TailCallAnalyzer.cs

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using System.Xml.Xsl.Qil;
 
namespace System.Xml.Xsl.IlGen;
 
internal static class TailCallAnalyzer
{
    public static void Analyze(QilExpression qil)
    {
        foreach (QilFunction function in qil.FunctionList)
        {
            if (XmlILConstructInfo.Read(function).ConstructMethod == XmlILConstructMethod.Writer)
            {
                AnalyzeDefinition(function.Definition);
            }
        }
    }
 
    private static void AnalyzeDefinition(QilNode nd)
    {
        switch (nd.NodeType)
        {
        case QilNodeType.Invoke:
            if (XmlILConstructInfo.Read(nd).ConstructMethod == XmlILConstructMethod.Writer)
            {
                OptimizerPatterns.Write(nd).AddPattern(OptimizerPatternName.TailCall);
            }
            break;
        case QilNodeType.Loop:
        {
            QilLoop qilLoop = (QilLoop)nd;
            if (qilLoop.Variable.NodeType == QilNodeType.Let || !qilLoop.Variable.Binding.XmlType.MaybeMany)
            {
                AnalyzeDefinition(qilLoop.Body);
            }
            break;
        }
        case QilNodeType.Sequence:
        {
            QilList qilList = (QilList)nd;
            if (qilList.Count > 0)
            {
                AnalyzeDefinition(qilList[qilList.Count - 1]);
            }
            break;
        }
        case QilNodeType.Choice:
        {
            QilChoice qilChoice = (QilChoice)nd;
            for (int i = 0; i < qilChoice.Branches.Count; i++)
            {
                AnalyzeDefinition(qilChoice.Branches[i]);
            }
            break;
        }
        case QilNodeType.Conditional:
        {
            QilTernary qilTernary = (QilTernary)nd;
            AnalyzeDefinition(qilTernary.Center);
            AnalyzeDefinition(qilTernary.Right);
            break;
        }
        case QilNodeType.Nop:
            AnalyzeDefinition(((QilUnary)nd).Child);
            break;
        }
    }
}