/* * Copyright © 2013 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. */ /** * \file brw_vec4_gs_visitor.cpp * * Geometry-shader-specific code derived from the vec4_visitor class. */ #include "brw_vec4_gs_visitor.h" #include "gen6_gs_visitor.h" #include "brw_fs.h" #include "brw_nir.h" #include "common/gen_debug.h" namespace brw { vec4_gs_visitor::vec4_gs_visitor(const struct brw_compiler *compiler, void *log_data, struct brw_gs_compile *c, struct brw_gs_prog_data *prog_data, const nir_shader *shader, void *mem_ctx, bool no_spills, int shader_time_index) : vec4_visitor(compiler, log_data, &c->key.tex, &prog_data->base, shader, mem_ctx, no_spills, shader_time_index), c(c), gs_prog_data(prog_data) { } dst_reg * vec4_gs_visitor::make_reg_for_system_value(int location) { dst_reg *reg = new(mem_ctx) dst_reg(this, glsl_type::int_type); switch (location) { case SYSTEM_VALUE_INVOCATION_ID: this->current_annotation = "initialize gl_InvocationID"; if (gs_prog_data->invocations > 1) emit(GS_OPCODE_GET_INSTANCE_ID, *reg); else emit(MOV(*reg, brw_imm_ud(0))); break; default: unreachable("not reached"); } return reg; } int vec4_gs_visitor::setup_varying_inputs(int payload_reg, int *attribute_map, int attributes_per_reg) { /* For geometry shaders there are N copies of the input attributes, where N * is the number of input vertices. attribute_map[BRW_VARYING_SLOT_COUNT * * i + j] represents attribute j for vertex i. * * Note that GS inputs are read from the VUE 256 bits (2 vec4's) at a time, * so the total number of input slots that will be delivered to the GS (and * thus the stride of the input arrays) is urb_read_length * 2. */ const unsigned num_input_vertices = nir->info->gs.vertices_in; assert(num_input_vertices <= MAX_GS_INPUT_VERTICES); unsigned input_array_stride = prog_data->urb_read_length * 2; for (int slot = 0; slot < c->input_vue_map.num_slots; slot++) { int varying = c->input_vue_map.slot_to_varying[slot]; for (unsigned vertex = 0; vertex < num_input_vertices; vertex++) { attribute_map[BRW_VARYING_SLOT_COUNT * vertex + varying] = attributes_per_reg * payload_reg + input_array_stride * vertex + slot; } } int regs_used = ALIGN(input_array_stride * num_input_vertices, attributes_per_reg) / attributes_per_reg; return payload_reg + regs_used; } void vec4_gs_visitor::setup_payload() { int attribute_map[BRW_VARYING_SLOT_COUNT * MAX_GS_INPUT_VERTICES]; /* If we are in dual instanced or single mode, then attributes are going * to be interleaved, so one register contains two attribute slots. */ int attributes_per_reg = prog_data->dispatch_mode == DISPATCH_MODE_4X2_DUAL_OBJECT ? 1 : 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, which contains * the URB handles that are passed on to the URB write at the end * of the thread. */ reg++; /* If the shader uses gl_PrimitiveIDIn, that goes in r1. */ if (gs_prog_data->include_primitive_id) attribute_map[VARYING_SLOT_PRIMITIVE_ID] = attributes_per_reg * reg++; reg = setup_uniforms(reg); reg = setup_varying_inputs(reg, attribute_map, attributes_per_reg); lower_attributes_to_hw_regs(attribute_map, attributes_per_reg > 1); this->first_non_payload_grf = reg; } void vec4_gs_visitor::emit_prolog() { /* In vertex shaders, r0.2 is guaranteed to be initialized to zero. In * geometry shaders, it isn't (it contains a bunch of information we don't * need, like the input primitive type). We need r0.2 to be zero in order * to build scratch read/write messages correctly (otherwise this value * will be interpreted as a global offset, causing us to do our scratch * reads/writes to garbage memory). So just set it to