1 / 30

CSC 415: Translators and Compilers Spring 2009

CSC 415: Translators and Compilers Spring 2009 Dr. Chuck Lillie Course Overview Translators and Compilers Textbook Programming Language Processors in Java , Authors: David A. Watts & Deryck F. Brown, 2000, Prentice Hall Syllabus http://www.uncp.edu/home/lilliec Homework & Project

Pat_Xavi
Download Presentation

CSC 415: Translators and Compilers Spring 2009

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. CSC 415: Translators and CompilersSpring 2009 Dr. Chuck Lillie

  2. Course Overview • Translators and Compilers • Textbook • Programming Language Processors in Java, Authors: David A. Watts & Deryck F. Brown, 2000, Prentice Hall • Syllabus • http://www.uncp.edu/home/lilliec • Homework & Project • First half of semester • Problems • Second half of semester • Modify Triangle compiler

  3. Course Outline • Major Programming Project • Project Definition and Planning • Implementation • Weekly Status Reports • Project Presentation • Translators and Compilers • Language Processors • Compilation • Syntactic Analysis • Contextual Analysis • Run-Time Organization • Code Generation • Interpretation

  4. Project • Modify a compiler for the programming language Triangle • Appendix B: Informal Specification of the Programming Language Triangle • Appendix D: Class Diagrams for the Triangle Compiler • Present Project Plan • What and How • Weekly Status Reports • Work accomplished during the reporting period • Deliverable progress, as a percentage of completion • Problem areas • Planned activities for the next reporting period

  5. CSC 415: Translators and CompilersSpring 2009 Chapter 1 Introduction to Programming Languages

  6. Chapter 1: Introduction to Programming Languages • Programming Language: A formal notation for expressing algorithms. • Programming Language Processors: Tools to enter, edit, translate, and interpret programs on machines. • Machine Code: Basic machine instructions • Keep track of exact address of each data item and each instruction • Encode each instruction as a bit string • Assembly Language: Symbolic names for operations, registers, and addresses.

  7. Programming Languages • High Level Languages: Notation similar to familiar mathematical notation • Expressions: +, -, *, / • Data Types: truth variables, characters, integers, records, arrays • Control Structures: if, case, while, for • Declarations: constant values, variables, procedures, functions, types • Abstraction: separates what is to be performed from how it is to be performed • Encapsulation (or data abstraction): group together related declarations and selectively hide some

  8. Programming Languages • Any system that manipulates programs expressed in some particular programming language • Editors: enter, modify, and save program text • Translators and Compilers: Translates text from one language to another. Compiler translates a program from a high-level language to a low-level language, preparing it to be run on a machine • Checks program for syntactic and contextual errors • Interpreters: Runs program without compilation • Command languages • Database query languages

  9. Programming Languages Specifications • Syntax • Form of the program • Defines symbols • How phrases are composed • Contextual constraints • Scope: determine scope of each declaration • Type: ensures each operation is supplied with operands of the correct type • Semantics • Meaning of the program – behavior when run on a machine

  10. Representation • Syntax • Backus-Naur Form (BNF): context-free grammar • Terminal symbols (>=, while, ;) • Non-terminal symbols (Program, Command, Expression, Declaration) • Start symbol (Program) • Production rules (defines how phrases are composed from terminals and sub-phrases) • N::=a|b|…. • Syntax Tree • Used to define language in terms of strings and terminal symbols

  11. Representation • Semantics • Abstract Syntax • Concentrate on phrase structure alone • Abstract Syntax Tree

  12. Contextual Constraints • Scope • Binding • Static: determined by language processor • Dynamic: determined at run-time • Type • Statically: language processor can detect all errors • Dynamically: type errors cannot be detected until run-time Will assume static binding and statically typed

  13. Semantics • Concerned with meaning of program • Behavior when run • Usually specified informally • Declarative sentences • Could include side effects • Correspond to production rules

  14. Structure of a Compiler Lexical Analyzer Source code Symbol Table tokens Parser & Semantic Analyzer parse tree Intermediate Code Generation intermediate representation Optimization intermediate representation Assembly Code Generation Assembly code

  15. Program Command Single-Command Expression ::= single-Command ::= single-Command | Command ; single-Command ::= V-name := Expression | Identifier ( Expression ) | if Expression then single-Command else single-Command | while Expression do single-Command | let Declaration in single-Command | begin Command end ::= primary-Expression | Expression Operator primary-Expression Mini-Triangle Syntax

  16. Primary-Expression V-name Declaration Single-Declaration Type-Denoter Operator Identifier Integer-Literal Comment Digit Letter ::= Integer-Literal | V-name | Operator primary-Expression | ( Expression ) ::= Identifier ::= single-Declaration | Declaration ; single-Declaration ::= const Identifier ~ Expression | var Identifier : Type-denoter ::= Identifier ::= + | - | * | / | < | > | = | \ ::= Letter | Identifier Letter | Identifier Digit ::= Digit | Integer-Literal Digit ::= ! Graphic* eol ::= 0|1|2|3|4|5|6|7|8|9 ::= a|b|c|d|…|z|A|B|C|…|Z Mini-Triangle Syntax

