[Mesa-dev] [PATCH 21/37] i965/gen6/gs: Implement support for gl_PrimitiveIdIn.
Jordan Justen
jljusten at gmail.com
Thu Sep 18 00:30:28 PDT 2014
On Thu, Aug 14, 2014 at 4:11 AM, Iago Toral Quiroga <itoral at igalia.com> wrote:
> For this we will need to move PrimitiveID information, delivered in the thread
> payload in r0.1, to a separate register (we use GS_OPCODE_SET_PRIMITIVE_ID
> for this), then map the corresponding varying slot to that register in the
> setup_payload() method.
>
> Notice that we cannot use a virtual register as the destination for the
> PrimitiveID because we need to map all input attributes to hardware registers
> in setup_payload(), which happens before virtual registers are mapped to
> hardware registers. We could work around that issue if we were able to compute
> the first non-payload register in emit_prolog() and move the PrimitiveID
> information to that register, but we can't because at that point we still
> don't know the final number uniforms that will be included in the payload.
>
> So, what we do is to place PrimitiveID information in r1, which is always
> delivered as part of the payload but its only populated with data
> relevant for transform feedback when we set GEN6_GS_SVBI_PAYLOAD_ENABLE
> in the 3DSTATE_GS state packet.
>
> When we implement transform feedback, we wil make sure to move the value of r1
> to another register before we overwrite it with the PrimitiveID.
> ---
> src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp | 69 ++++++++++++++++++++++++++-
> src/mesa/drivers/dri/i965/gen6_gs_visitor.h | 2 +
> 2 files changed, 70 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp b/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp
> index 4a440eb..b45c381 100644
> --- a/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/gen6_gs_visitor.cpp
> @@ -31,6 +31,8 @@
>
> #include "gen6_gs_visitor.h"
>
> +const unsigned MAX_GS_INPUT_VERTICES = 6;
> +
> namespace brw {
>
> void
> @@ -38,6 +40,7 @@ gen6_gs_visitor::emit_prolog()
> {
> vec4_gs_visitor::emit_prolog();
>
> + this->current_annotation = "gen6 prolog";
> /* Gen6 geometry shaders require to allocate an initial VUE handle via
> * FF_SYNC message, however the documentation remarks that only one thread
> * can write to the URB simultaneously and the FF_SYNC message provides the
> @@ -59,7 +62,6 @@ gen6_gs_visitor::emit_prolog()
> * flags for the next vertex come right after the data items and flags for
> * the previous vertex.
> */
> - this->current_annotation = "gen6 prolog";
Seems like this belongs in
"i965/gen6/gs: Add initial implementation for a gen6 geometry shader visitor."
(Or, perhaps just drop the change...)
Patches 21-26 (gs-support-snb-for-submission-02092014)
i965/gen6/gs: Implement support for gl_PrimitiveIdIn.
i965/gen6/gs: Assign geometry shader VUE map properly.
i965/gen6/gs: Enable texture units and upload sampler state.
i965/gen6/gs: implement GS_OPCODE_SVB_WRITE opcode
i965/gen6/gs: implement GS_OPCODE_SVB_SET_DST_INDEX opcode
i965/gen6/gs: implement GS_OPCODE_FF_SYNC_SET_PRIMITIVES opcode
Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>
> this->vertex_output = src_reg(this,
> glsl_type::uint_type,
> (prog_data->vue_map.num_slots + 1) *
> @@ -94,6 +96,30 @@ gen6_gs_visitor::emit_prolog()
> */
> this->prim_count = src_reg(this, glsl_type::uint_type);
> emit(MOV(dst_reg(this->prim_count), 0u));
> +
> + /* PrimitveID is delivered in r0.1 of the thread payload. If the program
> + * needs it we have to move it to a separate register where we can map
> + * the atttribute.
> + *
> + * Notice that we cannot use a virtual register for this, because we need to
> + * map all input attributes to hardware registers in setup_payload(),
> + * which happens before virtual registers are mapped to hardware registers.
> + * We could work around that issue if we were able to compute the first
> + * non-payload register here and move the PrimitiveID information to that
> + * register, but we can't because at this point we don't know the final
> + * number uniforms that will be included in the payload.
> + *
> + * So, what we do is to place PrimitiveID information in r1, which is always
> + * delivered as part of the payload, but its only populated with data
> + * relevant for transform feedback when we set GEN6_GS_SVBI_PAYLOAD_ENABLE
> + * in the 3DSTATE_GS state packet. That information can be obtained by other
> + * means though, so we can safely use r1 for this purpose.
> + */
> + if (c->prog_data.include_primitive_id) {
> + this->primitive_id =
> + src_reg(retype(brw_vec8_grf(1, 0), BRW_REGISTER_TYPE_UD));
> + emit(GS_OPCODE_SET_PRIMITIVE_ID, dst_reg(this->primitive_id));
> + }
> }
>
> void
> @@ -410,4 +436,45 @@ gen6_gs_visitor::emit_thread_end()
> inst->mlen = 1;
> }
>
> +void
> +gen6_gs_visitor::setup_payload()
> +{
> + int attribute_map[BRW_VARYING_SLOT_COUNT * MAX_GS_INPUT_VERTICES];
> +
> + /* Attributes are going to be interleaved, so one register contains two
> + * attribute slots.
> + */
> + int attributes_per_reg = 2;
> +
> + /* If a geometry shader tries to read from an input that wasn't written by
> + * the vertex shader, that produces undefined results, but it shouldn't
> + * crash anything. So initialize attribute_map to zeros--that ensures that
> + * these undefined results are read from r0.
> + */
> + memset(attribute_map, 0, sizeof(attribute_map));
> +
> + int reg = 0;
> +
> + /* The payload always contains important data in r0. */
> + reg++;
> +
> + /* r1 is always part of the payload and it holds information relevant
> + * for transform feedback when we set the GEN6_GS_SVBI_PAYLOAD_ENABLE bit in
> + * the 3DSTATE_GS packet. We will overwrite it with the PrimitiveID
> + * information (and move the original value to a virtual register if
> + * necessary).
> + */
> + if (c->prog_data.include_primitive_id)
> + attribute_map[VARYING_SLOT_PRIMITIVE_ID] = attributes_per_reg * reg;
> + reg++;
> +
> + reg = setup_uniforms(reg);
> +
> + reg = setup_varying_inputs(reg, attribute_map, attributes_per_reg);
> +
> + lower_attributes_to_hw_regs(attribute_map, true);
> +
> + this->first_non_payload_grf = reg;
> +}
> +
> } /* namespace brw */
> diff --git a/src/mesa/drivers/dri/i965/gen6_gs_visitor.h b/src/mesa/drivers/dri/i965/gen6_gs_visitor.h
> index 7af6405..8d2386c 100644
> --- a/src/mesa/drivers/dri/i965/gen6_gs_visitor.h
> +++ b/src/mesa/drivers/dri/i965/gen6_gs_visitor.h
> @@ -52,6 +52,7 @@ protected:
> int base_mrf,
> int last_mrf,
> int urb_offset);
> + virtual void setup_payload();
>
> private:
> src_reg vertex_output;
> @@ -59,6 +60,7 @@ private:
> src_reg temp;
> src_reg first_vertex;
> src_reg prim_count;
> + src_reg primitive_id;
> };
>
> } /* namespace brw */
> --
> 1.9.1
>
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