The recommended way of reporting bugs is using the infrastructure of the sourceforge site. You can follow the status of bug reports there and have an overview about the known bugs.
Bug reports are automatically forwarded to the developer mailing list and will be fixed ASAP. When reporting a bug, it is very useful to include a small test program (the smaller the better) which reproduces the problem. If you can isolate the problem by looking at the generated assembly code, this can be very helpful. Compiling your program with the --dumpall option can sometimes be useful in locating optimization problems. When reporting a bug please make sure you:
Please have a short check that you are using a recent version of SDCC and the bug is not yet known. This is the link for reporting bugs: http://sourceforge.net/tracker/?group_id=599&atid=100599. With SDCC on average having more than 200 downloads on sourceforge per day7.1 there must be some users. So it's not exactly easy to find a new bug. If you find one we need it: reporting bugs is good.