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blender-archive/source/blender/functions/intern/multi_function_network_optimization.cc
Jacques Lucke b53c46d760 BLI: add MultiValueMap
This is a convenience wrapper for `Map<Key, Vector<Value>>`.
It does not provide any performance benefits (yet). I need this
kind of map in a couple of places and before I was duplicating
the lookup logic in many places.
2020-07-24 12:15:13 +02:00

505 lines
16 KiB
C++

/*
* 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
*/
/* Used to check if two multi-functions have the exact same type. */
#include <typeinfo>
#include "FN_multi_function_builder.hh"
#include "FN_multi_function_network_evaluation.hh"
#include "FN_multi_function_network_optimization.hh"
#include "BLI_disjoint_set.hh"
#include "BLI_ghash.h"
#include "BLI_map.hh"
#include "BLI_multi_value_map.hh"
#include "BLI_rand.h"
#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<bool> mask_nodes_to_the_left(MFNetwork &network, Span<MFNode *> nodes)
{
Array<bool> is_to_the_left(network.node_id_amount(), false);
Stack<MFNode *> 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<bool> mask_nodes_to_the_right(MFNetwork &network, Span<MFNode *> nodes)
{
Array<bool> is_to_the_right(network.node_id_amount(), false);
Stack<MFNode *> 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<MFNode *> find_nodes_based_on_mask(MFNetwork &network,
Span<bool> id_mask,
bool mask_value)
{
Vector<MFNode *> nodes;
for (int 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<bool> node_is_used_mask = mask_nodes_to_the_left(network, network.dummy_nodes());
Vector<MFNode *> nodes_to_remove = find_nodes_based_on_mask(network, node_is_used_mask, false);
network.remove(nodes_to_remove);
}
/** \} */
/* -------------------------------------------------------------------- */
/** \name Constant Folding
*
* \{ */
static bool function_node_can_be_constant(MFFunctionNode *node)
{
if (node->has_unlinked_inputs()) {
return false;
}
if (node->function().depends_on_context()) {
return false;
}
return true;
}
static Vector<MFNode *> find_non_constant_nodes(MFNetwork &network)
{
Vector<MFNode *> non_constant_nodes;
non_constant_nodes.extend(network.dummy_nodes());
for (MFFunctionNode *node : network.function_nodes()) {
if (!function_node_can_be_constant(node)) {
non_constant_nodes.append(node);
}
}
return non_constant_nodes;
}
static bool output_has_non_constant_target_node(MFOutputSocket *output_socket,
Span<bool> 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<MFInputSocket *> find_constant_inputs_to_fold(
MFNetwork &network, Vector<MFDummyNode *> &r_temporary_nodes)
{
Vector<MFNode *> non_constant_nodes = find_non_constant_nodes(network);
Array<bool> is_not_constant_mask = mask_nodes_to_the_right(network, non_constant_nodes);
Vector<MFNode *> constant_nodes = find_nodes_based_on_mask(network, is_not_constant_mask, false);
Vector<MFInputSocket *> 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 &params,
ResourceCollector &resources)
{
for (int 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<GVectorArray>(AT, cpp_type, 1);
params.add_vector_output(vector_array);
break;
}
}
}
}
static Array<MFOutputSocket *> add_constant_folded_sockets(const MultiFunction &network_fn,
MFParamsBuilder &params,
ResourceCollector &resources,
MFNetwork &network)
{
Array<MFOutputSocket *> folded_sockets{network_fn.param_indices().size(), nullptr};
for (int 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.data();
resources.add(buffer, array.type().destruct_cb(), AT);
constant_fn = &resources.construct<CustomMF_GenericConstant>(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<CustomMF_GenericConstantArray>(AT, array);
break;
}
}
MFFunctionNode &folded_node = network.add_function(*constant_fn);
folded_sockets[param_index] = &folded_node.output(0);
}
return folded_sockets;
}
static Array<MFOutputSocket *> compute_constant_sockets_and_add_folded_nodes(
MFNetwork &network,
Span<const MFInputSocket *> 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<MFDummyNode *> temporary_nodes;
Vector<MFInputSocket *> inputs_to_fold = find_constant_inputs_to_fold(network, temporary_nodes);
if (inputs_to_fold.size() == 0) {
return;
}
Array<MFOutputSocket *> folded_sockets = compute_constant_sockets_and_add_folded_nodes(
network, inputs_to_fold, resources);
for (int 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);
}
/** \} */
/* -------------------------------------------------------------------- */
/** \name Common Sub-network Elimination
*
* \{ */
static uint64_t compute_node_hash(MFFunctionNode &node, RNG *rng, Span<uint64_t> node_hashes)
{
if (node.function().depends_on_context()) {
return BLI_rng_get_uint(rng);
}
if (node.has_unlinked_inputs()) {
return BLI_rng_get_uint(rng);
}
uint64_t combined_inputs_hash = 394659347u;
for (MFInputSocket *input_socket : node.inputs()) {
MFOutputSocket *origin_socket = input_socket->origin();
uint64_t input_hash = BLI_ghashutil_combine_hash(node_hashes[origin_socket->node().id()],
origin_socket->index());
combined_inputs_hash = BLI_ghashutil_combine_hash(combined_inputs_hash, input_hash);
}
uint64_t function_hash = node.function().hash();
uint64_t node_hash = BLI_ghashutil_combine_hash(combined_inputs_hash, function_hash);
return node_hash;
}
/**
* Produces a hash for every node. Two nodes with the same hash should have a high probability of
* outputting the same values.
