaluation, the Expression Stack (ES) Stack model of automatic storage, the Run Stack (RS) Today Managing

More information

Recursive Descent Parsers

Recursive Descent Parsers Recursive Descent Parsers Lecture 7 Robb T. Koether Hampden-Sydney College Wed, Jan 28, 2015 Robb T. Koether (Hampden-Sydney College) Recursive Descent Parsers Wed, Jan 28, 2015 1 / 18 1 Parsing 2 LL Parsers

More information

COMPILER DESIGN - QUICK GUIDE COMPILER DESIGN - OVERVIEW

COMPILER DESIGN - QUICK GUIDE COMPILER DESIGN - OVERVIEW COMPILER DESIGN - QUICK GUIDE http://www.tutorialspoint.com/compiler_design/compiler_design_quick_guide.htm COMPILER DESIGN - OVERVIEW Copyright tutorialspoint.com Computers are a balanced mix of software

More information

Concepts Introduced in Chapter 6

Concepts Introduced in Chapter 6 Concepts Introduced in Chapter 6 types of intermediate code representations translation of declarations arithmetic expressions boolean expressions flow-of-control statements backpatching EECS 665 Compiler

More information

Syntax. 2.1 Terminology

Syntax. 2.1 Terminology Syntax 2 Once you ve learned to program in one language, learning a similar programming language isn t all that hard. But, understanding just how to write in the new language takes looking at examples

More information

What is a compiler? Xiaokang Qiu Purdue University. August 21, 2017 ECE 573

What is a compiler? Xiaokang Qiu Purdue University. August 21, 2017 ECE 573 What is a compiler? Xiaokang Qiu Purdue University ECE 573 August 21, 2017 What is a compiler? What is a compiler? Traditionally: Program that analyzes and translates from a high level language (e.g.,

More information

PESIT Bangalore South Campus Hosur road, 1km before Electronic City, Bengaluru -100 Department of Computer Science and Engineering

PESIT Bangalore South Campus Hosur road, 1km before Electronic City, Bengaluru -100 Department of Computer Science and Engineering TEST 1 Date : 24 02 2015 Marks : 50 Subject & Code : Compiler Design ( 10CS63) Class : VI CSE A & B Name of faculty : Mrs. Shanthala P.T/ Mrs. Swati Gambhire Time : 8:30 10:00 AM SOLUTION MANUAL 1. a.

More information

Syntax-Directed Translation

Syntax-Directed Translation Syntax-Directed Translation What is syntax-directed translation? The compilation process is driven by the syntax. The semantic routines perform interpretation based on the syntax structure. Attaching attributes

More information

Design Issues. Subroutines and Control Abstraction. Subroutines and Control Abstraction. CSC 4101: Programming Languages 1. Textbook, Chapter 8

Design Issues. Subroutines and Control Abstraction. Subroutines and Control Abstraction. CSC 4101: Programming Languages 1. Textbook, Chapter 8 Subroutines and Control Abstraction Textbook, Chapter 8 1 Subroutines and Control Abstraction Mechanisms for process abstraction Single entry (except FORTRAN, PL/I) Caller is suspended Control returns

More information

Short Notes of CS201

Short Notes of CS201 #includes: Short Notes of CS201 The #include directive instructs the preprocessor to read and include a file into a source code file. The file name is typically enclosed with < and > if the file is a system

More information

Outline. Java Models for variables Types and type checking, type safety Interpretation vs. compilation. Reasoning about code. CSCI 2600 Spring

Outline. Java Models for variables Types and type checking, type safety Interpretation vs. compilation. Reasoning about code. CSCI 2600 Spring Java Outline Java Models for variables Types and type checking, type safety Interpretation vs. compilation Reasoning about code CSCI 2600 Spring 2017 2 Java Java is a successor to a number of languages,

More information

Comp 204: Computer Systems and Their Implementation. Lecture 25a: Revision Lectures (separate questions and answers)

Comp 204: Computer Systems and Their Implementation. Lecture 25a: Revision Lectures (separate questions and answers) Comp 204: Computer Systems and Their Implementation Lecture 25a: Revision Lectures (separate questions and answers) 1 Today Here are a sample of questions that could appear in the exam Please LET ME KNOW

More information

Using an LALR(1) Parser Generator

Using an LALR(1) Parser Generator Using an LALR(1) Parser Generator Yacc is an LALR(1) parser generator Developed by S.C. Johnson and others at AT&T Bell Labs Yacc is an acronym for Yet another compiler compiler Yacc generates an integrated

More information

Syntax Analysis. Amitabha Sanyal. (www.cse.iitb.ac.in/ as) Department of Computer Science and Engineering, Indian Institute of Technology, Bombay

