/*
* Copyright © 2014 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* This code is based on original work by Ilia Mirkin.
*/
/**
* \file gen6_gs_visitor.cpp
*
* Gen6 geometry shader implementation
*/
#include "gen6_gs_visitor.h"
#include "brw_eu.h"
namespace brw {
void
gen6_gs_visitor::emit_prolog()
{
vec4_gs_visitor::emit_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
* synchronization mechanism for this, so using this message effectively
* stalls the thread until it is its turn to write to the URB. Because of
* this, the best way to implement geometry shader algorithms in gen6 is to
* execute the algorithm before the FF_SYNC message to maximize parallelism.
*
* To achieve this we buffer the geometry shader outputs for each emitted
* vertex in vertex_output during operation. Then, when we have processed
* the last vertex (that is, at thread end time), we send the FF_SYNC
* message to allocate the initial VUE handle and write all buffered vertex
* data to the URB in one go.
*
* For each emitted vertex, vertex_output will hold vue_map.num_slots
* data items plus one additional item to hold required flags
* (PrimType, PrimStart, PrimEnd, as expected by the URB_WRITE message)
* which come right after the data items for that vertex. Vertex data and
* flags for the next vertex come right after the data items and flags for
* the previous vertex.
*/
this->current_annotation = "gen6 prolog";
this->vertex_output = src_reg(this,
glsl_type::uint_type,
(prog_data->vue_map.num_slots + 1) *
nir->info.gs.vertices_out);
this->vertex_output_offset = src_reg(this, glsl_type::uint_type);
emit(MOV(dst_reg(this->vertex_output_offset), brw_imm_ud(0u)));
/* MRF 1 will be the header for all messages (FF_SYNC and URB_WRITES),
* so initialize it once to R0.
*/
vec4_instruction *inst = emit(MOV(dst_reg(MRF, 1),
retype(brw_vec8_grf(0, 0),
BRW_REGISTER_TYPE_UD)));
inst->force_writemask_all = true;
/* This will be used as a temporary to store writeback data of FF_SYNC
* and URB_WRITE messages.
*/
this->temp = src_reg(this, glsl_type::uint_type);
/* This will be used to know when we are processing the first vertex of
* a primitive. We will set this to URB_WRITE_PRIM_START only when we know
* that we are processing the first vertex in the primitive and to zero
* otherwise. This way we can use its value directly in the URB write
* headers.
*/
this->first_vertex = src_reg(this, glsl_type::uint_type);
emit(MOV(dst_reg(this->first_vertex), brw_imm_ud(URB_WRITE_PRIM_START)));
/* The FF_SYNC message requires to know the number of primitives generated,
* so keep a counter for this.
*/
this->prim_count = src_reg(this, glsl_type::uint_type);
emit(MOV(dst_reg(this->prim_count), brw_imm_ud(0u)));
if (prog->info.has_transform_feedback_varyings) {
/* Create a virtual register to hold destination indices in SOL */
this->destination_indices = src_reg(this, glsl_type::uvec4_type);
/* Create a virtual register to hold number of written primitives */
this->sol_prim_written = src_reg(this, glsl_type::uint_type);
/* Create a virtual register to hold Streamed Vertex Buffer Indices */
this->svbi = src_reg(this, glsl_type::uvec4_type);
/* Create a virtual register to hold max values of SVBI */
this->max_svbi = src_reg(this, glsl_type::uvec4_type);
emit(MOV(dst_reg(this->max_svbi),
src_reg(retype(brw_vec1_grf(1, 4), BRW_REGISTER_TYPE_UD))));
xfb_setup();
}
/* 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 (gs_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
gen6_gs_visitor::gs_emit_vertex(int stream_id)
{
this->current_annotation = "gen6 emit vertex";
/* Buffer all output slots for this vertex in vertex_output */
for (int slot = 0; slot < prog_data->vue_map.num_slots; ++slot) {
int varying = prog_data->vue_map.slot_to_varying[slot];
if (varying != VARYING_SLOT_PSIZ) {
dst_reg dst(this->vertex_output);
dst.reladdr = ralloc(mem_ctx, src_reg);
memcpy(dst.reladdr, &this->vertex_output_offset, sizeof(src_reg));
emit_urb_slot(dst, varying);
} else {
/* The PSIZ slot can pack multiple varyings in different channels
* and emit_urb_slot() will produce a MOV instruction for each of
* them. Since we are writing to an array, that will translate to
* possibly multiple MOV instructions with an array destination and
* each will generate a scratch write with the same offset into
* scratch space (thus, each one overwriting the previous). This is
* not what we want. What we will do instead is emit PSIZ to a
* a regular temporary register, then move that resgister into the
* array. This way we only have one instruction with an array
* destination and we only produce a single scratch write.
