977_PCC-CSM504-Study Material-M1 (1).pdf

B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Study Material (Compiler Design (PCC-CSM504)) _____________________________________________________________________________________...

B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Study Material (Compiler Design (PCC-CSM504)) _____________________________________________________________________________________________ Table of Contents Introduction to Compiler Compilation Compiler Phases Cross-Compiler Analysis-Synthesis Model Cousins of the Compiler Multiple-choice questions (MCQs) Short Question Long Question ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 1 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Introduction to Compiler o A compiler is a translator that converts the high-level language into the machine language. o High-level language is written by a developer and machine language can be understood by the processor. o Compiler is used to show errors to the programmer. o The main purpose of compiler is to change the code written in one language without changing the meaning of the program. o When you execute a program which is written in HLL programming language then it executes into two parts. o In the first part, the source program compiled and translated into the object program (low level language). o In the second part, object program translated into the target program through the assembler. Fig: Execution process of source program in Compiler A compiler is a software translator program that converts pure high-level language instructions into a machine-understandable format. Generally, we write programs in languages like Python, C, etc... Machines/computers aren't capable of understanding these languages. It can only understand binary language. Writing a program in the binary language is hard. Hence, we use compilers as a medium. Compiling is the second step in a machine's language processing system. It expands the macros given by #define and then gives the pure high-level language code to the compiler. When we write a program in a high-level language, the preprocessor receives the code and performs a few operations like Macro- expansion and file inclusion. When preprocessor directives like #include and #define, the preprocessor includes the specified header files. The compiler then translates the source program into assembly language (a combination of high-level and binary language). It transfers it to the assembler for further encoding into the lowest-level machine code. ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 2 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Compilation The task of a compiler isn't just to translate but also to ensure that the given code is lexically, syntactically, and semantically correct. One of the compiler's major tasks is detecting and displaying error messages. When we write a program and compile it, the compiler takes the whole program at a time, processes the whole code, and displays the list of all error messages and warnings at a time, unlike an interpreter. An interpreter is another translator similar to a compiler. It reads the program line-by-line, and once it finds an error, it stops execution and displays the error message. It works phase-wise, dividing all the tasks it has to complete. Here are all the phases included in the compilation: ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 3 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 o The first four phases in the flowchart represent the Analysis stage o The last two phases represent the Synthesis stage. o In the Analysis stage, the given code in the high-level language is analyzed lexically, syntactically, and semantically and an intermediate code is generated. In contrast, in the Synthesis stage, assembly code generation takes place using the results of the analysis stage. o The Analysis stage of a compiler is machine-independent and language-dependent, while the synthesis stage is machine-dependent and language-independent. o Hence, if we want to build a new compiler, we need not build it from scratch; we can borrow another compiler's intermediate code generator and build it from there. This process is called "Retargeting". o The symbol table is the data structure a compiler uses to store and retrieve all the identifiers used in the program, along with necessary information categorized by data type and scope. Hence, a symbol table and error handler are used in every phase. Compiler Phases The compilation process contains the sequence of various phases. Each phase takes source program in one representation and produces output in another representation. Each phase takes input from its previous stage. There are the various phases of compiler: ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 4 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Lexical Analysis: Lexical analyzer phase is the first phase of compilation process. It takes source code as input. It reads the source program one character at a time and converts it into meaningful lexemes. Lexical analyzer represents these lexemes in the form of tokens. Syntax Analysis Syntax analysis is the second phase of compilation process. It takes tokens as input and generates a parse tree as output. In syntax analysis phase, the parser checks that the expression made by the tokens is syntactically correct or not. Semantic Analysis Semantic analysis is the third phase of compilation process. It checks whether the parse tree follows the rules of language. Semantic analyzer keeps track of identifiers, their types and expressions. The output of semantic analysis phase is the annotated tree syntax. Intermediate Code Generation In the intermediate code generation, compiler generates the source code into the intermediate code. Intermediate code is generated between the high-level language and the machine language. The intermediate code should be generated in such a way that you can easily translate it into the target machine code. Code Optimization Code optimization is an optional phase. It is used to improve the intermediate code so that the output of the program could run faster and take less space. It removes the unnecessary lines of the code and arranges the sequence of statements in order to speed up the program execution. Code Generation Code generation is the final stage of the compilation process. It takes the optimized intermediate code as input and maps it to the target machine language. Code generator translates the intermediate code into the machine code of the specified computer. Example: ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 5 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Cross-Compiler ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 6 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 A cross-compiler is a type of compiler that runs on one platform (host) and generates executable code for a different platform (target). In other words, it produces machine code that can be executed on a different architecture or operating system than the one on which the compiler itself is