Low Level Virtual Machinehttp://llvm.org/
LLVM is a compiler infrastructure designed for compile-time, link-time, runtime, and idle-time optimization of programs from arbitrary programming languages. LLVM is written in C++ and has been developed since 2000 at the University of Illinois and Apple. It currently supports compilation of C and C++ programs, using front-ends derived from GCC 4.0.1. A new front-end for the C family of languages is in development. The compiler infrastructure includes mirror sets of programming tools as well as libraries with equivalent functionality.