[Mesa-dev] [PATCH 1/2] nvc0/ir: Export viewport index in fragment shaders

[Ilia Mirkin]

On Wed, Apr 19, 2017 at 5:10 PM, Lyude <lyude at redhat.com> wrote:
> Since ABR_vertex_shader_layer/viewport_index enables the ability to
> interact with gl_ViewportIndex from the fragment shader, we don't want
> to skip emitting the viewport index for fragment shaders.
>
> As well, only save the viewport index into a scratch register for
> Geometry shaders, since EMIT is not a thing elsewhere.
>
> Signed-off-by: Lyude <lyude at redhat.com>
> ---
>  .../drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp  | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> index 92cc13d..5af0ac5 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> @@ -2150,18 +2150,16 @@ Converter::storeDst(const tgsi::Instruction::DstRegister dst, int c,
>        assert(!ptr);
>        mkOp2(OP_WRSV, TYPE_U32, NULL, dstToSym(dst, c), val);
>     } else
> -   if (f == TGSI_FILE_OUTPUT && prog->getType() != Program::TYPE_FRAGMENT) {
> -
> -      if (ptr || (info->out[idx].mask & (1 << c))) {
> -         /* Save the viewport index into a scratch register so that it can be
> -            exported at EMIT time */
> -         if (info->out[idx].sn == TGSI_SEMANTIC_VIEWPORT_INDEX &&
> -             viewport != NULL)
> -            mkOp1(OP_MOV, TYPE_U32, viewport, val);
> -         else
> -            mkStore(OP_EXPORT, TYPE_U32, dstToSym(dst, c), ptr, val)->perPatch =
> -               info->out[idx].patch;
> -      }
> +   if (f == TGSI_FILE_OUTPUT && (ptr || (info->out[idx].mask & (1 << c)))) {

This actually still needs to prog->getType() !=
Program::TYPE_FRAGMENT. Sorry. The original condition was correct.

> +      /* Save the viewport index into a scratch register so that it can be
> +         exported at EMIT time */
> +      if (prog->getType() == Program::TYPE_GEOMETRY &&

And that's what was missing before. So I think just adding that to the
existing code would solve the issue quite nicely.

> +          info->out[idx].sn == TGSI_SEMANTIC_VIEWPORT_INDEX &&
> +          viewport != NULL)
> +         mkOp1(OP_MOV, TYPE_U32, viewport, val);
> +      else
> +         mkStore(OP_EXPORT, TYPE_U32, dstToSym(dst, c), ptr, val)->perPatch =
> +            info->out[idx].patch;
>     } else
>     if (f == TGSI_FILE_TEMPORARY ||
>         f == TGSI_FILE_ADDRESS ||
> --
> 2.9.3
>
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