[Mesa-dev] TGSI declarations missing type info

Keith Whitwell keithw at vmware.com
Mon Nov 14 01:42:42 PST 2011

On Sun, 2011-11-13 at 14:43 -0600, Bryan Cain wrote:
> On 11/13/2011 09:06 AM, Dave Airlie wrote:
> > Hi guys,
> >
> > Just been looking at llvmpipe integer support and it seems like we
> > lose some information about the type of data stored into temporaries,
> >
> > after st_glsl_to_cpp we no longer know what type the temporaries are,
> > and llvm would really like to know and I can't see any reason that
> > TGSI doesn't contain the info. Having untyped temp decls means we'd
> > have to allocate some sort of "union" via aliases I guess in llvmpipe
> > for all temps so we can store int/float in them.
> >
> > I've attached a run of glsl-vs-loop from llvmpipe with integer opcodes
> > forced on. (llvmpipe-int-test branch of my repo).
> >
> > Dave.
> If you do add types to TGSI registers, it's worth noting that the
> internal IR used by glsl_to_tgsi (glsl_to_tgsi_instruction) already the
> types of all src and dst registers, and it's only lost when converting
> that to TGSI.  However, it was only intended to be good enough to
> determine whether to emit an integer or float instruction, so there
> might be some mistakes remaining somewhere that would need to be corrected.

I'd certainly support the idea of adding type information to TGSI.  It
would mean that any SM4-to-TGSI translator would have to do type
inference, but afaik SM4 is the only place where that would have to
happen -- all other potential sources of TGSI either have type
information (like IR as noted above), or are pretty much float-only
(like SM3).  


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