$(GLSL_SRCDIR)/nir/nir_lower_samplers.cpp \
$(GLSL_SRCDIR)/nir/nir_lower_system_values.c \
$(GLSL_SRCDIR)/nir/nir_lower_to_source_mods.c \
- $(GLSL_SRCDIR)/nir/nir_lower_variables.c \
+ $(GLSL_SRCDIR)/nir/nir_lower_vars_to_ssa.c \
$(GLSL_SRCDIR)/nir/nir_lower_vec_to_movs.c \
$(GLSL_SRCDIR)/nir/nir_metadata.c \
$(GLSL_SRCDIR)/nir/nir_opcodes.c \
void nir_lower_io(nir_shader *shader);
-void nir_lower_variables(nir_shader *shader);
+void nir_lower_vars_to_ssa(nir_shader *shader);
void nir_remove_dead_variables(nir_shader *shader);
+++ /dev/null
-/*
- * Copyright © 2014 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.
- *
- * Authors:
- * Jason Ekstrand (jason@jlekstrand.net)
- *
- */
-
-#include "nir.h"
-
-struct deref_node {
- struct deref_node *parent;
- const struct glsl_type *type;
-
- bool lower_to_ssa;
-
- struct set *loads;
- struct set *stores;
- struct set *copies;
-
- nir_ssa_def **def_stack;
- nir_ssa_def **def_stack_tail;
-
- struct deref_node *wildcard;
- struct deref_node *indirect;
- struct deref_node *children[0];
-};
-
-struct lower_variables_state {
- void *mem_ctx;
- void *dead_ctx;
- nir_function_impl *impl;
-
- /* A hash table mapping variables to deref_node data */
- struct hash_table *deref_var_nodes;
-
- /* A hash table mapping fully-qualified direct dereferences, i.e.
- * dereferences with no indirect or wildcard array dereferences, to
- * deref_node data.
- *
- * At the moment, we only lower loads, stores, and copies that can be
- * trivially lowered to loads and stores, i.e. copies with no indirects
- * and no wildcards. If a part of a variable that is being loaded from
- * and/or stored into is also involved in a copy operation with
- * wildcards, then we lower that copy operation to loads and stores, but
- * otherwise we leave copies with wildcards alone. Since the only derefs
- * used in these loads, stores, and trivial copies are ones with no
- * wildcards and no indirects, these are precisely the derefs that we
- * can actually consider lowering.
- */
- struct hash_table *direct_deref_nodes;
-
- /* A hash table mapping phi nodes to deref_state data */
- struct hash_table *phi_table;
-};
-
-/* The following two functions implement a hash and equality check for
- * variable dreferences. When the hash or equality function encounters an
- * array, all indirects are treated as equal and are never equal to a
- * direct dereference or a wildcard.
- */
-static uint32_t
-hash_deref(const void *void_deref)
-{
- uint32_t hash = _mesa_fnv32_1a_offset_bias;
-
- const nir_deref_var *deref_var = void_deref;
- hash = _mesa_fnv32_1a_accumulate(hash, deref_var->var);
-
- for (const nir_deref *deref = deref_var->deref.child;
- deref; deref = deref->child) {
- switch (deref->deref_type) {
- case nir_deref_type_array: {
- nir_deref_array *deref_array = nir_deref_as_array(deref);
-
- hash = _mesa_fnv32_1a_accumulate(hash, deref_array->deref_array_type);
-
- if (deref_array->deref_array_type == nir_deref_array_type_direct)
- hash = _mesa_fnv32_1a_accumulate(hash, deref_array->base_offset);
- break;
- }
- case nir_deref_type_struct: {
- nir_deref_struct *deref_struct = nir_deref_as_struct(deref);
- hash = _mesa_fnv32_1a_accumulate(hash, deref_struct->index);
- break;
- }
- default:
- assert("Invalid deref chain");
- }
- }
-
- return hash;
-}
-
-static bool
-derefs_equal(const void *void_a, const void *void_b)
-{
- const nir_deref_var *a_var = void_a;
- const nir_deref_var *b_var = void_b;
-
- if (a_var->var != b_var->var)
- return false;
-
- for (const nir_deref *a = a_var->deref.child, *b = b_var->deref.child;
- a != NULL; a = a->child, b = b->child) {
- if (a->deref_type != b->deref_type)
- return false;
-
- switch (a->deref_type) {
- case nir_deref_type_array: {
- nir_deref_array *a_arr = nir_deref_as_array(a);
- nir_deref_array *b_arr = nir_deref_as_array(b);
-
- if (a_arr->deref_array_type != b_arr->deref_array_type)
- return false;
-
- if (a_arr->deref_array_type == nir_deref_array_type_direct &&
- a_arr->base_offset != b_arr->base_offset)
- return false;
- break;
- }
- case nir_deref_type_struct:
- if (nir_deref_as_struct(a)->index != nir_deref_as_struct(b)->index)
- return false;
- break;
- default:
- assert("Invalid deref chain");
- return false;
- }
-
- assert((a->child == NULL) == (b->child == NULL));
- if((a->child == NULL) != (b->child == NULL))
- return false;
- }
-
- return true;
-}
-
-static int
-type_get_length(const struct glsl_type *type)
-{
- switch (glsl_get_base_type(type)) {
- case GLSL_TYPE_STRUCT:
- case GLSL_TYPE_ARRAY:
- return glsl_get_length(type);
- case GLSL_TYPE_FLOAT:
- case GLSL_TYPE_INT:
- case GLSL_TYPE_UINT:
- case GLSL_TYPE_BOOL:
- if (glsl_type_is_matrix(type))
- return glsl_get_matrix_columns(type);
- else
- return glsl_get_vector_elements(type);
- default:
- unreachable("Invalid deref base type");
- }
-}
-
-static struct deref_node *
-deref_node_create(struct deref_node *parent,
- const struct glsl_type *type, void *mem_ctx)
-{
- size_t size = sizeof(struct deref_node) +
- type_get_length(type) * sizeof(struct deref_node *);
-
- struct deref_node *node = rzalloc_size(mem_ctx, size);
- node->type = type;
- node->parent = parent;
-
- return node;
-}
-
-/* Gets the deref_node for the given deref chain and creates it if it
- * doesn't yet exist. If the deref is fully-qualified and direct and
- * add_to_direct_deref_nodes is true, it will be added to the hash table of
- * of fully-qualified direct derefs.
- */
-static struct deref_node *
-get_deref_node(nir_deref_var *deref, bool add_to_direct_deref_nodes,
- struct lower_variables_state *state)
-{
- bool is_direct = true;
-
- struct deref_node *node;
-
- struct hash_entry *var_entry =
- _mesa_hash_table_search(state->deref_var_nodes, deref->var);
-
- if (var_entry) {
- node = var_entry->data;
- } else {
- node = deref_node_create(NULL, deref->deref.type, state->dead_ctx);
- _mesa_hash_table_insert(state->deref_var_nodes, deref->var, node);
- }
-
- for (nir_deref *tail = deref->deref.child; tail; tail = tail->child) {
- switch (tail->deref_type) {
- case nir_deref_type_struct: {
- nir_deref_struct *deref_struct = nir_deref_as_struct(tail);
-
- assert(deref_struct->index < type_get_length(node->type));
-
- if (node->children[deref_struct->index] == NULL)
- node->children[deref_struct->index] =
- deref_node_create(node, tail->type, state->dead_ctx);
-
- node = node->children[deref_struct->index];
- break;
- }
-
- case nir_deref_type_array: {
- nir_deref_array *arr = nir_deref_as_array(tail);
-
- switch (arr->deref_array_type) {
- case nir_deref_array_type_direct:
- /* This is possible if a loop unrolls and generates an
- * out-of-bounds offset. We need to handle this at least
- * somewhat gracefully.
- */
- if (arr->base_offset >= type_get_length(node->type))
- return NULL;
-
- if (node->children[arr->base_offset] == NULL)
- node->children[arr->base_offset] =
- deref_node_create(node, tail->type, state->dead_ctx);
-
- node = node->children[arr->base_offset];
- break;
-
- case nir_deref_array_type_indirect:
- if (node->indirect == NULL)
- node->indirect = deref_node_create(node, tail->type,
- state->dead_ctx);
-
- node = node->indirect;
- is_direct = false;
- break;
-
- case nir_deref_array_type_wildcard:
- if (node->wildcard == NULL)
- node->wildcard = deref_node_create(node, tail->type,
- state->dead_ctx);
-
- node = node->wildcard;
- is_direct = false;
- break;
-
- default:
- unreachable("Invalid array deref type");
- }
- break;
- }
- default:
- unreachable("Invalid deref type");
- }
- }
-
- assert(node);
-
- if (is_direct && add_to_direct_deref_nodes)
- _mesa_hash_table_insert(state->direct_deref_nodes, deref, node);
-
- return node;
-}
-
-/* \sa foreach_deref_node_match */
-static bool
-foreach_deref_node_worker(struct deref_node *node, nir_deref *deref,
- bool (* cb)(struct deref_node *node,
- struct lower_variables_state *state),
- struct lower_variables_state *state)
-{
- if (deref->child == NULL) {
- return cb(node, state);
- } else {
- switch (deref->child->deref_type) {
- case nir_deref_type_array: {
- nir_deref_array *arr = nir_deref_as_array(deref->child);
- assert(arr->deref_array_type == nir_deref_array_type_direct);
- if (node->children[arr->base_offset] &&
- !foreach_deref_node_worker(node->children[arr->base_offset],
- deref->child, cb, state))
- return false;
-
- if (node->wildcard &&
- !foreach_deref_node_worker(node->wildcard,
- deref->child, cb, state))
- return false;
-
- return true;
- }
-
- case nir_deref_type_struct: {
- nir_deref_struct *str = nir_deref_as_struct(deref->child);
- return foreach_deref_node_worker(node->children[str->index],
- deref->child, cb, state);
- }
-
- default:
- unreachable("Invalid deref child type");
- }
- }
-}
-
-/* Walks over every "matching" deref_node and calls the callback. A node
- * is considered to "match" if either refers to that deref or matches up t
- * a wildcard. In other words, the following would match a[6].foo[3].bar:
- *
- * a[6].foo[3].bar
- * a[*].foo[3].bar
- * a[6].foo[*].bar
- * a[*].foo[*].bar
- *
- * The given deref must be a full-length and fully qualified (no wildcards
- * or indirects) deref chain.
