| /* |
| * Copyright © 2016 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. |
| */ |
| |
| #include "anv_nir.h" |
| #include "nir/nir_builder.h" |
| |
| /** |
| * This file implements the lowering required for VK_KHR_multiview. We |
| * implement multiview using instanced rendering. The number of instances in |
| * each draw call is multiplied by the number of views in the subpass. Then, |
| * in the shader, we divide gl_InstanceId by the number of views and use |
| * gl_InstanceId % view_count to compute the actual ViewIndex. |
| */ |
| |
| struct lower_multiview_state { |
| nir_builder builder; |
| |
| uint32_t view_mask; |
| |
| nir_ssa_def *instance_id; |
| nir_ssa_def *view_index; |
| }; |
| |
| static nir_ssa_def * |
| build_instance_id(struct lower_multiview_state *state) |
| { |
| assert(state->builder.shader->info.stage == MESA_SHADER_VERTEX); |
| |
| if (state->instance_id == NULL) { |
| nir_builder *b = &state->builder; |
| |
| b->cursor = nir_before_block(nir_start_block(b->impl)); |
| |
| /* We use instancing for implementing multiview. The actual instance id |
| * is given by dividing instance_id by the number of views in this |
| * subpass. |
| */ |
| state->instance_id = |
| nir_idiv(b, nir_load_instance_id(b), |
| nir_imm_int(b, util_bitcount(state->view_mask))); |
| } |
| |
| return state->instance_id; |
| } |
| |
| static nir_ssa_def * |
| build_view_index(struct lower_multiview_state *state) |
| { |
| if (state->view_index == NULL) { |
| nir_builder *b = &state->builder; |
| |
| b->cursor = nir_before_block(nir_start_block(b->impl)); |
| |
| assert(state->view_mask != 0); |
| if (util_bitcount(state->view_mask) == 1) { |
| /* Set the view index directly. */ |
| state->view_index = nir_imm_int(b, ffs(state->view_mask) - 1); |
| } else if (state->builder.shader->info.stage == MESA_SHADER_VERTEX) { |
| /* We only support 16 viewports */ |
| assert((state->view_mask & 0xffff0000) == 0); |
| |
| /* We use instancing for implementing multiview. The compacted view |
| * id is given by instance_id % view_count. We then have to convert |
| * that to an actual view id. |
| */ |
| nir_ssa_def *compacted = |
| nir_umod(b, nir_load_instance_id(b), |
| nir_imm_int(b, util_bitcount(state->view_mask))); |
| |
| if (util_is_power_of_two_or_zero(state->view_mask + 1)) { |
| /* If we have a full view mask, then compacted is what we want */ |
| state->view_index = compacted; |
| } else { |
| /* Now we define a map from compacted view index to the actual |
| * view index that's based on the view_mask. The map is given by |
| * 16 nibbles, each of which is a value from 0 to 15. |
| */ |
| uint64_t remap = 0; |
| uint32_t bit, i = 0; |
| for_each_bit(bit, state->view_mask) { |
| assert(bit < 16); |
| remap |= (uint64_t)bit << (i++ * 4); |
| } |
| |
| nir_ssa_def *shift = nir_imul(b, compacted, nir_imm_int(b, 4)); |
| |
| /* One of these days, when we have int64 everywhere, this will be |
| * easier. |
| */ |
| nir_ssa_def *shifted; |
| if (remap <= UINT32_MAX) { |
| shifted = nir_ushr(b, nir_imm_int(b, remap), shift); |
| } else { |
| nir_ssa_def *shifted_low = |
| nir_ushr(b, nir_imm_int(b, remap), shift); |
| nir_ssa_def *shifted_high = |
| nir_ushr(b, nir_imm_int(b, remap >> 32), |
| nir_isub(b, shift, nir_imm_int(b, 32))); |
| shifted = nir_bcsel(b, nir_ilt(b, shift, nir_imm_int(b, 32)), |
| shifted_low, shifted_high); |
| } |
