3. Used Technology

LLVM is a free, open-source compiler infrastructure under the Apache License 2.0. It is designed as a collection of tools including Front Ends parsers, Middle Ends optimizers, and Back Ends to produce machine code out of those programs.

Clang is a front-end that uses a LLVM license. Clang works by taking the source language (e.g. C++) and translating it into an intermediate representation that is then received by the compiler back end (i.e., the LLVM backend). Its library-based architecture makes it relatively easy to adapt Clang and build new tools based on it. Cling inherits a number of features from LLVM and Clang, such as: fast compiling and low memory use, efficient C++ parsing, extremely clear and concise diagnostics, Just-In-Time compilation, pluggable optimizers, and support for GCC extensions.

Interpreters allow for exploration of software development at the rate of human thought. Nevertheless, interpreter code can be slower than compiled code due to the fact that translating code at run time adds to the overhead and therefore causes the execution speed to be slower. This issue is overcome by exploiting the Just-In-Time (JIT) compilation method. With the JIT approach, assembly is generated by the interpreter with a pseudocode (an intermediate language that is not understood by the computer). The intermediate code is then translated into machine language when required for use. By following the JIT approach, Cling is able to evaluate whether a certain part of the source code is executed often, and then compile this part, therefore reducing the overall execution time.