- */
-static bool
-foreach_deref_node_match(nir_deref_var *deref,
- bool (* cb)(struct deref_node *node,
- struct lower_variables_state *state),
- struct lower_variables_state *state)
-{
- nir_deref_var var_deref = *deref;
- var_deref.deref.child = NULL;
- struct deref_node *node = get_deref_node(&var_deref, false, state);
-
- if (node == NULL)
- return false;
-
- return foreach_deref_node_worker(node, &deref->deref, cb, state);
-}
-
-/* \sa deref_may_be_aliased */
-static bool
-deref_may_be_aliased_node(struct deref_node *node, nir_deref *deref,
- struct lower_variables_state *state)
-{
- if (deref->child == NULL) {
- return false;
- } else {
- switch (deref->child->deref_type) {
- case nir_deref_type_array: {
- nir_deref_array *arr = nir_deref_as_array(deref->child);
- if (arr->deref_array_type == nir_deref_array_type_indirect)
- return true;
-
- assert(arr->deref_array_type == nir_deref_array_type_direct);
-
- if (node->children[arr->base_offset] &&
- deref_may_be_aliased_node(node->children[arr->base_offset],
- deref->child, state))
- return true;
-
- if (node->wildcard &&
- deref_may_be_aliased_node(node->wildcard, deref->child, state))
- return true;
-
- return false;
- }
-
- case nir_deref_type_struct: {
- nir_deref_struct *str = nir_deref_as_struct(deref->child);
- if (node->children[str->index]) {
- return deref_may_be_aliased_node(node->children[str->index],
- deref->child, state);
- } else {
- return false;
- }
- }
-
- default:
- unreachable("Invalid nir_deref child type");
- }
- }
-}
-
-/* Returns true if there are no indirects that can ever touch this deref.
- *
- * For example, if the given deref is a[6].foo, then any uses of a[i].foo
- * would cause this to return false, but a[i].bar would not affect it
- * because it's a different structure member. A var_copy involving of
- * a[*].bar also doesn't affect it because that can be lowered to entirely
- * direct load/stores.
- *
- * We only support asking this question about fully-qualified derefs.
- * Obviously, it's pointless to ask this about indirects, but we also
- * rule-out wildcards. Handling Wildcard dereferences would involve
- * checking each array index to make sure that there aren't any indirect
- * references.
- */
-static bool
-deref_may_be_aliased(nir_deref_var *deref,
- struct lower_variables_state *state)
-{
- nir_deref_var var_deref = *deref;
- var_deref.deref.child = NULL;
- struct deref_node *node = get_deref_node(&var_deref, false, state);
-
- /* An invalid dereference can't be aliased. */
- if (node == NULL)
- return false;
-
- return deref_may_be_aliased_node(node, &deref->deref, state);
-}
-
-static void
-register_load_instr(nir_intrinsic_instr *load_instr, bool create_node,
- struct lower_variables_state *state)
-{
- struct deref_node *node = get_deref_node(load_instr->variables[0],
- create_node, state);
- if (node == NULL)
- return;
-
- if (node->loads == NULL)
- node->loads = _mesa_set_create(state->dead_ctx,
- _mesa_key_pointer_equal);
-
- _mesa_set_add(node->loads, _mesa_hash_pointer(load_instr), load_instr);
-}
-
-static void
-register_store_instr(nir_intrinsic_instr *store_instr, bool create_node,
- struct lower_variables_state *state)
-{
- struct deref_node *node = get_deref_node(store_instr->variables[0],
- create_node, state);
- if (node == NULL)
- return;
-
- if (node->stores == NULL)
- node->stores = _mesa_set_create(state->dead_ctx,
- _mesa_key_pointer_equal);
-
- _mesa_set_add(node->stores, _mesa_hash_pointer(store_instr), store_instr);
-}
-
-static void
-register_copy_instr(nir_intrinsic_instr *copy_instr, bool create_node,
- struct lower_variables_state *state)
-{
- for (unsigned idx = 0; idx < 2; idx++) {
- struct deref_node *node = get_deref_node(copy_instr->variables[idx],
- create_node, state);
- if (node == NULL)
- continue;
-
- if (node->copies == NULL)
- node->copies = _mesa_set_create(state->dead_ctx,
- _mesa_key_pointer_equal);
-
- _mesa_set_add(node->copies, _mesa_hash_pointer(copy_instr), copy_instr);
- }
-}
-
-/* Registers all variable uses in the given block. */
-static bool
-register_variable_uses_block(nir_block *block, void *void_state)
-{
- struct lower_variables_state *state = void_state;
-
- nir_foreach_instr_safe(block, instr) {
- if (instr->type != nir_instr_type_intrinsic)
- continue;
-
- nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
-
- switch (intrin->intrinsic) {
- case nir_intrinsic_load_var:
- register_load_instr(intrin, true, state);
- break;
-
- case nir_intrinsic_store_var:
- register_store_instr(intrin, true, state);
- break;
-
- case nir_intrinsic_copy_var:
- register_copy_instr(intrin, true, state);
- break;
-
- default:
- continue;
- }
- }
-
- return true;
-}
-
-/* Walks down the deref chain and returns the next deref in the chain whose
- * child is a wildcard. In other words, given the chain a[1].foo[*].bar,
- * this function will return the deref to foo. Calling it a second time
- * with the [*].bar, it will return NULL.
- */
-static nir_deref *
-deref_next_wildcard_parent(nir_deref *deref)
-{
- for (nir_deref *tail = deref; tail->child; tail = tail->child) {
- if (tail->child->deref_type != nir_deref_type_array)
- continue;
-
- nir_deref_array *arr = nir_deref_as_array(tail->child);
-
- if (arr->deref_array_type == nir_deref_array_type_wildcard)
- return tail;
- }
-
- return NULL;
-}
-
-/* Returns the last deref in the chain.
- */
-static nir_deref *
-get_deref_tail(nir_deref *deref)
-{
- while (deref->child)
- deref = deref->child;
-
- return deref;
-}
-
-/* This function recursively walks the given deref chain and replaces the
- * given copy instruction with an equivalent sequence load/store
- * operations.
- *
- * @copy_instr The copy instruction to replace; new instructions will be
- * inserted before this one
- *
- * @dest_head The head of the destination variable deref chain
- *
- * @src_head The head of the source variable deref chain
- *
- * @dest_tail The current tail of the destination variable deref chain;
- * this is used for recursion and external callers of this
- * function should call it with tail == head
- *
- * @src_tail The current tail of the source variable deref chain;
- * this is used for recursion and external callers of this
- * function should call it with tail == head
- *
- * @state The current variable lowering state
- */
-static void
-emit_copy_load_store(nir_intrinsic_instr *copy_instr,
- nir_deref_var *dest_head, nir_deref_var *src_head,
- nir_deref *dest_tail, nir_deref *src_tail,
- struct lower_variables_state *state)
-{
- /* Find the next pair of wildcards */
- nir_deref *src_arr_parent = deref_next_wildcard_parent(src_tail);
- nir_deref *dest_arr_parent = deref_next_wildcard_parent(dest_tail);
-
- if (src_arr_parent || dest_arr_parent) {
- /* Wildcards had better come in matched pairs */
- assert(dest_arr_parent && dest_arr_parent);
-
- nir_deref_array *src_arr = nir_deref_as_array(src_arr_parent->child);
- nir_deref_array *dest_arr = nir_deref_as_array(dest_arr_parent->child);
-
- unsigned length = type_get_length(src_arr_parent->type);
- /* The wildcards should represent the same number of elements */
- assert(length == type_get_length(dest_arr_parent->type));
- assert(length > 0);
-
- /* Walk over all of the elements that this wildcard refers to and
- * call emit_copy_load_store on each one of them */
- src_arr->deref_array_type = nir_deref_array_type_direct;
- dest_arr->deref_array_type = nir_deref_array_type_direct;
- for (unsigned i = 0; i < length; i++) {
- src_arr->base_offset = i;
- dest_arr->base_offset = i;
- emit_copy_load_store(copy_instr, dest_head, src_head,
- &dest_arr->deref, &src_arr->deref, state);
- }
- src_arr->deref_array_type = nir_deref_array_type_wildcard;
- dest_arr->deref_array_type = nir_deref_array_type_wildcard;
- } else {
- /* In this case, we have no wildcards anymore, so all we have to do
- * is just emit the load and store operations. */
- src_tail = get_deref_tail(src_tail);
- dest_tail = get_deref_tail(dest_tail);
-
- assert(src_tail->type == dest_tail->type);
-
- unsigned num_components = glsl_get_vector_elements(src_tail->type);
-
- nir_deref *src_deref = nir_copy_deref(state->mem_ctx, &src_head->deref);
- nir_deref *dest_deref = nir_copy_deref(state->mem_ctx, &dest_head->deref);
-
- nir_intrinsic_instr *load =
- nir_intrinsic_instr_create(state->mem_ctx, nir_intrinsic_load_var);
- load->num_components = num_components;
- load->variables[0] = nir_deref_as_var(src_deref);
- load->dest.is_ssa = true;
- nir_ssa_def_init(&load->instr, &load->dest.ssa, num_components, NULL);
-
- nir_instr_insert_before(©_instr->instr, &load->instr);
- register_load_instr(load, false, state);
-
- nir_intrinsic_instr *store =
- nir_intrinsic_instr_create(state->mem_ctx, nir_intrinsic_store_var);
- store->num_components = num_components;
- store->variables[0] = nir_deref_as_var(dest_deref);
- store->src[0].is_ssa = true;
- store->src[0].ssa = &load->dest.ssa;
-
- nir_instr_insert_before(©_instr->instr, &store->instr);
- register_store_instr(store, false, state);
- }
-}
-
-/* Walks over all of the copy instructions to or from the given deref_node
- * and lowers them to load/store intrinsics.
