I believe some projects have attempted this, but there is just no way to deal with pointers without some pretty severe restrictions about what can access what (essentially they have to be converted into array indexes and arrays allocated instead of memory)
If you have C without too much reliance on pointers, and you want it into the JVM, you might just convert it to Java--should be pretty easy and the performance shouldn't be too bad. C still beats Java in most areas by about 2x with some areas much worse and in a few areas Java actually beats C (heap memory management, for one), but compared to most other languages (interpreted ones at least), java and c are 100x faster, so the difference between them is pretty meaningless from that point of view.
