--- /dev/null
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+
+#include "util/bitscan.h"
+
+/**
+ * Variable-based copy propagation
+ *
+ * Normally, NIR trusts in SSA form for most of its copy-propagation needs.
+ * However, there are cases, especially when dealing with indirects, where SSA
+ * won't help you. This pass is for those times. Specifically, it handles
+ * the following things that the rest of NIR can't:
+ *
+ * 1) Copy-propagation on variables that have indirect access. This includes
+ * propagating from indirect stores into indirect loads.
+ *
+ * 2) Dead code elimination of store_var and copy_var intrinsics based on
+ * killed destination values.
+ *
+ * 3) Removal of redundant load_var intrinsics. We can't trust regular CSE
+ * to do this because it isn't aware of variable writes that may alias the
+ * value and make the former load invalid.
+ *
+ * Unfortunately, properly handling all of those cases makes this path rather
+ * complex. In order to avoid additional complexity, this pass is entirely
+ * block-local. If we tried to make it global, the data-flow analysis would
+ * rapidly get out of hand. Fortunately, for anything that is only ever
+ * accessed directly, we get SSA based copy-propagation which is extremely
+ * powerful so this isn't that great a loss.
+ */
+
+struct value {
+ bool is_ssa;
+ union {
+ nir_ssa_def *ssa[4];
+ nir_deref_var *deref;
+ };
+};
+
+struct copy_entry {
+ struct list_head link;
+
+ nir_instr *store_instr[4];
+
+ unsigned comps_may_be_read;
+ struct value src;
+
+ nir_deref_var *dst;
+};
+
+struct copy_prop_var_state {
+ nir_shader *shader;
+
+ void *mem_ctx;
+
+ struct list_head copies;
+
+ /* We're going to be allocating and deleting a lot of copy entries so we'll
+ * keep a free list to avoid thrashing malloc too badly.
+ */
+ struct list_head copy_free_list;
+
+ bool progress;
+};
+
+static struct copy_entry *
+copy_entry_create(struct copy_prop_var_state *state,
+ nir_deref_var *dst_deref)
+{
+ struct copy_entry *entry;
+ if (!list_empty(&state->copy_free_list)) {
+ struct list_head *item = state->copy_free_list.next;
+ list_del(item);
+ entry = LIST_ENTRY(struct copy_entry, item, link);
+ memset(entry, 0, sizeof(*entry));
+ } else {
+ entry = rzalloc(state->mem_ctx, struct copy_entry);
+ }
+
+ entry->dst = dst_deref;
+ list_add(&entry->link, &state->copies);
+
+ return entry;
+}
+
+static void
+copy_entry_remove(struct copy_prop_var_state *state, struct copy_entry *entry)
+{
+ list_del(&entry->link);
+ list_add(&entry->link, &state->copy_free_list);
+}
+
+enum deref_compare_result {
+ derefs_equal_bit = (1 << 0),
+ derefs_may_alias_bit = (1 << 1),
+ derefs_a_contains_b_bit = (1 << 2),
+ derefs_b_contains_a_bit = (1 << 3),
+};
+
+/** Returns true if the storage referrenced to by deref completely contains
+ * the storage referenced by sub.
+ *
+ * NOTE: This is fairly general and could be moved to core NIR if someone else
+ * ever needs it.
+ */
+static enum deref_compare_result
+compare_derefs(nir_deref_var *a, nir_deref_var *b)
+{
+ if (a->var != b->var)
+ return 0;
+
+ /* Start off assuming they fully compare. We ignore equality for now. In
+ * the end, we'll determine that by containment.
