Demystifying Compilation: From Source Code to Executable


Compilation is in the core of software development, translating human-readable or high-level code into machine-executable instructions. In this blog post, we will explore the stages of compilation; lexical analysis, syntax analysis, code generation, and code optimization. Understanding these stages will provide insights into how the compiler translates the source code program and optimizes it for efficient execution.

Lexical Analysis: Converting Characters to Tokens

Lexical analysis is the initial stage of compilation. It involves converting a sequence of characters into a sequence of tokens. The compiler uses a keyword table and a symbol table for this purpose. The keyword table includes reserved words and operators used, mapping them to their matching tokens. The symbol table, on the other hand, stores identifier names, data types, roles (e.g., variable, constant, array, procedure), and locations or values of constants. During lexical analysis, white spaces, redundant characters, and comments are removed whilst errors are identified and reported.

Syntax Analysis: Interpreting Tokens and Building Parse Trees

Syntax analysis follows lexical analysis and involves interpreting the meaning of a sequence of tokens. Parsing algorithms are used to check if the tokens conform to the rules of the programming language. Syntax errors are reported if the tokens violate these rules. Additionally, this stage produces a parse tree, which represents the hierarchical structure of the code and aids in further processing.

Code Generation: Intermediate Representation to Object Code

Code generation transforms the intermediate representation of the source code into an executable form. This stage produces object code, which is in a machine-readable binary format. By utilizing the parse tree or other intermediate representations, the compiler generates low-level code, such as assembly language or an intermediate representation. This code serves as input for further processing and eventual execution.

Code Optimization: Enhancing Performance and Efficiency

Code optimization focuses on improving a program’s execution time and memory requirements. Redundant code is eliminated, resulting in fewer instructions and enhanced efficiency. Additionally, the compiler reorganizes the code to make it more optimized. Techniques such as constant folding, loop unrolling, and common subexpression elimination are employed to optimize the generated code. The goal is to minimize resource usage and maximize performance.


Compilation involves several important stages, including lexical analysis, syntax analysis, code generation, and code optimization. Understanding these stages provides valuable insights into the compilation process, enabling developers to write efficient and high-performing programs.

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