COMPILER DESIGN and Solved Tricky Questions CONTENT UNIT – I Introduction Language Processing, Structure of a compiler ,the evaluation of Programming language, The Science of building a Compiler, application of Compiler Technology,Programming Language Basics. Lexical Analysis-: The role of lexical analysis buffing, specification of tokens. Recognitions of okens the lexical analyzer generator lexical UNIT –II Syntax Analysis -: The Role of a parser, Context free Grammars, Writing A grammar, top down parsing bottom up parsing. Introduction to LR Parser. UNIT –III More Powerful LR parser (LR1, LALR) ,Using ambiguous Grammars ,error Recovery in LR parser, Syntax Directed Transactions Definition, Evaluation order of SDTS ,Application of SDTS, Syntax Directed Translation Schemes. UNIT – IV Intermediate Code Generation, Variants of Syntax trees, 3 Address code, Types and Deceleration, Translation of Expressions, Type Checking. Control Flow, Back patching. UNIT – V Runtime Environments, Stack allocation of space, access to Non Local data on the stack , Heap Management code generation , Issues in design of code generation,the target Language Address in the target code ,Basic blocks and Flow graphs. A Sample Code generation. UNIT –VI Machine Independent Optimization. The principle sources of Optimization peephole Optimization, Introduction to Data flow Analysis
UNIT – I Introduction Language Processing, Structure of a compiler, the evaluation of Programming language, The Science of building a Compiler application of Compiler Technology. Programming Language Basics. Lexical Analysis-: The role of lexical analysis, buffing, specification of tokens. Recognitions of tokens the lexical analyzer generator lexical Language processing system: What is language processing system? Any computer system is made of hardware and software. The hardware understands a language, which humans cannot understand. So we write programs in high-level language, which is easier for us to understand and remember. These programs are then fed into a series of tools and OS components to get the desired code that can be used by the machine. This is known as Language Processing System. The high-level language is converted into binary language in various phases. A compiler is a
program that converts high-level language to assembly language. Similarly, an assembler is a program that converts the assembly language to machine-level language. Let us first understand how a program, using C compiler, is executed on a host machine. ● User writes a program in C language (high-level language). ● The C compiler, compiles the program and translates it to assembly program (low-level language). ● An assembler then translates the assembly program into machine code (object). ● A linker tool is used to link all the parts of the program together for execution (executable machine code). ● A loader loads all of them into memory and then the program is executed. Before diving straight into the concepts of compilers, we should understand a few other tools that work closely with compilers. Preprocessor A preprocessor, generally considered as a part of compiler, is a tool that produces input for compilers. It deals with macro-processing, augmentation, file inclusion, language extension, etc. Eg. #include<stdio.h> this statement in C language includes header file stdio.h to our programme. Interpreter An interpreter, like a compiler, translates high-level language into low-level machine language. The difference lies in the way they read the source code or input. A compiler reads the whole source code at once, creates tokens, checks semantics, generates intermediate code, executes the whole program and may involve many passes. In contrast, an interpreter reads a statement from the input, converts it to an intermediate code, executes it, then takes the next statement in sequence. If an error occurs, an interpreter stops execution and reports it. whereas a compiler reads the whole program even if it encounters several errors. Assembler An assembler translates assembly language programs into machine code.The output of an assembler is called an object file, which contains a combination of machine instructions as well as the data required to place these instructions in memory. Linker Linker is a computer program that links and merges various object files together in order to make an executable file. All these files might have been compiled by separate assemblers. The major task of a linker is to search and locate referenced module/routines in a program and to determine the memory location where these codes will be loaded, making the program instruction to have absolute references. Loader Loader is a part of operating system and is responsible for loading executable files into memory and execute them.
It calculates the size of a program (instructions and data) and creates memory space for it. It initializes various registers to initiate execution. Cross-compiler A compiler that runs on platform (A) and is capable of generating executable code for platform (B) is called a cross-compiler. Source-to-source Compiler A compiler that takes the source code of one programming language and translates it into the source code of another programming language is called a source-to-source compiler Structure of a compiler A compiler can broadly be divided into two phases based on the way they compile. Analysis Phase Known as the front-end of the compiler, the analysis phase of the compiler reads the source program, divides it into core parts and then checks for lexical, grammar and syntax errors.The analysis phase generates an intermediate representation of the source program and symbol table, which should be fed to the Synthesis phase as input. Synthesis Phase Known as the back-end of the compiler, the synthesis phase generates the target program with the help of intermediate source code representation and symbol table. A compiler can have many phases and passes. ● Pass : A pass refers to the traversal of a compiler through the entire program. ● Phase : A phase of a compiler is a distinguishable stage, which takes input from the previous stage, processes and yields output that can be used as input for the next stage. A pass can have more than one phase. The compilation process is a sequence of various phases. Each phase takes input from its previous stage, has its own representation of source program, and feeds its output to the next phase of the compiler. Let us understand the phases of a compiler.