Syntax Analysis. Amitabha Sanyal. (www.cse.iitb.ac.in/ as) Department of Computer Science and Engineering, Indian Institute of Technology, Bombay Syntax Analysis (www.cse.iitb.ac.in/ as) Department of Computer Science and Engineering, Indian Institute of Technology, Bombay September 2007 College of Engineering, Pune Syntax Analysis: 2/124 Syntax

More information

Lexical Analysis (ASU Ch 3, Fig 3.1)

Lexical Analysis (ASU Ch 3, Fig 3.1) Lexical Analysis (ASU Ch 3, Fig 3.1) Implementation by hand automatically ((F)Lex) Lex generates a finite automaton recogniser uses regular expressions Tasks remove white space (ws) display source program

More information

The Decaf language 1

The Decaf language 1 The Decaf language 1 In this course, we will write a compiler for a simple object-oriented programming language called Decaf. Decaf is a strongly-typed, object-oriented language with support for inheritance

More information

LL(k) Parsing. Predictive Parsers. LL(k) Parser Structure. Sample Parse Table. LL(1) Parsing Algorithm. Push RHS in Reverse Order 10/17/2012

LL(k) Parsing. Predictive Parsers. LL(k) Parser Structure. Sample Parse Table. LL(1) Parsing Algorithm. Push RHS in Reverse Order 10/17/2012 Predictive Parsers LL(k) Parsing Can we avoid backtracking? es, if for a given input symbol and given nonterminal, we can choose the alternative appropriately. his is possible if the first terminal of

More information

Java Primer 1: Types, Classes and Operators

Java Primer 1: Types, Classes and Operators Java Primer 1 3/18/14 Presentation for use with the textbook Data Structures and Algorithms in Java, 6th edition, by M. T. Goodrich, R. Tamassia, and M. H. Goldwasser, Wiley, 2014 Java Primer 1: Types,

More information

4. Lexical and Syntax Analysis

4. Lexical and Syntax Analysis 4. Lexical and Syntax Analysis 4.1 Introduction Language implementation systems must analyze source code, regardless of the specific implementation approach Nearly all syntax analysis is based on a formal

More information

Chapter 3: Describing Syntax and Semantics. Introduction Formal methods of describing syntax (BNF)

Chapter 3: Describing Syntax and Semantics. Introduction Formal methods of describing syntax (BNF) Chapter 3: Describing Syntax and Semantics Introduction Formal methods of describing syntax (BNF) We can analyze syntax of a computer program on two levels: 1. Lexical level 2. Syntactic level Lexical

More information

Informatica 3 Syntax and Semantics

Informatica 3 Syntax and Semantics Informatica 3 Syntax and Semantics Marcello Restelli 9/15/07 Laurea in Ingegneria Informatica Politecnico di Milano Introduction Introduction to the concepts of syntax and semantics Binding Variables Routines

More information

CSCI Compiler Design

CSCI Compiler Design CSCI 565 - Compiler Design Spring 2015 Midterm Exam March 04, 2015 at 8:00 AM in class (RTH 217) Duration: 2h 30 min. Please label all pages you turn in with your name and student number. Name: Number:

More information

Chapter 4. Lexical and Syntax Analysis. Topics. Compilation. Language Implementation. Issues in Lexical and Syntax Analysis.

Chapter 4. Lexical and Syntax Analysis. Topics. Compilation. Language Implementation. Issues in Lexical and Syntax Analysis. Topics Chapter 4 Lexical and Syntax Analysis Introduction Lexical Analysis Syntax Analysis Recursive -Descent Parsing Bottom-Up parsing 2 Language Implementation Compilation There are three possible approaches

More information

Wednesday, September 9, 15. Parsers

Wednesday, September 9, 15. Parsers Parsers What is a parser A parser has two jobs: 1) Determine whether a string (program) is valid (think: grammatically correct) 2) Determine the structure of a program (think: diagramming a sentence) Agenda

More information

Describing Syntax and Semantics

Describing Syntax and Semantics Describing Syntax and Semantics Introduction Syntax: the form or structure of the expressions, statements, and program units Semantics: the meaning of the expressions, statements, and program units Syntax

More information

LECTURE 11. Semantic Analysis and Yacc

LECTURE 11. Semantic Analysis and Yacc LECTURE 11 Semantic Analysis and Yacc REVIEW OF LAST LECTURE In the last lecture, we introduced the basic idea behind semantic analysis. Instead of merely specifying valid structures with a context-free

More information

GUJARAT TECHNOLOGICAL UNIVERSITY

GUJARAT TECHNOLOGICAL UNIVERSITY Type of course: Core GUJARAT TECHNOLOGICAL UNIVERSITY SUBJECT NAME: Compiler Design SUBJECT CODE: 21701 B.E. 7 th SEMESTER Prerequisite: Data Structures and Algorithms, Theory of Computation, Rationale:

