private void DetermineCaptureAndDeclarationScopes(Dictionary <MethodDefinitionHandle, LocalFunctionInfo> .ValueCollection localFunctions)
{
foreach (var info in localFunctions)
{
context.CancellationToken.ThrowIfCancellationRequested();
if (info.Definition == null)
{
context.Function.Warnings.Add($"Could not decode local function '{info.Method}'");
continue;
}
context.StepStartGroup($"Determine and move to declaration scope of " + info.Definition.Name, info.Definition);
try
{
var localFunction = info.Definition;
foreach (var useSite in info.UseSites)
{
DetermineCaptureAndDeclarationScope(info, useSite);
if (context.Function.Method.IsConstructor && localFunction.DeclarationScope == null)
{
localFunction.DeclarationScope = BlockContainer.FindClosestContainer(useSite);
}
}
if (localFunction.DeclarationScope == null)
{
localFunction.DeclarationScope = (BlockContainer)context.Function.Body;
}
ILFunction declaringFunction = GetDeclaringFunction(localFunction);
if (declaringFunction != context.Function)
{
context.Step($"Move {localFunction.Name} from {context.Function.Name} to {declaringFunction.Name}", localFunction);
context.Function.LocalFunctions.Remove(localFunction);
declaringFunction.LocalFunctions.Add(localFunction);
}
if (TryValidateSkipCount(info, out int skipCount) && skipCount != localFunction.ReducedMethod.NumberOfCompilerGeneratedTypeParameters)
{
Debug.Assert(false);
context.Function.Warnings.Add($"Could not decode local function '{info.Method}'");
if (declaringFunction != context.Function)
{
declaringFunction.LocalFunctions.Remove(localFunction);
}
}
}
finally
{
context.StepEndGroup(keepIfEmpty: true);
}
}
}
public void Run(Block block, int pos, StatementTransformContext context)
{
this.context = context;
context.StepStartGroup($"ExpressionTransforms ({block.Label}:{pos})", block.Instructions[pos]);
block.Instructions[pos].AcceptVisitor(this);
context.StepEndGroup(keepIfEmpty: true);
}
void IILTransform.Run(ILFunction function, ILTransformContext context)
{
if (!context.Settings.AnonymousMethods)
{
return;
}
this.context = context;
this.decompilationContext = new SimpleTypeResolveContext(function.Method);
var orphanedVariableInits = new List <ILInstruction>();
var targetsToReplace = new List <IInstructionWithVariableOperand>();
var translatedDisplayClasses = new HashSet <ITypeDefinition>();
var cancellationToken = context.CancellationToken;
foreach (var inst in function.Descendants)
{
cancellationToken.ThrowIfCancellationRequested();
if (inst is NewObj call)
{
context.StepStartGroup($"TransformDelegateConstruction {call.StartILOffset}", call);
ILFunction f = TransformDelegateConstruction(call, out ILInstruction target);
if (f != null && target is IInstructionWithVariableOperand instWithVar)
{
if (instWithVar.Variable.Kind == VariableKind.Local)
{
instWithVar.Variable.Kind = VariableKind.DisplayClassLocal;
}
targetsToReplace.Add(instWithVar);
}
context.StepEndGroup();
}
if (inst.MatchStLoc(out ILVariable targetVariable, out ILInstruction value))
{
var newObj = value as NewObj;
// TODO : it is probably not a good idea to remove *all* display-classes
// is there a way to minimize the false-positives?
if (newObj != null && IsInSimpleDisplayClass(newObj.Method))
{
targetVariable.CaptureScope = BlockContainer.FindClosestContainer(inst);
targetsToReplace.Add((IInstructionWithVariableOperand)inst);
translatedDisplayClasses.Add(newObj.Method.DeclaringTypeDefinition);
}
}
}
foreach (var target in targetsToReplace.OrderByDescending(t => ((ILInstruction)t).StartILOffset))
{
context.Step($"TransformDisplayClassUsages {target.Variable}", (ILInstruction)target);
function.AcceptVisitor(new TransformDisplayClassUsages(function, target, target.Variable.CaptureScope, orphanedVariableInits, translatedDisplayClasses));
}
context.Step($"Remove orphanedVariableInits", function);
foreach (var store in orphanedVariableInits)
{
if (store.Parent is Block containingBlock)
{
containingBlock.Instructions.Remove(store);
}
}
}
/// <summary>
/// The transform works like this:
///
/// <para>
/// local functions can either be used in method calls, i.e., call and callvirt instructions,
/// or can be used as part of the "delegate construction" pattern, i.e., <c>newobj Delegate(<target-expression>, ldftn <method>)</c>.
