X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fintel%2Fvulkan%2Fanv_nir_lower_multiview.c;h=d239074c61bc54414ddcd2c9cad76c5637a0a829;hb=81201e461772a06ed2c20207d2901f6cf9a24114;hp=c42d9c2dfa2533264b1c283c8c39672b9c34199b;hpb=6cebeb4f71918aded1ddade5727f79fae83780fd;p=mesa.git diff --git a/src/intel/vulkan/anv_nir_lower_multiview.c b/src/intel/vulkan/anv_nir_lower_multiview.c index c42d9c2dfa2..d239074c61b 100644 --- a/src/intel/vulkan/anv_nir_lower_multiview.c +++ b/src/intel/vulkan/anv_nir_lower_multiview.c @@ -23,13 +23,18 @@ #include "anv_nir.h" #include "nir/nir_builder.h" +#include "util/debug.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. + * This file implements the lowering required for VK_KHR_multiview. + * + * When possible, Primitive Replication is used and the shader is modified to + * make gl_Position an array and fill it with values for each view. + * + * Otherwise 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 { @@ -136,7 +141,7 @@ build_view_index(struct lower_multiview_state *state) nir_deref_instr *deref = nir_build_deref_var(b, idx_var); if (glsl_type_is_array(type)) - deref = nir_build_deref_array(b, deref, nir_imm_int(b, 0)); + deref = nir_build_deref_array_imm(b, deref, 0); state->view_index = nir_load_deref(b, deref); } @@ -145,15 +150,180 @@ build_view_index(struct lower_multiview_state *state) return state->view_index; } +/* Primitive Replication allows a shader to write different positions for each + * view in the same execution. If only the position depends on the view, then + * it is possible to use the feature instead of instancing to implement + * multiview. + */ +static bool +lower_multiview_with_primitive_replication(nir_shader *shader, + struct anv_graphics_pipeline *pipeline) +{ + if (shader->info.stage == MESA_SHADER_FRAGMENT) + return false; + + assert(shader->info.stage == MESA_SHADER_VERTEX); + + uint32_t view_mask = pipeline->subpass->view_mask; + int view_count = util_bitcount(view_mask); + assert(view_count > 1 && view_count <= MAX_VIEWS_FOR_PRIMITIVE_REPLICATION); + + nir_function_impl *entrypoint = nir_shader_get_entrypoint(shader); + + /* Update position to refer to an array. */ + nir_variable *pos_var = NULL; + nir_foreach_variable(var, &shader->outputs) { + if (var->data.location == VARYING_SLOT_POS) { + assert(var->type == glsl_vec4_type()); + var->type = glsl_array_type(glsl_vec4_type(), view_count, 0); + var->data.per_view = true; + pos_var = var; + break; + } + } + + assert(pos_var); + + nir_cf_list body; + nir_cf_list_extract(&body, &entrypoint->body); + + nir_builder b; + nir_builder_init(&b, entrypoint); + b.cursor = nir_after_cf_list(&entrypoint->body); + + /* Fill Layer ID with zero. Replication will use that as base to apply the + * RTAI offsets. + */ + 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, nir_imm_zero(&b, 1, 32), 0x1); + + /* Loop Index will go from 0 to view_count. */ + nir_variable *loop_index_var = + nir_local_variable_create(entrypoint, glsl_uint_type(), "loop_index"); + nir_deref_instr *loop_index_deref = nir_build_deref_var(&b, loop_index_var); + nir_store_deref(&b, loop_index_deref, nir_imm_int(&b, 0), 1); + + /* Array of view index values that are active in the loop. Note that the + * loop index only matches the view index if there are no gaps in the + * view_mask. + */ + nir_variable *view_index_var = nir_local_variable_create( + entrypoint, glsl_array_type(glsl_uint_type(), view_count, 0), "view_index"); + nir_deref_instr *view_index_deref = nir_build_deref_var(&b, view_index_var); + { + int array_position = 0; + uint32_t view_index; + for_each_bit(view_index, view_mask) { + nir_store_deref(&b, nir_build_deref_array_imm(&b, view_index_deref, array_position), + nir_imm_int(&b, view_index), 1); + array_position++; + } + } + + /* Create the equivalent of + * + * while (true): + * if (loop_index >= view_count): + * break + * + * view_index = active_indices[loop_index] + * pos_deref = &pos[loop_index] + * + * # Placeholder for the body to be reinserted. + * + * loop_index += 1 + * + * Later both `view_index` and `pos_deref` will be used to rewrite the + * original shader body. + */ + + nir_loop* loop = nir_push_loop(&b); + + nir_ssa_def *loop_index = nir_load_deref(&b, loop_index_deref); + nir_ssa_def *cmp = nir_ige(&b, loop_index, nir_imm_int(&b, view_count)); + nir_if *loop_check = nir_push_if(&b, cmp); + nir_jump(&b, nir_jump_break); + nir_pop_if(&b, loop_check); + + nir_ssa_def *view_index = + nir_load_deref(&b, nir_build_deref_array(&b, view_index_deref, loop_index)); + nir_deref_instr *pos_deref = + nir_build_deref_array(&b, nir_build_deref_var(&b, pos_var), loop_index); + + nir_store_deref(&b, loop_index_deref, nir_iadd_imm(&b, loop_index, 1), 1); + nir_pop_loop(&b, loop); + + /* Reinsert the body. */ + b.cursor = nir_after_instr(&pos_deref->instr); + nir_cf_reinsert(&body, b.cursor); + + nir_foreach_block(block, entrypoint) { + nir_foreach_instr_safe(instr, block) { + if (instr->type != nir_instr_type_intrinsic) + continue; + + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + + switch (intrin->intrinsic) { + case nir_intrinsic_load_view_index: { + assert(intrin->dest.is_ssa); + nir_ssa_def_rewrite_uses(&intrin->dest.ssa, nir_src_for_ssa(view_index)); + break; + } + + case nir_intrinsic_store_deref: { + nir_variable *var = nir_intrinsic_get_var(intrin, 0); + if (var == pos_var) { + nir_deref_instr *old_deref = nir_src_as_deref(intrin->src[0]); + + nir_instr_rewrite_src(instr, &intrin->src[0], + nir_src_for_ssa(&pos_deref->dest.ssa)); + + /* Remove old deref since it has the wrong type. */ + nir_deref_instr_remove_if_unused(old_deref); + } + break; + } + + case nir_intrinsic_load_deref: + if (nir_intrinsic_get_var(intrin, 0) == pos_var) { + unreachable("Should have lowered I/O to temporaries " + "so no load_deref on position output is expected."); + } + break; + + case nir_intrinsic_copy_deref: + unreachable("Should have lowered copy_derefs at this point"); + break; + + default: + /* Do nothing. */ + break; + } + } + } + + nir_metadata_preserve(entrypoint, nir_metadata_none); + return true; +} + bool -anv_nir_lower_multiview(nir_shader *shader, uint32_t view_mask) +anv_nir_lower_multiview(nir_shader *shader, + struct anv_graphics_pipeline *pipeline) { assert(shader->info.stage != MESA_SHADER_COMPUTE); + uint32_t view_mask = pipeline->subpass->view_mask; /* If multiview isn't enabled, we have nothing to do. */ if (view_mask == 0) return false; + if (pipeline->use_primitive_replication) + return lower_multiview_with_primitive_replication(shader, pipeline); + struct lower_multiview_state state = { .view_mask = view_mask, }; @@ -230,3 +400,189 @@ anv_nir_lower_multiview(nir_shader *shader, uint32_t view_mask) return progress; } + +static bool +shader_writes_to_memory(nir_shader *shader) +{ + /* With multiview, we would need to ensure that memory writes happen either + * once or once per view. Since combination of multiview and memory writes + * is not expected, we'll just skip this optimization in this case. + */ + + nir_function_impl *entrypoint = nir_shader_get_entrypoint(shader); + + nir_foreach_block(block, entrypoint) { + nir_foreach_instr(instr, block) { + if (instr->type != nir_instr_type_intrinsic) + continue; + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + + switch (intrin->intrinsic) { + case nir_intrinsic_deref_atomic_add: + case nir_intrinsic_deref_atomic_imin: + case nir_intrinsic_deref_atomic_umin: + case nir_intrinsic_deref_atomic_imax: + case nir_intrinsic_deref_atomic_umax: + case nir_intrinsic_deref_atomic_and: + case nir_intrinsic_deref_atomic_or: + case nir_intrinsic_deref_atomic_xor: + case nir_intrinsic_deref_atomic_exchange: + case nir_intrinsic_deref_atomic_comp_swap: + case nir_intrinsic_store_ssbo: + case nir_intrinsic_ssbo_atomic_add: + case nir_intrinsic_ssbo_atomic_imin: + case nir_intrinsic_ssbo_atomic_umin: + case nir_intrinsic_ssbo_atomic_imax: + case nir_intrinsic_ssbo_atomic_umax: + case nir_intrinsic_ssbo_atomic_and: + case nir_intrinsic_ssbo_atomic_or: + case nir_intrinsic_ssbo_atomic_xor: + case nir_intrinsic_ssbo_atomic_exchange: + case nir_intrinsic_ssbo_atomic_comp_swap: + case nir_intrinsic_store_shared: + case nir_intrinsic_shared_atomic_add: + case nir_intrinsic_shared_atomic_imin: + case nir_intrinsic_shared_atomic_umin: + case nir_intrinsic_shared_atomic_imax: + case