zero at the top of * the shader. */ this->current_annotation = "clear r0.2"; dst_reg r0(retype(brw_vec4_grf(0, 0), BRW_REGISTER_TYPE_UD)); vec4_instruction *inst = emit(GS_OPCODE_SET_DWORD_2, r0, brw_imm_ud(0u)); inst->force_writemask_all = true; /* Create a virtual register to hold the vertex count */ this->vertex_count = src_reg(this, glsl_type::uint_type); /* Initialize the vertex_count register to 0 */ this->current_annotation = "initialize vertex_count"; inst = emit(MOV(dst_reg(this->vertex_count), brw_imm_ud(0u))); inst->force_writemask_all = true; if (c->control_data_header_size_bits > 0) { /* Create a virtual register to hold the current set of control data * bits. */ this->control_data_bits = src_reg(this, glsl_type::uint_type); /* If we're outputting more than 32 control data bits, then EmitVertex() * will set control_data_bits to 0 after emitting the first vertex. * Otherwise, we need to initialize it to 0 here. */ if (c->control_data_header_size_bits <= 32) { this->current_annotation = "initialize control data bits"; inst = emit(MOV(dst_reg(this->control_data_bits), brw_imm_ud(0u))); inst->force_writemask_all = true; } } this->current_annotation = NULL; } void vec4_gs_visitor::emit_thread_end() { if (c->control_data_header_size_bits > 0) { /* During shader execution, we only ever call emit_control_data_bits() * just prior to outputting a vertex. Therefore, the control data bits * corresponding to the most recently output vertex still need to be * emitted. */ current_annotation = "thread end: emit control data bits"; emit_control_data_bits(); } /* MRF 0 is reserved for the debugger, so start with message header * in MRF 1. */ int base_mrf = 1; bool static_vertex_count = gs_prog_data->static_vertex_count != -1; /* If the previous instruction was a URB write, we don't need to issue * a second one - we can just set the EOT bit on the previous write. * * Skip this on Gen8+ unless there's a static vertex count, as we also * need to write the vertex count out, and combining the two may not be * possible (or at least not straightforward). */ vec4_instruction *last = (vec4_instruction *) instructions.get_tail(); if (last && last->opcode == GS_OPCODE_URB_WRITE && !(INTEL_DEBUG & DEBUG_SHADER_TIME) && devinfo->gen >= 8 && static_vertex_count) { last->urb_write_flags = BRW_URB_WRITE_EOT | last->urb_write_flags; return; } current_annotation = "thread end"; dst_reg mrf_reg(MRF, base_mrf); src_reg r0(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD)); vec4_instruction *inst = emit(MOV(mrf_reg, r0)); inst->force_writemask_all = true; if (devinfo->gen < 8 || !static_vertex_count) emit(GS_OPCODE_SET_VERTEX_COUNT, mrf_reg, this->vertex_count); if (INTEL_DEBUG & DEBUG_SHADER_TIME) emit_shader_time_end(); inst = emit(GS_OPCODE_THREAD_END); inst->base_mrf = base_mrf; inst->mlen = devinfo->gen >= 8 && !static_vertex_count ? 2 : 1; } void vec4_gs_visitor::emit_urb_write_header(int mrf) { /* The SEND instruction that writes the vertex data to the VUE will use * per_slot_offset=true, which means that DWORDs 3 and 4 of the message * header specify an offset (in multiples of 256 bits) into the URB entry * at which the write should take place. * * So we have to prepare a message header with the appropriate offset * values. */ dst_reg mrf_reg(MRF, mrf); src_reg r0(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD)); this->current_annotation = "URB write header"; vec4_instruction *inst = emit(MOV(mrf_reg, r0)); inst->force_writemask_all = true; emit(GS_OPCODE_SET_WRITE_OFFSET, mrf_reg, this->vertex_count, brw_imm_ud(gs_prog_data->output_vertex_size_hwords)); } vec4_instruction * vec4_gs_visitor::emit_urb_write_opcode(bool complete) { /* We don't care whether the vertex is complete, because in general * geometry shaders output multiple vertices, and we don't terminate the * thread until all vertices are complete. */ (void) complete; vec4_instruction *inst = emit(GS_OPCODE_URB_WRITE); inst->offset = gs_prog_data->control_data_header_size_hwords; /* We need to increment Global Offset by 1 to make room for Broadwell's * extra "Vertex Count" payload at the beginning of the URB entry. */ if (devinfo->gen >= 8 && gs_prog_data->static_vertex_count == -1) inst->offset++; inst->urb_write_flags = BRW_URB_WRITE_PER_SLOT_OFFSET; return inst; } /** * Write out a batch of 32 control data bits from the control_data_bits * register to the URB. * * The current value of the vertex_count register determines which DWORD in * the URB receives the control data bits. The control_data_bits register is * assumed to contain the correct data for the vertex that was most recently * output, and all previous vertices that share the same DWORD. * * This function takes care of ensuring that if no vertices have been output * yet, no control bits are emitted. */ void vec4_gs_visitor::emit_control_data_bits() { assert(c->control_data_bits_per_vertex != 0); /* Since the URB_WRITE_OWORD message operates with 128-bit (vec4 sized) * granularity, we need to use two tricks to ensure that the batch of 32 * control data bits is written to the appropriate DWORD in the URB. To * select which vec4 we are writing to, we use the "slot {0,1} offset" * fields of the message header. To select which DWORD in the vec4 we are * writing to, we use the channel mask fields of the message header. To * avoid penalizing geometry shaders that emit a small number of vertices * with extra bookkeeping, we only do each of these tricks when * c->prog_data.control_data_header_size_bits is large enough to make it * necessary. * * Note: this means that if we're outputting just a single DWORD of control * data bits, we'll actually replicate it four times since we won't do any * channel masking. But that's not a problem since in this case the * hardware only pays attention to the first DWORD. */ enum brw_urb_write_flags urb_write_flags = BRW_URB_WRITE_OWORD; if (c->control_data_header_size_bits > 32) urb_write_flags = urb_write_flags | BRW_URB_WRITE_USE_CHANNEL_MASKS; if (c->control_data_header_size_bits > 128) urb_write_flags = urb_write_flags | BRW_URB_WRITE_PER_SLOT_OFFSET; /* If we are using either channel masks or a per-slot offset, then we * need to figure out which DWORD we are trying to write to, using the * formula: * * dword_index = (vertex_count - 1) * bits_per_vertex / 32 * * Since bits_per_vertex is a power of two, and is known at compile * time, this can be optimized to: * * dword_index = (vertex_count - 1) >> (6 - log2(bits_per_vertex)) */ src_reg dword_index(this, glsl_type::uint_type); if (urb_write_flags) { src_reg prev_count(this, glsl_type::uint_type); emit(ADD(dst_reg(prev_count), this->vertex_count, brw_imm_ud(0xffffffffu))); unsigned log2_bits_per_vertex = util_last_bit(c->control_data_bits_per_vertex); emit(SHR(dst_reg(dword_index), prev_count, brw_imm_ud(6 - log2_bits_per_vertex))); } /* Start building the URB write message. The first MRF gets a copy of * R0. */ int base_mrf = 1; dst_reg mrf_reg(MRF, base_mrf); src_reg r0(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD)); vec4_instruction *inst = emit(MOV(mrf_reg, r0)); inst->force_writemask_all = true; if (urb_write_flags & BRW_URB_WRITE_PER_SLOT_OFFSET) { /* Set the per-slot