*/
dst_reg tmp = dst_reg(src_reg(this, glsl_type::uvec4_type));
emit_urb_slot(tmp, varying);
dst_reg dst(this->vertex_output);
dst.reladdr = ralloc(mem_ctx, src_reg);
memcpy(dst.reladdr, &this->vertex_output_offset, sizeof(src_reg));
vec4_instruction *inst = emit(MOV(dst, src_reg(tmp)));
inst->force_writemask_all = true;
}
emit(ADD(dst_reg(this->vertex_output_offset),
this->vertex_output_offset, brw_imm_ud(1u)));
}
/* Now buffer flags for this vertex */
dst_reg dst(this->vertex_output);
dst.reladdr = ralloc(mem_ctx, src_reg);
memcpy(dst.reladdr, &this->vertex_output_offset, sizeof(src_reg));
if (nir->info.gs.output_primitive == GL_POINTS) {
/* If we are outputting points, then every vertex has PrimStart and
* PrimEnd set.
*/
emit(MOV(dst, brw_imm_d((_3DPRIM_POINTLIST << URB_WRITE_PRIM_TYPE_SHIFT) |
URB_WRITE_PRIM_START | URB_WRITE_PRIM_END)));
emit(ADD(dst_reg(this->prim_count), this->prim_count, brw_imm_ud(1u)));
} else {
/* Otherwise, we can only set the PrimStart flag, which we have stored
* in the first_vertex register. We will have to wait until we execute
* EndPrimitive() or we end the thread to set the PrimEnd flag on a
* vertex.
*/
emit(OR(dst, this->first_vertex,
brw_imm_ud(gs_prog_data->output_topology <<
URB_WRITE_PRIM_TYPE_SHIFT)));
emit(MOV(dst_reg(this->first_vertex), brw_imm_ud(0u)));
}
emit(ADD(dst_reg(this->vertex_output_offset),
this->vertex_output_offset, brw_imm_ud(1u)));
}
void
gen6_gs_visitor::gs_end_primitive()
{
this->current_annotation = "gen6 end primitive";
/* Calling EndPrimitive() is optional for point output. In this case we set
* the PrimEnd flag when we process EmitVertex().
*/
if (nir->info.gs.output_primitive == GL_POINTS)
return;
/* Otherwise we know that the last vertex we have processed was the last
* vertex in the primitive and we need to set its PrimEnd flag, so do this
* unless we haven't emitted that vertex at all (vertex_count != 0).
*
* Notice that we have already incremented vertex_count when we processed
* the last emit_vertex, so we need to take that into account in the
* comparison below (hence the num_output_vertices + 1 in the comparison
* below).
*/
unsigned num_output_vertices = nir->info.gs.vertices_out;
emit(CMP(dst_null_ud(), this->vertex_count,
brw_imm_ud(num_output_vertices + 1), BRW_CONDITIONAL_L));
vec4_instruction *inst = emit(CMP(dst_null_ud(),
this->vertex_count, brw_imm_ud(0u),
BRW_CONDITIONAL_NEQ));
inst->predicate = BRW_PREDICATE_NORMAL;
emit(IF(BRW_PREDICATE_NORMAL));
{
/* vertex_output_offset is already pointing at the first entry of the
* next vertex. So subtract 1 to modify the flags for the previous
* vertex.
*/
src_reg offset(this, glsl_type::uint_type);
emit(ADD(dst_reg(offset), this->vertex_output_offset, brw_imm_d(-1)));
src_reg dst(this->vertex_output);
dst.reladdr = ralloc(mem_ctx, src_reg);
memcpy(dst.reladdr, &offset, sizeof(src_reg));
emit(OR(dst_reg(dst), dst, brw_imm_d(URB_WRITE_PRIM_END)));
emit(ADD(dst_reg(this->prim_count), this->prim_count, brw_imm_ud(1u)));
/* Set the first vertex flag to indicate that the next vertex will start
* a primitive.
