// recovers the processing order within a recurrent loop
// TODO: Once we only use the nested network for recurrent traversal, this will be no longer necessary.
void ComputationNetwork::DetermineLoopForwardOrder(unordered_set<ComputationNodeBasePtr>& visited,
unordered_set<ComputationNodeBasePtr>& recStack,
list<ComputationNodeBasePtr>& nodesStack,
ComputationNodeBasePtr cur)
{
if (visited.find(cur) == visited.end())
{
visited.insert(cur);
recStack.insert(cur);
if (GetRecurrenceSteppingDirection(cur) == 0) // recurrence stops at delay nodes
{
for (size_t i = 0; i < cur->GetNumInputs(); i++)
if (cur->Input(i)->m_loopId == cur->m_loopId)
DetermineLoopForwardOrder(visited, recStack, nodesStack, cur->Input(i));
}
recStack.erase(cur);
nodesStack.push_back(cur);
}
else if (recStack.find(cur) != recStack.end())
LogicError("%ls %ls operation is part of an infinite loop that cannot be unrolled.", cur->NodeName().c_str(), cur->OperationName().c_str());
}
// traverse sub-graph feeding this node (which is a top-level node at start, e.g. training criterion) and list
// - all nodes that participate in a loop -> recurrentResult[loopId][]
// - all nodes that don't -> noRecurrentResult[]
// in order of traversal (depth-first).
// This is part of the FormRecurrentLoops() process, and only called from there from one place.
void ComputationNetwork::GatherLoopNodesR(const ComputationNodeBasePtr& node, unordered_set<ComputationNodeBasePtr>& visited,
map<int, list<ComputationNodeBasePtr>>& recurrentResult,
list<ComputationNodeBasePtr>& noRecurrentResult)
{
if (visited.find(node) != visited.end())
return; // do each node only once
visited.insert(node);
for (int i = 0; i < node->GetNumInputs(); i++)
GatherLoopNodesR(node->Input(i), visited, recurrentResult, noRecurrentResult);
if (node->m_loopId >= 0)
recurrentResult[node->m_loopId].push_back(node);
else
noRecurrentResult.push_back(node);
}
// TODO: how does the file distinguish float vs double nodes?
void ComputationNetwork::SaveToFileImpl(const wstring& fileName, const FileOptions fileFormat) const
{
File fstream(fileName, fileFormat | FileOptions::fileOptionsWrite);
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BCN");
// model version
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BVersion");
fstream << (size_t) CURRENT_CNTK_MODEL_VERSION;
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"EVersion");
fstream << (size_t) m_nameToNodeMap.size();
// put all node info first
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BNodeList");
for (auto nodeIter = m_nameToNodeMap.begin(); nodeIter != m_nameToNodeMap.end(); nodeIter++)
{
ComputationNodeBasePtr nodePtr = nodeIter->second;
nodePtr->Save(fstream);
}
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"ENodeList");
// put relationship
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BRelation");
for (auto nodeIter = m_nameToNodeMap.begin(); nodeIter != m_nameToNodeMap.end(); nodeIter++)
{
ComputationNodeBasePtr nodePtr = nodeIter->second;
fstream << nodePtr->NodeName() << nodePtr->GetNumInputs();
for (size_t i = 0; i < nodePtr->GetNumInputs(); i++)
{
if (!nodePtr->Input(i))
fprintf(stderr, "Warning: node %ls 's child is null, please check your ndl/mel file.\n", nodePtr->NodeName().c_str());
else
fstream << nodePtr->Input(i)->NodeName();
}
}
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"ERelation");
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BRootNodes");
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BFeatureNodes");
fstream << m_features.size();
for (size_t i = 0; i < m_features.size(); i++)
fstream << m_features[i]->NodeName();
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"EFeatureNodes");
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BLabelNodes");
fstream << m_labels.size();
for (size_t i = 0; i < m_labels.size(); i++)
fstream << m_labels[i]->NodeName();
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"ELabelNodes");
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BCriterionNodes");
fstream << m_finalCriteria.size();
for (size_t i = 0; i < m_finalCriteria.size(); i++)
fstream << m_finalCriteria[i]->NodeName();
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"ECriterionNodes");
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BEvalNodes");
fstream << m_evalNodes.size();
for (size_t i = 0; i < m_evalNodes.size(); i++)
fstream << m_evalNodes[i]->NodeName();
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"EEvalNodes");
fstream.PutMarker(FileMarker::fileMarkerBeginSection, L"BOutputNodes");
fstream << m_outputNodes.size();
for (size_t i = 0; i < m_outputNodes.size(); i++)
{
fstream << m_outputNodes[i]->NodeName();
}
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"EOutputNodes");
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"ERootNodes");
fstream.PutMarker(FileMarker::fileMarkerEndSection, L"ECN");
fstream.Flush();
}
// (recursive part of DetermineSCCs())
void ComputationNetwork::DetermineSCCsR(ComputationNodeBasePtr cur,
list<ComputationNodeBasePtr>& sccStack,
size_t& index, size_t& loopId)
{
assert(!cur->m_visited);
// set the index (in order of visitation)
cur->m_index = index; // TODO: can this be used as m_visitedOrder?