/// </para>
/// As local functions can be declared practically anywhere, we have to take a look at all use-sites and infer the declaration location from that. Use-sites can be call, callvirt and ldftn instructions.
/// After all use-sites are collected we construct the ILAst of the local function and add it to the parent function.
/// Then all use-sites of the local-function are transformed to a call to the <c>LocalFunctionMethod</c> or a ldftn of the <c>LocalFunctionMethod</c>.
/// In a next step we handle all nested local functions.
/// After all local functions are transformed, we move all local functions that capture any variables to their respective declaration scope.
/// </summary>
public void Run(ILFunction function, ILTransformContext context)
{
if (!context.Settings.LocalFunctions)
{
return;
}
this.context = context;
this.resolveContext = new SimpleTypeResolveContext(function.Method);
var localFunctions = new Dictionary <MethodDefinitionHandle, LocalFunctionInfo>();
var cancellationToken = context.CancellationToken;
// Find all local functions declared inside this method, including nested local functions or local functions declared in lambdas.
FindUseSites(function, context, localFunctions);
foreach (var(method, info) in localFunctions)
{
cancellationToken.ThrowIfCancellationRequested();
var firstUseSite = info.UseSites[0];
context.StepStartGroup($"Transform " + info.Definition.Name, info.Definition);
try {
var localFunction = info.Definition;
if (!localFunction.Method.IsStatic)
{
var target = firstUseSite.Arguments[0];
context.Step($"Replace 'this' with {target}", localFunction);
var thisVar = localFunction.Variables.SingleOrDefault(VariableKindExtensions.IsThis);
localFunction.AcceptVisitor(new DelegateConstruction.ReplaceDelegateTargetVisitor(target, thisVar));
}
foreach (var useSite in info.UseSites)
{
context.Step("Transform use site at " + useSite.StartILOffset, useSite);
if (useSite.OpCode == OpCode.NewObj)
{
TransformToLocalFunctionReference(localFunction, useSite);
}
else
{
DetermineCaptureAndDeclarationScope(localFunction, useSite);
TransformToLocalFunctionInvocation(localFunction.ReducedMethod, useSite);
}
}
if (localFunction.DeclarationScope == null)
{
localFunction.DeclarationScope = (BlockContainer)function.Body;
}
else if (localFunction.DeclarationScope != function.Body && localFunction.DeclarationScope.Parent is ILFunction declaringFunction)
{
function.LocalFunctions.Remove(localFunction);
declaringFunction.LocalFunctions.Add(localFunction);
}
} finally {
context.StepEndGroup();
}
}
}
protected internal override void VisitILFunction(ILFunction function)
{
context.StepStartGroup("Visit " + function.Name);
try {
this.currentFunctions.Push(function);
base.VisitILFunction(function);
} finally {
this.currentFunctions.Pop();
context.StepEndGroup(keepIfEmpty: true);
}
}
void IILTransform.Run(ILFunction function, ILTransformContext context)
{
if (!context.Settings.AnonymousMethods)
{
return;
}
var prevContext = this.context;
var prevDecompilationContext = this.decompilationContext;
try
{
activeMethods.Push((MethodDefinitionHandle)function.Method.MetadataToken);
this.context = context;
this.decompilationContext = new SimpleTypeResolveContext(function.Method);
var cancellationToken = context.CancellationToken;
foreach (var inst in function.Descendants)
{
cancellationToken.ThrowIfCancellationRequested();
if (!MatchDelegateConstruction(inst, out var targetMethod, out var target,
out var delegateType, allowTransformed: false))
{
continue;
}
context.StepStartGroup($"TransformDelegateConstruction {inst.StartILOffset}", inst);
ILFunction f = TransformDelegateConstruction(inst, targetMethod, target, delegateType);
if (f != null && target is IInstructionWithVariableOperand instWithVar)
{
var v = instWithVar.Variable;
if (v.Kind == VariableKind.Local)
{
v.Kind = VariableKind.DisplayClassLocal;
}
if (v.IsSingleDefinition &&
v.StoreInstructions.SingleOrDefault() is StLoc store &&
store.Value is NewObj)
{
v.CaptureScope = BlockContainer.FindClosestContainer(store);
}
}
context.StepEndGroup();
}
}
finally
{
this.context = prevContext;
this.decompilationContext = prevDecompilationContext;
activeMethods.Pop();
}
}
/// <summary>
/// catch E_189 : 0200007C System.Exception when (BlockContainer {
/// Block IL_0079 (incoming: 1) {
/// stloc S_30(ldloc E_189)
/// br IL_0085
/// }
///
/// Block IL_0085 (incoming: 1) {
/// stloc I_1(ldloc S_30)
/// where S_30 and I_1 are single definition
/// =>
/// copy-propagate E_189 to replace all uses of S_30 and I_1
/// </summary>
static void PropagateExceptionVariable(ILTransformContext context, TryCatchHandler handler)
{
var exceptionVariable = handler.Variable;
if (!exceptionVariable.IsSingleDefinition)
{
return;
}
context.StepStartGroup(nameof(PropagateExceptionVariable));
int i = 0;
while (i < exceptionVariable.LoadInstructions.Count)
{
var load = exceptionVariable.LoadInstructions[i];
if (!load.IsDescendantOf(handler))
{
i++;
continue;
}
// We are only interested in store "statements" copying the exception variable
// without modifying it.
