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//------------------------------------------------------------------------------
// <copyright file="XmlILTrace.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">akimball</owner>
//------------------------------------------------------------------------------
using System;
using System.IO;
using System.Security;
using System.Xml;
using System.Globalization;
using System.Xml.Xsl.Qil;
using System.Runtime.Versioning;
// This class is only for debug purposes so there is no need to have it in Retail builds
#if DEBUG
namespace System.Xml.Xsl.IlGen {
/// <summary>
/// Helper class that facilitates tracing of ILGen.
/// </summary>
internal static class XmlILTrace {
private const int MAX_REWRITES = 200;
/// <summary>
/// Check environment variable in order to determine whether to write out trace files. This really should be a
/// check of the configuration file, but System.Xml does not yet have a good tracing story.
/// </summary>
private static volatile string dirName = null;
private static volatile bool alreadyCheckedEnabled = false;
/// <summary>
/// True if tracing has been enabled (environment variable set).
/// </summary>
public static bool IsEnabled {
// SxS: This property poses potential SxS issue. However the class is used only in debug builds (it won't
// get compiled into ret build) so it's OK to suppress the SxS warning.
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
[ResourceExposure(ResourceScope.None)]
get {
// If environment variable has not yet been checked, do so now
if (!alreadyCheckedEnabled) {
try {
dirName = Environment.GetEnvironmentVariable("XmlILTrace");
}
catch (SecurityException) {
// If user does not have access to environment variables, tracing will remain disabled
}
alreadyCheckedEnabled = true;
}
return (dirName != null);
}
}
/// <summary>
/// If tracing is enabled, this method will delete the contents of "filename" in preparation for append
/// operations.
/// </summary>
[ResourceConsumption(ResourceScope.Machine)]
[ResourceExposure(ResourceScope.Machine)]
public static void PrepareTraceWriter(string fileName) {
if (!IsEnabled)
return;
File.Delete(dirName + "\\" + fileName);
}
/// <summary>
/// If tracing is enabled, this method will open a TextWriter over "fileName" and return it. Otherwise,
/// null will be returned.
/// </summary>
[ResourceConsumption(ResourceScope.Machine)]
[ResourceExposure(ResourceScope.Machine)]
public static TextWriter GetTraceWriter(string fileName) {
if (!IsEnabled)
return null;
return new StreamWriter(dirName + "\\" + fileName, true);
}
/// <summary>
/// Serialize Qil tree to "fileName", in the directory identified by "dirName".
/// </summary>
[ResourceConsumption(ResourceScope.Machine)]
[ResourceExposure(ResourceScope.Machine)]
public static void WriteQil(QilExpression qil, string fileName) {
if (!IsEnabled)
return;
XmlWriter w = XmlWriter.Create(dirName + "\\" + fileName);
try {
WriteQil(qil, w);
}
finally {
w.Close();
}
}
/// <summary>
/// Trace ILGen optimizations and log them to "fileName".
/// </summary>
[ResourceConsumption(ResourceScope.Machine)]
[ResourceExposure(ResourceScope.Machine)]
public static void TraceOptimizations(QilExpression qil, string fileName) {
if (!IsEnabled)
return;
XmlWriter w = XmlWriter.Create(dirName + "\\" + fileName);
w.WriteStartDocument();
w.WriteProcessingInstruction("xml-stylesheet", "href='qilo.xslt' type='text/xsl'");
w.WriteStartElement("QilOptimizer");
w.WriteAttributeString("timestamp", DateTime.Now.ToString(CultureInfo.InvariantCulture));
WriteQilRewrite(qil, w, null);
try {
// Then, rewrite the graph until "done" or some max value is reached.
for (int i = 1; i < MAX_REWRITES; i++) {
QilExpression qilTemp = (QilExpression) (new QilCloneVisitor(qil.Factory).Clone(qil));
XmlILOptimizerVisitor visitor = new XmlILOptimizerVisitor(qilTemp, !qilTemp.IsDebug);
visitor.Threshold = i;
qilTemp = visitor.Optimize();
// In debug code, ensure that QIL after N steps is correct
QilValidationVisitor.Validate(qilTemp);
// Trace the rewrite
WriteQilRewrite(qilTemp, w, OptimizationToString(visitor.LastReplacement));
if (visitor.ReplacementCount < i)
break;
}
}
catch (Exception e) {
if (!XmlException.IsCatchableException(e)) {
throw;
}
w.WriteElementString("Exception", null, e.ToString());
throw;
}
finally {
w.WriteEndElement();
w.WriteEndDocument();
w.Flush();
w.Close();
}
}
/// <summary>
/// Serialize Qil tree to writer "w".
/// </summary>
private static void WriteQil(QilExpression qil, XmlWriter w) {
QilXmlWriter qw = new QilXmlWriter(w);
qw.ToXml(qil);
}
/// <summary>
/// Serialize rewritten Qil tree to writer "w".
/// </summary>
private static void WriteQilRewrite(QilExpression qil, XmlWriter w, string rewriteName) {
w.WriteStartElement("Diff");
if (rewriteName != null)
w.WriteAttributeString("rewrite", rewriteName);
WriteQil(qil, w);
w.WriteEndElement();
}
/// <summary>
/// Get friendly string description of an ILGen optimization.
/// </summary>
private static string OptimizationToString(int opt) {
string s = Enum.GetName(typeof(XmlILOptimization), opt);
if (s.StartsWith("Introduce", StringComparison.Ordinal)) {
return s.Substring(9) + " introduction";
}
else if (s.StartsWith("Eliminate", StringComparison.Ordinal)) {
return s.Substring(9) + " elimination";
}
else if (s.StartsWith("Commute", StringComparison.Ordinal)) {
return s.Substring(7) + " commutation";
}
else if (s.StartsWith("Fold", StringComparison.Ordinal)) {
return s.Substring(4) + " folding";
}
else if (s.StartsWith("Misc", StringComparison.Ordinal)) {
return s.Substring(4);
}
return s;
}
}
}
#endif
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