--- /dev/null
+/*
+ * Copyright © 2018 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 "nir.h"
+#include "nir_builder.h"
+#include "nir_deref.h"
+
+struct split_var_state {
+ void *mem_ctx;
+
+ nir_shader *shader;
+ nir_function_impl *impl;
+
+ nir_variable *base_var;
+};
+
+struct field {
+ struct field *parent;
+
+ const struct glsl_type *type;
+
+ unsigned num_fields;
+ struct field *fields;
+
+ nir_variable *var;
+};
+
+static const struct glsl_type *
+wrap_type_in_array(const struct glsl_type *type,
+ const struct glsl_type *array_type)
+{
+ if (!glsl_type_is_array(array_type))
+ return type;
+
+ const struct glsl_type *elem_type =
+ wrap_type_in_array(type, glsl_get_array_element(array_type));
+ return glsl_array_type(elem_type, glsl_get_length(array_type));
+}
+
+static void
+init_field_for_type(struct field *field, struct field *parent,
+ const struct glsl_type *type,
+ const char *name,
+ struct split_var_state *state)
+{
+ *field = (struct field) {
+ .parent = parent,
+ .type = type,
+ };
+
+ const struct glsl_type *struct_type = glsl_without_array(type);
+ if (glsl_type_is_struct(struct_type)) {
+ field->num_fields = glsl_get_length(struct_type),
+ field->fields = ralloc_array(state->mem_ctx, struct field,
+ field->num_fields);
+ for (unsigned i = 0; i < field->num_fields; i++) {
+ char *field_name = NULL;
+ if (name) {
+ field_name = ralloc_asprintf(state->mem_ctx, "%s_%s", name,
+ glsl_get_struct_elem_name(struct_type, i));
+ } else {
+ field_name = ralloc_asprintf(state->mem_ctx, "{unnamed %s}_%s",
+ glsl_get_type_name(struct_type),
+ glsl_get_struct_elem_name(struct_type, i));
+ }
+ init_field_for_type(&field->fields[i], field,
+ glsl_get_struct_field(struct_type, i),
+ field_name, state);
+ }
+ } else {
+ const struct glsl_type *var_type = type;
+ for (struct field *f = field->parent; f; f = f->parent)
+ var_type = wrap_type_in_array(var_type, f->type);
+
+ nir_variable_mode mode = state->base_var->data.mode;
+ if (mode == nir_var_local) {
+ field->var = nir_local_variable_create(state->impl, var_type, name);
+ } else {
+ field->var = nir_variable_create(state->shader, mode, var_type, name);
+ }
+ }
+}
+
+static bool
+split_var_list_structs(nir_shader *shader,
+ nir_function_impl *impl,
+ struct exec_list *vars,
+ struct hash_table *var_field_map,
+ void *mem_ctx)
+{
+ struct split_var_state state = {
+ .mem_ctx = mem_ctx,
+ .shader = shader,
+ .impl = impl,
+ };
+
+ struct exec_list split_vars;
+ exec_list_make_empty(&split_vars);
+
+ /* To avoid list confusion (we'll be adding things as we split variables),
+ * pull all of the variables we plan to split off of the list
+ */
+ nir_foreach_variable_safe(var, vars) {
+ if (!glsl_type_is_struct(glsl_without_array(var->type)))
+ continue;
+
+ exec_node_remove(&var->node);
+ exec_list_push_tail(&split_vars, &var->node);
+ }
+
+ nir_foreach_variable(var, &split_vars) {
+ state.base_var = var;
+
+ struct field *root_field = ralloc(mem_ctx, struct field);
+ init_field_for_type(root_field, NULL, var->type, var->name, &state);
+ _mesa_hash_table_insert(var_field_map, var, root_field);
+ }
+
+ return !exec_list_is_empty(&split_vars);
+}
+
+static void
+split_struct_derefs_impl(nir_function_impl *impl,
+ struct hash_table *var_field_map,
+ nir_variable_mode modes,
+ void *mem_ctx)
+{
+ nir_builder b;
+ nir_builder_init(&b, impl);
+
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_deref)
+ continue;
+
+ nir_deref_instr *deref = nir_instr_as_deref(instr);
+ if (!(deref->mode & modes))
+ continue;
+
+ /* Clean up any dead derefs we find lying around. They may refer to
+ * variables we're planning to split.
