https://www.hex-rays.com/products/decompiler/manual/limit.shtml Currently the decompiler can handle compiler generated code. Manually crafted code may be decompiled too but the results are usually worse than for compiler code. Support for other processors will eventually be added (no deadlines are available, sorry).
Below are the most important limitations of our decompilers (all processors):
exception handling is not supported type recovery is not performed global program analysis is not performed