var statement = LocalFunctionDecompiler.GetStatement(load);
if (!(statement is StLoc stloc))
{
i++;
continue;
}
// simple copy case:
// stloc b(ldloc a)
if (stloc.Value == load)
{
PropagateExceptionInstance(stloc);
}
// if the type of the cast-class instruction matches the exceptionType,
// this cast can be removed without losing any side-effects.
// Note: this would also hold true iff exceptionType were an exception derived
// from cc.Type, however, we are more restrictive to match the pattern exactly.
// stloc b(castclass exceptionType(ldloc a))
else if (stloc.Value is CastClass cc && cc.Type.Equals(exceptionVariable.Type) && cc.Argument == load)
{
stloc.Value = load;
PropagateExceptionInstance(stloc);
}
void IILTransform.Run(ILFunction function, ILTransformContext context)
{
if (!context.Settings.AnonymousMethods)
{
return;
}
this.context = context;
this.decompilationContext = new SimpleTypeResolveContext(function.Method);
var cancellationToken = context.CancellationToken;
foreach (var inst in function.Descendants)
{
cancellationToken.ThrowIfCancellationRequested();
if (inst is NewObj call)
{
context.StepStartGroup($"TransformDelegateConstruction {call.StartILOffset}", call);
ILFunction f = TransformDelegateConstruction(call, out ILInstruction target);
if (f != null && target is IInstructionWithVariableOperand instWithVar)
{
if (instWithVar.Variable.Kind == VariableKind.Local)
{
instWithVar.Variable.Kind = VariableKind.DisplayClassLocal;
}
var displayClassTypeDef = instWithVar.Variable.Type.GetDefinition();
if (instWithVar.Variable.IsSingleDefinition && instWithVar.Variable.StoreInstructions.SingleOrDefault() is StLoc store)
{
if (store.Value is NewObj newObj)
{
instWithVar.Variable.CaptureScope = BlockContainer.FindClosestContainer(store);
}
}
}
context.StepEndGroup();
}
}
}
/// <summary>
/// The transform works like this:
///
/// <para>
/// local functions can either be used in method calls, i.e., call and callvirt instructions,
/// or can be used as part of the "delegate construction" pattern, i.e.,
/// <c>newobj Delegate(<target-expression>, ldftn <method>)</c>.
/// </para>
/// As local functions can be declared practically anywhere, we have to take a look at
/// all use-sites and infer the declaration location from that. Use-sites can be call,
/// callvirt and ldftn instructions.
/// After all use-sites are collected we construct the ILAst of the local function
/// and add it to the parent function.
/// Then all use-sites of the local-function are transformed to a call to the
/// <c>LocalFunctionMethod</c> or a ldftn of the <c>LocalFunctionMethod</c>.
/// In a next step we handle all nested local functions.
/// After all local functions are transformed, we move all local functions that capture
/// any variables to their respective declaration scope.