- */
-static bool
-lower_copies_to_load_store(struct deref_node *node,
- struct lower_variables_state *state)
-{
- if (!node->copies)
- return true;
-
- struct set_entry *copy_entry;
- set_foreach(node->copies, copy_entry) {
- nir_intrinsic_instr *copy = (void *)copy_entry->key;
-
- emit_copy_load_store(copy, copy->variables[0], copy->variables[1],
- ©->variables[0]->deref,
- ©->variables[1]->deref,
- state);
-
- for (unsigned i = 0; i < 2; ++i) {
- struct deref_node *arg_node = get_deref_node(copy->variables[i],
- false, state);
- if (arg_node == NULL)
- continue;
-
- struct set_entry *arg_entry = _mesa_set_search(arg_node->copies,
- copy_entry->hash,
- copy);
- assert(arg_entry);
- _mesa_set_remove(node->copies, arg_entry);
- }
-
- nir_instr_remove(©->instr);
- }
-
- return true;
-}
-
-/* Returns a load_const instruction that represents the constant
- * initializer for the given deref chain. The caller is responsible for
- * ensuring that there actually is a constant initializer.
- */
-static nir_load_const_instr *
-get_const_initializer_load(const nir_deref_var *deref,
- struct lower_variables_state *state)
-{
- nir_constant *constant = deref->var->constant_initializer;
- const nir_deref *tail = &deref->deref;
- unsigned matrix_offset = 0;
- while (tail->child) {
- switch (tail->child->deref_type) {
- case nir_deref_type_array: {
- nir_deref_array *arr = nir_deref_as_array(tail->child);
- assert(arr->deref_array_type == nir_deref_array_type_direct);
- if (glsl_type_is_matrix(tail->type)) {
- assert(arr->deref.child == NULL);
- matrix_offset = arr->base_offset;
- } else {
- constant = constant->elements[arr->base_offset];
- }
- break;
- }
-
- case nir_deref_type_struct: {
- constant = constant->elements[nir_deref_as_struct(tail->child)->index];
- break;
- }
-
- default:
- unreachable("Invalid deref child type");
- }
-
- tail = tail->child;
- }
-
- nir_load_const_instr *load =
- nir_load_const_instr_create(state->mem_ctx,
- glsl_get_vector_elements(tail->type));
-
- matrix_offset *= load->def.num_components;
- for (unsigned i = 0; i < load->def.num_components; i++) {
- switch (glsl_get_base_type(tail->type)) {
- case GLSL_TYPE_FLOAT:
- case GLSL_TYPE_INT:
- case GLSL_TYPE_UINT:
- load->value.u[i] = constant->value.u[matrix_offset + i];
- break;
- case GLSL_TYPE_BOOL:
- load->value.u[i] = constant->value.u[matrix_offset + i] ?
- NIR_TRUE : NIR_FALSE;
- break;
- default:
- unreachable("Invalid immediate type");
- }
- }
-
- return load;
-}
-
-/** Pushes an SSA def onto the def stack for the given node
- *
- * Each node is potentially associated with a stack of SSA definitions.
- * This stack is used for determining what SSA definition reaches a given
- * point in the program for variable renaming. The stack is always kept in
- * dominance-order with at most one SSA def per block. If the SSA
- * definition on the top of the stack is in the same block as the one being
- * pushed, the top element is replaced.
- */
-static void
-def_stack_push(struct deref_node *node, nir_ssa_def *def,
- struct lower_variables_state *state)
-{
- if (node->def_stack == NULL) {
- node->def_stack = ralloc_array(state->dead_ctx, nir_ssa_def *,
- state->impl->num_blocks);
- node->def_stack_tail = node->def_stack - 1;
- }
-
- if (node->def_stack_tail >= node->def_stack) {
- nir_ssa_def *top_def = *node->def_stack_tail;
-
- if (def->parent_instr->block == top_def->parent_instr->block) {
- /* They're in the same block, just replace the top */
- *node->def_stack_tail = def;
- return;
- }
- }
-
- *(++node->def_stack_tail) = def;
-}
-
-/* Pop the top of the def stack if it's in the given block */
-static void
-def_stack_pop_if_in_block(struct deref_node *node, nir_block *block)
-{
- /* If we're popping, then we have presumably pushed at some time in the
- * past so this should exist.
- */
- assert(node->def_stack != NULL);
-
- /* The stack is already empty. Do nothing. */
- if (node->def_stack_tail < node->def_stack)
- return;
-
- nir_ssa_def *def = *node->def_stack_tail;
- if (def->parent_instr->block == block)
- node->def_stack_tail--;
-}
-
-/** Retrieves the SSA definition on the top of the stack for the given
- * node, if one exists. If the stack is empty, then we return the constant
- * initializer (if it exists) or an SSA undef.
- */
-static nir_ssa_def *
-get_ssa_def_for_block(struct deref_node *node, nir_block *block,
- struct lower_variables_state *state)
-{
- /* If we have something on the stack, go ahead and return it. We're
- * assuming that the top of the stack dominates the given block.
- */
- if (node->def_stack && node->def_stack_tail >= node->def_stack)
- return *node->def_stack_tail;
-
- /* If we got here then we don't have a definition that dominates the
- * given block. This means that we need to add an undef and use that.
- */
- nir_ssa_undef_instr *undef =
- nir_ssa_undef_instr_create(state->mem_ctx,
- glsl_get_vector_elements(node->type));
- nir_instr_insert_before_cf_list(&state->impl->body, &undef->instr);
- def_stack_push(node, &undef->def, state);
- return &undef->def;
-}
-
-/* Given a block and one of its predecessors, this function fills in the
- * souces of the phi nodes to take SSA defs from the given predecessor.
- * This function must be called exactly once per block/predecessor pair.
- */
-static void
-add_phi_sources(nir_block *block, nir_block *pred,
- struct lower_variables_state *state)
-{
- nir_foreach_instr(block, instr) {
- if (instr->type != nir_instr_type_phi)
- break;
-
- nir_phi_instr *phi = nir_instr_as_phi(instr);
-
- struct hash_entry *entry =
- _mesa_hash_table_search(state->phi_table, phi);
- if (!entry)
- continue;
-
- struct deref_node *node = entry->data;
-
- nir_phi_src *src = ralloc(state->mem_ctx, nir_phi_src);
- src->pred = pred;
- src->src.is_ssa = true;
- src->src.ssa = get_ssa_def_for_block(node, pred, state);
-
- _mesa_set_add(src->src.ssa->uses, _mesa_hash_pointer(instr), instr);
-
- exec_list_push_tail(&phi->srcs, &src->node);
- }
-}
-
-/* Performs variable renaming by doing a DFS of the dominance tree
- *
- * This algorithm is very similar to the one outlined in "Efficiently
- * Computing Static Single Assignment Form and the Control Dependence
- * Graph" by Cytron et. al. The primary difference is that we only put one
- * SSA def on the stack per block.
- */
-static bool
-rename_variables_block(nir_block *block, struct lower_variables_state *state)
-{
- nir_foreach_instr_safe(block, instr) {
- if (instr->type == nir_instr_type_phi) {
- nir_phi_instr *phi = nir_instr_as_phi(instr);
-
- struct hash_entry *entry =
- _mesa_hash_table_search(state->phi_table, phi);
-
- /* This can happen if we already have phi nodes in the program
- * that were not created in this pass.
- */
- if (!entry)
- continue;
-
- struct deref_node *node = entry->data;
-
- def_stack_push(node, &phi->dest.ssa, state);
- } else if (instr->type == nir_instr_type_intrinsic) {
- nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
-
- switch (intrin->intrinsic) {
- case nir_intrinsic_load_var: {
- struct deref_node *node = get_deref_node(intrin->variables[0],
- false, state);
-
- if (node == NULL) {
- /* If we hit this path then we are referencing an invalid
- * value. Most likely, we unrolled something and are
- * reading past the end of some array. In any case, this
- * should result in an undefined value.
- */
- nir_ssa_undef_instr *undef =
- nir_ssa_undef_instr_create(state->mem_ctx,
- intrin->num_components);
-
- nir_instr_insert_before(&intrin->instr, &undef->instr);
- nir_instr_remove(&intrin->instr);
-
- nir_src new_src = {
- .is_ssa = true,
- .ssa = &undef->def,
- };
-
- nir_ssa_def_rewrite_uses(&intrin->dest.ssa, new_src,
- state->mem_ctx);
- continue;
- }
-
- if (!node->lower_to_ssa)
- continue;
-
- nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx,
- nir_op_imov);
- mov->src[0].src.is_ssa = true;
- mov->src[0].src.ssa = get_ssa_def_for_block(node, block, state);
- for (unsigned i = intrin->num_components; i < 4; i++)
- mov->src[0].swizzle[i] = 0;
-
- assert(intrin->dest.is_ssa);
-
- mov->dest.write_mask = (1 << intrin->num_components) - 1;
- mov->dest.dest.is_ssa = true;
- nir_ssa_def_init(&mov->instr, &mov->dest.dest.ssa,
- intrin->num_components, NULL);
-
- nir_instr_insert_before(&intrin->instr, &mov->instr);
- nir_instr_remove(&intrin->instr);
-
- nir_src new_src = {
- .is_ssa = true,
- .ssa = &mov->dest.dest.ssa,
- };
-
- nir_ssa_def_rewrite_uses(&intrin->dest.ssa, new_src,
- state->mem_ctx);
- break;
- }
-
- case nir_intrinsic_store_var: {
- struct deref_node *node = get_deref_node(intrin->variables[0],
- false, state);
-
- if (node == NULL) {
- /* Probably an out-of-bounds array store. That should be a
- * no-op. */
- nir_instr_remove(&intrin->instr);
- continue;
- }
-
- if (!node->lower_to_ssa)
- continue;
-
- assert(intrin->num_components ==
- glsl_get_vector_elements(node->type));
-
- assert(intrin->src[0].is_ssa);
-
- nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx,
- nir_op_imov);
- mov->src[0].src.is_ssa = true;
- mov->src[0].src.ssa = intrin->src[0].ssa;
- for (unsigned i = intrin->num_components; i < 4; i++)
- mov->src[0].swizzle[i] = 0;
-
- mov->dest.write_mask = (1 << intrin->num_components) - 1;
- mov->dest.dest.is_ssa = true;
- nir_ssa_def_init(&mov->instr, &mov->dest.dest.ssa,
- intrin->num_components, NULL);
-
- nir_instr_insert_before(&intrin->instr, &mov->instr);
-
- def_stack_push(node, &mov->dest.dest.ssa, state);
-
- /* We'll wait to remove the instruction until the next pass
- * where we pop the node we just pushed back off the stack.
