Hi, sorry for the delay of this reply but just returned from paternity leave.
> -----Original Message----- > From: Hans-Peter Nilsson [mailto:h...@bitrange.com] > Sent: 05 March 2013 01:45 > To: Paulo Matos > Cc: gcc@gcc.gnu.org > Subject: Re: Modeling predicate registers with more than one bit > > Except for CCmodes being dependent on source-modes, I'd sneak > peeks at PowerPC. > What do you mean by source modes? > > If not, is there any way to currently > > (as of HEAD) model this in GCC? > > IIUC, this sounds simply like having multiple separate > condition-code registers, just with a size-dependent CCmodes > twist; for each type of comparison where there'd be a separate > CCmode variant, you also need separate CCmodes for each source > mode M, all separated in cbranchM4 and cstoreM4. > I am not sure CC_MODE can solve the problem but I am not entirely experienced with using different CC_MODEs, the first thing that comes to mind is, how do you set the size of a CCmode? A predicate register in our backend can be set as if it had different sizes. So, even though the register has 8 bits. It's possible to have just 1 bit set, 2 bit sets, 4 bit sets of 8 bits sets depending if a comparison is of mode BI, QI, SI or DI. I might have to use proper registers like SH does (following Oleg suggestion). Thanks, Paulo Matos