+ */
+ enum deref_compare_result result = derefs_may_alias_bit |
+ derefs_a_contains_b_bit |
+ derefs_b_contains_a_bit;
+
+ nir_deref *a_tail = &a->deref;
+ nir_deref *b_tail = &b->deref;
+ while (a_tail->child && b_tail->child) {
+ a_tail = a_tail->child;
+ b_tail = b_tail->child;
+
+ assert(a_tail->deref_type == b_tail->deref_type);
+ switch (a_tail->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *a_arr = nir_deref_as_array(a_tail);
+ nir_deref_array *b_arr = nir_deref_as_array(b_tail);
+
+ if (a_arr->deref_array_type == nir_deref_array_type_direct &&
+ b_arr->deref_array_type == nir_deref_array_type_direct) {
+ /* If they're both direct and have different offsets, they
+ * don't even alias much less anything else.
+ */
+ if (a_arr->base_offset != b_arr->base_offset)
+ return 0;
+ } else if (a_arr->deref_array_type == nir_deref_array_type_wildcard) {
+ if (b_arr->deref_array_type != nir_deref_array_type_wildcard)
+ result &= ~derefs_b_contains_a_bit;
+ } else if (b_arr->deref_array_type == nir_deref_array_type_wildcard) {
+ if (a_arr->deref_array_type != nir_deref_array_type_wildcard)
+ result &= ~derefs_a_contains_b_bit;
+ } else if (a_arr->deref_array_type == nir_deref_array_type_indirect &&
+ b_arr->deref_array_type == nir_deref_array_type_indirect) {
+ assert(a_arr->indirect.is_ssa && b_arr->indirect.is_ssa);
+ if (a_arr->indirect.ssa == b_arr->indirect.ssa) {
+ /* If they're different constant offsets from the same indirect
+ * then they don't alias at all.
+ */
+ if (a_arr->base_offset != b_arr->base_offset)
+ return 0;
+ /* Otherwise the indirect and base both match */
+ } else {
+ /* If they're have different indirect offsets then we can't
+ * prove anything about containment.
+ */
+ result &= ~(derefs_a_contains_b_bit | derefs_b_contains_a_bit);
+ }
+ } else {
+ /* In this case, one is indirect and the other direct so we can't
+ * prove anything about containment.
+ */
+ result &= ~(derefs_a_contains_b_bit | derefs_b_contains_a_bit);
+ }
+ break;
+ }
+
+ case nir_deref_type_struct: {
+ nir_deref_struct *a_struct = nir_deref_as_struct(a_tail);
+ nir_deref_struct *b_struct = nir_deref_as_struct(b_tail);
+
+ /* If they're different struct members, they don't even alias */
+ if (a_struct->index != b_struct->index)
+ return 0;
+ break;
+ }
+
+ default:
+ unreachable("Invalid deref type");
+ }
+ }
+
+ /* If a is longer than b, then it can't contain b */
+ if (a_tail->child)
+ result &= ~derefs_a_contains_b_bit;
+ if (b_tail->child)
+ result &= ~derefs_b_contains_a_bit;
+
+ /* If a contains b and b contains a they must be equal. */
+ if ((result & derefs_a_contains_b_bit) && (result & derefs_b_contains_a_bit))
+ result |= derefs_equal_bit;
+
+ return result;
+}
+
+static void
+remove_dead_writes(struct copy_prop_var_state *state,
+ struct copy_entry *entry, unsigned write_mask)
+{
+ /* We're overwriting another entry. Some of it's components may not
+ * have been read yet and, if that's the case, we may be able to delete
+ * some instructions but we have to be careful.
