return true;
}
+static void
+replace_if_condition_use_with_const(nir_builder *b, nir_src *use,
+ nir_const_value nir_boolean,
+ bool if_condition)
+{
+ /* Create const */
+ nir_ssa_def *const_def = nir_build_imm(b, 1, 32, nir_boolean);
+
+ /* Rewrite use to use const */
+ nir_src new_src = nir_src_for_ssa(const_def);
+ if (if_condition)
+ nir_if_rewrite_condition(use->parent_if, new_src);
+ else
+ nir_instr_rewrite_src(use->parent_instr, use, new_src);
+}
+
+static bool
+evaluate_if_condition(nir_if *nif, nir_cursor cursor, uint32_t *value)
+{
+ nir_block *use_block = nir_cursor_current_block(cursor);
+ if (nir_block_dominates(nir_if_first_then_block(nif), use_block)) {
+ *value = NIR_TRUE;
+ return true;
+ } else if (nir_block_dominates(nir_if_first_else_block(nif), use_block)) {
+ *value = NIR_FALSE;
+ return true;
+ } else {
+ return false;
+ }
+}
+
+static bool
+evaluate_condition_use(nir_builder *b, nir_if *nif, nir_src *use_src,
+ bool is_if_condition)
+{
+ bool progress = false;
+
+ nir_const_value value;
+ b->cursor = nir_before_src(use_src, is_if_condition);
+
+ if (evaluate_if_condition(nif, b->cursor, &value.u32[0])) {
+ replace_if_condition_use_with_const(b, use_src, value, is_if_condition);
+ progress = true;
+ }
+
+ return progress;
+}
+
+static bool
+opt_if_evaluate_condition_use(nir_builder *b, nir_if *nif)
+{
+ bool progress = false;
+
+ /* Evaluate any uses of the if condition inside the if branches */
+ assert(nif->condition.is_ssa);
+ nir_foreach_use_safe(use_src, nif->condition.ssa) {
+ progress |= evaluate_condition_use(b, nif, use_src, false);
+ }
+
+ nir_foreach_if_use_safe(use_src, nif->condition.ssa) {
+ if (use_src->parent_if != nif)
+ progress |= evaluate_condition_use(b, nif, use_src, true);
+ }
+
+ return progress;
+}
+
static bool
opt_if_cf_list(nir_builder *b, struct exec_list *cf_list)
{
return progress;
}
+/**
+ * These optimisations depend on nir_metadata_block_index and therefore must
+ * not do anything to cause the metadata to become invalid.
+ */
+static bool
+opt_if_safe_cf_list(nir_builder *b, struct exec_list *cf_list)
+{
+ bool progress = false;
+ foreach_list_typed(nir_cf_node, cf_node, node, cf_list) {
+ switch (cf_node->type) {
+ case nir_cf_node_block:
+ break;
+
+ case nir_cf_node_if: {
+ nir_if *nif = nir_cf_node_as_if(cf_node);
+ progress |= opt_if_safe_cf_list(b, &nif->then_list);
+ progress |= opt_if_safe_cf_list(b, &nif->else_list);
+ progress |= opt_if_evaluate_condition_use(b, nif);
+ break;
+ }
+
+ case nir_cf_node_loop: {
+ nir_loop *loop = nir_cf_node_as_loop(cf_node);
+ progress |= opt_if_safe_cf_list(b, &loop->body);
+ break;
+ }
+
+ case nir_cf_node_function:
+ unreachable("Invalid cf type");
+ }
+ }
+
+ return progress;
+}
+
bool
nir_opt_if(nir_shader *shader)
{
nir_builder b;
nir_builder_init(&b, function->impl);
+ nir_metadata_require(function->impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+ progress = opt_if_safe_cf_list(&b, &function->impl->body);
+ nir_metadata_preserve(function->impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+
if (opt_if_cf_list(&b, &function->impl->body)) {
nir_metadata_preserve(function->impl, nir_metadata_none);