/// </summary>
public void Run(ILFunction function, ILTransformContext context)
{
if (!context.Settings.LocalFunctions)
{
return;
}
// Disable the transform if we are decompiling a display-class or local function method:
// This happens if a local function or display class is selected in the ILSpy tree view.
if (IsLocalFunctionMethod(function.Method, context) || IsLocalFunctionDisplayClass(function.Method.ParentModule.PEFile, (TypeDefinitionHandle)function.Method.DeclaringTypeDefinition.MetadataToken, context))
{
return;
}
this.context = context;
this.resolveContext = new SimpleTypeResolveContext(function.Method);
var localFunctions = new Dictionary <MethodDefinitionHandle, LocalFunctionInfo>();
var cancellationToken = context.CancellationToken;
// Find all local functions declared inside this method, including nested local functions or local functions declared in lambdas.
FindUseSites(function, context, localFunctions);
foreach (var(_, info) in localFunctions)
{
cancellationToken.ThrowIfCancellationRequested();
if (info.Definition == null)
{
function.Warnings.Add($"Could not decode local function '{info.Method}'");
continue;
}
context.StepStartGroup($"Transform " + info.Definition.Name, info.Definition);
try {
var localFunction = info.Definition;
if (!localFunction.Method.IsStatic)
{
var thisVar = localFunction.Variables.SingleOrDefault(VariableKindExtensions.IsThis);
var target = info.UseSites.Where(us => us.Arguments[0].MatchLdLoc(out _)).FirstOrDefault()?.Arguments[0];
if (target == null)
{
target = info.UseSites[0].Arguments[0];
if (target.MatchLdFld(out var target1, out var field) && thisVar.Type.Equals(field.Type) && field.Type.Kind == TypeKind.Class && TransformDisplayClassUsage.IsPotentialClosure(context, field.Type.GetDefinition()))
{
var variable = function.Descendants.OfType <ILFunction>().SelectMany(f => f.Variables).Where(v => !v.IsThis() && TransformDisplayClassUsage.IsClosure(context, v, out var varType, out _) && varType.Equals(field.Type)).OnlyOrDefault();
if (variable != null)
{
target = new LdLoc(variable);
HandleArgument(localFunction, 1, 0, target);
}
}
}
context.Step($"Replace 'this' with {target}", localFunction);
localFunction.AcceptVisitor(new DelegateConstruction.ReplaceDelegateTargetVisitor(target, thisVar));
}
foreach (var useSite in info.UseSites)
{
DetermineCaptureAndDeclarationScope(localFunction, useSite);
if (function.Method.IsConstructor && localFunction.DeclarationScope == null)
{
localFunction.DeclarationScope = BlockContainer.FindClosestContainer(useSite);
}
}
if (localFunction.DeclarationScope == null)
{
localFunction.DeclarationScope = (BlockContainer)function.Body;
}
ILFunction declaringFunction = GetDeclaringFunction(localFunction);
if (declaringFunction != function)
{
function.LocalFunctions.Remove(localFunction);
declaringFunction.LocalFunctions.Add(localFunction);
}
if (TryValidateSkipCount(info, out int skipCount) && skipCount != localFunction.ReducedMethod.NumberOfCompilerGeneratedTypeParameters)
{
Debug.Assert(false);
function.Warnings.Add($"Could not decode local function '{info.Method}'");
if (declaringFunction != function)
{
declaringFunction.LocalFunctions.Remove(localFunction);
}
continue;
}
foreach (var useSite in info.UseSites)
{
context.Step($"Transform use site at IL_{useSite.StartILOffset:x4}", useSite);
if (useSite.OpCode == OpCode.NewObj)
{
TransformToLocalFunctionReference(localFunction, useSite);
}
else
{
TransformToLocalFunctionInvocation(localFunction.ReducedMethod, useSite);
}
}
} finally {
context.StepEndGroup();
}
}
}
ILFunction TransformDelegateConstruction(NewObj value, out ILInstruction target)
{
target = null;
if (!IsDelegateConstruction(value))
{
return(null);
}
var targetMethod = ((IInstructionWithMethodOperand)value.Arguments[1]).Method;
if (!IsAnonymousMethod(decompilationContext.CurrentTypeDefinition, targetMethod))
{
return(null);
}
if (LocalFunctionDecompiler.IsLocalFunctionMethod(targetMethod.ParentModule.PEFile, (MethodDefinitionHandle)targetMethod.MetadataToken))
{
return(null);
}
target = value.Arguments[0];
if (targetMethod.MetadataToken.IsNil)
{
return(null);
}
var methodDefinition = context.PEFile.Metadata.GetMethodDefinition((MethodDefinitionHandle)targetMethod.MetadataToken);
if (!methodDefinition.HasBody())
{
return(null);
}
var genericContext = GenericContextFromTypeArguments(targetMethod.Substitution);
if (genericContext == null)
{
return(null);
}
var ilReader = context.CreateILReader();
var body = context.PEFile.Reader.GetMethodBody(methodDefinition.RelativeVirtualAddress);
var function = ilReader.ReadIL((MethodDefinitionHandle)targetMethod.MetadataToken, body, genericContext.Value, context.CancellationToken);
function.DelegateType = value.Method.DeclaringType;
function.CheckInvariant(ILPhase.Normal);
// Embed the lambda into the parent function's ILAst, so that "Show steps" can show
// how the lambda body is being transformed.