- */
- break;
- }
-
- default:
- break;
- }
- }
- }
-
- if (block->successors[0])
- add_phi_sources(block->successors[0], block, state);
- if (block->successors[1])
- add_phi_sources(block->successors[1], block, state);
-
- for (unsigned i = 0; i < block->num_dom_children; ++i)
- rename_variables_block(block->dom_children[i], state);
-
- /* Now we iterate over the instructions and pop off any SSA defs that we
- * pushed in the first loop.
- */
- nir_foreach_instr_safe(block, instr) {
- if (instr->type == nir_instr_type_phi) {
- nir_phi_instr *phi = nir_instr_as_phi(instr);
-
- struct hash_entry *entry =
- _mesa_hash_table_search(state->phi_table, phi);
-
- /* This can happen if we already have phi nodes in the program
- * that were not created in this pass.
- */
- if (!entry)
- continue;
-
- struct deref_node *node = entry->data;
-
- def_stack_pop_if_in_block(node, block);
- } else if (instr->type == nir_instr_type_intrinsic) {
- nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
-
- if (intrin->intrinsic != nir_intrinsic_store_var)
- continue;
-
- struct deref_node *node = get_deref_node(intrin->variables[0],
- false, state);
- if (!node)
- continue;
-
- if (!node->lower_to_ssa)
- continue;
-
- def_stack_pop_if_in_block(node, block);
- nir_instr_remove(&intrin->instr);
- }
- }
-
- return true;
-}
-
-/* Inserts phi nodes for all variables marked lower_to_ssa
- *
- * This is the same algorithm as presented in "Efficiently Computing Static
- * Single Assignment Form and the Control Dependence Graph" by Cytron et.
- * al.
- */
-static void
-insert_phi_nodes(struct lower_variables_state *state)
-{
- unsigned work[state->impl->num_blocks];
- unsigned has_already[state->impl->num_blocks];
-
- /*
- * Since the work flags already prevent us from inserting a node that has
- * ever been inserted into W, we don't need to use a set to represent W.
- * Also, since no block can ever be inserted into W more than once, we know
- * that the maximum size of W is the number of basic blocks in the
- * function. So all we need to handle W is an array and a pointer to the
- * next element to be inserted and the next element to be removed.
- */
- nir_block *W[state->impl->num_blocks];
-
- memset(work, 0, sizeof work);
- memset(has_already, 0, sizeof has_already);
-
- unsigned w_start, w_end;
- unsigned iter_count = 0;
-
- struct hash_entry *deref_entry;
- hash_table_foreach(state->direct_deref_nodes, deref_entry) {
- struct deref_node *node = deref_entry->data;
-
- if (node->stores == NULL)
- continue;
-
- if (!node->lower_to_ssa)
- continue;
-
- w_start = w_end = 0;
- iter_count++;
-
- struct set_entry *store_entry;
- set_foreach(node->stores, store_entry) {
- nir_intrinsic_instr *store = (nir_intrinsic_instr *)store_entry->key;
- if (work[store->instr.block->index] < iter_count)
- W[w_end++] = store->instr.block;
- work[store->instr.block->index] = iter_count;
- }
-
- while (w_start != w_end) {
- nir_block *cur = W[w_start++];
- struct set_entry *dom_entry;
- set_foreach(cur->dom_frontier, dom_entry) {
- nir_block *next = (nir_block *) dom_entry->key;
-
- /*
- * If there's more than one return statement, then the end block
- * can be a join point for some definitions. However, there are
- * no instructions in the end block, so nothing would use those
- * phi nodes. Of course, we couldn't place those phi nodes
- * anyways due to the restriction of having no instructions in the
- * end block...
- */
- if (next == state->impl->end_block)
- continue;
-
- if (has_already[next->index] < iter_count) {
- nir_phi_instr *phi = nir_phi_instr_create(state->mem_ctx);
- phi->dest.is_ssa = true;
- nir_ssa_def_init(&phi->instr, &phi->dest.ssa,
- glsl_get_vector_elements(node->type), NULL);
- nir_instr_insert_before_block(next, &phi->instr);
-
- _mesa_hash_table_insert(state->phi_table, phi, node);
-
- has_already[next->index] = iter_count;
- if (work[next->index] < iter_count) {
- work[next->index] = iter_count;
- W[w_end++] = next;
- }
- }
- }
- }
- }
-}
-
-
-/** Implements a pass to lower variable uses to SSA values
- *
- * This path walks the list of instructions and tries to lower as many
- * local variable load/store operations to SSA defs and uses as it can.
- * The process involves four passes:
- *
- * 1) Iterate over all of the instructions and mark where each local
- * variable deref is used in a load, store, or copy. While we're at
- * it, we keep track of all of the fully-qualified (no wildcards) and
- * fully-direct references we see and store them in the
- * direct_deref_nodes hash table.
- *
- * 2) Walk over the the list of fully-qualified direct derefs generated in
- * the previous pass. For each deref, we determine if it can ever be
- * aliased, i.e. if there is an indirect reference anywhere that may
- * refer to it. If it cannot be aliased, we mark it for lowering to an
- * SSA value. At this point, we lower any var_copy instructions that
- * use the given deref to load/store operations and, if the deref has a
- * constant initializer, we go ahead and add a load_const value at the
- * beginning of the function with the initialized value.
- *
- * 3) Walk over the list of derefs we plan to lower to SSA values and
- * insert phi nodes as needed.
- *
- * 4) Perform "variable renaming" by replacing the load/store instructions
- * with SSA definitions and SSA uses.
- */
-static bool
-nir_lower_variables_impl(nir_function_impl *impl)
-{
- struct lower_variables_state state;
-
- state.mem_ctx = ralloc_parent(impl);
- state.dead_ctx = ralloc_context(state.mem_ctx);
- state.impl = impl;
-
- state.deref_var_nodes = _mesa_hash_table_create(state.dead_ctx,
- _mesa_hash_pointer,
- _mesa_key_pointer_equal);
- state.direct_deref_nodes = _mesa_hash_table_create(state.dead_ctx,
- hash_deref, derefs_equal);
- state.phi_table = _mesa_hash_table_create(state.dead_ctx,
- _mesa_hash_pointer,
- _mesa_key_pointer_equal);
-
- nir_foreach_block(impl, register_variable_uses_block, &state);
-
- struct set *outputs = _mesa_set_create(state.dead_ctx,
- _mesa_key_pointer_equal);
-
- bool progress = false;
-
- nir_metadata_require(impl, nir_metadata_block_index);
-
- struct hash_entry *entry;
- hash_table_foreach(state.direct_deref_nodes, entry) {
- nir_deref_var *deref = (void *)entry->key;
- struct deref_node *node = entry->data;
-
- if (deref->var->data.mode != nir_var_local) {
- _mesa_hash_table_remove(state.direct_deref_nodes, entry);
- continue;
- }
-
- if (deref_may_be_aliased(deref, &state)) {
- _mesa_hash_table_remove(state.direct_deref_nodes, entry);
- continue;
- }
-
- node->lower_to_ssa = true;
- progress = true;
-
- if (deref->var->constant_initializer) {
- nir_load_const_instr *load = get_const_initializer_load(deref, &state);
- nir_ssa_def_init(&load->instr, &load->def,
- glsl_get_vector_elements(node->type), NULL);
- nir_instr_insert_before_cf_list(&impl->body, &load->instr);
- def_stack_push(node, &load->def, &state);
- }
-
- if (deref->var->data.mode == nir_var_shader_out)
- _mesa_set_add(outputs, _mesa_hash_pointer(node), node);
-
- foreach_deref_node_match(deref, lower_copies_to_load_store, &state);
- }
-
- if (!progress)
- return false;
-
- nir_metadata_require(impl, nir_metadata_dominance);
-
- insert_phi_nodes(&state);
- rename_variables_block(impl->start_block, &state);
-
- nir_metadata_preserve(impl, nir_metadata_block_index |
- nir_metadata_dominance);
-
- ralloc_free(state.dead_ctx);
-
- return progress;
-}
-
-void
-nir_lower_variables(nir_shader *shader)
-{
- nir_foreach_overload(shader, overload) {
- if (overload->impl)
- nir_lower_variables_impl(overload->impl);
- }
-}
--- /dev/null
+/*
+ * Copyright © 2014 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.
