--- /dev/null
+/*
+ * 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"
+
+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) *
+ c->gp->program.VerticesOut);
+ this->vertex_output_offset = src_reg(this, glsl_type::uint_type);
+ emit(MOV(dst_reg(this->vertex_output_offset), src_reg(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);
+}
+
+void
+gen6_gs_visitor::visit(ir_emit_vertex *)
+{
+ this->current_annotation = "gen6 emit vertex";
+ /* Honor max_vertex layout indication in geometry shader by ignoring any
+ * vertices coming after c->gp->program.VerticesOut.
+ */
+ 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));
+ {
+ /* Buffer all output slots for this vertex in vertex_output */
+ for (int slot = 0; slot < prog_data->vue_map.num_slots; ++slot) {
+ /* We will handle PSIZ for each vertex at thread end time since it
+ * is not computed by the GS algorithm and requires specific handling.
+ */
+ 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);
+ }
+ emit(ADD(dst_reg(this->vertex_output_offset),
+ this->vertex_output_offset, 1u));
+ }
+
+ /* Now buffer flags for this vertex (we only support point output
+ * for now).
+ */
+ dst_reg dst(this->vertex_output);
+ dst.reladdr = ralloc(mem_ctx, src_reg);
+ memcpy(dst.reladdr, &this->vertex_output_offset, sizeof(src_reg));
+ /* If we are outputting points, then every vertex has PrimStart and
+ * PrimEnd set.
+ */
+ if (c->gp->program.OutputType == GL_POINTS) {
+ emit(MOV(dst, (_3DPRIM_POINTLIST << URB_WRITE_PRIM_TYPE_SHIFT) |
+ URB_WRITE_PRIM_START | URB_WRITE_PRIM_END));
+ }
+ emit(ADD(dst_reg(this->vertex_output_offset),
+ this->vertex_output_offset, 1u));
+
+ /* Update vertex count */
+ emit(ADD(dst_reg(this->vertex_count), this->vertex_count, 1u));
+ }
+ emit(BRW_OPCODE_ENDIF);
+}
+
+void
+gen6_gs_visitor::visit(ir_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 (c->gp->program.OutputType == GL_POINTS)
+ return;
+}
+
+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, src_reg(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);
+}
+
+void
+gen6_gs_visitor::emit_urb_write_opcode(bool complete, src_reg vertex,
+ int base_mrf, int mlen, int urb_offset)
+{
+ vec4_instruction *inst = NULL;
+
+ /* If the vertex is not complete we don't have to do anything special */
+ if (!complete) {
+ inst = emit(GS_OPCODE_URB_WRITE);
+ inst->urb_write_flags = BRW_URB_WRITE_NO_FLAGS;
+ inst->base_mrf = base_mrf;
+ inst->mlen = mlen;
+ inst->offset = urb_offset;
+ return;
+ }
+
+ /* Otherwise, if this is not the last vertex we are going to write,
+ * we have to request a new VUE handle for the next vertex.
+ *
+ * Notice that the vertex parameter has been pre-incremented in
+ * emit_thread_end() to make this comparison easier.
+ */
+ emit(CMP(dst_null_d(), vertex, this->vertex_count, BRW_CONDITIONAL_L));
+ emit(IF(BRW_PREDICATE_NORMAL));
+ {
+ inst = emit(GS_OPCODE_URB_WRITE_ALLOCATE);
+ inst->urb_write_flags = BRW_URB_WRITE_COMPLETE;
+ inst->base_mrf = base_mrf;
+ inst->mlen = mlen;
+ inst->offset = urb_offset;
+ inst->dst = dst_reg(MRF, base_mrf);
+ inst->src[0] = this->temp;
+ }
+ emit(BRW_OPCODE_ELSE);
+ {
+ inst = emit(GS_OPCODE_URB_WRITE);
+ inst->urb_write_flags = BRW_URB_WRITE_COMPLETE;
+ inst->base_mrf = base_mrf;
+ inst->mlen = mlen;
+ inst->offset = urb_offset;
+ }
+ emit(BRW_OPCODE_ENDIF);
+}
+
+void
+gen6_gs_visitor::emit_thread_end()
+{
+ /* 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 14-15.
+ */
+ int max_usable_mrf = 13;
+
+ /* Issue the FF_SYNC message and obtain the initial VUE handle. */
+ this->current_annotation = "gen6 thread end: ff_sync";
+ vec4_instruction *inst =
+ emit(GS_OPCODE_FF_SYNC, dst_reg(this->temp), this->vertex_count);
+ 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), 0u));
+ emit(MOV(dst_reg(this->vertex_output_offset), 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));
+
+ if (varying == VARYING_SLOT_PSIZ) {
+ /* We did not buffer PSIZ, emit it directly here */
+ emit_urb_slot(dst_reg(MRF, mrf), varying);
+ } else {
+ /* Copy this slot to the appropriate message register */
+ dst_reg reg = dst_reg(MRF, mrf);
+ reg.type = output_reg[varying].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, 1u));
+
+ /* If this was max_usable_mrf, we can't fit anything more into this
+ * URB WRITE.
+ */
+ if (mrf > max_usable_mrf) {
+ slot++;
+ break;
+ }
+ }
+
+ complete = slot >= prog_data->vue_map.num_slots;
+
+ /* When we emit the URB_WRITE below we need to do different things
+ * depending on whether this is the last vertex we are going to
+ * write. That means that we will need to check if
+ * vertex >= vertex_count - 1. However, by increasing vertex early
+ * we transform that comparison into vertex >= vertex_count, which
+ * is more convenient.
+ */
+ if (complete)
+ emit(ADD(dst_reg(vertex), vertex, 1u));
+
+ /* 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.
+ */
+ int mlen = mrf - base_mrf;
+ if ((mlen % 2) != 1)
+ mlen++;
+ emit_urb_write_opcode(complete, vertex, base_mrf, mlen, 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, 1u));
+ }
+ emit(BRW_OPCODE_WHILE);
+
+ /* Finally, emit EOT message.
+ *
+ * In gen6 it looks like we have to set the complete flag too, otherwise
+ * the GPU hangs.
+ */
+ this->current_annotation = "gen6 thread end: EOT";
+ inst = emit(GS_OPCODE_THREAD_END);
+ inst->urb_write_flags = BRW_URB_WRITE_COMPLETE;
+ inst->base_mrf = base_mrf;
+ inst->mlen = 1;
+}
+
+} /* namespace brw */
projects / mesa.git / commitdiff