[Mesa-dev] TGSI declarations missing type info

[Jose Fonseca]

----- Original Message -----
> 
> 
> ----- Original Message -----
> > The next open question I have is whether this warrants additions to
> > the tgsi_opcode_info struct, mainly whether the return value is
> > uint/int/float,
> > and whether then src regs are uint/int/float, I'm not 100% that all
> > opcodes always take all int/uint/float srcs, but my memory is a bit
> > hazy on what the outliers might be.
> 
> I agree that adding this sort of info to tgsi_opcode_info would be a
> code typing saver for all drivers.
> 
> However I never looked at the integer/double opcode set, but from
> quickly skimming d3d10/11 headers, there are three buckets:
> - arithmetic: (u)ints -> (u)int
> - comparison: (u)ints -> mask (and I don't know what's the semantic
> of these masks: 0/~0, 1.0f/0.0f, 0/1, or what)
> - conversion: float <-> (u)int
> 
> 
> And likewise to double, minus the unsigned vs signed split.
> 
> So, probably we need tgsi_opcode_info to distuinguish the source type
> vs dest type, but we likely don't need per-source types.
> 
> 
> 
> A much more intricate question, is how to represent boolean mask in a
> mixed type world. My guess is one of two:
> 
> a) is that there are two we should not mandate the bit representation
> of a boolean (drivers are free to implement booleans as 1.0f/0.0f,
> 0/~0, etc). The only constrainsts is that the state tracker never
> tries to write a boolean directly to an output.

Oops. Some extra words in here. Strike "is that there are two" words out:


a) we should not mandate the bit representation
 of a boolean (drivers are free to implement booleans as 1.0f/0.0f,
 0/~0, etc). The only constrainsts is that the state tracker never
 tries to write a boolean directly to an output


> 
> b) if by some miracle, all hardware implements boolean vectors in the
> same way, then we could stick to that.  (For sse/avx/llvm-2.9, the
> natural way to represent a boolean vector is a bitmask (0/~0). llvm
> 3.0 finally added support for bit vectors.)

Jose