*/
emit(MOV(dst_reg(this->first_vertex), brw_imm_d(URB_WRITE_PRIM_START)));
}
emit(BRW_OPCODE_ENDIF);
}
void
gen6_gs_visitor::emit_urb_write_header(int mrf)
{
this->current_annotation = "gen6 urb header";
/* Compute offset of the flags for the current vertex in vertex_output and
* write them in dw2 of the message header.
*
* Notice that by the time that emit_thread_end() calls here
* vertex_output_offset should point to the first data item of the current
* vertex in vertex_output, thus we only need to add the number of output
* slots per vertex to that offset to obtain the flags data offset.
*/
src_reg flags_offset(this, glsl_type::uint_type);
emit(ADD(dst_reg(flags_offset),
this->vertex_output_offset,
brw_imm_d(prog_data->vue_map.num_slots)));
src_reg flags_data(this->vertex_output);
flags_data.reladdr = ralloc(mem_ctx, src_reg);
memcpy(flags_data.reladdr, &flags_offset, sizeof(src_reg));
emit(GS_OPCODE_SET_DWORD_2, dst_reg(MRF, mrf), flags_data);
}
static int
align_interleaved_urb_mlen(int mlen)
{
/* URB data written (does not include the message header reg) must
* be a multiple of 256 bits, or 2 VS registers. See vol5c.5,
* section 5.4.3.2.2: URB_INTERLEAVED.
*/
if ((mlen % 2) != 1)
mlen++;
return mlen;
}
void
gen6_gs_visitor::emit_urb_write_opcode(bool complete, int base_mrf,
int last_mrf, int urb_offset)
{
vec4_instruction *inst = NULL;
if (!complete) {
/* If the vertex is not complete we don't have to do anything special */
inst = emit(GS_OPCODE_URB_WRITE);
inst->urb_write_flags = BRW_URB_WRITE_NO_FLAGS;
} else {
/* Otherwise we always request to allocate a new VUE handle. If this is
* the last write before the EOT message and the new handle never gets
* used it will be dereferenced when we send the EOT message. This is
* necessary to avoid different setups for the EOT message (one for the
* case when there is no output and another for the case when there is)
* which would require to end the program with an IF/ELSE/ENDIF block,
* something we do not want.
*/
inst = emit(GS_OPCODE_URB_WRITE_ALLOCATE);
inst->urb_write_flags = BRW_URB_WRITE_COMPLETE;
inst->dst = dst_reg(MRF, base_mrf);
inst->src[0] = this->temp;
}
inst->base_mrf = base_mrf;
inst->mlen = align_interleaved_urb_mlen(last_mrf - base_mrf);
inst->offset = urb_offset;
}
void
gen6_gs_visitor::emit_thread_end()
{
/* Make sure the current primitive is ended: we know it is not ended when
* first_vertex is not zero. This is only relevant for outputs other than
* points because in the point case we set PrimEnd on all vertices.
*/
if (nir->info.gs.output_primitive != GL_POINTS) {
emit(CMP(dst_null_ud(), this->first_vertex, brw_imm_ud(0u), BRW_CONDITIONAL_Z));
emit(IF(BRW_PREDICATE_NORMAL));
gs_end_primitive();
emit(BRW_OPCODE_ENDIF);
}
/* Here we have to:
* 1) Emit an FF_SYNC messsage to obtain an initial VUE handle.
* 2) Loop over all buffered vertex data and write it to corresponding
* URB entries.
* 3) Allocate new VUE handles for all vertices other than the first.
* 4) Send a final EOT message.
*/
/* MRF 0 is reserved for the debugger, so start with message header
* in MRF 1.
