Compilers

Compilers are software tools that translate programs written in high-level programming languages into lower-level representations, typically executable machine code or an intermediate form that can be further processed. The primary aim is to produce correct, efficient, and portable code for a given target architecture, while providing helpful diagnostics when the source contains errors.

A typical compiler operates in stages. The front end performs lexical analysis to convert source text into tokens, parses those tokens to build a syntax tree, and performs semantic analysis, type checking, and symbol resolution. An intermediate representation is produced, suitable for analysis and optimization. The back end optimizes the IR and generates target-specific code, which may be assembly, object code, or directly machine code. A linker may then combine several object files into an executable.

Compilers may apply various optimizations to improve speed, size, or energy use. These range from local substitutions to whole-program analyses. Some languages are designed to run on managed runtimes, and compilers may emit bytecode for virtual machines instead of native code. Just-in-time compilers generate code at runtime to exploit runtime information, while ahead-of-time compilers translate code before execution for faster startup.

Overall, compilers enable language design to separate programming models from hardware details, support portability across platforms, and influence performance. They differ from interpreters, which execute source or bytecode directly, though many language implementations use a combination of both approaches.