[Mesa-dev] [PATCH v2 08/11] nir: Add a array-of-vector variable shrinking pass
Jason Ekstrand
jason at jlekstrand.net
Sun Jul 29 05:44:39 UTC 2018
This pass looks for variables with vector or array-of-vector types and
narrows the type to only the components used.
---
src/compiler/nir/nir.h | 1 +
src/compiler/nir/nir_split_vars.c | 694 ++++++++++++++++++++++++++++++
2 files changed, 695 insertions(+)
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index c6ed5bb5358..04ddd773af8 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2607,6 +2607,7 @@ void nir_dump_cfg(nir_shader *shader, FILE *fp);
int nir_gs_count_vertices(const nir_shader *shader);
+bool nir_shrink_vec_array_vars(nir_shader *shader, nir_variable_mode modes);
bool nir_split_array_vars(nir_shader *shader, nir_variable_mode modes);
bool nir_split_var_copies(nir_shader *shader);
bool nir_split_per_member_structs(nir_shader *shader);
diff --git a/src/compiler/nir/nir_split_vars.c b/src/compiler/nir/nir_split_vars.c
index f55f5c5eb7f..e2d03b517a7 100644
--- a/src/compiler/nir/nir_split_vars.c
+++ b/src/compiler/nir/nir_split_vars.c
@@ -26,6 +26,9 @@
#include "nir_deref.h"
#include "nir_vla.h"
+/* Needed for _mesa_bitcount() */
+#include "main/macros.h"
+
struct split_var_state {
void *mem_ctx;
@@ -852,3 +855,694 @@ nir_split_array_vars(nir_shader *shader, nir_variable_mode modes)
return progress;
}
+
+struct array_level_usage {
+ unsigned array_len;
+
+ /* The value UINT_MAX will be used to indicate an indirect */
+ unsigned max_read;
+ unsigned max_written;
+
+ /* True if there is a copy that isn't to/from a shrinkable array */
+ bool has_external_copy;
+ struct set *levels_copied;
+};
+
+struct vec_var_usage {
+ nir_component_mask_t comps_read;
+ nir_component_mask_t comps_written;
+
+ nir_component_mask_t comps_kept;
+
+ /* True if there is a copy that isn't to/from a shrinkable vector */
+ bool has_external_copy;
+ struct set *vars_copied;
+
+ unsigned num_levels;
+ struct array_level_usage levels[0];
+};
+
+static struct vec_var_usage *
+get_vec_var_usage(nir_variable *var,
+ struct hash_table *var_usage_map,
+ bool add_usage_entry, void *mem_ctx)
+{
+ struct hash_entry *entry = _mesa_hash_table_search(var_usage_map, var);
+ if (entry)
+ return entry->data;
+
+ if (!add_usage_entry)
+ return NULL;
+
+ /* Check to make sure that we are working with an array of vectors. We
+ * don't bother to shrink single vectors because we figure that we can
+ * clean it up better with SSA than by inserting piles of vecN instructions
+ * to compact results.
+ */
+ int num_levels = num_array_levels_in_array_of_vector_type(var->type);
+ if (num_levels < 1)
+ return NULL; /* Not an array of vectors */
+
+ struct vec_var_usage *usage =
+ rzalloc_size(mem_ctx, sizeof(*usage) +
+ num_levels * sizeof(usage->levels[0]));
+
+ usage->num_levels = num_levels;
+ const struct glsl_type *type = var->type;
+ for (unsigned i = 0; i < num_levels; i++) {
+ usage->levels[i].array_len = glsl_get_length(type);
+ type = glsl_get_array_element(type);
+ }
+ assert(glsl_type_is_vector_or_scalar(type));
+
+ _mesa_hash_table_insert(var_usage_map, var, usage);
+
+ return usage;
+}
+
+static struct vec_var_usage *
+get_vec_deref_usage(nir_deref_instr *deref,
+ struct hash_table *var_usage_map,
+ nir_variable_mode modes,
+ bool add_usage_entry, void *mem_ctx)
+{
+ if (!(deref->mode & modes))
+ return NULL;
+
+ return get_vec_var_usage(nir_deref_instr_get_variable(deref),
+ var_usage_map, add_usage_entry, mem_ctx);
+}
+
+static void
+mark_deref_used(nir_deref_instr *deref,
+ nir_component_mask_t comps_read,
+ nir_component_mask_t comps_written,
+ nir_deref_instr *copy_deref,
+ struct hash_table *var_usage_map,