*/
int base_mrf = 1;
/* In the process of generating our URB write message contents, we
* may need to unspill a register or load from an array. Those
* reads would use MRFs 21..23
*/
int max_usable_mrf = FIRST_SPILL_MRF(devinfo->gen);
/* Issue the FF_SYNC message and obtain the initial VUE handle. */
emit(CMP(dst_null_ud(), this->vertex_count, brw_imm_ud(0u), BRW_CONDITIONAL_G));
emit(IF(BRW_PREDICATE_NORMAL));
{
this->current_annotation = "gen6 thread end: ff_sync";
vec4_instruction *inst;
if (prog->info.has_transform_feedback_varyings) {
src_reg sol_temp(this, glsl_type::uvec4_type);
emit(GS_OPCODE_FF_SYNC_SET_PRIMITIVES,
dst_reg(this->svbi),
this->vertex_count,
this->prim_count,
sol_temp);
inst = emit(GS_OPCODE_FF_SYNC,
dst_reg(this->temp), this->prim_count, this->svbi);
} else {
inst = emit(GS_OPCODE_FF_SYNC,
dst_reg(this->temp), this->prim_count, brw_imm_ud(0u));
}
inst->base_mrf = base_mrf;
/* Loop over all buffered vertices and emit URB write messages */
this->current_annotation = "gen6 thread end: urb writes init";
src_reg vertex(this, glsl_type::uint_type);
emit(MOV(dst_reg(vertex), brw_imm_ud(0u)));
emit(MOV(dst_reg(this->vertex_output_offset), brw_imm_ud(0u)));
this->current_annotation = "gen6 thread end: urb writes";
emit(BRW_OPCODE_DO);
{
emit(CMP(dst_null_d(), vertex, this->vertex_count, BRW_CONDITIONAL_GE));
inst = emit(BRW_OPCODE_BREAK);
inst->predicate = BRW_PREDICATE_NORMAL;
/* First we prepare the message header */
emit_urb_write_header(base_mrf);
/* Then add vertex data to the message in interleaved fashion */
int slot = 0;
bool complete = false;
do {
int mrf = base_mrf + 1;
/* URB offset is in URB row increments, and each of our MRFs is half
* of one of those, since we're doing interleaved writes.
*/
int urb_offset = slot / 2;
for (; slot < prog_data->vue_map.num_slots; ++slot) {
int varying = prog_data->vue_map.slot_to_varying[slot];
current_annotation = output_reg_annotation[varying];
/* Compute offset of this slot for the current vertex
* in vertex_output
*/
src_reg data(this->vertex_output);
data.reladdr = ralloc(mem_ctx, src_reg);
memcpy(data.reladdr, &this->vertex_output_offset,
sizeof(src_reg));
/* Copy this slot to the appropriate message register */
dst_reg reg = dst_reg(MRF, mrf);
reg.type = output_reg[varying][0].type;
data.type = reg.type;
vec4_instruction *inst = emit(MOV(reg, data));
inst->force_writemask_all = true;
mrf++;
emit(ADD(dst_reg(this->vertex_output_offset),
this->vertex_output_offset, brw_imm_ud(1u)));
/* If this was max_usable_mrf, we can't fit anything more into
* this URB WRITE. Same if we reached the max. message length.
*/
if (mrf > max_usable_mrf ||
align_interleaved_urb_mlen(mrf - base_mrf + 1) > BRW_MAX_MSG_LENGTH) {
slot++;
break;
}
}
complete = slot >= prog_data->vue_map.num_slots;
emit_urb_write_opcode(complete, base_mrf, mrf, urb_offset);
} while (!complete);
/* Skip over the flags data item so that vertex_output_offset points
* to the first data item of the next vertex, so that we can start
* writing the next vertex.
*/
emit(ADD(dst_reg(this->vertex_output_offset),
this->vertex_output_offset, brw_imm_ud(1u)));
emit(ADD(dst_reg(vertex), vertex, brw_imm_ud(1u)));
}
emit(BRW_OPCODE_WHILE);
if (prog->info.has_transform_feedback_varyings)
xfb_write();
}
emit(BRW_OPCODE_ENDIF);
/* Finally, emit EOT message.
*
* 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 we can't use the COMPLETE flag.
*
* However, this would lead us to end the program with an ENDIF opcode,
* which we want to avoid, so what we do is that we always request a new
* VUE handle every time we do a 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.