+ */
+ if (nir_deref_instr_remove_if_unused(deref))
+ continue;
+
+ if (!glsl_type_is_vector_or_scalar(deref->type))
+ continue;
+
+ nir_variable *base_var = nir_deref_instr_get_variable(deref);
+ struct hash_entry *entry =
+ _mesa_hash_table_search(var_field_map, base_var);
+ if (!entry)
+ continue;
+
+ struct field *root_field = entry->data;
+
+ nir_deref_path path;
+ nir_deref_path_init(&path, deref, mem_ctx);
+
+ struct field *tail_field = root_field;
+ for (unsigned i = 0; path.path[i]; i++) {
+ if (path.path[i]->deref_type != nir_deref_type_struct)
+ continue;
+
+ assert(i > 0);
+ assert(glsl_type_is_struct(path.path[i - 1]->type));
+ assert(path.path[i - 1]->type ==
+ glsl_without_array(tail_field->type));
+
+ tail_field = &tail_field->fields[path.path[i]->strct.index];
+ }
+ nir_variable *split_var = tail_field->var;
+
+ nir_deref_instr *new_deref = NULL;
+ for (unsigned i = 0; path.path[i]; i++) {
+ nir_deref_instr *p = path.path[i];
+ b.cursor = nir_after_instr(&p->instr);
+
+ switch (p->deref_type) {
+ case nir_deref_type_var:
+ assert(new_deref == NULL);
+ new_deref = nir_build_deref_var(&b, split_var);
+ break;
+
+ case nir_deref_type_array:
+ case nir_deref_type_array_wildcard:
+ new_deref = nir_build_deref_follower(&b, new_deref, p);
+ break;
+
+ case nir_deref_type_struct:
+ /* Nothing to do; we're splitting structs */
+ break;
+
+ default:
+ unreachable("Invalid deref type in path");
+ }
+ }
+
+ assert(new_deref->type == deref->type);
+ nir_ssa_def_rewrite_uses(&deref->dest.ssa,
+ nir_src_for_ssa(&new_deref->dest.ssa));
+ nir_deref_instr_remove_if_unused(deref);
+ }
+ }
+}
+
+/** A pass for splitting structs into multiple variables
+ *
+ * This pass splits arrays of structs into multiple variables, one for each
+ * (possibly nested) structure member. After this pass completes, no
+ * variables of the given mode will contain a struct type.
+ */
+bool
+nir_split_struct_vars(nir_shader *shader, nir_variable_mode modes)
+{
+ void *mem_ctx = ralloc_context(NULL);
+ struct hash_table *var_field_map =
+ _mesa_hash_table_create(mem_ctx, _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+
+ assert((modes & (nir_var_global | nir_var_local)) == modes);
+
+ bool has_global_splits = false;
+ if (modes & nir_var_global) {
+ has_global_splits = split_var_list_structs(shader, NULL,
+ &shader->globals,
+ var_field_map, mem_ctx);
+ }
+
+ bool progress = false;
+ nir_foreach_function(function, shader) {
+ if (!function->impl)
+ continue;
+
+ bool has_local_splits = false;
+ if (modes & nir_var_local) {
+ has_local_splits = split_var_list_structs(shader, function->impl,
+ &function->impl->locals,
+ var_field_map, mem_ctx);
+ }
+
+ if (has_global_splits || has_local_splits) {
+ split_struct_derefs_impl(function->impl, var_field_map,
+ modes, mem_ctx);
+
+ nir_metadata_preserve(function->impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+ progress = true;
+ }
+ }
+
+ ralloc_free(mem_ctx);
+
+ return progress;
+}
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