void
vec4_gs_visitor::visit(ir_emit_vertex *ir)
{
this->current_annotation = "emit vertex: safety check";
/* To ensure that we don't output more vertices than the shader specified
* using max_vertices, do the logic inside a conditional of the form "if
* (vertex_count < MAX)"
*/
unsigned num_output_vertices = c->gp->program.VerticesOut;
emit(CMP(dst_null_d(), this->vertex_count,
src_reg(num_output_vertices), BRW_CONDITIONAL_L));
emit(IF(BRW_PREDICATE_NORMAL));
{
/* If we're outputting 32 control data bits or less, then we can wait
* until the shader is over to output them all. Otherwise we need to
* output them as we go. Now is the time to do it, since we're about to
* output the vertex_count'th vertex, so it's guaranteed that the
* control data bits associated with the (vertex_count - 1)th vertex are
* correct.
*/
if (c->control_data_header_size_bits > 32) {
this->current_annotation = "emit vertex: emit control data bits";
/* Only emit control data bits if we've finished accumulating a batch
* of 32 bits. This is the case when:
*
* (vertex_count * bits_per_vertex) % 32 == 0
*
* (in other words, when the last 5 bits of vertex_count *
* bits_per_vertex are 0). Assuming bits_per_vertex == 2^n for some
* integer n (which is always the case, since bits_per_vertex is
* always 1 or 2), this is equivalent to requiring that the last 5-n
* bits of vertex_count are 0:
*
* vertex_count & (2^(5-n) - 1) == 0
*
* 2^(5-n) == 2^5 / 2^n == 32 / bits_per_vertex, so this is
* equivalent to:
*
* vertex_count & (32 / bits_per_vertex - 1) == 0
*/
vec4_instruction *inst =
emit(AND(dst_null_d(), this->vertex_count,
(uint32_t) (32 / c->control_data_bits_per_vertex - 1)));
inst->conditional_mod = BRW_CONDITIONAL_Z;
emit(IF(BRW_PREDICATE_NORMAL));
{
emit_control_data_bits();
/* Reset control_data_bits to 0 so we can start accumulating a new
* batch.
*
* Note: in the case where vertex_count == 0, this neutralizes the
* effect of any call to EndPrimitive() that the shader may have
* made before outputting its first vertex.
*/
inst = emit(MOV(dst_reg(this->control_data_bits), 0u));
inst->force_writemask_all = true;
}
emit(BRW_OPCODE_ENDIF);
}
this->current_annotation = "emit vertex: vertex data";
emit_vertex();
/* In stream mode we have to set control data bits for all vertices
* unless we have disabled control data bits completely (which we do
* do for GL_POINTS outputs that don't use streams).
*/
if (c->control_data_header_size_bits > 0 &&
c->prog_data.control_data_format ==
GEN7_GS_CONTROL_DATA_FORMAT_GSCTL_SID) {
this->current_annotation = "emit vertex: Stream control data bits";
set_stream_control_data_bits(ir->stream_id());
}
this->current_annotation = "emit vertex: increment vertex count";
emit(ADD(dst_reg(this->vertex_count), this->vertex_count,
src_reg(1u)));
}
emit(BRW_OPCODE_ENDIF);
this->current_annotation = NULL;
}
void
vec4_gs_visitor::gs_emit_vertex(int stream_id)
{
this->current_annotation = "emit vertex: safety check";
/* Haswell and later hardware ignores the "Render Stream Select" bits
* from the 3DSTATE_STREAMOUT packet when the SOL stage is disabled,
* and instead sends all primitives down the pipeline for rasterization.
* If the SOL stage is enabled, "Render Stream Select" is honored and
* primitives bound to non-zero streams are discarded after stream output.
*
* Since the only purpose of primives sent to non-zero streams is to
* be recorded by transform feedback, we can simply discard all geometry
* bound to these streams when transform feedback is disabled.
*/
if (stream_id > 0 && !nir->info->has_transform_feedback_varyings)
return;
/* If we're outputting 32 control data bits or less, then we can wait
* until the shader is over to output them all. Otherwise we need to
* output them as we go. Now is the time to do it, since we're about to
* output the vertex_count'th vertex, so it's guaranteed that the
* control data bits associated with the (vertex_count - 1)th vertex are
* correct.
*/
if (c->control_data_header_size_bits > 32) {
this->current_annotation = "emit vertex: emit control data bits";
/* Only emit control data bits if we've finished accumulating a batch
* of 32 bits. This is the case when:
*
* (vertex_count * bits_per_vertex) % 32 == 0
*
* (in other words, when the last 5 bits of vertex_count *
* bits_per_vertex are 0). Assuming bits_per_vertex == 2^n for some
* integer n (which is always the case, since bits_per_vertex is
* always 1 or 2), this is equivalent to requiring that the last 5-n
* bits of vertex_count are 0:
*
* vertex_count & (2^(5-n) - 1) == 0
*
* 2^(5-n) == 2^5 / 2^n == 32 / bits_per_vertex, so this is
* equivalent to:
*
* vertex_count & (32 / bits_per_vertex - 1) == 0
*/
vec4_instruction *inst =
emit(AND(dst_null_ud(), this->vertex_count,
brw_imm_ud(32 / c->control_data_bits_per_vertex - 1)));
inst->conditional_mod = BRW_CONDITIONAL_Z;
emit(IF(BRW_PREDICATE_NORMAL));
{
/* If vertex_count is 0, then no control data bits have been
* accumulated yet, so we skip emitting them.
*/
emit(CMP(dst_null_ud(), this->vertex_count, brw_imm_ud(0u),
BRW_CONDITIONAL_NEQ));
emit(IF(BRW_PREDICATE_NORMAL));
emit_control_data_bits();
emit(BRW_OPCODE_ENDIF);
/* Reset control_data_bits to 0 so we can start accumulating a new
* batch.
*
* Note: in the case where vertex_count == 0, this neutralizes the
* effect of any call to EndPrimitive() that the shader may have
* made before outputting its first vertex.
*/
inst = emit(MOV(dst_reg(this->control_data_bits), brw_imm_ud(0u)));
inst->force_writemask_all = true;
}
emit(BRW_OPCODE_ENDIF);
}
this->current_annotation = "emit vertex: vertex data";
emit_vertex();
/* In stream mode we have to set control data bits for all vertices
* unless we have disabled control data bits completely (which we do
* do for GL_POINTS outputs that don't use streams).
*/
if (c->control_data_header_size_bits > 0 &&
gs_prog_data->control_data_format ==
GEN7_GS_CONTROL_DATA_FORMAT_GSCTL_SID) {
this->current_annotation = "emit vertex: Stream control data bits";
set_stream_control_data_bits(stream_id);
}
this->current_annotation = NULL;
}
