Debugging Crossgen2 documentation (#47363)

* Debugging Crossgen2 documentation and such
- Also new --print-repro-instructions command line switch to crossgen2 as requested by the JIT team

docs/workflow/debugging/coreclr/debugging.md

@@ -73,6 +73,10 @@ The "COMPlus_EnableDiagnostics" environment variable can be used to disable mana
 
     export COMPlus_EnableDiagnostics=0
 
+Debugging Crossgen2
+==================================
+
+Debugging Crossgen2 is described in [this](debugging-crossgen2.md) document.
 
 Using Visual Studio Code
 ========================

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs

@@ -232,6 +232,7 @@ public sealed class ReadyToRunCodegenCompilation : Compilation
         private bool _generateMapFile;
         private bool _generateMapCsvFile;
         private bool _generatePdbFile;
+        private Func<MethodDesc, string> _printReproInstructions;
         private string _pdbPath;
         private bool _generatePerfMapFile;
         private string _perfMapPath;
@@ -262,6 +263,7 @@ internal ReadyToRunCodegenCompilation(
             bool generateMapFile,
             bool generateMapCsvFile,
             bool generatePdbFile,
+            Func<MethodDesc, string> printReproInstructions,
             string pdbPath,
             bool generatePerfMapFile,
             string perfMapPath,
@@ -294,6 +296,7 @@ internal ReadyToRunCodegenCompilation(
             _corInfoImpls = new ConditionalWeakTable<Thread, CorInfoImpl>();
             _inputFiles = inputFiles;
             _compositeRootPath = compositeRootPath;
+            _printReproInstructions = printReproInstructions;
             CompilationModuleGroup = (ReadyToRunCompilationModuleGroupBase)nodeFactory.CompilationModuleGroup;
 
             // Generate baseline support specification for InstructionSetSupport. This will prevent usage of the generated
@@ -524,6 +527,11 @@ protected override void ComputeDependencyNodeDependencies(List<DependencyNodeCor
                         Logger.Writer.WriteLine("Compiling " + methodName);
                     }
 
+                    if (_printReproInstructions != null)
+                    {
+                        Logger.Writer.WriteLine($"Single method repro args:{_printReproInstructions(method)}");
+                    }
+
                     try
                     {
                         using (PerfEventSource.StartStopEvents.JitMethodEvents())

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilationBuilder.cs

@@ -12,6 +12,7 @@
 using Internal.IL;
 using Internal.JitInterface;
 using Internal.ReadyToRunConstants;
+using Internal.TypeSystem;
 using Internal.TypeSystem.Ecma;
 
 namespace ILCompiler
@@ -29,6 +30,7 @@ public sealed class ReadyToRunCodegenCompilationBuilder : CompilationBuilder
         private bool _generatePerfMapFile;
         private string _perfMapPath;
         private int _parallelism;
+        Func<MethodDesc, string> _printReproInstructions;
         private InstructionSetSupport _instructionSetSupport;
         private ProfileDataManager _profileData;
         private ReadyToRunMethodLayoutAlgorithm _r2rMethodLayoutAlgorithm;
@@ -157,6 +159,12 @@ public ReadyToRunCodegenCompilationBuilder UseParallelism(int parallelism)
             return this;
         }
 
+        public ReadyToRunCodegenCompilationBuilder UsePrintReproInstructions(Func<MethodDesc, string> printReproInstructions)
+        {
+            _printReproInstructions = printReproInstructions;
+            return this;
+        }
+
         public ReadyToRunCodegenCompilationBuilder UseInstructionSetSupport(InstructionSetSupport instructionSetSupport)
         {
             _instructionSetSupport = instructionSetSupport;
@@ -267,6 +275,7 @@ public override ICompilation ToCompilation()
                 generateMapFile: _generateMapFile,
                 generateMapCsvFile: _generateMapCsvFile,
                 generatePdbFile: _generatePdbFile,
+                printReproInstructions: _printReproInstructions,
                 pdbPath: _pdbPath,
                 generatePerfMapFile: _generatePerfMapFile,
                 perfMapPath: _perfMapPath,

src/coreclr/tools/aot/crossgen2/CommandLineOptions.cs

@@ -46,6 +46,7 @@ internal class CommandLineOptions
         public bool Resilient;
         public bool Map;
         public bool MapCsv;
+        public bool PrintReproInstructions;
         public bool Pdb;
         public string PdbPath;
         public bool PerfMap;
@@ -113,6 +114,7 @@ public CommandLineOptions(string[] args)
                 syntax.DefineOption("targetos", ref TargetOS, SR.TargetOSOption);
                 syntax.DefineOption("jitpath", ref JitPath, SR.JitPathOption);
 