More information

Part 3. Syntax analysis. Syntax analysis 96

Part 3. Syntax analysis. Syntax analysis 96 Part 3 Syntax analysis Syntax analysis 96 Outline 1. Introduction 2. Context-free grammar 3. Top-down parsing 4. Bottom-up parsing 5. Conclusion and some practical considerations Syntax analysis 97 Structure

More information

COMPILERS BASIC COMPILER FUNCTIONS

COMPILERS BASIC COMPILER FUNCTIONS COMPILERS BASIC COMPILER FUNCTIONS A compiler accepts a program written in a high level language as input and produces its machine language equivalent as output. For the purpose of compiler construction,

More information

CS201- Introduction to Programming Current Quizzes

CS201- Introduction to Programming Current Quizzes CS201- Introduction to Programming Current Quizzes Q.1 char name [] = Hello World ; In the above statement, a memory of characters will be allocated 13 11 12 (Ans) Q.2 A function is a block of statements

More information

5. Syntax-Directed Definitions & Type Analysis

5. Syntax-Directed Definitions & Type Analysis 5. Syntax-Directed Definitions & Type Analysis Eva Rose Kristoffer Rose NYU Courant Institute Compiler Construction (CSCI-GA.2130-001) http://cs.nyu.edu/courses/spring15/csci-ga.2130-001/lecture-5.pdf

More information

Language Translation. Compilation vs. interpretation. Compilation diagram. Step 1: compile. Step 2: run. compiler. Compiled program. program.

Language Translation. Compilation vs. interpretation. Compilation diagram. Step 1: compile. Step 2: run. compiler. Compiled program. program. Language Translation Compilation vs. interpretation Compilation diagram Step 1: compile program compiler Compiled program Step 2: run input Compiled program output Language Translation compilation is translation

More information

Object Code (Machine Code) Dr. D. M. Akbar Hussain Department of Software Engineering & Media Technology. Three Address Code

Object Code (Machine Code) Dr. D. M. Akbar Hussain Department of Software Engineering & Media Technology. Three Address Code Code Generation Intermediate Code? Assembly Code Object Code (Machine Code) 1 Intermediate Code P-Code Three Address Code 2 Compiler Construction F6S 1 Intermediate Representation Abstract Syntax Tree

More information

Lexical Analysis. COMP 524, Spring 2014 Bryan Ward

Lexical Analysis. COMP 524, Spring 2014 Bryan Ward Lexical Analysis COMP 524, Spring 2014 Bryan Ward Based in part on slides and notes by J. Erickson, S. Krishnan, B. Brandenburg, S. Olivier, A. Block and others The Big Picture Character Stream Scanner

More information

Lexical Analysis 1 / 52

Lexical Analysis 1 / 52 Lexical Analysis 1 / 52 Outline 1 Scanning Tokens 2 Regular Expresssions 3 Finite State Automata 4 Non-deterministic (NFA) Versus Deterministic Finite State Automata (DFA) 5 Regular Expresssions to NFA

More information

Parsing Algorithms. Parsing: continued. Top Down Parsing. Predictive Parser. David Notkin Autumn 2008

Parsing Algorithms. Parsing: continued. Top Down Parsing. Predictive Parser. David Notkin Autumn 2008 Parsing: continued David Notkin Autumn 2008 Parsing Algorithms Earley s algorithm (1970) works for all CFGs O(N 3 ) worst case performance O(N 2 ) for unambiguous grammars Based on dynamic programming,

More information

CS 432 Fall Mike Lam, Professor. Code Generation

CS 432 Fall Mike Lam, Professor. Code Generation CS 432 Fall 2015 Mike Lam, Professor Code Generation Compilers "Back end" Source code Tokens Syntax tree Machine code char data[20]; int main() { float x = 42.0; return 7; } 7f 45 4c 46 01 01 01 00 00

More information

VALLIAMMAI ENGNIEERING COLLEGE SRM Nagar, Kattankulathur

VALLIAMMAI ENGNIEERING COLLEGE SRM Nagar, Kattankulathur VALLIAMMAI ENGNIEERING COLLEGE SRM Nagar, Kattankulathur 603203. DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING Year & Semester : III & VI Section : CSE 1 & 2 Subject Code : CS6660 Subject Name : COMPILER

More information

Overview of Compiler. A. Introduction

Overview of Compiler. A. Introduction CMPSC 470 Lecture 01 Topics: Overview of compiler Compiling process Structure of compiler Programming language basics Overview of Compiler A. Introduction What is compiler? What is interpreter? A very

More information

CSE 413 Programming Languages & Implementation. Hal Perkins Autumn 2012 Grammars, Scanners & Regular Expressions

