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Incoming links: Just-in-time compilation
Compilation Created 2026-10-13 Updated 2026-10-14
Compilation is the translation process performed by a compiler, which may include checking and transforming an abstract syntax tree. Translation can finish before execution, or happen during execution through just-in-time compilation. Reusing the translated representation can avoid repeated parsing and repeated constant folding when only the inputs change. This does not guarantee a speedup: translation itself costs work, and the choice of representation and execution mechanism matters.
One possible compilation pipeline for
. Details. x*(2+3)-4, with execution from an abstract syntax tree, a stack machine instruction sequence, or machine code
Interpreter (computing) Created 2026-10-13 Updated 2026-10-14
An interpreter executes a program's operations according to its programming language semantics. It can recursively evaluate an abstract syntax tree, or follow an instruction sequence using an execution state such as a stack and an instruction pointer. It need not repeatedly read source code characters, and it need not use an abstract syntax tree at all.
Compilation and interpretation can coexist. In CPython, Python source code is compiled into bytecode for execution by an interpreter; its bytecode is not promised to remain stable between releases.[ref]
Glossary, Python 3.14 documentation. Python 3.14 documentation; Python 3.14 glossary: bytecode and virtual machine entries; compilation, execution and release-specific bytecodes
The Python 3.14 compile function accepts text or an abstract syntax tree and can produce a code object, which eval or exec can execute.[ref]Built-in Functions, Python 3.14 documentation. Python 3.14 documentation; Python 3.14 Built-in Functions: compile, accepted source forms, code objects and execution by eval or exec
These operations make translation and execution separately accessible without requiring them to live in different applications.Just-in-time compilation gives another combination: an interactive implementation can translate a submitted program expression into machine code and then execute it immediately. The LLVM 20.1.0 tutorial demonstrates this by adding an intermediate representation module to its just-in-time compilation facility, looking up the generated function, and calling it.[ref]
4. Kaleidoscope: Adding JIT and Optimizer Support. LLVM 20.1.0 documentation; Implementing a language with LLVM, chapter 4, section 4.4: HandleTopLevelExpression, addModule, lookup and calling the generated native function
Thus calling a programming language permanently "compiled" or "interpreted" hides an implementation choice: ask which representation is translated, which is executed, and when.