+ *
+ * Authors:
+ * Jason Ekstrand (jason@jlekstrand.net)
+ *
+ */
+
+#include "nir.h"
+
+struct deref_node {
+ struct deref_node *parent;
+ const struct glsl_type *type;
+
+ bool lower_to_ssa;
+
+ struct set *loads;
+ struct set *stores;
+ struct set *copies;
+
+ nir_ssa_def **def_stack;
+ nir_ssa_def **def_stack_tail;
+
+ struct deref_node *wildcard;
+ struct deref_node *indirect;
+ struct deref_node *children[0];
+};
+
+struct lower_variables_state {
+ void *mem_ctx;
+ void *dead_ctx;
+ nir_function_impl *impl;
+
+ /* A hash table mapping variables to deref_node data */
+ struct hash_table *deref_var_nodes;
+
+ /* A hash table mapping fully-qualified direct dereferences, i.e.
+ * dereferences with no indirect or wildcard array dereferences, to
+ * deref_node data.
+ *
+ * At the moment, we only lower loads, stores, and copies that can be
+ * trivially lowered to loads and stores, i.e. copies with no indirects
+ * and no wildcards. If a part of a variable that is being loaded from
+ * and/or stored into is also involved in a copy operation with
+ * wildcards, then we lower that copy operation to loads and stores, but
+ * otherwise we leave copies with wildcards alone. Since the only derefs
+ * used in these loads, stores, and trivial copies are ones with no
+ * wildcards and no indirects, these are precisely the derefs that we
+ * can actually consider lowering.
+ */
+ struct hash_table *direct_deref_nodes;
+
+ /* A hash table mapping phi nodes to deref_state data */
+ struct hash_table *phi_table;
+};
+
+/* The following two functions implement a hash and equality check for
+ * variable dreferences. When the hash or equality function encounters an
+ * array, all indirects are treated as equal and are never equal to a
+ * direct dereference or a wildcard.
+ */
+static uint32_t
+hash_deref(const void *void_deref)
+{
+ uint32_t hash = _mesa_fnv32_1a_offset_bias;
+
+ const nir_deref_var *deref_var = void_deref;
+ hash = _mesa_fnv32_1a_accumulate(hash, deref_var->var);
+
+ for (const nir_deref *deref = deref_var->deref.child;
+ deref; deref = deref->child) {
+ switch (deref->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *deref_array = nir_deref_as_array(deref);
+
+ hash = _mesa_fnv32_1a_accumulate(hash, deref_array->deref_array_type);
+
+ if (deref_array->deref_array_type == nir_deref_array_type_direct)
+ hash = _mesa_fnv32_1a_accumulate(hash, deref_array->base_offset);
+ break;
+ }
+ case nir_deref_type_struct: {
+ nir_deref_struct *deref_struct = nir_deref_as_struct(deref);
+ hash = _mesa_fnv32_1a_accumulate(hash, deref_struct->index);
+ break;
+ }
+ default:
+ assert("Invalid deref chain");
+ }
+ }
+
+ return hash;
+}
+
+static bool
+derefs_equal(const void *void_a, const void *void_b)
+{
+ const nir_deref_var *a_var = void_a;
+ const nir_deref_var *b_var = void_b;
+
+ if (a_var->var != b_var->var)
+ return false;
+
+ for (const nir_deref *a = a_var->deref.child, *b = b_var->deref.child;
+ a != NULL; a = a->child, b = b->child) {
+ if (a->deref_type != b->deref_type)
+ return false;
+
+ switch (a->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *a_arr = nir_deref_as_array(a);
+ nir_deref_array *b_arr = nir_deref_as_array(b);
+
+ if (a_arr->deref_array_type != b_arr->deref_array_type)
+ return false;
+
+ if (a_arr->deref_array_type == nir_deref_array_type_direct &&
+ a_arr->base_offset != b_arr->base_offset)
+ return false;
+ break;
+ }
+ case nir_deref_type_struct:
+ if (nir_deref_as_struct(a)->index != nir_deref_as_struct(b)->index)
+ return false;
+ break;
+ default:
+ assert("Invalid deref chain");
+ return false;
+ }
+
+ assert((a->child == NULL) == (b->child == NULL));
+ if((a->child == NULL) != (b->child == NULL))
+ return false;
+ }
+
+ return true;
+}
+
+static int
+type_get_length(const struct glsl_type *type)
+{
+ switch (glsl_get_base_type(type)) {
+ case GLSL_TYPE_STRUCT:
+ case GLSL_TYPE_ARRAY:
+ return glsl_get_length(type);
+ case GLSL_TYPE_FLOAT:
+ case GLSL_TYPE_INT:
+ case GLSL_TYPE_UINT:
+ case GLSL_TYPE_BOOL:
+ if (glsl_type_is_matrix(type))
+ return glsl_get_matrix_columns(type);
+ else
+ return glsl_get_vector_elements(type);
+ default:
+ unreachable("Invalid deref base type");
+ }
+}
+
+static struct deref_node *
+deref_node_create(struct deref_node *parent,
+ const struct glsl_type *type, void *mem_ctx)
+{
+ size_t size = sizeof(struct deref_node) +
+ type_get_length(type) * sizeof(struct deref_node *);
+
+ struct deref_node *node = rzalloc_size(mem_ctx, size);
+ node->type = type;
+ node->parent = parent;
+
+ return node;
+}
+
+/* Gets the deref_node for the given deref chain and creates it if it
+ * doesn't yet exist. If the deref is fully-qualified and direct and
+ * add_to_direct_deref_nodes is true, it will be added to the hash table of
+ * of fully-qualified direct derefs.
+ */
+static struct deref_node *
+get_deref_node(nir_deref_var *deref, bool add_to_direct_deref_nodes,
+ struct lower_variables_state *state)
+{
+ bool is_direct = true;
+
+ struct deref_node *node;
+
+ struct hash_entry *var_entry =
+ _mesa_hash_table_search(state->deref_var_nodes, deref->var);
+
+ if (var_entry) {
+ node = var_entry->data;
+ } else {
+ node = deref_node_create(NULL, deref->deref.type, state->dead_ctx);
+ _mesa_hash_table_insert(state->deref_var_nodes, deref->var, node);
+ }
+
+ for (nir_deref *tail = deref->deref.child; tail; tail = tail->child) {
+ switch (tail->deref_type) {
+ case nir_deref_type_struct: {
+ nir_deref_struct *deref_struct = nir_deref_as_struct(tail);
+
+ assert(deref_struct->index < type_get_length(node->type));
+
+ if (node->children[deref_struct->index] == NULL)
+ node->children[deref_struct->index] =
+ deref_node_create(node, tail->type, state->dead_ctx);
+
+ node = node->children[deref_struct->index];
+ break;
+ }
+
+ case nir_deref_type_array: {
+ nir_deref_array *arr = nir_deref_as_array(tail);
+
+ switch (arr->deref_array_type) {
+ case nir_deref_array_type_direct:
+ /* This is possible if a loop unrolls and generates an
+ * out-of-bounds offset. We need to handle this at least
+ * somewhat gracefully.
+ */
+ if (arr->base_offset >= type_get_length(node->type))
+ return NULL;
+
+ if (node->children[arr->base_offset] == NULL)
+ node->children[arr->base_offset] =
+ deref_node_create(node, tail->type, state->dead_ctx);
+
+ node = node->children[arr->base_offset];
+ break;
+
+ case nir_deref_array_type_indirect:
+ if (node->indirect == NULL)
+ node->indirect = deref_node_create(node, tail->type,
+ state->dead_ctx);
+
+ node = node->indirect;
+ is_direct = false;
+ break;
+
+ case nir_deref_array_type_wildcard:
+ if (node->wildcard == NULL)
+ node->wildcard = deref_node_create(node, tail->type,
+ state->dead_ctx);
+
+ node = node->wildcard;
+ is_direct = false;
+ break;
+
+ default:
+ unreachable("Invalid array deref type");
+ }
+ break;
+ }
+ default:
+ unreachable("Invalid deref type");
+ }
+ }
+
+ assert(node);
+
+ if (is_direct && add_to_direct_deref_nodes)
+ _mesa_hash_table_insert(state->direct_deref_nodes, deref, node);
+
+ return node;
+}
+
+/* \sa foreach_deref_node_match */
+static bool
+foreach_deref_node_worker(struct deref_node *node, nir_deref *deref,
+ bool (* cb)(struct deref_node *node,
+ struct lower_variables_state *state),
+ struct lower_variables_state *state)
+{
+ if (deref->child == NULL) {
+ return cb(node, state);
+ } else {
+ switch (deref->child->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *arr = nir_deref_as_array(deref->child);
+ assert(arr->deref_array_type == nir_deref_array_type_direct);
+ if (node->children[arr->base_offset] &&
+ !foreach_deref_node_worker(node->children[arr->base_offset],
+ deref->child, cb, state))
+ return false;
+
+ if (node->wildcard &&
+ !foreach_deref_node_worker(node->wildcard,
+ deref->child, cb, state))
+ return false;
+
+ return true;
+ }
+
+ case nir_deref_type_struct: {
+ nir_deref_struct *str = nir_deref_as_struct(deref->child);
+ return foreach_deref_node_worker(node->children[str->index],
+ deref->child, cb, state);
+ }
+
+ default:
+ unreachable("Invalid deref child type");
+ }
+ }
+}
+
+/* Walks over every "matching" deref_node and calls the callback. A node
+ * is considered to "match" if either refers to that deref or matches up t
+ * a wildcard. In other words, the following would match a[6].foo[3].bar:
+ *
+ * a[6].foo[3].bar
+ * a[*].foo[3].bar
+ * a[6].foo[*].bar
+ * a[*].foo[*].bar
+ *
+ * The given deref must be a full-length and fully qualified (no wildcards
+ * or indirects) deref chain.
