From 45004d82e04d8cdd9cc57fc5ee2b243f8bfd7ee3 Mon Sep 17 00:00:00 2001 From: Jacques Lucke Date: Wed, 8 Jul 2020 11:18:43 +0200 Subject: Functions: add dead node removal and constant folding optimization Those optimizations work on the multi-function network level. Not only will they make the network evaluation faster, but they also simplify the network a lot. That makes it easier to understand the exported dot graph. --- .../intern/multi_function_network_optimization.cc | 295 +++++++++++++++++++++ 1 file changed, 295 insertions(+) create mode 100644 source/blender/functions/intern/multi_function_network_optimization.cc (limited to 'source/blender/functions/intern') diff --git a/source/blender/functions/intern/multi_function_network_optimization.cc b/source/blender/functions/intern/multi_function_network_optimization.cc new file mode 100644 index 00000000000..cd6a25e5502 --- /dev/null +++ b/source/blender/functions/intern/multi_function_network_optimization.cc @@ -0,0 +1,295 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +/** \file + * \ingroup fn + */ + +#include "FN_multi_function_builder.hh" +#include "FN_multi_function_network_evaluation.hh" +#include "FN_multi_function_network_optimization.hh" + +#include "BLI_stack.hh" + +namespace blender::fn::mf_network_optimization { + +/* -------------------------------------------------------------------- */ +/** \name Utility functions to find nodes in a network. + * + * \{ */ + +static bool set_tag_and_check_if_modified(bool &tag, bool new_value) +{ + if (tag != new_value) { + tag = new_value; + return true; + } + else { + return false; + } +} + +static Array mask_nodes_to_the_left(MFNetwork &network, Span nodes) +{ + Array is_to_the_left(network.node_id_amount(), false); + Stack nodes_to_check; + + for (MFNode *node : nodes) { + is_to_the_left[node->id()] = true; + nodes_to_check.push(node); + } + + while (!nodes_to_check.is_empty()) { + MFNode &node = *nodes_to_check.pop(); + + for (MFInputSocket *input_socket : node.inputs()) { + MFOutputSocket *origin = input_socket->origin(); + if (origin != nullptr) { + MFNode &origin_node = origin->node(); + if (set_tag_and_check_if_modified(is_to_the_left[origin_node.id()], true)) { + nodes_to_check.push(&origin_node); + } + } + } + } + + return is_to_the_left; +} + +static Array mask_nodes_to_the_right(MFNetwork &network, Span nodes) +{ + Array is_to_the_right(network.node_id_amount(), false); + Stack nodes_to_check; + + for (MFNode *node : nodes) { + is_to_the_right[node->id()] = true; + nodes_to_check.push(node); + } + + while (!nodes_to_check.is_empty()) { + MFNode &node = *nodes_to_check.pop(); + + for (MFOutputSocket *output_socket : node.outputs()) { + for (MFInputSocket *target_socket : output_socket->targets()) { + MFNode &target_node = target_socket->node(); + if (set_tag_and_check_if_modified(is_to_the_right[target_node.id()], true)) { + nodes_to_check.push(&target_node); + } + } + } + } + + return is_to_the_right; +} + +static Vector find_nodes_based_on_mask(MFNetwork &network, + Span id_mask, + bool mask_value) +{ + Vector nodes; + for (uint id : id_mask.index_range()) { + if (id_mask[id] == mask_value) { + MFNode *node = network.node_or_null_by_id(id); + if (node != nullptr) { + nodes.append(node); + } + } + } + return nodes; +} + +/** \} */ + +/* -------------------------------------------------------------------- */ +/** \name Dead Node Removal + * + * \{ */ + +/** + * Unused nodes are all those nodes that no dummy node depends upon. + */ +void dead_node_removal(MFNetwork &network) +{ + Array node_is_used_mask = mask_nodes_to_the_left(network, network.dummy_nodes()); + Vector nodes_to_remove = find_nodes_based_on_mask(network, node_is_used_mask, false); + network.remove(nodes_to_remove); +} + +/** \} */ + +/* -------------------------------------------------------------------- */ +/** \name Constant Folding + * + * \{ */ + +static bool output_has_non_constant_target_node(MFOutputSocket *output_socket, + Span is_not_constant_mask) +{ + for (MFInputSocket *target_socket : output_socket->targets()) { + MFNode &target_node = target_socket->node(); + bool target_is_not_constant = is_not_constant_mask[target_node.id()]; + if (target_is_not_constant) { + return true; + } + } + return false; +} + +static MFInputSocket *try_find_dummy_target_socket(MFOutputSocket *output_socket) +{ + for (MFInputSocket *target_socket : output_socket->targets()) { + if (target_socket->node().is_dummy()) { + return target_socket; + } + } + return nullptr; +} + +static Vector find_constant_inputs_to_fold( + MFNetwork &network, Vector &r_temporary_nodes) +{ + Span non_constant_nodes = network.dummy_nodes(); + Array is_not_constant_mask = mask_nodes_to_the_right(network, non_constant_nodes); + Vector constant_nodes = find_nodes_based_on_mask(network, is_not_constant_mask, false); + + Vector sockets_to_compute; + for (MFNode *node : constant_nodes) { + if (node->inputs().size() == 0) { + continue; + } + + for (MFOutputSocket *output_socket : node->outputs()) { + MFDataType data_type = output_socket->data_type(); + if (output_has_non_constant_target_node(output_socket, is_not_constant_mask)) { + MFInputSocket *dummy_target = try_find_dummy_target_socket(output_socket); + if (dummy_target == nullptr) { + dummy_target = &network.add_output("Dummy", data_type); + network.add_link(*output_socket, *dummy_target); + r_temporary_nodes.append(&dummy_target->node().as_dummy()); + } + + sockets_to_compute.append(dummy_target); + } + } + } + return sockets_to_compute; +} + +static void prepare_params_for_constant_folding(const MultiFunction &network_fn, + MFParamsBuilder ¶ms, + ResourceCollector &resources) +{ + for (uint param_index : network_fn.param_indices()) { + MFParamType param_type = network_fn.param_type(param_index); + MFDataType data_type = param_type.data_type(); + + switch (data_type.category()) { + case MFDataType::Single: { + /* Allocates memory for a single constant folded value. */ + const CPPType &cpp_type = data_type.single_type(); + void *buffer = resources.linear_allocator().allocate(cpp_type.size(), + cpp_type.alignment()); + GMutableSpan array{cpp_type, buffer, 1}; + params.add_uninitialized_single_output(array); + break; + } + case MFDataType::Vector: { + /* Allocates memory for a constant folded vector. */ + const CPPType &cpp_type = data_type.vector_base_type(); + GVectorArray &vector_array = resources.construct(AT, cpp_type, 1); + params.add_vector_output(vector_array); + break; + } + } + } +} + +static Array add_constant_folded_sockets(const MultiFunction &network_fn, + MFParamsBuilder ¶ms, + ResourceCollector &resources, + MFNetwork &network) +{ + Array folded_sockets{network_fn.param_indices().size(), nullptr}; + + for (uint param_index : network_fn.param_indices()) { + MFParamType param_type = network_fn.param_type(param_index); + MFDataType data_type = param_type.data_type(); + + const MultiFunction *constant_fn = nullptr; + + switch (data_type.category()) { + case MFDataType::Single: { + const CPPType &cpp_type = data_type.single_type(); + GMutableSpan array = params.computed_array(param_index); + void *buffer = array.buffer(); + resources.add(buffer, array.type().destruct_cb(), AT); + + constant_fn = &resources.construct(AT, cpp_type, buffer); + break; + } + case MFDataType::Vector: { + GVectorArray &vector_array = params.computed_vector_array(param_index); + GSpan array = vector_array[0]; + constant_fn = &resources.construct(AT, array); + break; + } + } + + MFFunctionNode &folded_node = network.add_function(*constant_fn); + folded_sockets[param_index] = &folded_node.output(0); + } + return folded_sockets; +} + +static Array compute_constant_sockets_and_add_folded_nodes( + MFNetwork &network, + Span sockets_to_compute, + ResourceCollector &resources) +{ + MFNetworkEvaluator network_fn{{}, sockets_to_compute}; + + MFContextBuilder context; + MFParamsBuilder params{network_fn, 1}; + prepare_params_for_constant_folding(network_fn, params, resources); + network_fn.call({0}, params, context); + return add_constant_folded_sockets(network_fn, params, resources, network); +} + +/** + * Find function nodes that always output the same value and replace those with constant nodes. + */ +void constant_folding(MFNetwork &network, ResourceCollector &resources) +{ + Vector temporary_nodes; + Vector inputs_to_fold = find_constant_inputs_to_fold(network, temporary_nodes); + if (inputs_to_fold.size() == 0) { + return; + } + + Array folded_sockets = compute_constant_sockets_and_add_folded_nodes( + network, inputs_to_fold.as_span(), resources); + + for (uint i : inputs_to_fold.index_range()) { + MFOutputSocket &original_socket = *inputs_to_fold[i]->origin(); + network.relink(original_socket, *folded_sockets[i]); + } + + network.remove(temporary_nodes.as_span()); +} + +/** \} */ + +} // namespace blender::fn::mf_network_optimization -- cgit v1.2.3