protected IList <IStatement> Schedule(IReadOnlyList <IStatement> isc)
{
DependencyGraph g = new DependencyGraph(context, isc, ignoreMissingNodes: false, ignoreRequirements: true, readAfterWriteOnly: true);
// The uniform statements must be removed first, before doing the search backward from outputs.
// This is important because it allows dependencies of uniform statements to be pruned.
// For example, suppose A requires B and C, B is uniform. This means that A is uniform and A will be pruned.
// As a result, C doesn't need to be computed (even if it might be non-uniform).
if (PruneUniformStmts)
{
g.PropagateUniformNodes();
}
// Propagate DependsOnIteration
DependsOnIteration attr = null;
DepthFirstSearch <NodeIndex> dfsIter = new DepthFirstSearch <EdgeIndex>(g.dependencyGraph.TargetsOf, g.nodeData);
dfsIter.DiscoverNode += delegate(NodeIndex node) {
if (!context.OutputAttributes.Has <DependsOnIteration>(isc[node]))
{
context.OutputAttributes.Set(isc[node], attr);
}
};
foreach (NodeIndex node in g.dependencyGraph.Nodes)
{
attr = context.GetAttribute <DependsOnIteration>(isc[node]);
if (attr != null)
{
dfsIter.SearchFrom(node);
}
}
// search backward from the outputs to find statements that are relevant.
DepthFirstSearch <NodeIndex> dfs = new DepthFirstSearch <NodeIndex>(
PruneUniformStmts ? (Converter <int, IEnumerable <int> >)g.SourcesNeededForOutput : g.dependencyGraph.SourcesOf,
g.nodeData);
dfs.SearchFrom(g.outputNodes);
List <NodeIndex> schedule = new List <NodeIndex>();
foreach (NodeIndex node in g.dependencyGraph.Nodes)
{
// any statement found in the search is relevant. other statements are pruned.
if (dfs.IsVisited[node] == VisitState.Finished)
{
schedule.Add(node);
}
}
if (debug)
{
var itdOut = context.FindOutputForAncestor <ITypeDeclaration, ITypeDeclaration>();
IBlockStatement block = Builder.BlockStmt();
foreach (var line in StringUtil.Lines(g.dependencyGraph.ToString()))
{
block.Statements.Add(Builder.CommentStmt(line));
}
foreach (NodeIndex node in g.dependencyGraph.Nodes)
{
block.Statements.Add(Builder.CommentStmt($"{node} {isc[node]}"));
}
context.OutputAttributes.Add(itdOut, new DebugInfo()
{
Transform = this,
Name = "Graph",
Value = block
});
}
if (PruneUniformStmts)
{
// When statements are pruned from the code, they must also be pruned from the DependencyInformation attributes of all other statements that might refer to them.
Dictionary <IStatement, IStatement> replacements = new Dictionary <IStatement, IStatement>(ReferenceEqualityComparer <IStatement> .Instance);
foreach (NodeIndex targetIndex in g.dependencyGraph.Nodes)
{
if (g.isUniform[targetIndex])
{
IStatement ist = isc[targetIndex];
DependencyInformation di = context.InputAttributes.Get <DependencyInformation>(ist);
// this is needed for detection of non-uniform initializers
di.IsUniform = true;
}
if (g.isUniform[targetIndex] && !g.isEssential[targetIndex])
{
NodeIndex source = g.FindInitializer(targetIndex);
if (source != targetIndex)
{
IStatement target = isc[targetIndex];
IStatement replacement = isc[source];
replacements[target] = replacement;
}
}
}
foreach (NodeIndex targetIndex in schedule)
{
IStatement target = isc[targetIndex];
DependencyInformation di = context.InputAttributes.Get <DependencyInformation>(target);
di.Replace(replacements);
}
}
IList <IStatement> sc = Builder.StmtCollection();
foreach (NodeIndex i in schedule)
{
IStatement st = isc[i];
sc.Add(st);
}
return(sc);
}