+ nir_variable_mode modes,
+ void *mem_ctx)
+{
+ if (!(deref->mode & modes))
+ return;
+
+ nir_variable *var = nir_deref_instr_get_variable(deref);
+
+ struct vec_var_usage *usage =
+ get_vec_var_usage(var, var_usage_map, true, mem_ctx);
+ if (!usage)
+ return;
+
+ const unsigned num_var_components =
+ glsl_get_components(glsl_without_array_or_matrix(var->type));
+
+ usage->comps_read |= comps_read & ((1u << num_var_components) - 1);
+ usage->comps_written |= comps_written & ((1u << num_var_components) - 1);
+
+ struct vec_var_usage *copy_usage = NULL;
+ if (copy_deref) {
+ copy_usage = get_vec_deref_usage(copy_deref, var_usage_map, modes,
+ true, mem_ctx);
+ if (copy_usage) {
+ if (usage->vars_copied == NULL) {
+ usage->vars_copied = _mesa_set_create(mem_ctx, _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+ }
+ _mesa_set_add(usage->vars_copied, copy_usage);
+ } else {
+ usage->has_external_copy = true;
+ }
+ }
+
+ nir_deref_path path;
+ nir_deref_path_init(&path, deref, mem_ctx);
+
+ nir_deref_path copy_path;
+ if (copy_usage)
+ nir_deref_path_init(©_path, copy_deref, mem_ctx);
+
+ unsigned copy_i = 0;
+ for (unsigned i = 0; i < usage->num_levels; i++) {
+ struct array_level_usage *level = &usage->levels[i];
+ nir_deref_instr *deref = path.path[i + 1];
+ assert(deref->deref_type == nir_deref_type_array ||
+ deref->deref_type == nir_deref_type_array_wildcard);
+
+ unsigned max_used;
+ if (deref->deref_type == nir_deref_type_array) {
+ nir_const_value *const_index =
+ nir_src_as_const_value(deref->arr.index);
+ max_used = const_index ? const_index->u32[0] : UINT_MAX;
+ } else {
+ /* For wildcards, we read or wrote the whole thing. */
+ assert(deref->deref_type == nir_deref_type_array_wildcard);
+ max_used = level->array_len - 1;
+
+ if (copy_usage) {
+ /* Match each wildcard level with the level on copy_usage */
+ for (; copy_path.path[copy_i + 1]; copy_i++) {
+ if (copy_path.path[copy_i + 1]->deref_type ==
+ nir_deref_type_array_wildcard)
+ break;
+ }
+ struct array_level_usage *copy_level =
+ ©_usage->levels[copy_i++];
+
+ if (level->levels_copied == NULL) {
+ level->levels_copied =
+ _mesa_set_create(mem_ctx, _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+ }
+ _mesa_set_add(level->levels_copied, copy_level);
+ } else {
+ /* We have a wildcard and we don't know where this copy came from,
+ * flag it and we'll know to not shorten this array.
+ */
+ level->has_external_copy = true;
+ }
+ }
+
+ if (comps_written)
+ level->max_written = MAX2(level->max_written, max_used);
+ if (comps_read)
+ level->max_read = MAX2(level->max_read, max_used);
+ }
+}
+
+static bool
+src_is_load_deref(nir_src src, nir_src deref_src)
+{
+ assert(src.is_ssa);
+ assert(deref_src.is_ssa);
+
+ if (src.ssa->parent_instr->type != nir_instr_type_intrinsic)
+ return false;
+
+ nir_intrinsic_instr *load = nir_instr_as_intrinsic(src.ssa->parent_instr);
+ if (load->intrinsic != nir_intrinsic_load_deref)
+ return false;
+
+ assert(load->src[0].is_ssa);
+
+ return load->src[0].ssa == deref_src.ssa;
+}
+
+/* Returns all non-self-referential components of a store instruction. A
+ * component is self-referential if it comes from the same component of a load
+ * instruction on the same deref. If the only data in a particular component
+ * of a variable came directly from that component then it's undefined. The
+ * only way to get defined data into a component of a variable is for it to
+ * get written there by something outside or from a different component.
+ *
+ * This is a fairly common pattern in shaders that come from either GLSL IR or
+ * GLSLang because both glsl_to_nir and GLSLang implement write-masking with
+ * load-vec-store.
