compiles

Compiles is the third-person singular present tense of compile; in computing, to compile means to translate a program written in a high-level language into a lower-level form such as machine code, an intermediate representation, or bytecode. Compiling is a core step in producing executable software, as opposed to interpretation, where code is executed directly or via a virtual machine without full ahead-of-time translation.

Process and structure: Most compilers have a front end that analyzes source syntax and semantics and a back end that generates target code. The front end performs lexical analysis, parsing, and semantic analysis; the back end applies optimizations and emits code. Many compilers produce an intermediate representation (IR) that enables optimizations independent of the final target.

Outputs: Compilers can produce native machine code, such as an executable or a library for a specific architecture, or bytecode for a virtual machine (e.g., Java bytecode). Object files (.o, .obj) are common intermediate outputs that are later linked with other objects to form a program. Some compilers also perform just-in-time or ahead-of-time compilation for managed languages.

Examples and concepts: Notable compilers include GCC and Clang for C/C++, Javac for Java, and Rustc for Rust. Other language ecosystems provide their own toolchains. Cross-compilation targets a different architecture or operating system from the host system. Build systems and reproducible builds help manage dependencies and ensure consistent compilation results.

History and impact: Early compilers emerged in the 1950s and 1960s, enabling higher productivity and performance gains. Efficient compilation and optimization are central to software performance and security, as poorly optimized or miscompiled code can introduce flaws.