+ */
+ unsigned dead_comps = write_mask & ~entry->comps_may_be_read;
+
+ for (unsigned mask = dead_comps; mask;) {
+ unsigned i = u_bit_scan(&mask);
+
+ nir_instr *instr = entry->store_instr[i];
+
+ /* We may have already deleted it on a previous iteration */
+ if (!instr)
+ continue;
+
+ /* See if this instr is used anywhere that it's not dead */
+ bool keep = false;
+ for (unsigned j = 0; j < 4; j++) {
+ if (entry->store_instr[j] == instr) {
+ if (dead_comps & (1 << j)) {
+ entry->store_instr[j] = NULL;
+ } else {
+ keep = true;
+ }
+ }
+ }
+
+ if (!keep) {
+ nir_instr_remove(instr);
+ state->progress = true;
+ }
+ }
+}
+
+static struct copy_entry *
+lookup_entry_for_deref(struct copy_prop_var_state *state,
+ nir_deref_var *deref,
+ enum deref_compare_result allowed_comparisons)
+{
+ list_for_each_entry(struct copy_entry, iter, &state->copies, link) {
+ if (compare_derefs(iter->dst, deref) & allowed_comparisons)
+ return iter;
+ }
+
+ return NULL;
+}
+
+static void
+mark_aliased_entries_as_read(struct copy_prop_var_state *state,
+ nir_deref_var *deref, unsigned components)
+{
+ list_for_each_entry(struct copy_entry, iter, &state->copies, link) {
+ if (compare_derefs(iter->dst, deref) & derefs_may_alias_bit)
+ iter->comps_may_be_read |= components;
+ }
+}
+
+static struct copy_entry *
+get_entry_and_kill_aliases(struct copy_prop_var_state *state,
+ nir_deref_var *deref,
+ unsigned write_mask)
+{
+ struct copy_entry *entry = NULL;
+ list_for_each_entry_safe(struct copy_entry, iter, &state->copies, link) {
+ if (!iter->src.is_ssa) {
+ /* If this write aliases the source of some entry, get rid of it */
+ if (compare_derefs(iter->src.deref, deref) & derefs_may_alias_bit) {
+ copy_entry_remove(state, iter);
+ continue;
+ }
+ }
+
+ enum deref_compare_result comp = compare_derefs(iter->dst, deref);
+ /* This is a store operation. If we completely overwrite some value, we
+ * want to delete any dead writes that may be present.
+ */
+ if (comp & derefs_b_contains_a_bit)
+ remove_dead_writes(state, iter, write_mask);
+
+ if (comp & derefs_equal_bit) {
+ assert(entry == NULL);
+ entry = iter;
+ } else if (comp & derefs_may_alias_bit) {
+ copy_entry_remove(state, iter);
+ }
+ }
+
+ if (entry == NULL)
+ entry = copy_entry_create(state, deref);
+
+ return entry;
+}
+
+static void
+apply_barrier_for_modes(struct copy_prop_var_state *state,
+ nir_variable_mode modes)
+{
+ list_for_each_entry_safe(struct copy_entry, iter, &state->copies, link) {
+ if ((iter->dst->var->data.mode & modes) ||
+ (!iter->src.is_ssa && (iter->src.deref->var->data.mode & modes)))
+ copy_entry_remove(state, iter);
+ }
+}
+
+static void
+store_to_entry(struct copy_prop_var_state *state, struct copy_entry *entry,
+ const struct value *value, unsigned write_mask,
+ nir_instr *store_instr)
+{
+ entry->comps_may_be_read &= ~write_mask;
+ if (value->is_ssa) {
+ entry->src.is_ssa = true;
+ /* Only overwrite the written components */
+ for (unsigned i = 0; i < 4; i++) {
+ if (write_mask & (1 << i)) {
+ entry->store_instr[i] = store_instr;
+ entry->src.ssa[i] = value->ssa[i];
+ }
+ }
+ } else {
+ /* Non-ssa stores always write everything */
+ entry->src.is_ssa = false;
+ entry->src.deref = value->deref;
+ for (unsigned i = 0; i < 4; i++)
+ entry->store_instr[i] = store_instr;
+ }
+}
+
+/* Remove an instruction and return a cursor pointing to where it was */
+static nir_cursor
+instr_remove_cursor(nir_instr *instr)
+{
+ nir_cursor cursor;
+ nir_instr *prev = nir_instr_prev(instr);
+ if (prev) {
+ cursor = nir_after_instr(prev);
+ } else {
+ cursor = nir_before_block(instr->block);
+ }
+ nir_instr_remove(instr);
+ return cursor;
+}
+
+/* Do a "load" from an SSA-based entry return it in "value" as a value with a
+ * single SSA def. Because an entry could reference up to 4 different SSA
+ * defs, a vecN operation may be inserted to combine them into a single SSA
+ * def before handing it back to the caller. If the load instruction is no
+ * longer needed, it is removed and nir_instr::block is set to NULL. (It is
+ * possible, in some cases, for the load to be used in the vecN operation in
+ * which case it isn't deleted.)
