JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III Year PRINCIPLES OF PROGRAMMING LANGUAGES Previous Question Paper (August - 2022 - R18)

A successful programming language is evaluated based on several key criteria that determine its usability, reliability, and efficiency:

• Readability: The ease with which programs can be read and understood. This is influenced by simplicity, orthogonality, control structures, and data types.
• Writability: The ease with which a language can be used to create programs. It depends on the expressivity of the language, support for abstraction, and the presence of powerful built-in features.
• Reliability: A language is reliable if it performs to its specifications under all conditions. Key factors include type checking, exception handling, and aliasing restrictions.
• Cost: This includes the cost of training programmers, writing code, compiling, executing, and maintaining the software.
• Generality: The applicability of the language to a wide range of problem domains.
• Extensibility: The ability of the language to allow users to add new features or data types.

A phase is a logically distinct step in the compilation process where the compiler performs a specific task, such as lexical analysis, syntax analysis, or code generation. A pass refers to the traversal of the entire source program or its intermediate representation by the compiler. A single pass may involve multiple phases, or a single phase may be split across multiple passes.

Compilers use multiple phases for the following reasons:

• Complexity Management: Breaking the compilation process into smaller, manageable phases simplifies the design and implementation of the compiler.
• Portability: By separating machine-independent phases (like parsing) from machine-dependent phases (like code generation), the compiler can be easily adapted to different hardware architectures.
• Optimization: Multiple phases allow for iterative analysis of the code, enabling more sophisticated optimizations that would be impossible in a single pass.
• Memory Constraints: In environments with limited memory, the compiler may need to process the code in multiple passes to avoid loading the entire program representation into memory at once.