GCC [C, C++ (G++), Java (GCJ), Ada (GNAT), Objective-C, Objective-C++, and Fortran (GFortran). Also available, but not in standard are: Modula-2, Modula-3, Pascal, PL/I, D, Mercury, VHDL] [Linux, the BSDs, Mac OS X, NeXTSTEP, Microsoft Windows and BeOS, among others]
libJIT Just-In-Time compilation library, a library by Rhys Weatherley, Klaus Treichel, Aleksey Demakov, and Kirill Kononenko for development of Just-In-Time compilers (JIT) in Virtual Machine implementations, Dynamic programming languages, and Scripting languages.
Research compilers are mostly not robust or complete enough to handle real, large applications. They are used mostly for fast prototyping new language features and new optimizations in research areas.
MILEPOST GCC: popular interactive plugin-based open-source research compiler that combines the strength of the production quality stable GCC that supports more than 30 families of architectures, multiple languages and can compile real, large applications including Linux, and the flexibility of the common Interactive Compilation Interface that transforms production compilers into interactive research toolsets. It is the first production compiler that features interactive plugin framework and machine learning engine to be able to adapt to any architecture automatically and predict profitable optimizations. It has been originally developed during 2006-2009 by the MILEPOST consortium including IBM, INRIA, University of Edinburgh, ARC and CAPS Entreprise. Since 2009, MILEPOST GCC is a part of the community-driven Collective Tuning Initiative to improve the quality and reproducibility of the research on code and architecture optimization, develop collaborative research infrastructure with unified interfaces and common optimization repository and boost innovation.
Programming Without Coding Technology (PWCT) A specialist innovative technology wherein the programmer need not write code but can visually specify every functional aspect of the program similar to flowcharts and algorithms. PWCT include (Mahmoud Programming Language, RPWI Environment & DoubleS [Super Server] Programming Paradigm).PWCT is free-open source. PWCT uses Interaction by presenting a GUI between a Human language and a Programming language so doing anything require knowing Procedure instead of being Declarative.
Open64: one of the most popular research compilers today, many branches exist. Here is a list of research papers from the CGO 2009. (Open64 merges the open source changes from the PathScale compiler mentioned.)
Interactive Compilation Interface - a plugin system with high-level API to transform production-quality compilers such as GCC into powerful and stable research infrastructure while avoiding developing new research compilers from scratch.