diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp | 240 | ||||
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h | 2 |
2 files changed, 241 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp index 37cde64..960f970 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp +++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp @@ -135,6 +135,23 @@ vec4_gs_visitor::emit_prolog() vec4_instruction *inst = emit(MOV(dst_reg(this->vertex_count), 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), 0u)); + inst->force_writemask_all = true; + } + } + this->current_annotation = NULL; } @@ -150,6 +167,16 @@ vec4_gs_visitor::emit_program_code() 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. */ @@ -224,6 +251,124 @@ vec4_gs_visitor::compute_array_stride(ir_dereference_array *ir) } +/** + * 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 vertex_count is 0, then no control data bits have been accumulated + * yet, so we should do nothing. + */ + emit(CMP(dst_null_d(), this->vertex_count, 0u, BRW_CONDITIONAL_NEQ)); + emit(IF(BRW_PREDICATE_NORMAL)); + { + /* 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, 0xffffffffu)); + unsigned log2_bits_per_vertex = + _mesa_fls(c->control_data_bits_per_vertex); + emit(SHR(dst_reg(dword_index), prev_count, + (uint32_t) (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, 2u)); + emit(GS_OPCODE_SET_WRITE_OFFSET, mrf_reg, per_slot_offset, 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, 3u)); + inst->force_writemask_all = true; + src_reg one(this, glsl_type::uint_type); + inst = emit(MOV(dst_reg(one), 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)); + 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; + inst->base_mrf = base_mrf; + inst->mlen = 2; + } + emit(BRW_OPCODE_ENDIF); +} + + void vec4_gs_visitor::visit(ir_emit_vertex *) { @@ -238,6 +383,54 @@ vec4_gs_visitor::visit(ir_emit_vertex *) 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(); @@ -253,7 +446,52 @@ vec4_gs_visitor::visit(ir_emit_vertex *) void vec4_gs_visitor::visit(ir_end_primitive *) { - assert(!"Not implemented yet"); + /* 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 (c->prog_data.control_data_format != + GEN7_GS_CONTROL_DATA_FORMAT_GSCTL_CUT) { + 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), 1u)); + src_reg prev_count(this, glsl_type::uint_type); + emit(ADD(dst_reg(prev_count), this->vertex_count, 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)); } diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h index 1193e28..90dd1de 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h +++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h @@ -96,8 +96,10 @@ protected: private: int setup_varying_inputs(int payload_reg, int *attribute_map); + void emit_control_data_bits(); src_reg vertex_count; + src_reg control_data_bits; const struct brw_gs_compile * const c; }; |