cur->m_minIndex = index; // also set m_minIndex
index++;
cur->m_visited = true;
sccStack.push_back(cur);
cur->m_inStack = true;
// set m_minIndex to min over m_lowLinks of children
for (int i = 0; i < cur->GetNumInputs(); i++)
{
if (!cur->Input(i)->m_visited)
{
DetermineSCCsR(cur->Input(i), sccStack, index, loopId);
cur->m_minIndex = min(cur->m_minIndex, cur->Input(i)->m_minIndex);
}
else if (cur->Input(i)->m_inStack)
{
cur->m_minIndex = min(cur->m_minIndex, cur->Input(i)->m_minIndex);
}
}
// if we closed a loop then create an entry in m_allSEQNodes
if (cur->m_minIndex == cur->m_index) // m_minIndex is still equal to m_index, as we set it at the start of this function: we closed a loop
{
// gather the list of all nodes in this loop
vector<ComputationNodeBasePtr> nestedNodes;
// TODO: build array first in a local array. Only if succeeds, then construct the node off it.
SEQTraversalFlowControlNode rInfo(m_allSEQNodes.size() /*loopId*/, cur);
for (;;)
{
ComputationNodeBasePtr w = sccStack.back();
sccStack.pop_back();
w->m_inStack = false;
nestedNodes.push_back(w);
if (w == cur) // hit our starting point: done
break;
}
// insert loop into m_allSEQNodes
if (nestedNodes.size() > 1) // non-looped nodes are detected here as loops of size 1 --skip those
{
// only add to the array if the loop is not already there
// We end up producing the same loop multiple times because:
// - FormRecurrentLoops() is called multiple times from different roots
// - depth-first traversal might have led us to enter a loop multiple times?
// TODO: Check whether this edge case of idempotence is done correctly:
// - a recurrent loop with two delay nodes
// - two root nodes
// - the first root takes the first delay node's value, the second root that of the second delay node
// I.e. the depth-first tree traversals enter the loop at two different places (m_sourceNode).
// -> Are these two loops detected as identical? (determined by m_minIndex, but m_index depends on traversal from each root, so maybe not)
bool bFound = false; // find a dup --TODO: check whether there is an STL algorithm for this
for (const auto& iter2 : m_allSEQNodes)
{
if (iter2->m_sourceNode == cur)
{
bFound = true;
break;
}
}
if (!bFound)
{
#if 1
if (loopId != m_allSEQNodes.size())
LogicError("DetermineSCCsR(): inconsistent loopId (%d) vs. m_allSEQNodes.size() (%d)", (int) loopId, (int) m_allSEQNodes.size());
SEQTraversalFlowControlNode rInfo(m_allSEQNodes.size(), cur);
#else
assert(loopId == m_allSEQNodes.size()); // BUGBUG: Only true if all loops are shared among roots. Fix: use m_allSEQNodes.size() instead
SEQTraversalFlowControlNode rInfo(loopId, cur);
#endif
// TODO: can we prove that 'cur' == nestedNodes.front()? If so, we won't need to store it separately.
rInfo.m_nestedNodes = move(nestedNodes); // TODO: make these two part of the constructor
rInfo.m_steppingDirection = DetermineLoopDirection(rInfo.m_nestedNodes);
m_allSEQNodes.push_back(make_shared<SEQTraversalFlowControlNode>(move(rInfo)));
loopId++; // and count it TODO: may be removed
}
}
}
}