GCC hasn't ventured much beyond its static compilation roles while LLVM continues to be adopted by numerous software projects for its Just-In-Time compilation abilities. However, David Malcom of Red Hat has published a "proof of concept" embeddable JIT compiler based upon the GNU Compiler Collection.
The code published on Wednesday is still a work-in-progress but it's a patch to GCC that allows the compiler to have an embeddable JIT compilation API that uses GCC as its back-end via a libgccjit.so library. The shared library can be dynamically linked into bytecode interpreters and other programs for generating native machine code at run-time.
While the code is still experimental, the Red Hat employee working on GCC hopes to eventually merge it into the mainline compiler code-base. More details on this GCC JIT compiler embeddable library can be found via its mailing list announcement.