abs insn with QI and HI mode

Rask Ingemann Lambertsen rask@sygehus.dk
Wed Jul 11 19:52:00 GMT 2007


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



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