+ */
+static nir_component_mask_t
+get_non_self_referential_store_comps(nir_intrinsic_instr *store)
+{
+ nir_component_mask_t comps = nir_intrinsic_write_mask(store);
+
+ assert(store->src[1].is_ssa);
+ nir_instr *src_instr = store->src[1].ssa->parent_instr;
+ if (src_instr->type != nir_instr_type_alu)
+ return comps;
+
+ nir_alu_instr *src_alu = nir_instr_as_alu(src_instr);
+
+ if (src_alu->op == nir_op_imov ||
+ src_alu->op == nir_op_fmov) {
+ /* If it's just a swizzle of a load from the same deref, discount any
+ * channels that don't move in the swizzle.
+ */
+ if (src_is_load_deref(src_alu->src[0].src, store->src[0])) {
+ for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++) {
+ if (src_alu->src[0].swizzle[i] == i)
+ comps &= ~(1u << i);
+ }
+ }
+ } else if (src_alu->op == nir_op_vec2 ||
+ src_alu->op == nir_op_vec3 ||
+ src_alu->op == nir_op_vec4) {
+ /* If it's a vec, discount any channels that are just loads from the
+ * same deref put in the same spot.
+ */
+ for (unsigned i = 0; i < nir_op_infos[src_alu->op].num_inputs; i++) {
+ if (src_is_load_deref(src_alu->src[i].src, store->src[0]) &&
+ src_alu->src[i].swizzle[0] == i)
+ comps &= ~(1u << i);
+ }
+ }
+
+ return comps;
+}
+
+static void
+find_used_components_impl(nir_function_impl *impl,
+ struct hash_table *var_usage_map,
+ nir_variable_mode modes,
+ void *mem_ctx)
+{
+ nir_foreach_block(block, impl) {
+ 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_deref:
+ mark_deref_used(nir_src_as_deref(intrin->src[0]),
+ nir_ssa_def_components_read(&intrin->dest.ssa), 0,
+ NULL, var_usage_map, modes, mem_ctx);
+ break;
+
+ case nir_intrinsic_store_deref:
+ mark_deref_used(nir_src_as_deref(intrin->src[0]),
+ 0, get_non_self_referential_store_comps(intrin),
+ NULL, var_usage_map, modes, mem_ctx);
+ break;
+
+ case nir_intrinsic_copy_deref: {
+ /* Just mark everything used for copies. */
+ nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
+ nir_deref_instr *src = nir_src_as_deref(intrin->src[1]);
+ mark_deref_used(dst, 0, ~0, src, var_usage_map, modes, mem_ctx);
+ mark_deref_used(src, ~0, 0, dst, var_usage_map, modes, mem_ctx);
+ break;
+ }
+
+ default:
+ break;
+ }
+ }
+ }
+}
+
+static bool
+shrink_vec_var_list(struct exec_list *vars,
+ struct hash_table *var_usage_map)
+{
+ /* Initialize the components kept field of each variable. This is the
+ * AND of the components written and components read. If a component is
+ * written but never read, it's dead. If it is read but never written,
+ * then all values read are undefined garbage and we may as well not read
+ * them.
+ *
+ * The same logic applies to the array length. We make the array length
+ * the minimum needed required length between read and write and plan to
+ * discard any OOB access. The one exception here is indirect writes
+ * because we don't know where they will land and we can't shrink an array
+ * with indirect writes because previously in-bounds writes may become
+ * out-of-bounds and have undefined behavior.
+ *
+ * Also, if we have a copy that to/from something we can't shrink, we need
+ * to leave components and array_len of any wildcards alone.
+ */
+ nir_foreach_variable(var, vars) {
+ struct vec_var_usage *usage =
+ get_vec_var_usage(var, var_usage_map, false, NULL);
+ if (!usage)
+ continue;
+
+ const unsigned var_num_components =
+ glsl_get_components(glsl_without_array_or_matrix(var->type));
+
+ assert(usage->comps_kept == 0);
+ if (usage->has_external_copy)
+ usage->comps_kept = (1u << var_num_components) - 1;
+ else
+ usage->comps_kept = usage->comps_read & usage->comps_written;
+
+ for (unsigned i = 0; i < usage->num_levels; i++) {
+ struct array_level_usage *level = &usage->levels[i];
+ assert(level->array_len > 0);
+
+ if (level->max_written == UINT_MAX || level->has_external_copy)
+ continue; /* Can't shrink */
+
+ unsigned max_used = MIN2(level->max_read, level->max_written);
+ level->array_len = MIN2(max_used, level->array_len - 1) + 1;
+ }
+ }
+
+ /* In order for variable copies to work, we have to have the same data type
+ * on the source and the destination. In order to satisfy this, we run a
+ * little fixed-point algorithm to transitively ensure that we get enough
+ * components and array elements for this to hold for all copies.
