return true;
}
+static bool
+is_access_out_of_bounds(nir_loop_terminator *term, nir_deref_instr *deref,
+ unsigned trip_count)
+{
+ for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
+ if (d->deref_type != nir_deref_type_array)
+ continue;
+
+ nir_alu_instr *alu = nir_instr_as_alu(term->conditional_instr);
+ nir_src src = term->induction_rhs ? alu->src[1].src : alu->src[0].src;
+ if (!nir_srcs_equal(d->arr.index, src))
+ continue;
+
+ nir_deref_instr *parent = nir_deref_instr_parent(d);
+ assert(glsl_type_is_array(parent->type) ||
+ glsl_type_is_matrix(parent->type));
+
+ /* We have already unrolled the loop and the new one will be imbedded in
+ * the innermost continue branch. So unless the array is greater than
+ * the trip count any iteration over the loop will be an out of bounds
+ * access of the array.
+ */
+ return glsl_get_length(parent->type) <= trip_count;
+ }
+
+ return false;
+}
+
+/* If we know an array access is going to be out of bounds remove or replace
+ * the access with an undef. This can later result in the entire loop being
+ * removed by nir_opt_dead_cf().
+ */
+static void
+remove_out_of_bounds_induction_use(nir_shader *shader, nir_loop *loop,
+ nir_loop_terminator *term,
+ nir_cf_list *lp_header,
+ nir_cf_list *lp_body,
+ unsigned trip_count)
+{
+ if (!loop->info->guessed_trip_count)
+ return;
+
+ /* Temporarily recreate the original loop so we can alter it */
+ nir_cf_reinsert(lp_header, nir_after_block(nir_loop_last_block(loop)));
+ nir_cf_reinsert(lp_body, nir_after_block(nir_loop_last_block(loop)));
+
+ nir_builder b;
+ nir_builder_init(&b, nir_cf_node_get_function(&loop->cf_node));
+
+ nir_foreach_block_in_cf_node(block, &loop->cf_node) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+
+ /* Check for arrays variably-indexed by a loop induction variable.
+ * If this access is out of bounds remove the instruction or replace
+ * its use with an undefined instruction.
+ * If the loop is no longer useful we leave it for the appropriate
+ * pass to clean it up for us.
+ */
+ if (intrin->intrinsic == nir_intrinsic_load_deref ||
+ intrin->intrinsic == nir_intrinsic_store_deref ||
+ intrin->intrinsic == nir_intrinsic_copy_deref) {
+
+ if (is_access_out_of_bounds(term, nir_src_as_deref(intrin->src[0]),
+ trip_count)) {
+ if (intrin->intrinsic == nir_intrinsic_load_deref) {
+ assert(intrin->src[0].is_ssa);
+ nir_ssa_def *a_ssa = intrin->src[0].ssa;
+ nir_ssa_def *undef =
+ nir_ssa_undef(&b, intrin->num_components,
+ a_ssa->bit_size);
+ nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
+ nir_src_for_ssa(undef));
+ } else {
+ nir_instr_remove(instr);
+ continue;
+ }
+ }
+
+ if (intrin->intrinsic == nir_intrinsic_copy_deref &&
+ is_access_out_of_bounds(term, nir_src_as_deref(intrin->src[1]),
+ trip_count)) {
+ assert(intrin->src[1].is_ssa);
+ nir_ssa_def *a_ssa = intrin->src[1].ssa;
+ nir_ssa_def *undef =
+ nir_ssa_undef(&b, intrin->num_components, a_ssa->bit_size);
+
+ /* Replace the copy with a store of the undefined value */
+ b.cursor = nir_before_instr(instr);
+ nir_store_deref(&b, nir_src_as_deref(intrin->src[0]), undef, ~0);
+ nir_instr_remove(instr);
+ }
+ }
+ }
+ }
+
+ /* Now that we are done extract the loop header and body again */
+ nir_cf_extract(lp_header, nir_before_block(nir_loop_first_block(loop)),
+ nir_before_cf_node(&term->nif->cf_node));
+ nir_cf_extract(lp_body, nir_before_block(nir_loop_first_block(loop)),
+ nir_after_block(nir_loop_last_block(loop)));
+}
+
+/* Partially unrolls loops that don't have a known trip count.
