CSC 415: Translators and Compilers Spring 2009

1. CSC 415: Translators and CompilersSpring 2009 Chapters 8, 9 & Wrap-Up Interpretation & Design Principles

2. Chapter 8: Interpretation • Interactive Interpretation • Interactive Interpretations of Machine Code • Interactive Interpretation of Command Languages • Interactive Interpretation of Simple Programming Languages • Recursive Interpretation • Case Study: The TAM Interpreter

3. Chapter 9: Conclusion • The Programming Language Life Cycle • Design • Specification • Prototype • Compilers • Error Reporting • Compile-time Error Reporting • Run-time Error Reporting • Efficiency • Compile-time Efficiency • Run-time Efficiency

4. Semantic Analyzer Identification Type checking Structure of a Compiler Lexical Analyzer Source code Symbol Table tokens Semantic Analyzer Parser parse tree Intermediate Code Generation intermediate representation Optimization intermediate representation Assembly Code Generation Assembly code

5. Programming Language Lifecycle:Concepts • Values • Types • Storage • Bindings • Abstractions • Encapsulation • Polymorphism • Exceptions • Concurrency Concepts Advanced Concepts

6. Programming Language Lifecycle:Simplicity & Regularity • Strive for simplicity and regularity • Simplicity: support only the concepts essential to the applications for which language is intended • Regularity: should combine those concepts in a systematic way, avoiding restrictions that might surprise programmers or make their task more difficult

7. Design Principles • Type completeness: no operation should be arbitrarily restricted in the types of its operands • Operations like assignment and parameter passing should, ideally, be applied to all types • Abstraction: for phrase that specifies some kind of computation, should be a way to abstract that phrase and parameterize it • Should be possible to abstract any expression and make it a function • Correspondence: for each form of declaration there should be corresponding parameter mechanism • Take a block with a constant definition and transform it into as procedure (or function) with a constant parameter

8. Design Specification Prototype Compilers Manuals, textbooks Programming Language Lifecycle

9. Specification • Precise specification for language’s syntax and semantics must be written • Informal or formal or hybrid Informal Formal BNF, EBNF Syntax English phrases Axiomatic method (based on mathematical logic) English phrases Semantics

10. Prototypes • Cheap, low quality implementation • Highlights features of language that are hard to implement • Try out language • Interpreter might be a ghood prototype • Interpretive compiler • From source to abstract machine code

11. Compile-Time Error Reporting • Rejecting ill-formed programs • Report location of each error with some explanation • Distinguish between the major categories of compile-time errors: • Syntactic error: missing or unexpected characters or tokens • Indicate what characters or tokens were expected • Scope error: a violation of the language’s scope rules • Indicate which identifier was used twice, or used with declaration • Type error: a violation of the language’s type rule • Indicate which type rule was violated and/or what type was expected

12. Run-Time Error Reporting • Common run-time errors • Arithmetic overflow • Division by zero • Out-of-range array indexing • Can be detected only at run-time, because they depend on values computed at run-time