offset to dword_index / 4, to that we'll write to * the appropriate OWORD within the control data header. */ src_reg per_slot_offset(this, glsl_type::uint_type); emit(SHR(dst_reg(per_slot_offset), dword_index, brw_imm_ud(2u))); emit(GS_OPCODE_SET_WRITE_OFFSET, mrf_reg, per_slot_offset, brw_imm_ud(1u)); } if (urb_write_flags & BRW_URB_WRITE_USE_CHANNEL_MASKS) { /* Set the channel masks to 1 << (dword_index % 4), so that we'll * write to the appropriate DWORD within the OWORD. We need to do * this computation with force_writemask_all, otherwise garbage data * from invocation 0 might clobber the mask for invocation 1 when * GS_OPCODE_PREPARE_CHANNEL_MASKS tries to OR the two masks * together. */ src_reg channel(this, glsl_type::uint_type); inst = emit(AND(dst_reg(channel), dword_index, brw_imm_ud(3u))); inst->force_writemask_all = true; src_reg one(this, glsl_type::uint_type); inst = emit(MOV(dst_reg(one), brw_imm_ud(1u))); inst->force_writemask_all = true; src_reg channel_mask(this, glsl_type::uint_type); inst = emit(SHL(dst_reg(channel_mask), one, channel)); inst->force_writemask_all = true; emit(GS_OPCODE_PREPARE_CHANNEL_MASKS, dst_reg(channel_mask), channel_mask); emit(GS_OPCODE_SET_CHANNEL_MASKS, mrf_reg, channel_mask); } /* Store the control data bits in the message payload and send it. */ dst_reg mrf_reg2(MRF, base_mrf + 1); inst = emit(MOV(mrf_reg2, this->control_data_bits)); inst->force_writemask_all = true; inst = emit(GS_OPCODE_URB_WRITE); inst->urb_write_flags = urb_write_flags; /* We need to increment Global Offset by 256-bits to make room for * Broadwell's extra "Vertex Count" payload at the beginning of the * URB entry. Since this is an OWord message, Global Offset is counted * in 128-bit units, so we must set it to 2. */ if (devinfo->gen >= 8 && gs_prog_data->static_vertex_count == -1) inst->offset = 2; inst->base_mrf = base_mrf; inst->mlen = 2; } void vec4_gs_visitor::set_stream_control_data_bits(unsigned stream_id) { /* control_data_bits |= stream_id << ((2 * (vertex_count - 1)) % 32) */ /* Note: we are calling this *before* increasing vertex_count, so * this->vertex_count == vertex_count - 1 in the formula above. */ /* Stream mode uses 2 bits per vertex */ assert(c->control_data_bits_per_vertex == 2); /* Must be a valid stream */ assert(stream_id >= 0 && stream_id < MAX_VERTEX_STREAMS); /* Control data bits are initialized to 0 so we don't have to set any * bits when sending vertices to stream 0. */ if (stream_id == 0) return; /* reg::sid = stream_id */ src_reg sid(this, glsl_type::uint_type); emit(MOV(dst_reg(sid), brw_imm_ud(stream_id))); /* reg:shift_count = 2 * (vertex_count - 1) */ src_reg shift_count(this, glsl_type::uint_type); emit(SHL(dst_reg(shift_count), this->vertex_count, brw_imm_ud(1u))); /* Note: we're relying on the fact that the GEN SHL instruction only pays * attention to the lower 5 bits of its second source argument, so on this * architecture, stream_id << 2 * (vertex_count - 1) is equivalent to * stream_id << ((2 * (vertex_count - 1)) % 32). */ src_reg mask(this, glsl_type::uint_type); emit(SHL(dst_reg(mask), sid, shift_count)); emit(OR(dst_reg(this->control_data_bits), this->control_data_bits, mask)); } 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; } void vec4_gs_visitor::gs_end_primitive() { /* We can only do EndPrimitive() functionality when the control data * consists of cut bits. Fortunately, the only time it isn't is when the * output type is points, in which case EndPrimitive() is a no-op. */ if (gs_prog_data->control_data_format != GEN7_GS_CONTROL_DATA_FORMAT_GSCTL_CUT) { return; } if (c->control_data_header_size_bits == 0) return; /* Cut bits use one bit per vertex. */ assert(c->control_data_bits_per_vertex == 1); /* Cut bit n should be set to 1 if EndPrimitive() was called after emitting * vertex n, 0 otherwise. So all we need to do here is mark bit * (vertex_count - 1) % 32 in the cut_bits register to indicate that * EndPrimitive() was called after emitting vertex (vertex_count - 1); * vec4_gs_visitor::emit_control_data_bits() will take care of the rest. * * Note that if EndPrimitve() is called before emitting any vertices, this * will cause us to set bit 31 of the control_data_bits register to 1. * That's fine because: * * - If max_vertices < 32, then vertex number 31 (zero-based) will never be * output, so the hardware will ignore cut bit 31. * * - If max_vertices == 32, then vertex number 31 is guaranteed to be the * last vertex, so setting cut bit 31 has no effect (since the primitive * is automatically ended when the GS terminates). * * - If max_vertices > 32, then the ir_emit_vertex visitor will reset the * control_data_bits register to 0 when the first vertex is emitted. */ /* control_data_bits |= 1 << ((vertex_count - 1) % 32) */ src_reg one(this, glsl_type::uint_type); emit(MOV(dst_reg(one), brw_imm_ud(1u))); src_reg prev_count(this, glsl_type::uint_type); emit(ADD(dst_reg(prev_count), this->vertex_count, brw_imm_ud(0xffffffffu))); src_reg mask(this, glsl_type::uint_type); /* Note: we're relying on the fact that the GEN SHL instruction only pays * attention to the lower 5 bits of its second source argument, so on this * architecture, 1 << (vertex_count - 1) is equivalent to 1 << * ((vertex_count - 1) % 32). */ emit(SHL(dst_reg(mask), one, prev_count)); emit(OR(dst_reg(this->control_data_bits), this->control_data_bits, mask)); } static const GLuint gl_prim_to_hw_prim[GL_TRIANGLE_STRIP_ADJACENCY+1] = { [GL_POINTS] =_3DPRIM_POINTLIST, [GL_LINES] = _3DPRIM_LINELIST, [GL_LINE_LOOP] = _3DPRIM_LINELOOP, [GL_LINE_STRIP] = _3DPRIM_LINESTRIP, [GL_TRIANGLES] = _3DPRIM_TRILIST, [GL_TRIANGLE_STRIP] = _3DPRIM_TRISTRIP, [GL_TRIANGLE_FAN] = _3DPRIM_TRIFAN, [GL_QUADS] = _3DPRIM_QUADLIST, [GL_QUAD_STRIP] = _3DPRIM_QUADSTRIP, [GL_POLYGON] = _3DPRIM_POLYGON, [GL_LINES_ADJACENCY] = _3DPRIM_LINELIST_ADJ, [GL_LINE_STRIP_ADJACENCY] = _3DPRIM_LINESTRIP_ADJ, [GL_TRIANGLES_ADJACENCY] = _3DPRIM_TRILIST_ADJ, [GL_TRIANGLE_STRIP_ADJACENCY] = _3DPRIM_TRISTRIP_ADJ, }; extern "C" const unsigned * brw_compile_gs(const struct brw_compiler *compiler, void *log_data, void *mem_ctx, const struct brw_gs_prog_key *key, struct brw_gs_prog_data *prog_data, const nir_shader *src_shader, struct gl_program *prog, int shader_time_index, unsigned *final_assembly_size, char **error_str) { struct brw_gs_compile c; memset(&c, 0, sizeof(c)); c.key = *key; const bool is_scalar = compiler->scalar_stage[MESA_SHADER_GEOMETRY]; nir_shader *shader = nir_shader_clone(mem_ctx, src_shader); /* The GLSL linker will have already matched up GS inputs and the outputs * of prior stages. The driver does extend VS outputs in some cases, but * only for legacy OpenGL or Gen4-5 hardware, neither of which offer * geometry shader support. So we can safely ignore that. * * For SSO pipelines, we use a fixed VUE map layout based on variable * locations, so we can rely on rendezvous-by-location making this work. */ GLbitfield64 inputs_read = shader->info->inputs_read; brw_compute_vue_map(compiler->devinfo, &c.input_vue_map, inputs_read, shader->info->separate_shader); shader = brw_nir_apply_sampler_key(shader, compiler, &key->tex, is_scalar); brw_nir_lower_vue_inputs(shader, is_scalar, &c.input_vue_map); brw_nir_lower_vue_outputs(shader, is_scalar); shader = brw_postprocess_nir(shader, compiler, is_scalar); prog_data->base.clip_distance_mask = ((1 << shader->info->clip_distance_array_size) - 1); prog_data->base.cull_distance_mask = ((1 << shader->info->cull_distance_array_size) - 1) << shader->info->clip_distance_array_size; prog_data->include_primitive_id = (shader->info->system_values_read & (1 << SYSTEM_VALUE_PRIMITIVE_ID)) != 0; prog_data->invocations = shader->info->gs.invocations; if (compiler->devinfo->gen >= 8) prog_data->static_vertex_count = nir_gs_count_vertices(shader); if (compiler->devinfo->gen >= 7) { if (shader->info->gs.output_primitive == GL_POINTS) { /* When the output type is points, the geometry shader may output data * to multiple streams, and EndPrimitive() has no effect. So we * configure the hardware to interpret the control data as stream ID. */ prog_data->control_data_format = GEN7_GS_CONTROL_DATA_FORMAT_GSCTL_SID; /* We only have to emit control bits if we are using streams */ if (prog && prog->info.gs.uses_streams) c.control_data_bits_per_vertex = 2; else c.control_data_bits_per_vertex = 0; } else { /* When the output type is triangle_strip or line_strip, EndPrimitive() * may be used to terminate the current strip and start a new one * (similar to primitive restart), and outputting data to multiple * streams is not supported. So we configure the hardware to interpret * the control data as EndPrimitive information (a.k.a. "cut bits"). */ prog_data->control_data_format = GEN7_GS_CONTROL_DATA_FORMAT_GSCTL_CUT; /* We only need to output control data if the shader actually calls * EndPrimitive(). */ c.control_data_bits_per_vertex = shader->info->gs.uses_end_primitive ? 1 : 0; } } else { /* There are no control data bits in gen6. */ c.control_data_bits_per_vertex = 0; } c.control_data_header_size_bits = shader->info->gs.vertices_out * c.control_data_bits_per_vertex; /* 1 HWORD = 32 bytes = 256 bits */ prog_data->control_data_header_size_hwords = ALIGN(c.control_data_header_size_bits, 256) / 256; /* Compute the output vertex size. * * From the Ivy Bridge PRM, Vol2 Part1 7.2.1.1 STATE_GS - Output Vertex * Size (p168): * * [0,62] indicating [1,63] 16B units * * Specifies the size of each vertex stored in the GS output entry * (following any Control Header data) as a number of 128-bit units * (minus one). * * Programming Restrictions: The vertex size must be programmed as a * multiple of 32B units with the following exception: Rendering is * disabled (as per SOL stage state) and the vertex size output by the * GS thread is 16B. * * If rendering is enabled (as per SOL state) the vertex size must be * programmed as a multiple of 32B units. In other words, the only time * software can program a vertex size with an odd number of 16B units * is when rendering is disabled. * * Note: B=bytes in the above text. * * It doesn't seem worth the extra trouble to optimize the case where the * vertex size is 16B (especially since this would require special-casing * the GEN assembly that writes to the URB). So we just set the vertex * size to a multiple of 32B (2 vec4's) in all cases. * * The maximum output vertex size is 62*16 = 992 bytes (31 hwords). We * budget that as follows: * * 512 bytes for varyings (a varying component is 4 bytes and * gl_MaxGeometryOutputComponents = 128) * 16 bytes overhead for VARYING_SLOT_PSIZ (each varying slot is 16 * bytes) * 16 bytes overhead for gl_Position (we allocate it a slot in the VUE * even if it's not used) * 32 bytes overhead for gl_ClipDistance (we allocate it 2 VUE slots * whenever