+ */
+static bool
+load_from_ssa_entry_value(struct copy_prop_var_state *state,
+ struct copy_entry *entry,
+ nir_builder *b, nir_intrinsic_instr *intrin,
+ struct value *value)
+{
+ *value = entry->src;
+ assert(value->is_ssa);
+
+ const struct glsl_type *type = nir_deref_tail(&entry->dst->deref)->type;
+ unsigned num_components = glsl_get_vector_elements(type);
+
+ uint8_t available = 0;
+ bool all_same = true;
+ for (unsigned i = 0; i < num_components; i++) {
+ if (value->ssa[i])
+ available |= (1 << i);
+
+ if (value->ssa[i] != value->ssa[0])
+ all_same = false;
+ }
+
+ if (all_same) {
+ /* Our work here is done */
+ b->cursor = instr_remove_cursor(&intrin->instr);
+ intrin->instr.block = NULL;
+ return true;
+ }
+
+ if (available != (1 << num_components) - 1 &&
+ intrin->intrinsic == nir_intrinsic_load_var &&
+ (available & nir_ssa_def_components_read(&intrin->dest.ssa)) == 0) {
+ /* If none of the components read are available as SSA values, then we
+ * should just bail. Otherwise, we would end up replacing the uses of
+ * the load_var a vecN() that just gathers up its components.
+ */
+ return false;
+ }
+
+ b->cursor = nir_after_instr(&intrin->instr);
+
+ nir_ssa_def *load_def =
+ intrin->intrinsic == nir_intrinsic_load_var ? &intrin->dest.ssa : NULL;
+
+ bool keep_intrin = false;
+ nir_ssa_def *comps[4];
+ for (unsigned i = 0; i < num_components; i++) {
+ if (value->ssa[i]) {
+ comps[i] = nir_channel(b, value->ssa[i], i);
+ } else {
+ /* We don't have anything for this component in our
+ * list. Just re-use a channel from the load.
+ */
+ if (load_def == NULL)
+ load_def = nir_load_deref_var(b, entry->dst);
+
+ if (load_def->parent_instr == &intrin->instr)
+ keep_intrin = true;
+
+ comps[i] = nir_channel(b, load_def, i);
+ }
+ }
+
+ nir_ssa_def *vec = nir_vec(b, comps, num_components);
+ for (unsigned i = 0; i < num_components; i++)
+ value->ssa[i] = vec;
+
+ if (!keep_intrin) {
+ /* Removing this instruction should not touch the cursor because we
+ * created the cursor after the intrinsic and have added at least one
+ * instruction (the vec) since then.
+ */
+ assert(b->cursor.instr != &intrin->instr);
+ nir_instr_remove(&intrin->instr);
+ intrin->instr.block = NULL;
+ }
+
+ return true;
+}
+
+/**
+ * Specialize the wildcards in a deref chain
+ *
+ * This function returns a deref chain identical to \param deref except that
+ * some of its wildcards are replaced with indices from \param specific. The
+ * process is guided by \param guide which references the same type as \param
+ * specific but has the same wildcard array lengths as \param deref.
