i965/gs: Use single dispatch mode as fallback to dual object mode when possible.

Currently, when a geometry shader can't use dual object mode we fall back to
dual instance mode, however, when invocations == 1, single dispatch mode is
more performant and equally efficient in terms of register pressure.

Single dispatch mode requires that the driver can handle interleaving of
input registers, but this is already supported (dual instance mode has
the same requirement). However, to take full advantage of single dispatch mode
to reduce register pressure we would also need the ability to store two
separate vec4 output values into vec8 registers, which would approximately
double our capacity to store temporary values, but currently the vec4 visitor
and generator classes do not support this, so at the moment register pressure
in single and dual instance modes is the same.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6/gs: Skeleton for user GS program support

Currently, gen6 only uses geometry shaders for transform feedback so the state
we emit is not suitable to accomodate general purpose, user-provided geometry
shaders. This patch paves the way to add these support and the needed
3DSTATE_GS packet modifications for it.

Previous code that emitted state to implement transform feedback in gen6 goes
to upload_gs_state_adhoc_tf().

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6/gs: use brw_gs_prog atom instead of brw_ff_gs_prog

This is needed to support user-provided geometry shaders, since the
brw_ff_gs_prog atom in gen6 only takes care of implementing transform feedback
for vertex shaders.

If there is no user-provided geometry shader the implementation falls back to
the original code.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6/gs: Set brw->gs.enabled to FALSE in gen6_blorp_emit_gs_disable()

See 7dfb4b2d00ddb8e5ee24d4c58eb9415dc4ccc21c for more details.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6/gs: Setup constant push buffers for gen6 geometry shaders.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gs: Reuse gen6 constant push buffers setup code in gen7+.

The code required for gen6 and gen7+ is almost the same, so reuse it.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
i965/gen6/gs: Implement GS_OPCODE_FF_SYNC.

This implements the FF_SYNC message required in gen6  geometry shaders to
get the initial URB handle.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Implement GS_OPCODE_URB_WRITE_ALLOCATE.

Gen6 geometry shaders need to allocate URB handles for each new vertex they
emit after the first (the URB handle for the first vertex is obtained via the
FF_SYNC message).

This opcode adds the URB allocation mechanism to regular URB writes.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Add instruction URB flags to geometry shaders EOT message.

Gen6 seems to require that EOT messages include the complete flag too or else
the GPU hangs. We add will this flag to the instruction when we emit the
thread end opcode.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Compute URB entry size for user-provided geometry shaders.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Enable URB space for user-provided geometry shaders.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Upload binding table for user-provided geometry shaders.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Implement GS_OPCODE_SET_DWORD_2.

We had GS_OPCODE_SET_DWORD_2_IMMED but this required its source argument to be
an immediate. In gen6 we need to set dword 2 of the URB write message header
from values stored in separate register, so we need something more flexible.
This change replaces GS_OPCODE_SET_DWORD_2_IMMED with GS_OPCODE_SET_DWORD_2.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965: Provide means to create registers of a given size.

Implemented by Ilia Mirkin <imirkin@alum.mit.edu>.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965: Generalize emit_urb_slot() to emit to any dst_reg.

In gen7+ we emit vertices as they come, however in gen6 geometry shaders we
have to buffer vertex data for all vertices and then emit it all in one go
at the end. To achieve this we need to generalize emit_urb_slot() to store
vertex data in general purpose registers and not only MRF registers.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Add initial implementation for a gen6 geometry shader visitor.

Geometry shaders in gen6 are significantly different from gen7+ so it is better
to have them implemented in a different file rather than adding gen6 branching
paths all over brw_vec4_gs_visitor.cpp.

This commit adds an initial implementation that only handles point output, which
is the simplest case.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Implement geometry shaders for outputs other than points.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Make sure we complete the last primitive.

Just in case the GS algorithm does not call EndPrimitive() for the last
primitive produced. This is relevant only for non point outputs, since for
this we are already setting the PrimEnd flag on each vertex we emit.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Handle the case where a geometry shader emits no output.

In gen6 we need to end the thread differently depending on whether we have
emitted at least one vertex or not. In case we did, the EOT message must
always include the COMPLETE flag or else the GPU hangs. If we have not
produced any output, however, we can't use the COMPLETE flag.

This would lead us to end the program with an ENDIF opcode, which we want
to avoid (and actually is not permitted since it hits an assertion), so
instead what we do is that we always request a new VUE handle every time we do
an URB WRITE, even for the last vertex we emit. With this we make sure that
whether we have emitted at least one vertex or none at all we have to finish the
thread without writing to the URB, which works for both cases by setting the
COMPLETE and UNUSED flags in the EOT message.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
i965/gen6/gs: Implement GS_OPCODE_SET_PRIMITIVE_ID.

In gen6 the geometry shader payload includes the PrimitiveID information in
r0.1. When the shader code uses glPimitiveIdIn we will have to move this to
a separate hardware register where we can map this attribute. This opcode
takes the selected destination register and moves r0.1 there.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>