On Fri, 24 Mar 2023, Peter Bergner via Gcc-patches wrote: > On 3/23/23 6:12 PM, Jeff Law via Gcc-patches wrote: > >>>> Is there a reason why REE cannot see that our (reg:QI 4) is a param > >>>> register > >>>> and thus due to our ABI, already correctly sign/zero extended? > >>> > >>> I don't think REE has ever considered exploiting ABI constraints. Handling > >>> that might be a notable improvement on various targets. It'd be a great > >>> place to do some experimentation. > >> > >> Ok, so sounds like a good follow-on project after this patch is reviewed > >> and committed (stage1). Thanks for your input! > > > > Agreed. I suspect that risc-v will benefit from such work as well. > > With that in mind, if y'all start poking at this, please loop in Raphael > > (on cc) who's expressed an interest in this space. > > Will do. I suspect that it'll be best to come up with some generic interface > using target hooks like "param regs are sign/zero extended" or "call return > values are sign/zero extended", etc. that targets can conditionally opt into > depending on their ABI that is in effect.
Pardon the arm-chair development mode but it sounds like re-inventing the TARGET_PROMOTE_* hooks... Maybe just hook up TARGET_PROMOTE_FUNCTION_MODE to ree.c (as "you" already already define it for "rs6000")? brgds, H-P