+ */
+static nir_deref_var *
+specialize_wildcards(nir_deref_var *deref,
+ nir_deref_var *guide,
+ nir_deref_var *specific,
+ void *mem_ctx)
+{
+ nir_deref_var *ret = nir_deref_var_create(mem_ctx, deref->var);
+
+ nir_deref *deref_tail = deref->deref.child;
+ nir_deref *guide_tail = guide->deref.child;
+ nir_deref *spec_tail = specific->deref.child;
+ nir_deref *ret_tail = &ret->deref;
+ while (deref_tail) {
+ switch (deref_tail->deref_type) {
+ case nir_deref_type_array: {
+ nir_deref_array *deref_arr = nir_deref_as_array(deref_tail);
+
+ nir_deref_array *ret_arr = nir_deref_array_create(ret_tail);
+ ret_arr->deref.type = deref_arr->deref.type;
+ ret_arr->deref_array_type = deref_arr->deref_array_type;
+
+ switch (deref_arr->deref_array_type) {
+ case nir_deref_array_type_direct:
+ ret_arr->base_offset = deref_arr->base_offset;
+ break;
+ case nir_deref_array_type_indirect:
+ ret_arr->base_offset = deref_arr->base_offset;
+ assert(deref_arr->indirect.is_ssa);
+ ret_arr->indirect = deref_arr->indirect;
+ break;
+ case nir_deref_array_type_wildcard:
+ /* This is where things get tricky. We have to search through
+ * the entry deref to find its corresponding wildcard and fill
+ * this slot in with the value from the src.
+ */
+ while (guide_tail) {
+ if (guide_tail->deref_type == nir_deref_type_array &&
+ nir_deref_as_array(guide_tail)->deref_array_type ==
+ nir_deref_array_type_wildcard)
+ break;
+
+ guide_tail = guide_tail->child;
+ spec_tail = spec_tail->child;
+ }
+
+ nir_deref_array *spec_arr = nir_deref_as_array(spec_tail);
+ ret_arr->deref_array_type = spec_arr->deref_array_type;
+ ret_arr->base_offset = spec_arr->base_offset;
+ ret_arr->indirect = spec_arr->indirect;
+ }
+
+ ret_tail->child = &ret_arr->deref;
+ break;
+ }
+ case nir_deref_type_struct: {
+ nir_deref_struct *deref_struct = nir_deref_as_struct(deref_tail);
+
+ nir_deref_struct *ret_struct =
+ nir_deref_struct_create(ret_tail, deref_struct->index);
+ ret_struct->deref.type = deref_struct->deref.type;
+
+ ret_tail->child = &ret_struct->deref;
+ break;
+ }
+ case nir_deref_type_var:
+ unreachable("Invalid deref type");
+ }
+
+ deref_tail = deref_tail->child;
+ ret_tail = ret_tail->child;
+ }
+
+ return ret;
+}
+
+/* Do a "load" from an deref-based entry return it in "value" as a value. The
+ * deref returned in "value" will always be a fresh copy so the caller can
+ * steal it and assign it to the instruction directly without copying it
+ * again.
+ */
+static bool
+load_from_deref_entry_value(struct copy_prop_var_state *state,
+ struct copy_entry *entry,
+ nir_builder *b, nir_intrinsic_instr *intrin,
+ nir_deref_var *src, struct value *value)
+{
+ *value = entry->src;
+
+ /* Walk the deref to get the two tails and also figure out if we need to
+ * specialize any wildcards.
+ */
+ bool need_to_specialize_wildcards = false;
+ nir_deref *entry_tail = &entry->dst->deref;
+ nir_deref *src_tail = &src->deref;
+ while (entry_tail->child && src_tail->child) {
+ assert(src_tail->child->deref_type == entry_tail->child->deref_type);
+ if (src_tail->child->deref_type == nir_deref_type_array) {
+ nir_deref_array *entry_arr = nir_deref_as_array(entry_tail->child);
+ nir_deref_array *src_arr = nir_deref_as_array(src_tail->child);
+
+ if (src_arr->deref_array_type != nir_deref_array_type_wildcard &&
+ entry_arr->deref_array_type == nir_deref_array_type_wildcard)
+ need_to_specialize_wildcards = true;
+ }
+
+ entry_tail = entry_tail->child;
+ src_tail = src_tail->child;
+ }
+
+ /* If the entry deref is longer than the source deref then it refers to a
+ * smaller type and we can't source from it.
+ */
+ assert(entry_tail->child == NULL);
+
+ if (need_to_specialize_wildcards) {
+ /* The entry has some wildcards that are not in src. This means we need
+ * to construct a new deref based on the entry but using the wildcards
+ * from the source and guided by the entry dst. Oof.