+ */
+ bool fp_progress;
+ do {
+ fp_progress = false;
+ nir_foreach_variable(var, vars) {
+ struct vec_var_usage *var_usage =
+ get_vec_var_usage(var, var_usage_map, false, NULL);
+ if (!var_usage || !var_usage->vars_copied)
+ continue;
+
+ struct set_entry *copy_entry;
+ set_foreach(var_usage->vars_copied, copy_entry) {
+ const struct vec_var_usage *copy_usage = copy_entry->key;
+ if (copy_usage->comps_kept & ~var_usage->comps_kept) {
+ var_usage->comps_kept |= copy_usage->comps_kept;
+ fp_progress = true;
+ }
+ }
+
+ for (unsigned i = 0; i < var_usage->num_levels; i++) {
+ struct array_level_usage *var_level = &var_usage->levels[i];
+ if (!var_level->levels_copied)
+ continue;
+
+ set_foreach(var_level->levels_copied, copy_entry) {
+ const struct array_level_usage *copy_level = copy_entry->key;
+ if (var_level->array_len < copy_level->array_len) {
+ var_level->array_len = copy_level->array_len;
+ fp_progress = true;
+ }
+ }
+ }
+ }
+ } while (fp_progress);
+
+ bool vars_shrunk = false;
+ nir_foreach_variable_safe(var, vars) {
+ struct vec_var_usage *usage =
+ get_vec_var_usage(var, var_usage_map, false, NULL);
+ if (!usage)
+ continue;
+
+ bool shrunk = false;
+ const struct glsl_type *vec_type = var->type;
+ for (unsigned i = 0; i < usage->num_levels; i++) {
+ /* If we've reduced the array to zero elements at some level, just
+ * set comps_kept to 0 and delete the variable.
+ */
+ if (usage->levels[i].array_len == 0)
+ usage->comps_kept = 0;
+
+ assert(usage->levels[i].array_len <= glsl_get_length(vec_type));
+ if (usage->levels[i].array_len < glsl_get_length(vec_type))
+ shrunk = true;
+ vec_type = glsl_get_array_element(vec_type);
+ }
+ assert(glsl_type_is_vector_or_scalar(vec_type));
+
+ assert(usage->comps_kept < (1u << glsl_get_components(vec_type)));
+ if (usage->comps_kept != (1u << glsl_get_components(vec_type)) - 1)
+ shrunk = true;
+
+ if (usage->comps_kept == 0) {
+ /* This variable is dead, remove it */
+ vars_shrunk = true;
+ exec_node_remove(&var->node);
+ continue;
+ }
+
+ if (!shrunk) {
+ /* This variable doesn't need to be shrunk. Remove it from the
+ * hash table so later passes will ignore it.
+ */
+ _mesa_hash_table_remove_key(var_usage_map, var);
+ continue;
+ }
+
+ /* Build the new var type */
+ unsigned new_num_comps = _mesa_bitcount(usage->comps_kept);
+ const struct glsl_type *new_type =
+ glsl_vector_type(glsl_get_base_type(vec_type), new_num_comps);
+ for (int i = usage->num_levels - 1; i >= 0; i--) {
+ assert(usage->levels[i].array_len > 0);
+ /* If the original type was a matrix type, we'd like to keep that so
+ * we don't convert matrices into arrays.