+ */
+static void
+partial_unroll(nir_shader *shader, nir_loop *loop, unsigned trip_count)
+{
+ assert(list_length(&loop->info->loop_terminator_list) == 1);
+
+ nir_loop_terminator *terminator =
+ list_first_entry(&loop->info->loop_terminator_list,
+ nir_loop_terminator, loop_terminator_link);
+
+ assert(nir_is_trivial_loop_if(terminator->nif, terminator->break_block));
+
+ loop_prepare_for_unroll(loop);
+
+ /* Pluck out the loop header */
+ nir_cf_list lp_header;
+ nir_cf_extract(&lp_header, nir_before_block(nir_loop_first_block(loop)),
+ nir_before_cf_node(&terminator->nif->cf_node));
+
+ struct hash_table *remap_table =
+ _mesa_hash_table_create(NULL, _mesa_hash_pointer,
+ _mesa_key_pointer_equal);
+
+ nir_cf_list lp_body;
+ nir_cf_node *unroll_loc =
+ complex_unroll_loop_body(loop, terminator, &lp_header, &lp_body,
+ remap_table, trip_count);
+
+ /* Attempt to remove out of bounds array access */
+ remove_out_of_bounds_induction_use(shader, loop, terminator, &lp_header,
+ &lp_body, trip_count);
+
+ nir_cursor cursor =
+ get_complex_unroll_insert_location(unroll_loc,
+ terminator->continue_from_then);
+
+ /* Reinsert the loop in the innermost nested continue branch of the unrolled
+ * loop.
+ */
+ nir_loop *new_loop = nir_loop_create(shader);
+ nir_cf_node_insert(cursor, &new_loop->cf_node);
+ new_loop->partially_unrolled = true;
+
+ /* Clone loop header and insert into new loop */
+ nir_cf_list_clone_and_reinsert(&lp_header, loop->cf_node.parent,
+ nir_after_cf_list(&new_loop->body),
+ remap_table);
+
+ /* Clone loop body and insert into new loop */
+ nir_cf_list_clone_and_reinsert(&lp_body, loop->cf_node.parent,
+ nir_after_cf_list(&new_loop->body),
+ remap_table);
+
+ /* Insert break back into terminator */
+ nir_jump_instr *brk = nir_jump_instr_create(shader, nir_jump_break);
+ nir_if *nif = nir_block_get_following_if(nir_loop_first_block(new_loop));
+ if (terminator->continue_from_then) {
+ nir_instr_insert_after_block(nir_if_last_else_block(nif), &brk->instr);
+ } else {
+ nir_instr_insert_after_block(nir_if_last_then_block(nif), &brk->instr);
+ }
+
+ /* Delete the original loop header and body */
+ nir_cf_delete(&lp_header);
+ nir_cf_delete(&lp_body);
+
+ /* The original loop has been replaced so remove it. */
+ nir_cf_node_remove(&loop->cf_node);
+
+ _mesa_hash_table_destroy(remap_table, NULL);
+}
+
static bool
is_loop_small_enough_to_unroll(nir_shader *shader, nir_loop_info *li)
{
unsigned max_iter = shader->options->max_unroll_iterations;
- if (li->max_trip_count > max_iter)
+ unsigned trip_count =
+ li->max_trip_count ? li->max_trip_count : li->guessed_trip_count;
+
+ if (trip_count > max_iter)
return false;
- if (li->force_unroll)
+ if (li->force_unroll && !li->guessed_trip_count)
return true;
bool loop_not_too_large =
- li->instr_cost * li->max_trip_count <= max_iter * LOOP_UNROLL_LIMIT;
+ li->instr_cost * trip_count <= max_iter * LOOP_UNROLL_LIMIT;
return loop_not_too_large;
}
!loop->info->complex_loop) {
nir_block *last_loop_blk = nir_loop_last_block(loop);
- if (!nir_block_ends_in_break(last_loop_blk))
+ if (nir_block_ends_in_break(last_loop_blk)) {
+ progress = wrapper_unroll(loop);
goto exit;
+ }
- progress = wrapper_unroll(loop);
-
- goto exit;
+ /* If we were able to guess the loop iteration based on array access
+ * then do a partial unroll.
+ */
+ unsigned num_lt = list_length(&loop->info->loop_terminator_list);
+ if (!has_nested_loop && num_lt == 1 && !loop->partially_unrolled &&
+ loop->info->guessed_trip_count &&
+ is_loop_small_enough_to_unroll(sh, loop->info)) {
+ partial_unroll(sh, loop, loop->info->guessed_trip_count);
+ progress = true;
+ }
}
- if (has_nested_loop || loop->info->limiting_terminator == NULL)
+ if (has_nested_loop || !loop->info->limiting_terminator)
goto exit;
if (!is_loop_small_enough_to_unroll(sh, loop->info))
projects / mesa.git / commitdiff