+ */
+ value->deref = specialize_wildcards(entry->src.deref, entry->dst, src,
+ state->mem_ctx);
+ } else {
+ /* We're going to need to make a copy in case we modify it below */
+ value->deref = nir_deref_var_clone(value->deref, state->mem_ctx);
+ }
+
+ if (src_tail->child) {
+ /* If our source deref is longer than the entry deref, that's ok because
+ * it just means the entry deref needs to be extended a bit.
+ */
+ nir_deref *value_tail = nir_deref_tail(&value->deref->deref);
+ value_tail->child = nir_deref_clone(src_tail->child, value_tail);
+ }
+
+ b->cursor = instr_remove_cursor(&intrin->instr);
+
+ return true;
+}
+
+static bool
+try_load_from_entry(struct copy_prop_var_state *state, struct copy_entry *entry,
+ nir_builder *b, nir_intrinsic_instr *intrin,
+ nir_deref_var *src, struct value *value)
+{
+ if (entry == NULL)
+ return false;
+
+ if (entry->src.is_ssa) {
+ return load_from_ssa_entry_value(state, entry, b, intrin, value);
+ } else {
+ return load_from_deref_entry_value(state, entry, b, intrin, src, value);
+ }
+}
+
+static void
+copy_prop_vars_block(struct copy_prop_var_state *state,
+ nir_builder *b, nir_block *block)
+{
+ /* Start each block with a blank slate */
+ list_for_each_entry_safe(struct copy_entry, iter, &state->copies, link)
+ copy_entry_remove(state, iter);
+
+ 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_barrier:
+ case nir_intrinsic_memory_barrier:
+ /* If we hit a barrier, we need to trash everything that may possibly
+ * be accessible to another thread. Locals, globals, and things of
+ * the like are safe, however.
+ */
+ apply_barrier_for_modes(state, ~(nir_var_local | nir_var_global |
+ nir_var_shader_in | nir_var_uniform));
+ break;
+
+ case nir_intrinsic_emit_vertex:
+ case nir_intrinsic_emit_vertex_with_counter:
+ apply_barrier_for_modes(state, nir_var_shader_out);
+ break;
+
+ case nir_intrinsic_load_var: {
+ nir_deref_var *src = intrin->variables[0];
+
+ uint8_t comps_read = nir_ssa_def_components_read(&intrin->dest.ssa);
+ mark_aliased_entries_as_read(state, src, comps_read);
+
+ struct copy_entry *src_entry =
+ lookup_entry_for_deref(state, src, derefs_a_contains_b_bit);
+ struct value value;
+ if (try_load_from_entry(state, src_entry, b, intrin, src, &value)) {
+ if (value.is_ssa) {
+ /* lookup_load has already ensured that we get a single SSA
+ * value that has all of the channels. We just have to do the
+ * rewrite operation.
+ */
+ if (intrin->instr.block) {
+ /* The lookup left our instruction in-place. This means it
+ * must have used it to vec up a bunch of different sources.
+ * We need to be careful when rewriting uses so we don't
+ * rewrite the vecN itself.
+ */
+ nir_ssa_def_rewrite_uses_after(&intrin->dest.ssa,
+ nir_src_for_ssa(value.ssa[0]),
+ value.ssa[0]->parent_instr);
+ } else {
+ nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
+ nir_src_for_ssa(value.ssa[0]));
+ }
+ } else {
+ /* We're turning it into a load of a different variable */
+ ralloc_steal(intrin, value.deref);
+ intrin->variables[0] = value.deref;
+
+ /* Put it back in again. */
+ nir_builder_instr_insert(b, instr);
+
+ value.is_ssa = true;
+ for (unsigned i = 0; i < intrin->num_components; i++)
+ value.ssa[i] = &intrin->dest.ssa;
+ }
+ state->progress = true;
+ } else {
+ value.is_ssa = true;
+ for (unsigned i = 0; i < intrin->num_components; i++)
+ value.ssa[i] = &intrin->dest.ssa;
+ }
+
+ /* Now that we have a value, we're going to store it back so that we
+ * have the right value next time we come looking for it. In order
+ * to do this, we need an exact match, not just something that
+ * contains what we're looking for.
