Retargetable compilers can generate assembly code for a variety of different target processor architectures. Owing to their use in the design of application-specific embedded processors, they bridge the gap between the traditionally separate disciplines of compiler construction and electronic design automation. In particular, they assist in architecture exploration for tailoring processors towards a certain application domain. The paper reviews the state-of-the-art in retargetable compilers for embedded processors. Based on some essential compiler background, several representative retargetable compiler systems are discussed, while also outlining their use in iterative, profiling-based architecture exploration. The LISATek C compiler is presented as a detailed case study, and promising areas of future work are proposed.