value.ReplaceWith(function);
var contextPrefix = targetMethod.Name;
foreach (ILVariable v in function.Variables.Where(v => v.Kind != VariableKind.Parameter))
{
v.Name = contextPrefix + v.Name;
}
var nestedContext = new ILTransformContext(context, function);
function.RunTransforms(CSharpDecompiler.GetILTransforms().TakeWhile(t => !(t is DelegateConstruction)).Concat(GetTransforms()), nestedContext);
nestedContext.Step("DelegateConstruction (ReplaceDelegateTargetVisitor)", function);
function.AcceptVisitor(new ReplaceDelegateTargetVisitor(target, function.Variables.SingleOrDefault(v => v.Index == -1 && v.Kind == VariableKind.Parameter)));
// handle nested lambdas
nestedContext.StepStartGroup("DelegateConstruction (nested lambdas)", function);
((IILTransform) new DelegateConstruction()).Run(function, nestedContext);
nestedContext.StepEndGroup();
function.AddILRange(target);
function.AddILRange(value);
function.AddILRange(value.Arguments[1]);
return(function);
}
ILFunction TransformDelegateConstruction(
ILInstruction value, IMethod targetMethod,
ILInstruction target, IType delegateType)
{
if (!IsAnonymousMethod(decompilationContext.CurrentTypeDefinition, targetMethod))
{
return(null);
}
if (targetMethod.MetadataToken.IsNil)
{
return(null);
}
if (LocalFunctionDecompiler.IsLocalFunctionMethod(targetMethod, context))
{
return(null);
}
if (!ValidateDelegateTarget(target))
{
return(null);
}
var handle = (MethodDefinitionHandle)targetMethod.MetadataToken;
if (activeMethods.Contains(handle))
{
this.context.Function.Warnings.Add(" Found self-referencing delegate construction. Abort transformation to avoid stack overflow.");
return(null);
}
var methodDefinition = context.PEFile.Metadata.GetMethodDefinition((MethodDefinitionHandle)targetMethod.MetadataToken);
if (!methodDefinition.HasBody())
{
return(null);
}
var genericContext = GenericContextFromTypeArguments(targetMethod.Substitution);
if (genericContext == null)
{
return(null);
}
var ilReader = context.CreateILReader();
var body = context.PEFile.Reader.GetMethodBody(methodDefinition.RelativeVirtualAddress);
var function = ilReader.ReadIL((MethodDefinitionHandle)targetMethod.MetadataToken, body, genericContext.Value, ILFunctionKind.Delegate, context.CancellationToken);
function.DelegateType = delegateType;
// Embed the lambda into the parent function's ILAst, so that "Show steps" can show
// how the lambda body is being transformed.
value.ReplaceWith(function);
function.CheckInvariant(ILPhase.Normal);
var contextPrefix = targetMethod.Name;
foreach (ILVariable v in function.Variables.Where(v => v.Kind != VariableKind.Parameter))
{
v.Name = contextPrefix + v.Name;
}
var nestedContext = new ILTransformContext(context, function);
function.RunTransforms(CSharpDecompiler.GetILTransforms().TakeWhile(t => !(t is DelegateConstruction)).Concat(GetTransforms()), nestedContext);
nestedContext.Step("DelegateConstruction (ReplaceDelegateTargetVisitor)", function);
function.AcceptVisitor(new ReplaceDelegateTargetVisitor(target, function.Variables.SingleOrDefault(VariableKindExtensions.IsThis)));
// handle nested lambdas
nestedContext.StepStartGroup("DelegateConstruction (nested lambdas)", function);
((IILTransform)this).Run(function, nestedContext);
nestedContext.StepEndGroup();
function.AddILRange(target);
function.AddILRange(value);
if (value is Call call)
{
function.AddILRange(call.Arguments[1]);
}
return(function);
}