On 14 November 2014 18:50, Ilia Mirkin <imir...@alum.mit.edu> wrote:
> I can't speak for the radeon guys, but I know I sure would love to see
> any reports of poor code being generated by nouveau in response to
> legitimate-seeming TGSI (or GLSL). In some cases, a simple
> optimization can be added to take care of it, and I'd definitely
> appreciate the extra pair of eyeballs on driver-generated code :)
>
> The report can be as simple as "here is the TGSI snippet, take a look
> at how crappy the code it generates is". At least for nouveau, I can
> feed that directly into a compiler that can target any of the relevant
> backends.
>
> [Note, r600g didn't have an optimizer enabled until ~1y ago; not sure
> if your analysis was with or without sb.]
>
It was with sb, but probably before TGSI got FSLT/FSGE/etc.
For reference, what currently happens for r600g is something like this:
D3D:
cnd r[0], r[0].w, c[1], c[2]
GLSL:
R0.xyzw = (R0.w > 0.5 ? ps_c[1].xyzw : ps_c[2].xyzw);
TGSI:
FSLT TEMP[0].x, IMM[0].xxxx, TEMP[0].xxxx
UIF TEMP[0].xxxx :0
MOV TEMP[0], CONST[1]
ELSE :0
MOV TEMP[0], CONST[2]
ENDIF
R600:
SETGE_DX10 T0.x, 0.5, T0.x
CNDE_INT R0.x, T0.x, KC0[1].x, KC0[2].x
CNDE_INT R0.y, T0.x, KC0[1].y, KC0[2].y
CNDE_INT R0.z, T0.x, KC0[1].z, KC0[2].z
CNDE_INT R0.w, T0.x, KC0[1].w, KC0[2].w
While ideally that would just be 4 CNDGE's, that's better than what I
remember. IIRC there used to be a bunch of int/float conversions as
well.
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