+ */
+ struct copy_entry *store_entry =
+ lookup_entry_for_deref(state, src, derefs_equal_bit);
+ if (!store_entry)
+ store_entry = copy_entry_create(state, src);
+
+ /* Set up a store to this entry with the value of the load. This way
+ * we can potentially remove subsequent loads. However, we use a
+ * NULL instruction so we don't try and delete the load on a
+ * subsequent store.
+ */
+ store_to_entry(state, store_entry, &value,
+ ((1 << intrin->num_components) - 1), NULL);
+ break;
+ }
+
+ case nir_intrinsic_store_var: {
+ struct value value = {
+ .is_ssa = true
+ };
+
+ for (unsigned i = 0; i < intrin->num_components; i++)
+ value.ssa[i] = intrin->src[0].ssa;
+
+ nir_deref_var *dst = intrin->variables[0];
+ unsigned wrmask = nir_intrinsic_write_mask(intrin);
+ struct copy_entry *entry =
+ get_entry_and_kill_aliases(state, dst, wrmask);
+ store_to_entry(state, entry, &value, wrmask, &intrin->instr);
+ break;
+ }
+
+ case nir_intrinsic_copy_var: {
+ nir_deref_var *dst = intrin->variables[0];
+ nir_deref_var *src = intrin->variables[1];
+
+ if (compare_derefs(src, dst) & derefs_equal_bit) {
+ /* This is a no-op self-copy. Get rid of it */
+ nir_instr_remove(instr);
+ continue;
+ }
+
+ mark_aliased_entries_as_read(state, src, 0xf);
+
+ struct copy_entry *src_entry =
+ lookup_entry_for_deref(state, src, derefs_a_contains_b_bit);
+ struct value value;
+ if (try_load_from_entry(state, src_entry, b, intrin, src, &value)) {
+ if (value.is_ssa) {
+ nir_store_deref_var(b, dst, value.ssa[0], 0xf);
+ intrin = nir_instr_as_intrinsic(nir_builder_last_instr(b));
+ } else {
+ /* If this would be a no-op self-copy, don't bother. */
+ if (compare_derefs(value.deref, dst) & derefs_equal_bit)
+ continue;
+
+ /* Just turn it into a copy of a different deref */
+ ralloc_steal(intrin, value.deref);
+ intrin->variables[1] = value.deref;
+
+ /* Put it back in again. */
+ nir_builder_instr_insert(b, instr);
+ }
+
+ state->progress = true;
+ } else {
+ value = (struct value) {
+ .is_ssa = false,
+ .deref = src,
+ };
+ }
+
+ struct copy_entry *dst_entry =
+ get_entry_and_kill_aliases(state, dst, 0xf);
+ store_to_entry(state, dst_entry, &value, 0xf, &intrin->instr);
+ break;
+ }
+
+ default:
+ break;
+ }
+ }
+}
+
+bool
+nir_opt_copy_prop_vars(nir_shader *shader)
+{
+ struct copy_prop_var_state state;
+
+ state.shader = shader;
+ state.mem_ctx = ralloc_context(NULL);
+ list_inithead(&state.copies);
+ list_inithead(&state.copy_free_list);
+
+ bool global_progress = false;
+ nir_foreach_function(function, shader) {
+ if (!function->impl)
+ continue;
+
+ nir_builder b;
+ nir_builder_init(&b, function->impl);
+
+ state.progress = false;
+ nir_foreach_block(block, function->impl)
+ copy_prop_vars_block(&state, &b, block);
+
+ if (state.progress) {
+ nir_metadata_preserve(function->impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+ global_progress = true;
+ }
+ }
+
+ ralloc_free(state.mem_ctx);
+
+ return global_progress;
+}
projects / mesa.git / commitdiff