+ */
+static bool
+foreach_deref_node_match(nir_deref_var *deref,
+ bool (* cb)(struct deref_node *node,
+ struct lower_variables_state *state),
+ struct lower_variables_state *state)
+{
+ nir_deref_var var_deref = *deref;
+ var_deref.deref.child = NULL;
+ struct deref_node *node = get_deref_node(&var_deref, false, state);
+
+ if (node == NULL)
+ return false;
+
+ return foreach_deref_node_worker(node, &deref->deref, cb, state);
+}
+
+/* \sa deref_may_be_aliased */
+static bool
+deref_may_be_aliased_node(struct deref_node *node, nir_deref *deref,
+ struct lower_variables_state *state)
+{
+ if (deref->child == NULL) {
+ return false;
+ } else {
+ switch (deref->child->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *arr = nir_deref_as_array(deref->child);
+ if (arr->deref_array_type == nir_deref_array_type_indirect)
+ return true;
+
+ assert(arr->deref_array_type == nir_deref_array_type_direct);
+
+ if (node->children[arr->base_offset] &&
+ deref_may_be_aliased_node(node->children[arr->base_offset],
+ deref->child, state))
+ return true;
+
+ if (node->wildcard &&
+ deref_may_be_aliased_node(node->wildcard, deref->child, state))
+ return true;
+
+ return false;
+ }
+
+ case nir_deref_type_struct: {
+ nir_deref_struct *str = nir_deref_as_struct(deref->child);
+ if (node->children[str->index]) {
+ return deref_may_be_aliased_node(node->children[str->index],
+ deref->child, state);
+ } else {
+ return false;
+ }
+ }
+
+ default:
+ unreachable("Invalid nir_deref child type");
+ }
+ }
+}
+
+/* Returns true if there are no indirects that can ever touch this deref.
+ *
+ * For example, if the given deref is a[6].foo, then any uses of a[i].foo
+ * would cause this to return false, but a[i].bar would not affect it
+ * because it's a different structure member. A var_copy involving of
+ * a[*].bar also doesn't affect it because that can be lowered to entirely
+ * direct load/stores.
+ *
+ * We only support asking this question about fully-qualified derefs.
+ * Obviously, it's pointless to ask this about indirects, but we also
+ * rule-out wildcards. Handling Wildcard dereferences would involve
+ * checking each array index to make sure that there aren't any indirect
+ * references.
+ */
+static bool
+deref_may_be_aliased(nir_deref_var *deref,
+ struct lower_variables_state *state)
+{
+ nir_deref_var var_deref = *deref;
+ var_deref.deref.child = NULL;
+ struct deref_node *node = get_deref_node(&var_deref, false, state);
+
+ /* An invalid dereference can't be aliased. */
+ if (node == NULL)
+ return false;
+
+ return deref_may_be_aliased_node(node, &deref->deref, state);
+}
+
+static void
+register_load_instr(nir_intrinsic_instr *load_instr, bool create_node,
+ struct lower_variables_state *state)
+{
+ struct deref_node *node = get_deref_node(load_instr->variables[0],
+ create_node, state);
+ if (node == NULL)
+ return;
+
+ if (node->loads == NULL)
+ node->loads = _mesa_set_create(state->dead_ctx,
+ _mesa_key_pointer_equal);
+
+ _mesa_set_add(node->loads, _mesa_hash_pointer(load_instr), load_instr);
+}
+
+static void
+register_store_instr(nir_intrinsic_instr *store_instr, bool create_node,
+ struct lower_variables_state *state)
+{
+ struct deref_node *node = get_deref_node(store_instr->variables[0],
+ create_node, state);
+ if (node == NULL)
+ return;
+
+ if (node->stores == NULL)
+ node->stores = _mesa_set_create(state->dead_ctx,
+ _mesa_key_pointer_equal);
+
+ _mesa_set_add(node->stores, _mesa_hash_pointer(store_instr), store_instr);
+}
+
+static void
+register_copy_instr(nir_intrinsic_instr *copy_instr, bool create_node,
+ struct lower_variables_state *state)
+{
+ for (unsigned idx = 0; idx < 2; idx++) {
+ struct deref_node *node = get_deref_node(copy_instr->variables[idx],
+ create_node, state);
+ if (node == NULL)
+ continue;
+
+ if (node->copies == NULL)
+ node->copies = _mesa_set_create(state->dead_ctx,
+ _mesa_key_pointer_equal);
+
+ _mesa_set_add(node->copies, _mesa_hash_pointer(copy_instr), copy_instr);
+ }
+}
+
+/* Registers all variable uses in the given block. */
+static bool
+register_variable_uses_block(nir_block *block, void *void_state)
+{
+ struct lower_variables_state *state = void_state;
+
+ nir_foreach_instr_safe(block, instr) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+ switch (intrin->intrinsic) {
+ case nir_intrinsic_load_var:
+ register_load_instr(intrin, true, state);
+ break;
+
+ case nir_intrinsic_store_var:
+ register_store_instr(intrin, true, state);
+ break;
+
+ case nir_intrinsic_copy_var:
+ register_copy_instr(intrin, true, state);
+ break;
+
+ default:
+ continue;
+ }
+ }
+
+ return true;
+}
+
+/* Walks down the deref chain and returns the next deref in the chain whose
+ * child is a wildcard. In other words, given the chain a[1].foo[*].bar,
+ * this function will return the deref to foo. Calling it a second time
+ * with the [*].bar, it will return NULL.
+ */
+static nir_deref *
+deref_next_wildcard_parent(nir_deref *deref)
+{
+ for (nir_deref *tail = deref; tail->child; tail = tail->child) {
+ if (tail->child->deref_type != nir_deref_type_array)
+ continue;
+
+ nir_deref_array *arr = nir_deref_as_array(tail->child);
+
+ if (arr->deref_array_type == nir_deref_array_type_wildcard)
+ return tail;
+ }
+
+ return NULL;
+}
+
+/* Returns the last deref in the chain.
+ */
+static nir_deref *
+get_deref_tail(nir_deref *deref)
+{
+ while (deref->child)
+ deref = deref->child;
+
+ return deref;
+}
+
+/* This function recursively walks the given deref chain and replaces the
+ * given copy instruction with an equivalent sequence load/store
+ * operations.
+ *
+ * @copy_instr The copy instruction to replace; new instructions will be
+ * inserted before this one
+ *
+ * @dest_head The head of the destination variable deref chain
+ *
+ * @src_head The head of the source variable deref chain
+ *
+ * @dest_tail The current tail of the destination variable deref chain;
+ * this is used for recursion and external callers of this
+ * function should call it with tail == head
+ *
+ * @src_tail The current tail of the source variable deref chain;
+ * this is used for recursion and external callers of this
+ * function should call it with tail == head
+ *
+ * @state The current variable lowering state
+ */
+static void
+emit_copy_load_store(nir_intrinsic_instr *copy_instr,
+ nir_deref_var *dest_head, nir_deref_var *src_head,
+ nir_deref *dest_tail, nir_deref *src_tail,
+ struct lower_variables_state *state)
+{
+ /* Find the next pair of wildcards */
+ nir_deref *src_arr_parent = deref_next_wildcard_parent(src_tail);
+ nir_deref *dest_arr_parent = deref_next_wildcard_parent(dest_tail);
+
+ if (src_arr_parent || dest_arr_parent) {
+ /* Wildcards had better come in matched pairs */
+ assert(dest_arr_parent && dest_arr_parent);
+
+ nir_deref_array *src_arr = nir_deref_as_array(src_arr_parent->child);
+ nir_deref_array *dest_arr = nir_deref_as_array(dest_arr_parent->child);
+
+ unsigned length = type_get_length(src_arr_parent->type);
+ /* The wildcards should represent the same number of elements */
+ assert(length == type_get_length(dest_arr_parent->type));
+ assert(length > 0);
+
+ /* Walk over all of the elements that this wildcard refers to and
+ * call emit_copy_load_store on each one of them */
+ src_arr->deref_array_type = nir_deref_array_type_direct;
+ dest_arr->deref_array_type = nir_deref_array_type_direct;
+ for (unsigned i = 0; i < length; i++) {
+ src_arr->base_offset = i;
+ dest_arr->base_offset = i;
+ emit_copy_load_store(copy_instr, dest_head, src_head,
+ &dest_arr->deref, &src_arr->deref, state);
+ }
+ src_arr->deref_array_type = nir_deref_array_type_wildcard;
+ dest_arr->deref_array_type = nir_deref_array_type_wildcard;
+ } else {
+ /* In this case, we have no wildcards anymore, so all we have to do
+ * is just emit the load and store operations. */
+ src_tail = get_deref_tail(src_tail);
+ dest_tail = get_deref_tail(dest_tail);
+
+ assert(src_tail->type == dest_tail->type);
+
+ unsigned num_components = glsl_get_vector_elements(src_tail->type);
+
+ nir_deref *src_deref = nir_copy_deref(state->mem_ctx, &src_head->deref);
+ nir_deref *dest_deref = nir_copy_deref(state->mem_ctx, &dest_head->deref);
+
+ nir_intrinsic_instr *load =
+ nir_intrinsic_instr_create(state->mem_ctx, nir_intrinsic_load_var);
+ load->num_components = num_components;
+ load->variables[0] = nir_deref_as_var(src_deref);
+ load->dest.is_ssa = true;
+ nir_ssa_def_init(&load->instr, &load->dest.ssa, num_components, NULL);
+
+ nir_instr_insert_before(©_instr->instr, &load->instr);
+ register_load_instr(load, false, state);
+
+ nir_intrinsic_instr *store =
+ nir_intrinsic_instr_create(state->mem_ctx, nir_intrinsic_store_var);
+ store->num_components = num_components;
+ store->variables[0] = nir_deref_as_var(dest_deref);
+ store->src[0].is_ssa = true;
+ store->src[0].ssa = &load->dest.ssa;
+
+ nir_instr_insert_before(©_instr->instr, &store->instr);
+ register_store_instr(store, false, state);
+ }
+}
+
+/* Walks over all of the copy instructions to or from the given deref_node
+ * and lowers them to load/store intrinsics.
