[Mesa-dev] [PATCH 07/12] i965/blorp: Instruct vertex fetcher to provide prim instance id

[Jason Ekstrand]

On Aug 31, 2016 9:06 AM, "Topi Pohjolainen" <topi.pohjolainen at intel.com>
wrote:
>
> This will indicate target layer (Render Target Array Index) needed
> for layered clears.
>
> v2: Use 3DSTATE_VF_SGVS for gen8+
>
> Signed-off-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> ---
>  src/intel/blorp/blorp_genX_exec.h | 26 ++++++++++++++++++++++----
>  1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/src/intel/blorp/blorp_genX_exec.h
b/src/intel/blorp/blorp_genX_exec.h
> index f44076e..7312847 100644
> --- a/src/intel/blorp/blorp_genX_exec.h
> +++ b/src/intel/blorp/blorp_genX_exec.h
> @@ -298,8 +298,10 @@ blorp_emit_vertex_elements(struct blorp_batch *batch,
>      * the URB. This is controlled by the 3DSTATE_VERTEX_BUFFERS and
>      * 3DSTATE_VERTEX_ELEMENTS packets below. The VUE contents are as
follows:
>      *   dw0: Reserved, MBZ.
> -    *   dw1: Render Target Array Index. The HiZ op does not use indexed
> -    *        vertices, so set the dword to 0.
> +    *   dw1: Render Target Array Index. Below vertex fetcher gets
programmed
> +    *        to assign this with primitive instance identifier which
will be
> +    *        used for layered clears. All other renders have only one
instance
> +    *        and therefore the value will be effectively zero.
>      *   dw2: Viewport Index. The HiZ op disables viewport mapping and
>      *        scissoring, so set the dword to 0.
>      *   dw3: Point Width: The HiZ op does not emit the POINTLIST
primitive,
> @@ -318,7 +320,7 @@ blorp_emit_vertex_elements(struct blorp_batch *batch,
>      * "Vertex URB Entry (VUE) Formats".
>      *
>      * Only vertex position X and Y are going to be variable, Z is fixed
to
> -    * zero and W to one. Header words dw0-3 are all zero. There is no
need to
> +    * zero and W to one. Header words dw0,2,3 are zero. There is no need
to
>      * include the fixed values in the vertex buffer. Vertex fetcher can
be
>      * instructed to fill vertex elements with constant values of one and
zero
>      * instead of reading them from the buffer.
> @@ -332,7 +334,16 @@ blorp_emit_vertex_elements(struct blorp_batch *batch,
>     ve[0].SourceElementFormat = ISL_FORMAT_R32G32B32A32_FLOAT;
>     ve[0].SourceElementOffset = 0;
>     ve[0].Component0Control = VFCOMP_STORE_0;
> +
> +   /* From Gen8 onwards hardware is no more instructed to overwrite
components
> +    * using an element specifier. Instead one has separate
3DSTATE_VF_SGVS
> +    * (System Generated Value Setup) state packet for it.
> +    */
> +#if GEN_GEN >= 8
>     ve[0].Component1Control = VFCOMP_STORE_0;
> +#else
> +   ve[0].Component1Control = VFCOMP_STORE_IID;
> +#endif
>     ve[0].Component2Control = VFCOMP_STORE_0;
>     ve[0].Component3Control = VFCOMP_STORE_0;
>
> @@ -366,7 +377,14 @@ blorp_emit_vertex_elements(struct blorp_batch *batch,
>     }
>
>  #if GEN_GEN >= 8
> -   blorp_emit(batch, GENX(3DSTATE_VF_SGVS), sgvs);
> +   /* Overwrite Render Target Array Index (2nd dword) in the VUE header
with
> +    * primitive instance identifier. This is used for layered clears.
> +    */
> +   blorp_emit(batch, GENX(3DSTATE_VF_SGVS), sgvs) {
> +      sgvs.InstanceIDEnable = true;
> +      sgvs.InstanceIDComponentNumber = COMP_1;
> +      sgvs.InstanceIDElementOffset = 0;
> +   }

I love the fact that we can use SVGS this way.  I cc'd Kristian so he can
enjoy it too!

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

>     for (unsigned i = 0; i < num_elements; i++) {
>        blorp_emit(batch, GENX(3DSTATE_VF_INSTANCING), vf) {
> --
> 2.5.5
>
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