*/
this->current_annotation = "gen6 thread end: EOT";
if (prog->info.has_transform_feedback_varyings) {
/* When emitting EOT, set SONumPrimsWritten Increment Value. */
src_reg data(this, glsl_type::uint_type);
emit(AND(dst_reg(data), this->sol_prim_written, brw_imm_ud(0xffffu)));
emit(SHL(dst_reg(data), data, brw_imm_ud(16u)));
emit(GS_OPCODE_SET_DWORD_2, dst_reg(MRF, base_mrf), data);
}
vec4_instruction *inst = emit(GS_OPCODE_THREAD_END);
inst->urb_write_flags = BRW_URB_WRITE_COMPLETE | BRW_URB_WRITE_UNUSED;
inst->base_mrf = base_mrf;
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 (gs_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, attributes_per_reg);
this->first_non_payload_grf = reg;
}
void
gen6_gs_visitor::xfb_setup()
{
static const unsigned swizzle_for_offset[4] = {
BRW_SWIZZLE4(0, 1, 2, 3),
BRW_SWIZZLE4(1, 2, 3, 3),
BRW_SWIZZLE4(2, 3, 3, 3),
BRW_SWIZZLE4(3, 3, 3, 3)
};
const struct gl_transform_feedback_info *linked_xfb_info =
this->prog->sh.LinkedTransformFeedback;
int i;
/* Make sure that the VUE slots won't overflow the unsigned chars in
* prog_data->transform_feedback_bindings[].
*/
STATIC_ASSERT(BRW_VARYING_SLOT_COUNT <= 256);
/* Make sure that we don't need more binding table entries than we've
* set aside for use in transform feedback. (We shouldn't, since we
* set aside enough binding table entries to have one per component).
*/
assert(linked_xfb_info->NumOutputs <= BRW_MAX_SOL_BINDINGS);
gs_prog_data->num_transform_feedback_bindings = linked_xfb_info->NumOutputs;
for (i = 0; i < gs_prog_data->num_transform_feedback_bindings; i++) {
gs_prog_data->transform_feedback_bindings[i] =
linked_xfb_info->Outputs[i].OutputRegister;
gs_prog_data->transform_feedback_swizzles[i] =
swizzle_for_offset[linked_xfb_info->Outputs[i].ComponentOffset];
}
}
void
gen6_gs_visitor::xfb_write()
{
unsigned num_verts;
if (!gs_prog_data->num_transform_feedback_bindings)
return;
switch (gs_prog_data->output_topology) {
case _3DPRIM_POINTLIST:
num_verts = 1;
break;
case _3DPRIM_LINELIST:
case _3DPRIM_LINESTRIP:
case _3DPRIM_LINELOOP:
num_verts = 2;
break;
case _3DPRIM_TRILIST:
case _3DPRIM_TRIFAN:
case _3DPRIM_TRISTRIP:
case _3DPRIM_RECTLIST:
num_verts = 3;
break;
case _3DPRIM_QUADLIST:
case _3DPRIM_QUADSTRIP:
case _3DPRIM_POLYGON:
num_verts = 3;
break;
default:
unreachable("Unexpected primitive type in Gen6 SOL program.");
}
this->current_annotation = "gen6 thread end: svb writes init";
emit(MOV(dst_reg(this->vertex_output_offset), brw_imm_ud(0u)));
emit(MOV(dst_reg(this->sol_prim_written), brw_imm_ud(0u)));
/* Check that at least one primitive can be written
*
* Note: since we use the binding table to keep track of buffer offsets
* and stride, the GS doesn't need to keep track of a separate pointer
* into each buffer; it uses a single pointer which increments by 1 for
* each vertex. So we use SVBI0 for this pointer, regardless of whether
* transform feedback is in interleaved or separate attribs mode.
*/
src_reg sol_temp(this, glsl_type::uvec4_type);
emit(ADD(dst_reg(sol_temp), this->svbi, brw_imm_ud(num_verts)));
/* Compare SVBI calculated number with the maximum value, which is
* in R1.4 (previously saved in this->max_svbi) for gen6.