+ */
+ if (i == usage->num_levels - 1 &&
+ glsl_type_is_matrix(glsl_without_array(var->type)) &&
+ new_num_comps > 1 && usage->levels[i].array_len > 1) {
+ new_type = glsl_matrix_type(glsl_get_base_type(new_type),
+ new_num_comps,
+ usage->levels[i].array_len);
+ } else {
+ new_type = glsl_array_type(new_type, usage->levels[i].array_len);
+ }
+ }
+ var->type = new_type;
+
+ vars_shrunk = true;
+ }
+
+ return vars_shrunk;
+}
+
+static bool
+vec_deref_is_oob(nir_deref_instr *deref,
+ struct vec_var_usage *usage)
+{
+ nir_deref_path path;
+ nir_deref_path_init(&path, deref, NULL);
+
+ bool oob = false;
+ for (unsigned i = 0; i < usage->num_levels; i++) {
+ nir_deref_instr *p = path.path[i + 1];
+ if (p->deref_type == nir_deref_type_array_wildcard)
+ continue;
+
+ nir_const_value *const_index = nir_src_as_const_value(p->arr.index);
+ if (const_index && const_index->u32[0] >= usage->levels[i].array_len) {
+ oob = true;
+ break;
+ }
+ }
+
+ nir_deref_path_finish(&path);
+
+ return oob;
+}
+
+static bool
+vec_deref_is_dead_or_oob(nir_deref_instr *deref,
+ struct hash_table *var_usage_map,
+ nir_variable_mode modes)
+{
+ struct vec_var_usage *usage =
+ get_vec_deref_usage(deref, var_usage_map, modes, false, NULL);
+ if (!usage)
+ return false;
+
+ return usage->comps_kept == 0 || vec_deref_is_oob(deref, usage);
+}
+
+static void
+shrink_vec_var_access_impl(nir_function_impl *impl,
+ struct hash_table *var_usage_map,
+ nir_variable_mode modes)
+{
+ nir_builder b;
+ nir_builder_init(&b, impl);
+
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr_safe(instr, block) {
+ switch (instr->type) {
+ case nir_instr_type_deref: {
+ nir_deref_instr *deref = nir_instr_as_deref(instr);
+ if (!(deref->mode & modes))
+ break;
+
+ /* Clean up any dead derefs we find lying around. They may refer
+ * to variables we've deleted.
+ */
+ if (nir_deref_instr_remove_if_unused(deref))
+ break;
+
+ /* We don't need to check if this is one of the derefs we're
+ * shrinking because this is a no-op if it isn't. The worst that
+ * could happen is that we accidentally fix an invalid deref.
+ */
+ if (deref->deref_type == nir_deref_type_var) {
+ deref->type = deref->var->type;
+ } else if (deref->deref_type == nir_deref_type_array ||
+ deref->deref_type == nir_deref_type_array_wildcard) {
+ nir_deref_instr *parent = nir_deref_instr_parent(deref);
+ assert(glsl_type_is_array(parent->type) ||
+ glsl_type_is_matrix(parent->type));
+ deref->type = glsl_get_array_element(parent->type);
+ }
+ break;
+ }
+
+ case nir_instr_type_intrinsic: {
+ nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+ /* If we have a copy whose source or destination has been deleted
+ * because we determined the variable was dead, then we just
+ * delete the copy instruction. If the source variable was dead
+ * then it was writing undefined garbage anyway and if it's the
+ * destination variable that's dead then the write isn't needed.
+ */
+ if (intrin->intrinsic == nir_intrinsic_copy_deref) {
+ nir_deref_instr *dst = nir_src_as_deref(intrin->src[0]);
+ nir_deref_instr *src = nir_src_as_deref(intrin->src[1]);
+ if (vec_deref_is_dead_or_oob(dst, var_usage_map, modes) ||
+ vec_deref_is_dead_or_oob(src, var_usage_map, modes)) {
+ nir_instr_remove(&intrin->instr);
+ nir_deref_instr_remove_if_unused(dst);
+ nir_deref_instr_remove_if_unused(src);
+ }
+ continue;
+ }
+
+ if (intrin->intrinsic != nir_intrinsic_load_deref &&
+ intrin->intrinsic != nir_intrinsic_store_deref)
+ continue;
+
+ nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
+ if (!(deref->mode & modes))
+ continue;
+
+ struct vec_var_usage *usage =
+ get_vec_deref_usage(deref, var_usage_map, modes, false, NULL);
+ if (!usage)
+ continue;
+
+ if (usage->comps_kept == 0 || vec_deref_is_oob(deref, usage)) {
+ if (intrin->intrinsic == nir_intrinsic_load_deref) {
+ nir_ssa_def *u =
+ nir_ssa_undef(&b, intrin->dest.ssa.num_components,
+ intrin->dest.ssa.bit_size);
+ nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
+ nir_src_for_ssa(u));
+ }
+ nir_instr_remove(&intrin->instr);
+ nir_deref_instr_remove_if_unused(deref);
+ continue;
+ }
+
+ if (intrin->intrinsic == nir_intrinsic_load_deref) {
+ b.cursor = nir_after_instr(&intrin->instr);
+
+ nir_ssa_def *undef =
+ nir_ssa_undef(&b, 1, intrin->dest.ssa.bit_size);
+ nir_ssa_def *vec_srcs[NIR_MAX_VEC_COMPONENTS];
+ unsigned c = 0;
+ for (unsigned i = 0; i < intrin->num_components; i++) {
+ if (usage->comps_kept & (1u << i))
+ vec_srcs[i] = nir_channel(&b, &intrin->dest.ssa, c++);
+ else
+ vec_srcs[i] = undef;
+ }
+ nir_ssa_def *vec = nir_vec(&b, vec_srcs, intrin->num_components);
+
+ nir_ssa_def_rewrite_uses_after(&intrin->dest.ssa,
+ nir_src_for_ssa(vec),
+ vec->parent_instr);
+
+ /* The SSA def is now only used by the swizzle. It's safe to
+ * shrink the number of components.