CSE 413 Programming Languages & Implementation. Hal Perkins Autumn 2012 Grammars, Scanners & Regular Expressions CSE 413 Programming Languages & Implementation Hal Perkins Autumn 2012 Grammars, Scanners & Regular Expressions 1 Agenda Overview of language recognizers Basic concepts of formal grammars Scanner Theory

More information

Chapter 4 - Semantic Analysis. June 2, 2015

Chapter 4 - Semantic Analysis. June 2, 2015 Chapter 4 - Semantic Analysis June 2, 2015 The role of the semantic analyzer Compilers use semantic analysis to enforce the static semantic rules of a language It is hard to generalize the exact boundaries

More information

Sprite an animation manipulation language Language Reference Manual

Sprite an animation manipulation language Language Reference Manual Sprite an animation manipulation language Language Reference Manual Team Leader Dave Smith Team Members Dan Benamy John Morales Monica Ranadive Table of Contents A. Introduction...3 B. Lexical Conventions...3

More information

Type Checking. Outline. General properties of type systems. Types in programming languages. Notation for type rules.

Type Checking. Outline. General properties of type systems. Types in programming languages. Notation for type rules. Outline Type Checking General properties of type systems Types in programming languages Notation for type rules Logical rules of inference Common type rules 2 Static Checking Refers to the compile-time

More information

Operational Semantics. One-Slide Summary. Lecture Outline

Operational Semantics. One-Slide Summary. Lecture Outline Operational Semantics #1 One-Slide Summary Operational semantics are a precise way of specifying how to evaluate a program. A formal semantics tells you what each expression means. Meaning depends on context:

More information

Defining Program Syntax. Chapter Two Modern Programming Languages, 2nd ed. 1

Defining Program Syntax. Chapter Two Modern Programming Languages, 2nd ed. 1 Defining Program Syntax Chapter Two Modern Programming Languages, 2nd ed. 1 Syntax And Semantics Programming language syntax: how programs look, their form and structure Syntax is defined using a kind

More information

Outline. General properties of type systems. Types in programming languages. Notation for type rules. Common type rules. Logical rules of inference

Outline. General properties of type systems. Types in programming languages. Notation for type rules. Common type rules. Logical rules of inference Type Checking Outline General properties of type systems Types in programming languages Notation for type rules Logical rules of inference Common type rules 2 Static Checking Refers to the compile-time

More information

Concepts Introduced in Chapter 6

Concepts Introduced in Chapter 6 Concepts Introduced in Chapter 6 types of intermediate code representations translation of declarations arithmetic expressions boolean expressions flow-of-control statements backpatching EECS 665 Compiler

More information

Group B Assignment 9. Code generation using DAG. Title of Assignment: Problem Definition: Code generation using DAG / labeled tree.

Group B Assignment 9. Code generation using DAG. Title of Assignment: Problem Definition: Code generation using DAG / labeled tree. Group B Assignment 9 Att (2) Perm(3) Oral(5) Total(10) Sign Title of Assignment: Code generation using DAG. 9.1.1 Problem Definition: Code generation using DAG / labeled tree. 9.1.2 Perquisite: Lex, Yacc,

More information

Lecture Outline. COOL operational semantics. Operational Semantics of Cool. Motivation. Lecture 13. Notation. The rules. Evaluation Rules So Far

Lecture Outline. COOL operational semantics. Operational Semantics of Cool. Motivation. Lecture 13. Notation. The rules. Evaluation Rules So Far Lecture Outline Operational Semantics of Cool Lecture 13 COOL operational semantics Motivation Notation The rules Prof. Aiken CS 143 Lecture 13 1 Prof. Aiken CS 143 Lecture 13 2 Motivation We must specify

More information

Outline. Top Down Parsing. SLL(1) Parsing. Where We Are 1/24/2013

Outline. Top Down Parsing. SLL(1) Parsing. Where We Are 1/24/2013 Outline Top Down Parsing Top-down parsing SLL(1) grammars Transforming a grammar into SLL(1) form Recursive-descent parsing 1 CS 412/413 Spring 2008 Introduction to Compilers 2 Where We Are SLL(1) Parsing

More information

Compiler construction in4020 lecture 5

Compiler construction in4020 lecture 5 Compiler construction in4020 lecture 5 Semantic analysis Assignment #1 Chapter 6.1 Overview semantic analysis identification symbol tables type checking CS assignment yacc LLgen language grammar parser

More information

CMSC 330: Organization of Programming Languages

CMSC 330: Organization of Programming Languages CMSC 330: Organization of Programming Languages Context Free Grammars and Parsing 1 Recall: Architecture of Compilers, Interpreters Source Parser Static Analyzer Intermediate Representation Front End Back

More information