[Mesa-dev] [PATCH 21/37] i965/gen6/gs: Implement support for gl_PrimitiveIdIn.
Iago Toral Quiroga
itoral at igalia.com
Thu Sep 18 01:33:03 PDT 2014
On jue, 2014-09-18 at 00:30 -0700, Jordan Justen wrote:
> 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...)
You are right, I'll fix it.
Iago
> 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
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
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