#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 {
static nir_ssa_def *
build_instance_id(struct lower_multiview_state *state)
{
- assert(state->builder.shader->stage == MESA_SHADER_VERTEX);
+ assert(state->builder.shader->info.stage == MESA_SHADER_VERTEX);
if (state->instance_id == NULL) {
nir_builder *b = &state->builder;
*/
state->instance_id =
nir_idiv(b, nir_load_instance_id(b),
- nir_imm_int(b, _mesa_bitcount(state->view_mask)));
+ nir_imm_int(b, util_bitcount(state->view_mask)));
}
return state->instance_id;
b->cursor = nir_before_block(nir_start_block(b->impl));
assert(state->view_mask != 0);
- if (0 && _mesa_bitcount(state->view_mask) == 1) {
+ 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->stage == MESA_SHADER_VERTEX) {
+ } else if (state->builder.shader->info.stage == MESA_SHADER_VERTEX) {
/* We only support 16 viewports */
assert((state->view_mask & 0xffff0000) == 0);
*/
nir_ssa_def *compacted =
nir_umod(b, nir_load_instance_id(b),
- nir_imm_int(b, _mesa_bitcount(state->view_mask)));
+ nir_imm_int(b, util_bitcount(state->view_mask)));
- if (0 && util_is_power_of_two(state->view_mask + 1)) {
+ 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 {
}
} else {
const struct glsl_type *type = glsl_int_type();
- if (b->shader->stage == MESA_SHADER_TESS_CTRL ||
- b->shader->stage == MESA_SHADER_GEOMETRY)
- type = glsl_array_type(type, 1);
+ 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->stage == MESA_SHADER_FRAGMENT)
+ if (b->shader->info.stage == MESA_SHADER_FRAGMENT)
idx_var->data.interpolation = INTERP_MODE_FLAT;
- if (glsl_type_is_array(type)) {
- nir_deref_var *deref = nir_deref_var_create(b->shader, idx_var);
- nir_deref_array *arr = nir_deref_array_create(b->shader);
- arr->deref.type = glsl_int_type();
- arr->deref_array_type = nir_deref_array_type_direct;
- arr->base_offset = 0;
- deref->deref.child = &arr->deref;
+ 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_var(b, deref);
- } else {
- state->view_index = nir_load_var(b, idx_var);
- }
+ state->view_index = nir_load_deref(b, deref);
}
}
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_shader_out_variable(var, shader) {
+ 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->stage != MESA_SHADER_COMPUTE);
+ 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,
};
* 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->stage != MESA_SHADER_FRAGMENT) {
+ 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);
- 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);
+ /* 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,
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_shader_out_variable(var, shaders[MESA_SHADER_VERTEX]) {
+ 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]);
+}
projects / mesa.git / blobdiff