nir_intrinsic_shared_atomic_umax: + case nir_intrinsic_shared_atomic_and: + case nir_intrinsic_shared_atomic_or: + case nir_intrinsic_shared_atomic_xor: + case nir_intrinsic_shared_atomic_exchange: + case nir_intrinsic_shared_atomic_comp_swap: + case nir_intrinsic_image_deref_store: + case nir_intrinsic_image_deref_atomic_add: + case nir_intrinsic_image_deref_atomic_umin: + case nir_intrinsic_image_deref_atomic_umax: + case nir_intrinsic_image_deref_atomic_imin: + case nir_intrinsic_image_deref_atomic_imax: + case nir_intrinsic_image_deref_atomic_and: + case nir_intrinsic_image_deref_atomic_or: + case nir_intrinsic_image_deref_atomic_xor: + case nir_intrinsic_image_deref_atomic_exchange: + case nir_intrinsic_image_deref_atomic_comp_swap: + return true; + + default: + /* Keep walking. */ + break; + } + } + } + + return false; +} + +static bool +shader_uses_view_index(nir_shader *shader) +{ + nir_function_impl *entrypoint = nir_shader_get_entrypoint(shader); + + nir_foreach_block(block, entrypoint) { + nir_foreach_instr(instr, block) { + if (instr->type != nir_instr_type_intrinsic) + continue; + + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + if (intrin->intrinsic == nir_intrinsic_load_view_index) + return true; + } + } + + return false; +} + +static bool +shader_only_position_uses_view_index(nir_shader *shader) +{ + nir_shader *shader_no_position = nir_shader_clone(NULL, shader); + nir_function_impl *entrypoint = nir_shader_get_entrypoint(shader_no_position); + + /* Remove the store position from a cloned shader. */ + nir_foreach_block(block, entrypoint) { + nir_foreach_instr_safe(instr, block) { + if (instr->type != nir_instr_type_intrinsic) + continue; + + nir_intrinsic_instr *store = nir_instr_as_intrinsic(instr); + if (store->intrinsic != nir_intrinsic_store_deref) + continue; + + nir_variable *var = nir_intrinsic_get_var(store, 0); + if (var->data.location != VARYING_SLOT_POS) + continue; + + nir_instr_remove(&store->instr); + } + } + + /* Clean up shader so unused load_view_index intrinsics are removed. */ + bool progress; + do { + progress = false; + progress |= nir_opt_dead_cf(shader_no_position); + + /* Peephole select will drop if-blocks that have then and else empty, + * which will remove the usage of an SSA in the condition. + */ + progress |= nir_opt_peephole_select(shader_no_position, 0, false, false); + + progress |= nir_opt_dce(shader_no_position); + } while (progress); + + bool uses_view_index = shader_uses_view_index(shader_no_position); + + ralloc_free(shader_no_position); + return !uses_view_index; +} + +bool +anv_check_for_primitive_replication(nir_shader **shaders, + struct anv_graphics_pipeline *pipeline) +{ + assert(pipeline->base.device->info.gen >= 12); + + static int primitive_replication_max_views = -1; + if (primitive_replication_max_views < 0) { + /* TODO: Figure out why we are not getting same benefits for larger than + * 2 views. For now use Primitive Replication just for the 2-view case + * by default. + */ + const unsigned default_max_views = 2; + + primitive_replication_max_views = + MIN2(MAX_VIEWS_FOR_PRIMITIVE_REPLICATION, + env_var_as_unsigned("ANV_PRIMITIVE_REPLICATION_MAX_VIEWS", + default_max_views)); + } + + /* TODO: We should be able to support replication at 'geometry' stages + * later than Vertex. In that case only the last stage can refer to + * gl_ViewIndex. + */ + if (pipeline->active_stages != (VK_SHADER_STAGE_VERTEX_BIT | + VK_SHADER_STAGE_FRAGMENT_BIT)) { + return false; + } + + uint32_t view_mask = pipeline->subpass->view_mask; + int view_count = util_bitcount(view_mask); + if (view_count == 1 || view_count > primitive_replication_max_views) + return false; + + bool vs_writes_position = false; + nir_foreach_variable(var, &shaders[MESA_SHADER_VERTEX]->outputs) { + if (var->data.location == VARYING_SLOT_POS) { + vs_writes_position = true; + break; + } + } + + /* Don't bother handling this edge case with Primitive Replication. */ + if (!vs_writes_position) + return false; + + return !shader_uses_view_index(shaders[MESA_SHADER_FRAGMENT]) && + !shader_writes_to_memory(shaders[MESA_SHADER_VERTEX]) && + shader_only_position_uses_view_index(shaders[MESA_SHADER_VERTEX]); +}