+                syntax.DefineOption("print-repro-instructions", ref PrintReproInstructions, SR.PrintReproInstructionsOption);
                 syntax.DefineOption("singlemethodtypename", ref SingleMethodTypeName, SR.SingleMethodTypeName);
                 syntax.DefineOption("singlemethodname", ref SingleMethodName, SR.SingleMethodMethodName);
                 syntax.DefineOption("singlemethodindex", ref SingleMethodIndex, SR.SingleMethodIndex);

src/coreclr/tools/aot/crossgen2/Program.cs

@@ -7,6 +7,7 @@
 using System.Reflection.Metadata;
 using System.Reflection.PortableExecutable;
 using System.Runtime.InteropServices;
+using System.Text;
 
 using Internal.CommandLine;
 using Internal.IL;
@@ -607,6 +608,9 @@ private int Run(string[] args)
                         .UseCompilationRoots(compilationRoots)
                         .UseOptimizationMode(_optimizationMode);
 
+                    if (_commandLineOptions.PrintReproInstructions)
+                        builder.UsePrintReproInstructions(CreateReproArgumentString);
+
                     compilation = builder.ToCompilation();
 
                 }
@@ -722,35 +726,41 @@ private MethodDesc CheckAndParseSingleMethodModeArguments(CompilerTypeSystemCont
             return method;
         }
 
-        private static bool DumpReproArguments(CodeGenerationFailedException ex)
+        private static string CreateReproArgumentString(MethodDesc method)
         {
-            Console.WriteLine(SR.DumpReproInstructions);
+            StringBuilder sb = new StringBuilder();
 
-            MethodDesc failingMethod = ex.Method;
-
-            var formatter = new CustomAttributeTypeNameFormatter((IAssemblyDesc)failingMethod.Context.SystemModule);
+            var formatter = new CustomAttributeTypeNameFormatter((IAssemblyDesc)method.Context.SystemModule);
 
-            Console.Write($"--singlemethodtypename \"{formatter.FormatName(failingMethod.OwningType, true)}\"");
-            Console.Write($" --singlemethodname {failingMethod.Name}");
+            sb.Append($"--singlemethodtypename \"{formatter.FormatName(method.OwningType, true)}\"");
+            sb.Append($" --singlemethodname {method.Name}");
             {
                 int curIndex = 0;
-                foreach (var searchMethod in failingMethod.OwningType.GetMethods())
+                foreach (var searchMethod in method.OwningType.GetMethods())
                 {
-                    if (searchMethod.Name != failingMethod.Name)
+                    if (searchMethod.Name != method.Name)
                         continue;
 
                     curIndex++;
-                    if (searchMethod == failingMethod.GetMethodDefinition())
+                    if (searchMethod == method.GetMethodDefinition())
                     {
-                        Console.Write($" --singlemethodindex {curIndex}");
+                        sb.Append($" --singlemethodindex {curIndex}");
                     }
                 }
             }
 
-            for (int i = 0; i < failingMethod.Instantiation.Length; i++)
-                Console.Write($" --singlemethodgenericarg \"{formatter.FormatName(failingMethod.Instantiation[i], true)}\"");
+            for (int i = 0; i < method.Instantiation.Length; i++)
+                sb.Append($" --singlemethodgenericarg \"{formatter.FormatName(method.Instantiation[i], true)}\"");
+
+            return sb.ToString();
+        }
+
+        private static bool DumpReproArguments(CodeGenerationFailedException ex)
+        {
+            Console.WriteLine(SR.DumpReproInstructions);
 
-            Console.WriteLine();
+            MethodDesc failingMethod = ex.Method;
+            Console.WriteLine(CreateReproArgumentString(failingMethod));
             return false;
         }
 

src/coreclr/tools/aot/crossgen2/Properties/Resources.resx

@@ -222,6 +222,9 @@
   <data name="SaveDetailedLogOption" xml:space="preserve">
     <value>Save detailed log of dependency analysis</value>
   </data>
+  <data name="PrintReproInstructionsOption" xml:space="preserve">
+    <value>When compiling each method, print out the set of arguments needed to compile that method only</value>
+  </data>
   <data name="SingleMethodGenericArgs" xml:space="preserve">
     <value>Single method compilation: generic arguments to the method</value>
   </data>