+ */
+static bool
+lower_copies_to_load_store(struct deref_node *node,
+ struct lower_variables_state *state)
+{
+ if (!node->copies)
+ return true;
+
+ struct set_entry *copy_entry;
+ set_foreach(node->copies, copy_entry) {
+ nir_intrinsic_instr *copy = (void *)copy_entry->key;
+
+ emit_copy_load_store(copy, copy->variables[0], copy->variables[1],
+ ©->variables[0]->deref,
+ ©->variables[1]->deref,
+ state);
+
+ for (unsigned i = 0; i < 2; ++i) {
+ struct deref_node *arg_node = get_deref_node(copy->variables[i],
+ false, state);
+ if (arg_node == NULL)
+ continue;
+
+ struct set_entry *arg_entry = _mesa_set_search(arg_node->copies,
+ copy_entry->hash,
+ copy);
+ assert(arg_entry);
+ _mesa_set_remove(node->copies, arg_entry);
+ }
+
+ nir_instr_remove(©->instr);
+ }
+
+ return true;
+}
+
+/* Returns a load_const instruction that represents the constant
+ * initializer for the given deref chain. The caller is responsible for
+ * ensuring that there actually is a constant initializer.
+ */
+static nir_load_const_instr *
+get_const_initializer_load(const nir_deref_var *deref,
+ struct lower_variables_state *state)
+{
+ nir_constant *constant = deref->var->constant_initializer;
+ const nir_deref *tail = &deref->deref;
+ unsigned matrix_offset = 0;
+ while (tail->child) {
+ switch (tail->child->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *arr = nir_deref_as_array(tail->child);
+ assert(arr->deref_array_type == nir_deref_array_type_direct);
+ if (glsl_type_is_matrix(tail->type)) {
+ assert(arr->deref.child == NULL);
+ matrix_offset = arr->base_offset;
+ } else {
+ constant = constant->elements[arr->base_offset];
+ }
+ break;
+ }
+
+ case nir_deref_type_struct: {
+ constant = constant->elements[nir_deref_as_struct(tail->child)->index];
+ break;
+ }
+
+ default:
+ unreachable("Invalid deref child type");
+ }
+
+ tail = tail->child;
+ }
+
+ nir_load_const_instr *load =
+ nir_load_const_instr_create(state->mem_ctx,
+ glsl_get_vector_elements(tail->type));
+
+ matrix_offset *= load->def.num_components;
+ for (unsigned i = 0; i < load->def.num_components; i++) {
+ switch (glsl_get_base_type(tail->type)) {
+ case GLSL_TYPE_FLOAT:
+ case GLSL_TYPE_INT:
+ case GLSL_TYPE_UINT:
+ load->value.u[i] = constant->value.u[matrix_offset + i];
+ break;
+ case GLSL_TYPE_BOOL:
+ load->value.u[i] = constant->value.u[matrix_offset + i] ?
+ NIR_TRUE : NIR_FALSE;
+ break;
+ default:
+ unreachable("Invalid immediate type");
+ }
+ }
+
+ return load;
+}
+
+/** Pushes an SSA def onto the def stack for the given node
+ *
+ * Each node is potentially associated with a stack of SSA definitions.
+ * This stack is used for determining what SSA definition reaches a given
+ * point in the program for variable renaming. The stack is always kept in
+ * dominance-order with at most one SSA def per block. If the SSA
+ * definition on the top of the stack is in the same block as the one being
+ * pushed, the top element is replaced.
+ */
+static void
+def_stack_push(struct deref_node *node, nir_ssa_def *def,
+ struct lower_variables_state *state)
+{
+ if (node->def_stack == NULL) {
+ node->def_stack = ralloc_array(state->dead_ctx, nir_ssa_def *,
+ state->impl->num_blocks);
+ node->def_stack_tail = node->def_stack - 1;
+ }
+
+ if (node->def_stack_tail >= node->def_stack) {
+ nir_ssa_def *top_def = *node->def_stack_tail;
+
+ if (def->parent_instr->block == top_def->parent_instr->block) {
+ /* They're in the same block, just replace the top */
+ *node->def_stack_tail = def;
+ return;
+ }
+ }
+
+ *(++node->def_stack_tail) = def;
+}
+
+/* Pop the top of the def stack if it's in the given block */
+static void
+def_stack_pop_if_in_block(struct deref_node *node, nir_block *block)
+{
+ /* If we're popping, then we have presumably pushed at some time in the
+ * past so this should exist.
+ */
+ assert(node->def_stack != NULL);
+
+ /* The stack is already empty. Do nothing. */
+ if (node->def_stack_tail < node->def_stack)
+ return;
+
+ nir_ssa_def *def = *node->def_stack_tail;
+ if (def->parent_instr->block == block)
+ node->def_stack_tail--;
+}
+
+/** Retrieves the SSA definition on the top of the stack for the given
+ * node, if one exists. If the stack is empty, then we return the constant
+ * initializer (if it exists) or an SSA undef.
+ */
+static nir_ssa_def *
+get_ssa_def_for_block(struct deref_node *node, nir_block *block,
+ struct lower_variables_state *state)
+{
+ /* If we have something on the stack, go ahead and return it. We're
+ * assuming that the top of the stack dominates the given block.
+ */
+ if (node->def_stack && node->def_stack_tail >= node->def_stack)
+ return *node->def_stack_tail;
+
+ /* If we got here then we don't have a definition that dominates the
+ * given block. This means that we need to add an undef and use that.
+ */
+ nir_ssa_undef_instr *undef =
+ nir_ssa_undef_instr_create(state->mem_ctx,
+ glsl_get_vector_elements(node->type));
+ nir_instr_insert_before_cf_list(&state->impl->body, &undef->instr);
+ def_stack_push(node, &undef->def, state);
+ return &undef->def;
+}
+
+/* Given a block and one of its predecessors, this function fills in the
+ * souces of the phi nodes to take SSA defs from the given predecessor.
+ * This function must be called exactly once per block/predecessor pair.
+ */
+static void
+add_phi_sources(nir_block *block, nir_block *pred,
+ struct lower_variables_state *state)
+{
+ nir_foreach_instr(block, instr) {
+ if (instr->type != nir_instr_type_phi)
+ break;
+
+ nir_phi_instr *phi = nir_instr_as_phi(instr);
+
+ struct hash_entry *entry =
+ _mesa_hash_table_search(state->phi_table, phi);
+ if (!entry)
+ continue;
+
+ struct deref_node *node = entry->data;
+
+ nir_phi_src *src = ralloc(state->mem_ctx, nir_phi_src);
+ src->pred = pred;
+ src->src.is_ssa = true;
+ src->src.ssa = get_ssa_def_for_block(node, pred, state);
+
+ _mesa_set_add(src->src.ssa->uses, _mesa_hash_pointer(instr), instr);
+
+ exec_list_push_tail(&phi->srcs, &src->node);
+ }
+}
+
+/* Performs variable renaming by doing a DFS of the dominance tree
+ *
+ * This algorithm is very similar to the one outlined in "Efficiently
+ * Computing Static Single Assignment Form and the Control Dependence
+ * Graph" by Cytron et. al. The primary difference is that we only put one
+ * SSA def on the stack per block.
+ */
+static bool
+rename_variables_block(nir_block *block, struct lower_variables_state *state)
+{
+ nir_foreach_instr_safe(block, instr) {
+ if (instr->type == nir_instr_type_phi) {
+ nir_phi_instr *phi = nir_instr_as_phi(instr);
+
+ struct hash_entry *entry =
+ _mesa_hash_table_search(state->phi_table, phi);
+
+ /* This can happen if we already have phi nodes in the program
+ * that were not created in this pass.
+ */
+ if (!entry)
+ continue;
+
+ struct deref_node *node = entry->data;
+
+ def_stack_push(node, &phi->dest.ssa, state);
+ } else if (instr->type == nir_instr_type_intrinsic) {
+ nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+ switch (intrin->intrinsic) {
+ case nir_intrinsic_load_var: {
+ struct deref_node *node = get_deref_node(intrin->variables[0],
+ false, state);
+
+ if (node == NULL) {
+ /* If we hit this path then we are referencing an invalid
+ * value. Most likely, we unrolled something and are
+ * reading past the end of some array. In any case, this
+ * should result in an undefined value.
+ */
+ nir_ssa_undef_instr *undef =
+ nir_ssa_undef_instr_create(state->mem_ctx,
+ intrin->num_components);
+
+ nir_instr_insert_before(&intrin->instr, &undef->instr);
+ nir_instr_remove(&intrin->instr);
+
+ nir_src new_src = {
+ .is_ssa = true,
+ .ssa = &undef->def,
+ };
+
+ nir_ssa_def_rewrite_uses(&intrin->dest.ssa, new_src,
+ state->mem_ctx);
+ continue;
+ }
+
+ if (!node->lower_to_ssa)
+ continue;
+
+ nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx,
+ nir_op_imov);
+ mov->src[0].src.is_ssa = true;
+ mov->src[0].src.ssa = get_ssa_def_for_block(node, block, state);
+ for (unsigned i = intrin->num_components; i < 4; i++)
+ mov->src[0].swizzle[i] = 0;
+
+ assert(intrin->dest.is_ssa);
+
+ mov->dest.write_mask = (1 << intrin->num_components) - 1;
+ mov->dest.dest.is_ssa = true;
+ nir_ssa_def_init(&mov->instr, &mov->dest.dest.ssa,
+ intrin->num_components, NULL);
+
+ nir_instr_insert_before(&intrin->instr, &mov->instr);
+ nir_instr_remove(&intrin->instr);
+
+ nir_src new_src = {
+ .is_ssa = true,
+ .ssa = &mov->dest.dest.ssa,
+ };
+
+ nir_ssa_def_rewrite_uses(&intrin->dest.ssa, new_src,
+ state->mem_ctx);
+ break;
+ }
+
+ case nir_intrinsic_store_var: {
+ struct deref_node *node = get_deref_node(intrin->variables[0],
+ false, state);
+
+ if (node == NULL) {
+ /* Probably an out-of-bounds array store. That should be a
+ * no-op. */
+ nir_instr_remove(&intrin->instr);
+ continue;
+ }
+
+ if (!node->lower_to_ssa)
+ continue;
+
+ assert(intrin->num_components ==
+ glsl_get_vector_elements(node->type));
+
+ assert(intrin->src[0].is_ssa);
+
+ nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx,
+ nir_op_imov);
+ mov->src[0].src.is_ssa = true;
+ mov->src[0].src.ssa = intrin->src[0].ssa;
+ for (unsigned i = intrin->num_components; i < 4; i++)
+ mov->src[0].swizzle[i] = 0;
+
+ mov->dest.write_mask = (1 << intrin->num_components) - 1;
+ mov->dest.dest.is_ssa = true;
+ nir_ssa_def_init(&mov->instr, &mov->dest.dest.ssa,
+ intrin->num_components, NULL);
+
+ nir_instr_insert_before(&intrin->instr, &mov->instr);
+
+ def_stack_push(node, &mov->dest.dest.ssa, state);
+
+ /* We'll wait to remove the instruction until the next pass
+ * where we pop the node we just pushed back off the stack.