clip planes are enabled, even if the shader doesn't * write to gl_ClipDistance) * 16 bytes overhead since the VUE size must be a multiple of 32 bytes * (see below)--this causes up to 1 VUE slot to be wasted * 400 bytes available for varying packing overhead * * Worst-case varying packing overhead is 3/4 of a varying slot (12 bytes) * per interpolation type, so this is plenty. * */ unsigned output_vertex_size_bytes = prog_data->base.vue_map.num_slots * 16; assert(compiler->devinfo->gen == 6 || output_vertex_size_bytes <= GEN7_MAX_GS_OUTPUT_VERTEX_SIZE_BYTES); prog_data->output_vertex_size_hwords = ALIGN(output_vertex_size_bytes, 32) / 32; /* Compute URB entry size. The maximum allowed URB entry size is 32k. * That divides up as follows: * * 64 bytes for the control data header (cut indices or StreamID bits) * 4096 bytes for varyings (a varying component is 4 bytes and * gl_MaxGeometryTotalOutputComponents = 1024) * 4096 bytes overhead for VARYING_SLOT_PSIZ (each varying slot is 16 * bytes/vertex and gl_MaxGeometryOutputVertices is 256) * 4096 bytes overhead for gl_Position (we allocate it a slot in the VUE * even if it's not used) * 8192 bytes overhead for gl_ClipDistance (we allocate it 2 VUE slots * whenever clip planes are enabled, even if the shader doesn't * write to gl_ClipDistance) * 4096 bytes overhead since the VUE size must be a multiple of 32 * bytes (see above)--this causes up to 1 VUE slot to be wasted * 8128 bytes available for varying packing overhead * * Worst-case varying packing overhead is 3/4 of a varying slot per * interpolation type, which works out to 3072 bytes, so this would allow * us to accommodate 2 interpolation types without any danger of running * out of URB space. * * In practice, the risk of running out of URB space is very small, since * the above figures are all worst-case, and most of them scale with the * number of output vertices. So we'll just calculate the amount of space * we need, and if it's too large, fail to compile. * * The above is for gen7+ where we have a single URB entry that will hold * all the output. In gen6, we will have to allocate URB entries for every * vertex we emit, so our URB entries only need to be large enough to hold * a single vertex. Also, gen6 does not have a control data header. */ unsigned output_size_bytes; if (compiler->devinfo->gen >= 7) { output_size_bytes = prog_data->output_vertex_size_hwords * 32 * shader->info->gs.vertices_out; output_size_bytes += 32 * prog_data->control_data_header_size_hwords; } else { output_size_bytes = prog_data->output_vertex_size_hwords * 32; } /* Broadwell stores "Vertex Count" as a full 8 DWord (32 byte) URB output, * which comes before the control header. */ if (compiler->devinfo->gen >= 8) output_size_bytes += 32; /* Shaders can technically set max_vertices = 0, at which point we * may have a URB size of 0 bytes. Nothing good can come from that, * so enforce a minimum size. */ if (output_size_bytes == 0) output_size_bytes = 1; unsigned max_output_size_bytes = GEN7_MAX_GS_URB_ENTRY_SIZE_BYTES; if (compiler->devinfo->gen == 6) max_output_size_bytes = GEN6_MAX_GS_URB_ENTRY_SIZE_BYTES; if (output_size_bytes > max_output_size_bytes) return NULL; /* URB entry sizes are stored as a multiple of 64 bytes in gen7+ and * a multiple of 128 bytes in gen6. */ if (compiler->devinfo->gen >= 7) prog_data->base.urb_entry_size = ALIGN(output_size_bytes, 64) / 64; else prog_data->base.urb_entry_size = ALIGN(output_size_bytes, 128) / 128; assert(shader->info->gs.output_primitive < ARRAY_SIZE(gl_prim_to_hw_prim)); prog_data->output_topology = gl_prim_to_hw_prim[shader->info->gs.output_primitive]; prog_data->vertices_in = shader->info->gs.vertices_in; /* GS inputs are read from the VUE 256 bits (2 vec4's) at a time, so we * need to program a URB read length of ceiling(num_slots / 2). */ prog_data->base.urb_read_length = (c.input_vue_map.num_slots + 1) / 2; /* Now that prog_data setup is done, we are ready to actually compile the * program. */ if (unlikely(INTEL_DEBUG & DEBUG_GS)) { fprintf(stderr, "GS Input "); brw_print_vue_map(stderr, &c.input_vue_map); fprintf(stderr, "GS Output "); brw_print_vue_map(stderr, &prog_data->base.vue_map); } if (is_scalar) { fs_visitor v(compiler, log_data, mem_ctx, &c, prog_data, shader, shader_time_index); if (v.run_gs()) { prog_data->base.dispatch_mode = DISPATCH_MODE_SIMD8; prog_data->base.base.dispatch_grf_start_reg = v.payload.num_regs; fs_generator g(compiler, log_data, mem_ctx, &c.key, &prog_data->base.base, v.promoted_constants, false, MESA_SHADER_GEOMETRY); if (unlikely(INTEL_DEBUG & DEBUG_GS)) { const char *label = shader->info->label ? shader->info->label : "unnamed"; char *name = ralloc_asprintf(mem_ctx, "%s geometry shader %s", label, shader->info->name); g.enable_debug(name); } g.generate_code(v.cfg, 8); return g.get_assembly(final_assembly_size); } } if (compiler->devinfo->gen >= 7) { /* Compile the geometry shader in DUAL_OBJECT dispatch mode, if we can do * so without spilling. If the GS invocations count > 1, then we can't use * dual object mode. */ if (prog_data->invocations <= 1 && likely(!(INTEL_DEBUG & DEBUG_NO_DUAL_OBJECT_GS))) { prog_data->base.dispatch_mode = DISPATCH_MODE_4X2_DUAL_OBJECT; vec4_gs_visitor v(compiler, log_data, &c, prog_data, shader, mem_ctx, true /* no_spills */, shader_time_index); if (v.run()) { return brw_vec4_generate_assembly(compiler, log_data, mem_ctx, shader, &prog_data->base, v.cfg, final_assembly_size); } } } /* Either we failed to compile in DUAL_OBJECT mode (probably because it * would have required spilling) or DUAL_OBJECT mode is disabled. So fall * back to DUAL_INSTANCED or SINGLE mode, which consumes fewer registers. * * FIXME: 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 to * do interleaved outputs, 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. * * From the Ivy Bridge PRM, Vol2 Part1 7.2.1.1 "3DSTATE_GS" * "If InstanceCount>1, DUAL_OBJECT mode is invalid. Software will likely * want to use DUAL_INSTANCE mode for higher performance, but SINGLE mode * is also supported. When InstanceCount=1 (one instance per object) software * can decide which dispatch mode to use. DUAL_OBJECT mode would likely be * the best choice for performance, followed by SINGLE mode." * * So SINGLE mode is more performant when invocations == 1 and DUAL_INSTANCE * mode is more performant when invocations > 1. Gen6 only supports * SINGLE mode. */ if (prog_data->invocations <= 1 || compiler->devinfo->gen < 7) prog_data->base.dispatch_mode = DISPATCH_MODE_4X1_SINGLE; else prog_data->base.dispatch_mode = DISPATCH_MODE_4X2_DUAL_INSTANCE; vec4_gs_visitor *gs = NULL; const unsigned *ret = NULL; if (compiler->devinfo->gen >= 7) gs = new vec4_gs_visitor(compiler, log_data, &c, prog_data, shader, mem_ctx, false /* no_spills */, shader_time_index); else gs = new gen6_gs_visitor(compiler, log_data, &c, prog_data, prog, shader, mem_ctx, false /* no_spills */, shader_time_index); if (!gs->run()) { if (error_str) *error_str = ralloc_strdup(mem_ctx, gs->fail_msg); } else { ret = brw_vec4_generate_assembly(compiler, log_data, mem_ctx, shader, &prog_data->base, gs->cfg, final_assembly_size); } delete gs; return ret; } } /* namespace brw */