+ */
+ assert(list_is_singular(&intrin->dest.ssa.uses));
+ intrin->num_components = c;
+ intrin->dest.ssa.num_components = c;
+ } else {
+ nir_component_mask_t write_mask =
+ nir_intrinsic_write_mask(intrin);
+
+ unsigned swizzle[NIR_MAX_VEC_COMPONENTS];
+ nir_component_mask_t new_write_mask = 0;
+ unsigned c = 0;
+ for (unsigned i = 0; i < intrin->num_components; i++) {
+ if (usage->comps_kept & (1u << i)) {
+ swizzle[c] = i;
+ if (write_mask & (1u << i))
+ new_write_mask |= 1u << c;
+ c++;
+ }
+ }
+
+ b.cursor = nir_before_instr(&intrin->instr);
+
+ nir_ssa_def *swizzled =
+ nir_swizzle(&b, intrin->src[1].ssa, swizzle, c, false);
+
+ /* Rewrite to use the compacted source */
+ nir_instr_rewrite_src(&intrin->instr, &intrin->src[1],
+ nir_src_for_ssa(swizzled));
+ nir_intrinsic_set_write_mask(intrin, new_write_mask);
+ intrin->num_components = c;
+ }
+ break;
+ }
+
+ default:
+ break;
+ }
+ }
+ }
+}
+
+/** Attempt to shrink arrays of vectors
+ *
+ * This pass looks at variables which contain a vector or an array (possibly
+ * multiple dimensions) of vectors and attempts to lower to a smaller vector
+ * or array. If the pass can prove that a component of a vector (or array of
+ * vectors) is never really used, then that component will be removed.
+ * Similarly, the pass attempts to shorten arrays based on what elements it
+ * can prove are never read or never contain valid data.
+ */
+bool
+nir_shrink_vec_array_vars(nir_shader *shader, nir_variable_mode modes)
+{
+ assert((modes & (nir_var_global | nir_var_local)) == modes);
+
+ void *mem_ctx = ralloc_context(NULL);
+
+ struct hash_table *var_usage_map =
+ _mesa_hash_table_create(mem_ctx, _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+
+ bool has_vars_to_shrink = false;
+ nir_foreach_function(function, shader) {
+ if (!function->impl)
+ continue;
+
+ /* Don't even bother crawling the IR if we don't have any variables.
+ * Given that this pass deletes any unused variables, it's likely that
+ * we will be in this scenario eventually.
+ */
+ if (!exec_list_is_empty(&shader->globals) ||
+ !exec_list_is_empty(&function->impl->locals)) {
+ has_vars_to_shrink = true;
+ find_used_components_impl(function->impl, var_usage_map,
+ modes, mem_ctx);
+ }
+ }
+ if (!has_vars_to_shrink) {
+ ralloc_free(mem_ctx);
+ return false;
+ }
+
+ bool globals_shrunk = false;
+ if (modes & nir_var_global)
+ globals_shrunk = shrink_vec_var_list(&shader->globals, var_usage_map);
+
+ bool progress = false;
+ nir_foreach_function(function, shader) {
+ if (!function->impl)
+ continue;
+
+ bool locals_shrunk = false;
+ if (modes & nir_var_local) {
+ locals_shrunk = shrink_vec_var_list(&function->impl->locals,
+ var_usage_map);
+ }
+
+ if (globals_shrunk || locals_shrunk) {
+ shrink_vec_var_access_impl(function->impl, var_usage_map, modes);
+
+ nir_metadata_preserve(function->impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+ progress = true;
+ }
+ }
+
+ ralloc_free(mem_ctx);
+
+ return progress;
+}
--
2.17.1
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