*/
emit(CMP(dst_null_d(), sol_temp, this->max_svbi, BRW_CONDITIONAL_LE));
emit(IF(BRW_PREDICATE_NORMAL));
{
vec4_instruction *inst = emit(MOV(dst_reg(destination_indices),
brw_imm_vf4(brw_float_to_vf(0.0),
brw_float_to_vf(1.0),
brw_float_to_vf(2.0),
brw_float_to_vf(0.0))));
inst->force_writemask_all = true;
emit(ADD(dst_reg(this->destination_indices),
this->destination_indices,
this->svbi));
}
emit(BRW_OPCODE_ENDIF);
/* Write transform feedback data for all processed vertices. */
for (int i = 0; i < (int)nir->info.gs.vertices_out; i++) {
emit(MOV(dst_reg(sol_temp), brw_imm_d(i)));
emit(CMP(dst_null_d(), sol_temp, this->vertex_count,
BRW_CONDITIONAL_L));
emit(IF(BRW_PREDICATE_NORMAL));
{
xfb_program(i, num_verts);
}
emit(BRW_OPCODE_ENDIF);
}
}
void
gen6_gs_visitor::xfb_program(unsigned vertex, unsigned num_verts)
{
unsigned binding;
unsigned num_bindings = gs_prog_data->num_transform_feedback_bindings;
src_reg sol_temp(this, glsl_type::uvec4_type);
/* Check for buffer overflow: we need room to write the complete primitive
* (all vertices). Otherwise, avoid writing any vertices for it
*/
emit(ADD(dst_reg(sol_temp), this->sol_prim_written, brw_imm_ud(1u)));
emit(MUL(dst_reg(sol_temp), sol_temp, brw_imm_ud(num_verts)));
emit(ADD(dst_reg(sol_temp), sol_temp, this->svbi));
emit(CMP(dst_null_d(), sol_temp, this->max_svbi, BRW_CONDITIONAL_LE));
emit(IF(BRW_PREDICATE_NORMAL));
{
/* Avoid overwriting MRF 1 as it is used as URB write message header */
dst_reg mrf_reg(MRF, 2);
this->current_annotation = "gen6: emit SOL vertex data";
/* For each vertex, generate code to output each varying using the
* appropriate binding table entry.
*/
for (binding = 0; binding < num_bindings; ++binding) {
unsigned char varying =
gs_prog_data->transform_feedback_bindings[binding];
/* Set up the correct destination index for this vertex */
vec4_instruction *inst = emit(GS_OPCODE_SVB_SET_DST_INDEX,
mrf_reg,
this->destination_indices);
inst->sol_vertex = vertex % num_verts;
/* From the Sandybridge PRM, Volume 2, Part 1, Section 4.5.1:
*
* "Prior to End of Thread with a URB_WRITE, the kernel must
* ensure that all writes are complete by sending the final
* write as a committed write."
*/
bool final_write = binding == (unsigned) num_bindings - 1 &&
inst->sol_vertex == num_verts - 1;
/* Compute offset of this varying for the current vertex
* in vertex_output
*/
this->current_annotation = output_reg_annotation[varying];
src_reg data(this->vertex_output);
data.reladdr = ralloc(mem_ctx, src_reg);
int offset = get_vertex_output_offset_for_varying(vertex, varying);
emit(MOV(dst_reg(this->vertex_output_offset), brw_imm_d(offset)));
memcpy(data.reladdr, &this->vertex_output_offset, sizeof(src_reg));
data.type = output_reg[varying][0].type;
data.swizzle = gs_prog_data->transform_feedback_swizzles[binding];
/* Write data */
inst = emit(GS_OPCODE_SVB_WRITE, mrf_reg, data, sol_temp);
inst->sol_binding = binding;
inst->sol_final_write = final_write;
if (final_write) {
/* This is the last vertex of the primitive, then increment
* SO num primitive counter and destination indices.
*/
emit(ADD(dst_reg(this->destination_indices),
this->destination_indices,
brw_imm_ud(num_verts)));
emit(ADD(dst_reg(this->sol_prim_written),
this->sol_prim_written, brw_imm_ud(1u)));
}
}
this->current_annotation = NULL;
}
emit(BRW_OPCODE_ENDIF);
}
int
gen6_gs_visitor::get_vertex_output_offset_for_varying(int vertex, int varying)
{
/* Find the output slot assigned to this varying.
*
* VARYING_SLOT_LAYER and VARYING_SLOT_VIEWPORT are packed in the same slot
* as VARYING_SLOT_PSIZ.
*/
if (varying == VARYING_SLOT_LAYER || varying == VARYING_SLOT_VIEWPORT)
varying = VARYING_SLOT_PSIZ;
int slot = prog_data->vue_map.varying_to_slot[varying];
if (slot < 0) {
/* This varying does not exist in the VUE so we are not writing to it
* and its value is undefined. We still want to return a valid offset
* into vertex_output though, to prevent any out-of-bound accesses into
* the vertex_output array. Since the value for this varying is undefined
* we don't really care for the value we assign to it, so any offset
* within the limits of vertex_output will do.
*/
slot = 0;
}
return vertex * (prog_data->vue_map.num_slots + 1) + slot;
}
} /* namespace brw */