mie: select: track all side-effect-chains in a graph; support combining them all

mie/select/graph.c

@@ -62,6 +62,43 @@ void mie_select_graph_destroy(struct mie_select_graph *graph)
 	free(graph);
 }
 
+static enum mie_status update_chain_ends(
+	struct mie_select_graph *graph, struct mie_select_value *new_chain)
+{
+	struct mie_select_node *new_node = new_chain->v_node;
+
+	b_queue_entry *entry = b_queue_first(&graph->g_chain_ends);
+	while (entry) {
+		struct mie_select_chain_end *end
+			= b_unbox(struct mie_select_chain_end, entry, c_entry);
+		struct mie_select_node *value_node = end->c_value.v_node;
+
+		for (size_t i = 0; i < new_node->n_nr_operands; i++) {
+			struct mie_select_node *operand_node
+				= new_node->n_operands[i].u_value.v_node;
+
+			if (value_node == operand_node) {
+				memcpy(&end->c_value, new_chain, sizeof *new_chain);
+				return MIE_SUCCESS;
+			}
+		}
+
+		entry = b_queue_next(entry);
+	}
+
+	struct mie_select_chain_end *end = malloc(sizeof *end);
+	if (!end) {
+		return MIE_ERR_NO_MEMORY;
+	}
+
+	memset(end, 0x0, sizeof *end);
+	memcpy(&end->c_value, new_chain, sizeof *new_chain);
+
+	b_queue_push_back(&graph->g_chain_ends, &end->c_entry);
+
+	return MIE_SUCCESS;
+}
+
 enum mie_status mie_select_graph_get_node(
 	struct mie_select_graph *graph, const struct mie_target *target,
 	unsigned int op, struct mie_select_value **operands, size_t nr_operands,
@@ -87,9 +124,18 @@ enum mie_status mie_select_graph_get_node(
 	node->n_target = target;
 
 	for (size_t i = 0; i < nr_values; i++) {
-		if (values[i]->t_id == MIE_TYPE_OTHER) {
-			graph->g_last_chain.v_node = node;
-			graph->g_last_chain.v_index = i;
+		if (values[i]->t_id != MIE_TYPE_OTHER) {
+			continue;
+		}
+
+		struct mie_select_value chain = {
+			.v_node = node,
+			.v_index = i,
+		};
+
+		enum mie_status status = update_chain_ends(graph, &chain);
+		if (status != MIE_SUCCESS) {
+			return status;
 		}
 	}