private ISet <VariableAlias> _CollectAliases(string source)
{
var semanticModel = _documentFactory.CreateSemanticModel(source);
var forStatement = semanticModel.SyntaxTree.GetRoot().DescendantNodes().OfType <ForStatementSyntax>().Single();
var code = CodeFactory.Create(forStatement, semanticModel);
var variableAccesses = VariableAccesses.Collect(code);
var cfg = ControlFlowGraphFactory.Create(code);
return(ExternalArrayAliasCollector.Collect(semanticModel, forStatement, variableAccesses));
}
private bool _HasConflictingArrayAccesses(TLoopStatementSyntax loopStatement, string loopIndex, Code code, VariableAccesses variableAccesses)
{
var optimized = OptimizationRunner.Optimize(code);
code = optimized.Code;
variableAccesses = optimized.Changed ? VariableAccesses.Collect(code) : variableAccesses;
var cfg = ControlFlowGraphFactory.Create(code, true);
var callGraph = CallGraphFactory.Create(cfg, _methods);
var calledMethods = callGraph.Methods.Select(methodName => _methods[methodName]).ToImmutableList();
var aliasAnalysis = AliasAnalysis.Analyze(cfg, callGraph, _methods.Values, _GetAliasesAtLoopEntry(loopStatement, variableAccesses));
return(ArrayAccessVerifier.HasConflictingAccesses(loopIndex, cfg, aliasAnalysis, callGraph, calledMethods));
}
public void Scan(TLoopStatementSyntax loopStatement, SyntaxNode body, string loopIndex, Location location)
{
var code = ThreeAddressCodeFactory.Create(CodeFactory.Create(body, _semanticModel));
var variableAccesses = VariableAccesses.Collect(code);
if (!WriteAccessVerifier.HasNoWriteAccessToSharedVariables(variableAccesses))
{
Debug.WriteLine("the loop contains write accesses to shared variables");
return;
}
if (_HasConflictingArrayAccesses(loopStatement, loopIndex, code, variableAccesses))
{
Debug.WriteLine("the loop contains loop carried dependencies");
return;
}
_ReportLoopForParallelization(loopStatement, location);
}
/// <summary>
/// Checks that there are no write accesses to shared variables.
/// </summary>
/// <param name="variableAccesses">A prelimary applied variable access collection on the loop's body.</param>
/// <returns><code>True</code> if there are no write accesses to shared variables.</returns>
public static bool HasNoWriteAccessToSharedVariables(VariableAccesses variableAccesses)
{
return(!new WriteAccessVerifier(variableAccesses)._ContainsWriteAccessesToSharedVariables());
}
private WriteAccessVerifier(VariableAccesses variableAccesses)
{
_variableAccesses = variableAccesses;
}
private VariableAccesses _CollectAccesses(string body)
{
return(VariableAccesses.Collect(TestCodeFactory.CreateCode(body)));
}
private IEnumerable <VariableAlias> _GetAliasesAtLoopEntry(TLoopStatementSyntax loopStatement, VariableAccesses variableAccesses)
{
// TODO maybe use a different Expression to setup the input aliases instead of variables. This might cause trouble when forgetting this situation in further changes.
var filtered = variableAccesses.DeclaredVariables
.Concat(variableAccesses.ReadArrays.Concat(variableAccesses.WrittenArrays).Select(array => array.Name))
.ToImmutableHashSet();
var variables = variableAccesses.ReadVariables
.Union(variableAccesses.WrittenVariables)
.Except(filtered)
.Select(variableName => new VariableAlias(variableName, new VariableExpression(variableName)))
.Concat(ExternalArrayAliasCollector.Collect(_semanticModel, loopStatement, variableAccesses))
.ToImmutableHashSet();
return(variables);
}