running. The need for cross-compilers arises in scenarios where developers want to build software for devices or systems with different architectures or operating systems. For example: i. Embedded Systems Development: Embedded systems often have limited resources and may use specialized processors or microcontrollers. Cross-compilers allow developers to write code on a more powerful computer and generate binaries that can run on the target embedded system. ii. Platform Portability: Developers may want to create applications that can be deployed on multiple platforms (e.g., Windows, macOS, Linux) without the need to set up the development environment on each platform. iii. Cross-Platform Game Development: Game developers may use cross-compilers to create games that can run on various gaming consoles or mobile devices without having to rewrite the entire codebase for each platform. iv. Legacy System Support: Cross-compilers can be used to maintain and update software for legacy systems that are no longer directly supported by modern development tools. Cross-compilation involves several challenges, such as differences in hardware architecture, system libraries, and operating system interfaces between the host and target platforms. To address these challenges, cross-compilers need to include specialized features, such as: i. Cross-Compilation Toolchain: The toolchain consists of the cross-compiler, linker, assembler, and other necessary tools to convert source code into executable code for the target platform. ii. Target Platform Header Files and Libraries: The cross-compiler requires header files and libraries for the target platform to properly link and interact with the target system. iii. ABI (Application Binary Interface) Considerations: The cross-compiler must be aware of the target platform's ABI to ensure that the generated code is compatible with the target system's calling conventions and memory layout. iv. Runtime Environment: Depending on the target platform, there might be a need to provide a custom runtime environment or adapt existing runtime libraries to work on the target system. Cross-compilation is a powerful technique that facilitates software development for a wide range of platforms and architectures, enabling efficient and flexible development in diverse computing environments. Analysis-Synthesis Model The Analysis-Synthesis Model is a conceptual framework used to describe the two main phases of a compiler: the analysis phase and the synthesis phase. These phases are responsible for breaking down the source code into meaningful components, analyzing it for correctness, and then generating the target code from the analyzed information. The model helps to understand the logical flow of compilation and the tasks performed by each phase. Let's explore each phase in detail: Analysis Phase: ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 7 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 The analysis phase is the first step in the compilation process. Its primary goal is to understand the structure and semantics of the source code. This phase consists of several sub-phases, each focusing on specific tasks: a. Lexical Analysis (Scanning): The source code is divided into tokens, which are the smallest units of meaning in the programming language. These tokens include keywords, identifiers, literals, operators, and punctuation symbols. The lexical analyzer reads the source code character by character and groups them into tokens. b. Syntax Analysis (Parsing): The tokens obtained from lexical analysis are used to build a hierarchical structure called the Abstract Syntax Tree (AST). The parser analyzes the sequence of tokens based on the grammar rules of the programming language to construct the AST. The AST represents the syntactic structure of the source code. c. Semantic Analysis: The semantic analyzer examines the AST to verify the correctness of the source code according to the language rules. It checks for type compatibility, undefined variables, function signatures, and other semantic errors. Additionally, it may perform symbol table management to keep track of identifiers and their properties. Synthesis Phase: The synthesis phase is the second step of compilation, where the compiler generates the target code (machine code, intermediate code, or assembly code) from the analyzed source code. This phase also consists of several sub-phases: a. Intermediate Code Generation: In some compilers, an intermediate representation (IR) is generated that is closer to the target machine but independent of the specific hardware architecture. This IR serves as an intermediate step before generating the final target code. b. Code Optimization: The compiler performs various code optimization techniques on the intermediate code to improve the efficiency of the final executable. Optimization aims to reduce execution time, decrease memory usage, and enhance the overall performance of the program. c. Code Generation: The code generator produces the final target code (e.g., machine code or assembly code) based on the information obtained from the analysis phase. The target code is specific to the architecture or platform for which the compiler is intended. In summary, the Analysis-Synthesis Model of a compiler emphasizes the separation of concerns between understanding the source code through analysis and generating efficient target code through synthesis. This modular approach allows for better maintainability, flexibility, and extensibility of the compiler. Each phase can be designed independently, and improvements in one phase can be made without affecting the other. ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 8 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 Cousins of the Compiler In the context of software development and programming languages, there are several related tools and concepts that can be considered "cousins" of the compiler. These tools serve different purposes but share some similarities with compilers in terms of their roles in software development and code processing. Some of the notable "cousins" of the compiler include: i. Interpreter: An interpreter is a program that directly executes source code line by line, without the need for a separate compilation step. Instead of generating machine code like a compiler, an interpreter reads the source code and executes it directly, translating each line into machine instructions or intermediate code on-the-fly. Interpreters are often used for scripting languages like Python and JavaScript, allowing for rapid development and easier debugging, as the code is executed directly without the need for explicit compilation. ii. Assembler: An assembler is a tool that converts assembly language code (low-level symbolic representation of machine instructions) into machine code or object code. Unlike compilers, assemblers work with a one-to-one mapping of assembly instructions to machine instructions. They facilitate programming for specific hardware architectures, and the output is typically directly executable on the target platform without further processing. iii. Linker: A linker is a utility responsible for combining multiple object files produced by the compiler or assembler into a single executable or library file. It resolves references to external symbols, such as functions and global variables, across different object files, ensuring that all parts of the program can work together cohesively. Linkers are an essential part of the software development process when dealing with larger programs that span multiple source files. iv. Preprocessor: The preprocessor is a phase in the compilation process that performs textual manipulations on the source code before it is passed to the compiler. It handles directives such as #include (for header file inclusion), macros, and conditional compilation (#ifdef, #ifndef, etc.). The preprocessor simplifies code organization, enables code reuse, and allows conditional compilation based on the target platform or configuration. ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 9 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 v. Virtual Machine (VM): A virtual machine is a software emulation of a physical computer that runs an intermediate code or bytecode generated by a compiler. Instead of generating machine code for a specific hardware platform, the compiler produces bytecode that is executed by the virtual machine. This approach provides platform independence and is often used in languages like Java (Java Virtual Machine) and C# (Common Language Runtime). vi. Just-In-Time (JIT) Compiler: A JIT compiler is a hybrid approach that combines features of both compilers and interpreters. It translates the source code into an intermediate representation or bytecode, similar to an interpreter. However, instead of interpreting the bytecode line by line, the JIT compiler converts it into machine code just before execution. This allows for a balance between the performance of compiled code and the flexibility of interpretation. JIT compilation is used in environments like the.NET Framework and modern JavaScript engines. These "cousins" of the compiler play essential roles in modern software development, and each has its strengths and use cases depending on the programming language, platform, and performance requirements. Multiple-choice questions (MCQs) 1. What is the primary purpose of a compiler? A) To convert source code into machine code B) To interpret source code line by line C) To execute the program directly without compilation D) To debug and analyze code errors Correct answer: A 2. Which phase of the compiler is responsible for dividing the source code into tokens? A) Code Generation B) Syntax Analysis (Parsing) C) Lexical Analysis (Scanning) D) Semantic Analysis Correct answer: C 3. What is the role of the Abstract Syntax Tree (AST) in the compilation process? A) It generates the final machine code. B) It represents the syntactic structure of the source code. C) It optimizes the intermediate code. D) It interprets the source code line by line. Correct answer: B 4. What does the Semantic Analysis phase of a compiler check for? A) Syntactic errors in the source code B) Division by zero errors C) Type compatibility and semantic correctness D) Lexical errors in the source code Correct answer: C ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 10 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 5. Which of the following is true about an interpreter? A) It converts source code to machine code before execution. B) It directly executes the source code without separate compilation. C) It generates intermediate code during the compilation process. D) It links multiple object files into a single executable. Correct answer: B 6. What does the Linker do during the software development process? A) Converts assembly code to machine code. B) Combines multiple object files into a single executable or library. C) Executes the source code line by line. D) Analyzes the source code for semantic errors. Correct answer: B 7. Which phase of the compiler is responsible for optimizing the code to improve performance? A) Semantic Analysis B) Code Generation C) Code Optimization D) Lexical Analysis Correct answer: C 8. What is the purpose of the preprocessor in the compilation process? A) To generate machine code from source code. B) To combine multiple object files into an executable. C) To perform textual manipulations on the source code before compilation. D) To interpret the source code line by line. Correct answer: C 9. Which programming languages often use a Virtual Machine (VM) for execution? A) Python B) C++ C) Assembly language D) C# Correct answer: D 10. What does a Just-In-Time (JIT) compiler do? A) It directly executes the source code without compilation. B) It generates machine code before the execution of each line. C) It converts the source code into bytecode just before execution. D) It optimizes the code during the parsing phase. Correct answer: C Short questions ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 11 B.Tech CSE (AIML) and 5th Semester Compiler Design (PCC-CSM504) Academic Session 2023-2024 1. What is Compiler Design? 2. What is the main goal of a compiler? 3. Mention two primary phases of a compiler. 4. What is the purpose of lexical analysis (scanning) in compilation? 5. Explain the role of the Abstract Syntax Tree (AST) in the compilation process. 6. What does the semantic analysis phase of a compiler check for? 7. What is the preprocessor, and what does it do during compilation? 8. Describe the role of a linker in software development. 9. What is code optimization, and why is it important in the compilation process? 10. How does a Just-In-Time (JIT) compiler differ from a traditional compiler? Long questions 1. Explain the compilation process in detail, including the main phases a source code undergoes to become an executable program. Elaborate on the tasks performed during each phase and the purpose of generating intermediate representations. 2. Discuss the key differences between a compiler and an interpreter. Compare their advantages and disadvantages in terms of performance, portability, development time, and debugging capabilities. 3. Describe the importance of lexical analysis (scanning) and syntax analysis (parsing) in the context of the compilation process. Provide examples of how lexical analysis breaks down source code into tokens, and how syntax analysis constructs the Abstract Syntax Tree (AST). 4. In the context of compiler optimization, explain various techniques used to improve the efficiency of generated code. Discuss the trade-offs between code optimization and compilation time, and highlight real-world scenarios where optimization plays a crucial role. 5. Analyze the role of a linker in software development and its significance in creating executable files. Explain how a linker resolves references to external symbols, handles libraries, and helps in modularizing large software projects. Provide an example of a situation where a linker is essential. ANUPAMA SEN Designation and Department: - Assistant Professor, CSE-AI Brainware University, Kolkata 12