  17. Syntax Tree – let var y: Integer in y := y + 1 Program single-Command single-Command Expression Declaration Expression primary-Expression primary-Expression single-Declaration Type-denoter V-name V-name Integer-Literal Identifier Operator Identifier Identifier Identifier y var y y : Integer in let 1 := +

  18. Representation • Semantics • Abstract Syntax • Concentrate on phrase structure alone • Abstract Syntax Tree

  19. Mini-Triangle Program ! This is a comment. It continues to the end-of-line let const m ~ 7; var n: Integer in begin n := 2 * m * m; putint (n) end

  20. Mini-Triangle Terminal Symbols begin const do else end if in let then var while ; : := ~ ( ) + - * / < > = \

  21. Mini-Triangle Non-Terminals Program (start symbol) Command single-Command Expression primary-Expression V-name Declaration single-Declaration Type-denoter Operator identifier Integer-Literal

  22. Program Command single-Command Expression Primary-Expression ::= single-Command ::= single-Command | Command ; single-Command ::= V-name := Expression | Identifier ( Expression ) | if Expression then single-Command else single-Command | while Expression do single-Command | let Declaration in single-Command | begin Command end := primary-Expression | Expression Operator primary-Expression ::= Integer-Literal | V-name | Operator primary-Expression | ( Expression ) Mini-Triangle Production Rules

  23. V-name Declaration single-Declaration Type-denoter Operator Identifier Integer-Literal Comment ::= Identifier ::= single-Declaration | Declaration ; single-Declaratiion ::= const Identifier ~ Expression | var Identifier : Type-denoter ::= Identifier ::= + | - | * | / | < | > | = | \ ::= Letter | Identifier Letter | Identifier Digit ::= Digit |Integer-Literal Digit ::= ! Graphic* eol Mini-Triangle Production Rules

  24. Program Command Expression ::= Command ::= V-name := Expression | Identifier ( Expression ) | Command ; Command | if Expression then Command else Command | while Expression do Command | let Declaration in Command ::= Integer-Literal | V-name | Operator Expression | Expression Operator Expression Mini-Triangle Abstract Syntax Label Program AssignCommand CallCommand SequentialCommand IfCommand WhileCommand LetCommand IntegerExpression VnameExpression UnaryExpression BinaryExpression

  25. V-name Declaration Type-Denoter ::= Identifier ::= const Identifier ~ Expression | var Identifier : Type-denoter | Declaration ; Declaration ::= Identifier Mini-Triangle Abstract Syntax Label SimpleVname ConstDeclaration VarDeclaration SequentialDeclaration SimpleTypeDenoter

  26. Abstract Syntax Tree – let var y: Integer in y := y + 1 Program LetCommand AssignmentCommand BinaryExpression VarDeclaration Expression IntegerExpression VnameExpression SimpleTypeDenoter SimpleVname SimpleVname Integer-Literal Identifier Operator Identifier Identifier Identifier y y y Integer 1 +

  27. Semantics • Concerned with the meaning of the program • Their behavior when run • Specifying semantics • Specify in general terms what will be the semantics of each class of phrase in the language • Semantics of commands, expressions, and declarations • A command is executed to update variables • May also have side effect of performing input-output • An expression is evaluated to yield a value • May also have side effect of updating variables • A declaration is elaborated to produce bindings • May also have the side effect of allocating and initializing variables • Specify the semantics of each specific form of command, expression, declaration, and so on • One clause for each form of phrase

  28. Mini-Triangle Semantics • A command C is executed in order to update variables (this includes input and output) • The assignment statement V := E is executed as follows. The expression E is evaluated to yield a value v; then v is assigned to the value-or-variable-name V. • The call-command I (E) is executed as follows. The expression E is evaluated to yield a value v; then the procedure bound to I is called with v as its argument. • The sequence command C1 ; C2 is executed as follows. First C1 is executed; then C2 is executed.

  29. Mini-Triangle Semantics (cont) • A command C is executed in order to update variables (this includes input and output) cont… • The if-command if E then C1 else C2 is executed as follows. The expression E is evaluated to yield a truth-value t; If t is true, C1 is executed; if t is false, C2 is executed. • The while-command while E do C is executed as follows. The expression E is evaluated to yield a truth-value t; if t is true, C is executed, and then the while-command is executed again; if t is false, execution of the while-command is completed.

  30. Mini-Triangle Semantics (cont) • A command C is executed in order to update variables (this includes input and output) cont… • The let-command let D in C is executed as follows. The declaration D is elaborated to produce bindings b; C is executed, in the environment of the let-command overlaid by the bindings b. The bindings b have no effect outside the let-command.

More Related