31-10-2012, 04:30 PM
CS416 Compiler Design
CS416 Compiler.ppt (Size: 61.5 KB / Downloads: 47)
Preliminaries Required
Basic knowledge of programming languages.
Basic knowledge of FSA and CFG.
Knowledge of a high programming language for the programming assignments.
Other Applications
In addition to the development of a compiler, the techniques used in compiler design can be applicable to many problems in computer science.
Techniques used in a lexical analyzer can be used in text editors, information retrieval system, and pattern recognition programs.
Techniques used in a parser can be used in a query processing system such as SQL.
Many software having a complex front-end may need techniques used in compiler design.
A symbolic equation solver which takes an equation as input. That program should parse the given input equation.
Most of the techniques used in compiler design can be used in Natural Language Processing (NLP) systems.
Major Parts of Compilers
There are two major parts of a compiler: Analysis and Synthesis
In analysis phase, an intermediate representation is created from the given source program.
Lexical Analyzer, Syntax Analyzer and Semantic Analyzer are the parts of this phase.
In synthesis phase, the equivalent target program is created from this intermediate representation.
Intermediate Code Generator, Code Generator, and Code Optimizer are the parts of this phase.
Syntax Analyzer versus Lexical Analyzer
Which constructs of a program should be recognized by the lexical analyzer, and which ones by the syntax analyzer?
Both of them do similar things; But the lexical analyzer deals with simple non-recursive constructs of the language.
The syntax analyzer deals with recursive constructs of the language.
The lexical analyzer simplifies the job of the syntax analyzer.
The lexical analyzer recognizes the smallest meaningful units (tokens) in a source program.
The syntax analyzer works on the smallest meaningful units (tokens) in a source program to recognize meaningful structures in our programming language.
Parsing Techniques
Depending on how the parse tree is created, there are different parsing techniques.
These parsing techniques are categorized into two groups:
Top-Down Parsing,
Bottom-Up Parsing
Top-Down Parsing:
Construction of the parse tree starts at the root, and proceeds towards the leaves.
Efficient top-down parsers can be easily constructed by hand.
Recursive Predictive Parsing, Non-Recursive Predictive Parsing (LL Parsing).
Bottom-Up Parsing:
Construction of the parse tree starts at the leaves, and proceeds towards the root.
Normally efficient bottom-up parsers are created with the help of some software tools.
Bottom-up parsing is also known as shift-reduce parsing.
Operator-Precedence Parsing – simple, restrictive, easy to implement
LR Parsing – much general form of shift-reduce parsing, LR, SLR, LALR
Semantic Analyzer
A semantic analyzer checks the source program for semantic errors and collects the type information for the code generation.
Type-checking is an important part of semantic analyzer.
Normally semantic information cannot be represented by a context-free language used in syntax analyzers.
Context-free grammars used in the syntax analysis are integrated with attributes (semantic rules)
the result is a syntax-directed translation,
Attribute grammars