*/
static Array<uint64_t> compute_node_hashes(MFNetwork &network)
{
RNG *rng = BLI_rng_new(0);
Array<uint64_t> node_hashes(network.node_id_amount());
Array<bool> node_is_hashed(network.node_id_amount(), false);
/* No dummy nodes are not assumed to output the same values. */
for (MFDummyNode *node : network.dummy_nodes()) {
uint64_t node_hash = BLI_rng_get_uint(rng);
node_hashes[node->id()] = node_hash;
node_is_hashed[node->id()] = true;
}
Stack<MFFunctionNode *> nodes_to_check;
nodes_to_check.push_multiple(network.function_nodes());
while (!nodes_to_check.is_empty()) {
MFFunctionNode &node = *nodes_to_check.peek();
if (node_is_hashed[node.id()]) {
nodes_to_check.pop();
continue;
}
/* Make sure that origin nodes are hashed first. */
bool all_dependencies_ready = true;
for (MFInputSocket *input_socket : node.inputs()) {
MFOutputSocket *origin_socket = input_socket->origin();
if (origin_socket != nullptr) {
MFNode &origin_node = origin_socket->node();
if (!node_is_hashed[origin_node.id()]) {
all_dependencies_ready = false;
nodes_to_check.push(&origin_node.as_function());
}
}
}
if (!all_dependencies_ready) {
continue;
}
uint64_t node_hash = compute_node_hash(node, rng, node_hashes);
node_hashes[node.id()] = node_hash;
node_is_hashed[node.id()] = true;
nodes_to_check.pop();
}
BLI_rng_free(rng);
return node_hashes;
}
static MultiValueMap<uint64_t, MFNode *> group_nodes_by_hash(MFNetwork &network,
Span<uint64_t> node_hashes)
{
MultiValueMap<uint64_t, MFNode *> nodes_by_hash;
for (int id : IndexRange(network.node_id_amount())) {
MFNode *node = network.node_or_null_by_id(id);
if (node != nullptr) {
uint64_t node_hash = node_hashes[id];
nodes_by_hash.add(node_hash, node);
}
}
return nodes_by_hash;
}
static bool functions_are_equal(const MultiFunction &a, const MultiFunction &b)
{
if (&a == &b) {
return true;
}
if (typeid(a) == typeid(b)) {
return a.equals(b);
}
return false;
}
static bool nodes_output_same_values(DisjointSet &cache, const MFNode &a, const MFNode &b)
{
if (cache.in_same_set(a.id(), b.id())) {
return true;
}
if (a.is_dummy() || b.is_dummy()) {
return false;
}
if (!functions_are_equal(a.as_function().function(), b.as_function().function())) {
return false;
}
for (int i : a.inputs().index_range()) {
const MFOutputSocket *origin_a = a.input(i).origin();
const MFOutputSocket *origin_b = b.input(i).origin();
if (origin_a == nullptr || origin_b == nullptr) {
return false;
}
if (!nodes_output_same_values(cache, origin_a->node(), origin_b->node())) {
return false;
}
}
cache.join(a.id(), b.id());
return true;
}
static void relink_duplicate_nodes(MFNetwork &network,
MultiValueMap<uint64_t, MFNode *> &nodes_by_hash)
{
DisjointSet same_node_cache{network.node_id_amount()};
for (Span<MFNode *> nodes_with_same_hash : nodes_by_hash.values()) {
if (nodes_with_same_hash.size() <= 1) {
continue;
}
Vector<MFNode *, 16> nodes_to_check = nodes_with_same_hash;
while (nodes_to_check.size() >= 2) {
Vector<MFNode *, 16> remaining_nodes;
MFNode &deduplicated_node = *nodes_to_check[0];
for (MFNode *node : nodes_to_check.as_span().drop_front(1)) {
/* This is true with fairly high probability, but hash collisions can happen. So we have to
* check if the node actually output the same values. */
if (nodes_output_same_values(same_node_cache, deduplicated_node, *node)) {
for (int i : deduplicated_node.outputs().index_range()) {
network.relink(node->output(i), deduplicated_node.output(i));
}
}
else {
remaining_nodes.append(node);
}
}
nodes_to_check = std::move(remaining_nodes);
}
}
}
/**
* Tries to detect duplicate sub-networks and eliminates them. This can help quite a lot when node
* groups were used to create the network.
*/
void common_subnetwork_elimination(MFNetwork &network)
{
Array<uint64_t> node_hashes = compute_node_hashes(network);
MultiValueMap<uint64_t, MFNode *> nodes_by_hash = group_nodes_by_hash(network, node_hashes);
relink_duplicate_nodes(network, nodes_by_hash);
}
/** \} */
} // namespace blender::fn::mf_network_optimization