Editing Just-in-time compilation (section)

== Uses ==
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JIT compilation can be applied to some programs, or can be used for certain capacities, particularly dynamic capacities such as [[regular expression]]s. For example, a text editor may compile a regular expression provided at runtime to machine code to allow faster matching: this cannot be done ahead of time, as the pattern is only provided at runtime. Several modern [[runtime environment]]s rely on JIT compilation for high-speed code execution, including most implementations of [[Java (programming language)|Java]], together with [[Microsoft]]'s [[.NET]]. Similarly, many regular-expression libraries feature JIT compilation of regular expressions, either to bytecode or to machine code. JIT compilation is also used in some emulators, in order to translate machine code from one CPU architecture to another.

A common implementation of JIT compilation is to first have AOT compilation to bytecode ([[virtual machine]] code), known as ''bytecode compilation'', and then have JIT compilation to machine code (dynamic compilation), rather than interpretation of the bytecode. This improves the runtime performance compared to interpretation, at the cost of lag due to compilation. JIT compilers translate continuously, as with interpreters, but caching of compiled code minimizes lag on future execution of the same code during a given run. Since only part of the program is compiled, there is significantly less lag than if the entire program were compiled prior to execution.