+ */
+ break;
+ }
+
+ default:
+ break;
+ }
+ }
+ }
+
+ if (block->successors[0])
+ add_phi_sources(block->successors[0], block, state);
+ if (block->successors[1])
+ add_phi_sources(block->successors[1], block, state);
+
+ for (unsigned i = 0; i < block->num_dom_children; ++i)
+ rename_variables_block(block->dom_children[i], state);
+
+ /* Now we iterate over the instructions and pop off any SSA defs that we
+ * pushed in the first loop.
+ */
+ nir_foreach_instr_safe(block, instr) {
+ if (instr->type == nir_instr_type_phi) {
+ nir_phi_instr *phi = nir_instr_as_phi(instr);
+
+ struct hash_entry *entry =
+ _mesa_hash_table_search(state->phi_table, phi);
+
+ /* This can happen if we already have phi nodes in the program
+ * that were not created in this pass.
+ */
+ if (!entry)
+ continue;
+
+ struct deref_node *node = entry->data;
+
+ def_stack_pop_if_in_block(node, block);
+ } else if (instr->type == nir_instr_type_intrinsic) {
+ nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+ if (intrin->intrinsic != nir_intrinsic_store_var)
+ continue;
+
+ struct deref_node *node = get_deref_node(intrin->variables[0],
+ false, state);
+ if (!node)
+ continue;
+
+ if (!node->lower_to_ssa)
+ continue;
+
+ def_stack_pop_if_in_block(node, block);
+ nir_instr_remove(&intrin->instr);
+ }
+ }
+
+ return true;
+}
+
+/* Inserts phi nodes for all variables marked lower_to_ssa
+ *
+ * This is the same algorithm as presented in "Efficiently Computing Static
+ * Single Assignment Form and the Control Dependence Graph" by Cytron et.
+ * al.
+ */
+static void
+insert_phi_nodes(struct lower_variables_state *state)
+{
+ unsigned work[state->impl->num_blocks];
+ unsigned has_already[state->impl->num_blocks];
+
+ /*
+ * Since the work flags already prevent us from inserting a node that has
+ * ever been inserted into W, we don't need to use a set to represent W.
+ * Also, since no block can ever be inserted into W more than once, we know
+ * that the maximum size of W is the number of basic blocks in the
+ * function. So all we need to handle W is an array and a pointer to the
+ * next element to be inserted and the next element to be removed.
+ */
+ nir_block *W[state->impl->num_blocks];
+
+ memset(work, 0, sizeof work);
+ memset(has_already, 0, sizeof has_already);
+
+ unsigned w_start, w_end;
+ unsigned iter_count = 0;
+
+ struct hash_entry *deref_entry;
+ hash_table_foreach(state->direct_deref_nodes, deref_entry) {
+ struct deref_node *node = deref_entry->data;
+
+ if (node->stores == NULL)
+ continue;
+
+ if (!node->lower_to_ssa)
+ continue;
+
+ w_start = w_end = 0;
+ iter_count++;
+
+ struct set_entry *store_entry;
+ set_foreach(node->stores, store_entry) {
+ nir_intrinsic_instr *store = (nir_intrinsic_instr *)store_entry->key;
+ if (work[store->instr.block->index] < iter_count)
+ W[w_end++] = store->instr.block;
+ work[store->instr.block->index] = iter_count;
+ }
+
+ while (w_start != w_end) {
+ nir_block *cur = W[w_start++];
+ struct set_entry *dom_entry;
+ set_foreach(cur->dom_frontier, dom_entry) {
+ nir_block *next = (nir_block *) dom_entry->key;
+
+ /*
+ * If there's more than one return statement, then the end block
+ * can be a join point for some definitions. However, there are
+ * no instructions in the end block, so nothing would use those
+ * phi nodes. Of course, we couldn't place those phi nodes
+ * anyways due to the restriction of having no instructions in the
+ * end block...
+ */
+ if (next == state->impl->end_block)
+ continue;
+
+ if (has_already[next->index] < iter_count) {
+ nir_phi_instr *phi = nir_phi_instr_create(state->mem_ctx);
+ phi->dest.is_ssa = true;
+ nir_ssa_def_init(&phi->instr, &phi->dest.ssa,
+ glsl_get_vector_elements(node->type), NULL);
+ nir_instr_insert_before_block(next, &phi->instr);
+
+ _mesa_hash_table_insert(state->phi_table, phi, node);
+
+ has_already[next->index] = iter_count;
+ if (work[next->index] < iter_count) {
+ work[next->index] = iter_count;
+ W[w_end++] = next;
+ }
+ }
+ }
+ }
+ }
+}
+
+
+/** Implements a pass to lower variable uses to SSA values
+ *
+ * This path walks the list of instructions and tries to lower as many
+ * local variable load/store operations to SSA defs and uses as it can.
+ * The process involves four passes:
+ *
+ * 1) Iterate over all of the instructions and mark where each local
+ * variable deref is used in a load, store, or copy. While we're at
+ * it, we keep track of all of the fully-qualified (no wildcards) and
+ * fully-direct references we see and store them in the
+ * direct_deref_nodes hash table.
+ *
+ * 2) Walk over the the list of fully-qualified direct derefs generated in
+ * the previous pass. For each deref, we determine if it can ever be
+ * aliased, i.e. if there is an indirect reference anywhere that may
+ * refer to it. If it cannot be aliased, we mark it for lowering to an
+ * SSA value. At this point, we lower any var_copy instructions that
+ * use the given deref to load/store operations and, if the deref has a
+ * constant initializer, we go ahead and add a load_const value at the
+ * beginning of the function with the initialized value.
+ *
+ * 3) Walk over the list of derefs we plan to lower to SSA values and
+ * insert phi nodes as needed.
+ *
+ * 4) Perform "variable renaming" by replacing the load/store instructions
+ * with SSA definitions and SSA uses.
+ */
+static bool
+nir_lower_vars_to_ssa_impl(nir_function_impl *impl)
+{
+ struct lower_variables_state state;
+
+ state.mem_ctx = ralloc_parent(impl);
+ state.dead_ctx = ralloc_context(state.mem_ctx);
+ state.impl = impl;
+
+ state.deref_var_nodes = _mesa_hash_table_create(state.dead_ctx,
+ _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+ state.direct_deref_nodes = _mesa_hash_table_create(state.dead_ctx,
+ hash_deref, derefs_equal);
+ state.phi_table = _mesa_hash_table_create(state.dead_ctx,
+ _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+
+ nir_foreach_block(impl, register_variable_uses_block, &state);
+
+ struct set *outputs = _mesa_set_create(state.dead_ctx,
+ _mesa_key_pointer_equal);
+
+ bool progress = false;
+
+ nir_metadata_require(impl, nir_metadata_block_index);
+
+ struct hash_entry *entry;
+ hash_table_foreach(state.direct_deref_nodes, entry) {
+ nir_deref_var *deref = (void *)entry->key;
+ struct deref_node *node = entry->data;
+
+ if (deref->var->data.mode != nir_var_local) {
+ _mesa_hash_table_remove(state.direct_deref_nodes, entry);
+ continue;
+ }
+
+ if (deref_may_be_aliased(deref, &state)) {
+ _mesa_hash_table_remove(state.direct_deref_nodes, entry);
+ continue;
+ }
+
+ node->lower_to_ssa = true;
+ progress = true;
+
+ if (deref->var->constant_initializer) {
+ nir_load_const_instr *load = get_const_initializer_load(deref, &state);
+ nir_ssa_def_init(&load->instr, &load->def,
+ glsl_get_vector_elements(node->type), NULL);
+ nir_instr_insert_before_cf_list(&impl->body, &load->instr);
+ def_stack_push(node, &load->def, &state);
+ }
+
+ if (deref->var->data.mode == nir_var_shader_out)
+ _mesa_set_add(outputs, _mesa_hash_pointer(node), node);
+
+ foreach_deref_node_match(deref, lower_copies_to_load_store, &state);
+ }
+
+ if (!progress)
+ return false;
+
+ nir_metadata_require(impl, nir_metadata_dominance);
+
+ insert_phi_nodes(&state);
+ rename_variables_block(impl->start_block, &state);
+
+ nir_metadata_preserve(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+
+ ralloc_free(state.dead_ctx);
+
+ return progress;
+}
+
+void
+nir_lower_vars_to_ssa(nir_shader *shader)
+{
+ nir_foreach_overload(shader, overload) {
+ if (overload->impl)
+ nir_lower_vars_to_ssa_impl(overload->impl);
+ }
+}
bool progress;
do {
progress = false;
- nir_lower_variables(nir);
+ nir_lower_vars_to_ssa(nir);
nir_validate_shader(nir);
progress |= nir_copy_prop(nir);
nir_validate_shader(nir);
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