On Tue, Jul 10, 2007 at 10:35:01AM +0100, Ying Yi wrote: > Hi Jim, > >To get your special char/short abs instructions, we need one of two things > >1) Optimization support to recognize a sign-extend followed by an abs, > >where the target has an abs instruction that operates on the > >pre-extended value. We can then optimize away the sign extend > >instruction. This optimization support apparently does not exist at > >the moment, perhaps because no one has needed it before. > > Thanks very much for your email. Will gcc add the optimization support > in the future (method 1)?
Please don't top post. Thanks. Shameless plug: Get trunk revision 126251 or later and compile with -fdump-rtl-combine-details, then look at the dump file. There is a good chance that combine is already looking for such an instruction. -- Rask Ingemann Lambertsen
