[LLVMdev] Adding multiples-of-8 integer types to MVT

Ken Dyck
Thu, 03 Dec 2009 12:28:48 -0000

On Wednesday, December 02, 2009 7:09 PM, Chris Lattner
wrote:
>
> On Dec 2, 2009, at 12:32 PM, Ken Dyck wrote:
>
> > Would there be any interest/opposition to extending the set
> of simple
> > integer types in MVT to include the missing multiples of 8
> (up to 64
> > bits)? That is: i24, i40, i48, i56?
> >
> > Adding the types to MVT (and ValueTypes.td) would allow LLVM to be
> > targeted to architectures that have registers and
> operations of these
> > sizes (for example, a 24-bit DSP that I'd like to develop a
> back end
> > for has 24-, 48- and 56-bit native integer types). Back ends are
> > currently limited to using power-of-2 types in their TableGen
> > descriptions.
>
> I'm fine with doing this, but please only add the MVT types
> you actually need.  Don't bother adding i40 unless you
> support i40.  If someone needs it in the future, we can add
> it at that point.

Judging from a comment near the end of BlackfinRegisterInfo.td, it looks
like the Blackfin back end could make use i40. Would you still like it
left out?

-Ken