| state->view_index = nir_iand(b, shifted, nir_imm_int(b, 0xf)); |
| } |
| } else { |
| const struct glsl_type *type = glsl_int_type(); |
| if (b->shader->info.stage == MESA_SHADER_TESS_CTRL || |
| b->shader->info.stage == MESA_SHADER_GEOMETRY) |
| type = glsl_array_type(type, 1, 0); |
| |
| nir_variable *idx_var = |
| nir_variable_create(b->shader, nir_var_shader_in, |
| type, "view index"); |
| idx_var->data.location = VARYING_SLOT_VIEW_INDEX; |
| if (b->shader->info.stage == MESA_SHADER_FRAGMENT) |
| idx_var->data.interpolation = INTERP_MODE_FLAT; |
| |
| nir_deref_instr *deref = nir_build_deref_var(b, idx_var); |
| if (glsl_type_is_array(type)) |
| deref = nir_build_deref_array_imm(b, deref, 0); |
| |
| state->view_index = nir_load_deref(b, deref); |
| } |
| } |
| |
| return state->view_index; |
| } |
| |
| bool |
| anv_nir_lower_multiview(nir_shader *shader, uint32_t view_mask) |
| { |
| assert(shader->info.stage != MESA_SHADER_COMPUTE); |
| |
| /* If multiview isn't enabled, we have nothing to do. */ |
| if (view_mask == 0) |
| return false; |
| |
| struct lower_multiview_state state = { |
| .view_mask = view_mask, |
| }; |
| |
| /* This pass assumes a single entrypoint */ |
| nir_function_impl *entrypoint = nir_shader_get_entrypoint(shader); |
| |
| nir_builder_init(&state.builder, entrypoint); |
| |
| bool progress = false; |
| nir_foreach_block(block, entrypoint) { |
| nir_foreach_instr_safe(instr, block) { |
| if (instr->type != nir_instr_type_intrinsic) |
| continue; |
| |
| nir_intrinsic_instr *load = nir_instr_as_intrinsic(instr); |
| |
| if (load->intrinsic != nir_intrinsic_load_instance_id && |
| load->intrinsic != nir_intrinsic_load_view_index) |
| continue; |
| |
| assert(load->dest.is_ssa); |
| |
| nir_ssa_def *value; |
| if (load->intrinsic == nir_intrinsic_load_instance_id) { |
| value = build_instance_id(&state); |
| } else { |
| assert(load->intrinsic == nir_intrinsic_load_view_index); |
| value = build_view_index(&state); |
| } |
| |
| nir_ssa_def_rewrite_uses(&load->dest.ssa, nir_src_for_ssa(value)); |
| |
| nir_instr_remove(&load->instr); |
| progress = true; |
| } |
| } |
| |
| /* The view index is available in all stages but the instance id is only |
| * available in the VS. If it's not a fragment shader, we need to pass |
| * the view index on to the next stage. |
| */ |
| if (shader->info.stage != MESA_SHADER_FRAGMENT) { |
| nir_ssa_def *view_index = build_view_index(&state); |
| |
| nir_builder *b = &state.builder; |
| |
| assert(view_index->parent_instr->block == nir_start_block(entrypoint)); |
| b->cursor = nir_after_instr(view_index->parent_instr); |
| |
| /* Unless there is only one possible view index (that would be set |
| * directly), pass it to the next stage. */ |
| if (util_bitcount(state.view_mask) != 1) { |
| nir_variable *view_index_out = |
| nir_variable_create(shader, nir_var_shader_out, |
| glsl_int_type(), "view index"); |
| view_index_out->data.location = VARYING_SLOT_VIEW_INDEX; |
| nir_store_var(b, view_index_out, view_index, 0x1); |
| } |
| |
| nir_variable *layer_id_out = |
| nir_variable_create(shader, nir_var_shader_out, |
| glsl_int_type(), "layer ID"); |
| layer_id_out->data.location = VARYING_SLOT_LAYER; |
| nir_store_var(b, layer_id_out, view_index, 0x1); |
| |
| progress = true; |
| } |
| |
| if (progress) { |
| nir_metadata_preserve(entrypoint, nir_metadata_block_index | |
| nir_metadata_dominance); |
| } |
| |
| return progress; |
| } |