private ILVariable ResolveAncestorScopeReference(ILInstruction inst)
{
if (!inst.MatchLdFld(out var target, out var field))
{
return(null);
}
if (field.Type.Kind != TypeKind.Class)
{
return(null);
}
if (!(TransformDisplayClassUsage.IsPotentialClosure(context, field.Type.GetDefinition()) || context.Function.Method.DeclaringType.Equals(field.Type)))
{
return(null);
}
foreach (var v in context.Function.Descendants.OfType <ILFunction>().SelectMany(f => f.Variables))
{
if (v.Kind != VariableKind.Local && v.Kind != VariableKind.DisplayClassLocal && v.Kind != VariableKind.StackSlot)
{
if (!(v.Kind == VariableKind.Parameter && v.Index == -1))
{
continue;
}
if (v.Type.Equals(field.Type))
{
return(v);
}
}
if (!(TransformDisplayClassUsage.IsClosure(context, v, out var varType, out _) && varType.Equals(field.Type)))
{
continue;
}
return(v);
}
return(null);
}
static bool IsAnonymousMethod(ITypeDefinition decompiledTypeDefinition, IMethod method)
{
if (method == null)
{
return(false);
}
if (!(method.HasGeneratedName() ||
method.Name.Contains("$") ||
method.IsCompilerGeneratedOrIsInCompilerGeneratedClass() ||
TransformDisplayClassUsage.IsPotentialClosure(decompiledTypeDefinition, method.DeclaringTypeDefinition) ||
ContainsAnonymousType(method)))
{
return(false);
}
return(true);
}
bool DoTransform(Block body, int pos)
{
ILInstruction inst = body.Instructions[pos];
// Match stloc(v, newobj)
if (inst.MatchStLoc(out var v, out var initInst) && (v.Kind == VariableKind.Local || v.Kind == VariableKind.StackSlot))
{
IType instType;
switch (initInst)
{
case NewObj newObjInst:
if (newObjInst.ILStackWasEmpty && v.Kind == VariableKind.Local && !context.Function.Method.IsConstructor && !context.Function.Method.IsCompilerGeneratedOrIsInCompilerGeneratedClass())
{
// on statement level (no other expressions on IL stack),
// prefer to keep local variables (but not stack slots),
// unless we are in a constructor (where inlining object initializers might be critical
// for the base ctor call) or a compiler-generated delegate method, which might be used in a query expression.
return(false);
}
// Do not try to transform delegate construction.
// DelegateConstruction transform cannot deal with this.
if (DelegateConstruction.IsDelegateConstruction(newObjInst) || TransformDisplayClassUsage.IsPotentialClosure(context, newObjInst))
{
return(false);
}
// Cannot build a collection/object initializer attached to an AnonymousTypeCreateExpression:s
// anon = new { A = 5 } { 3,4,5 } is invalid syntax.
if (newObjInst.Method.DeclaringType.ContainsAnonymousType())
{
return(false);
}
instType = newObjInst.Method.DeclaringType;
break;
case DefaultValue defaultVal:
if (defaultVal.ILStackWasEmpty && v.Kind == VariableKind.Local && !context.Function.Method.IsConstructor)
{
// on statement level (no other expressions on IL stack),
// prefer to keep local variables (but not stack slots),
// unless we are in a constructor (where inlining object initializers might be critical
// for the base ctor call)
return(false);
}
instType = defaultVal.Type;
break;
default:
return(false);
}
int initializerItemsCount = 0;
var blockKind = BlockKind.CollectionInitializer;
possibleIndexVariables = new Dictionary <ILVariable, (int Index, ILInstruction Value)>();
currentPath = new List <AccessPathElement>();
isCollection = false;
pathStack = new Stack <HashSet <AccessPathElement> >();
pathStack.Push(new HashSet <AccessPathElement>());
// Detect initializer type by scanning the following statements
// each must be a callvirt with ldloc v as first argument
// if the method is a setter we're dealing with an object initializer
// if the method is named Add and has at least 2 arguments we're dealing with a collection/dictionary initializer
while (pos + initializerItemsCount + 1 < body.Instructions.Count &&
IsPartOfInitializer(body.Instructions, pos + initializerItemsCount + 1, v, instType, ref blockKind))
{
initializerItemsCount++;
}
// Do not convert the statements into an initializer if there's an incompatible usage of the initializer variable
// directly after the possible initializer.
if (IsMethodCallOnVariable(body.Instructions[pos + initializerItemsCount + 1], v))
{
return(false);
}
// Calculate the correct number of statements inside the initializer:
// All index variables that were used in the initializer have Index set to -1.
// We fetch the first unused variable from the list and remove all instructions after its
// first usage (i.e. the init store) from the initializer.
var index = possibleIndexVariables.Where(info => info.Value.Index > -1).Min(info => (int?)info.Value.Index);
if (index != null)
{
initializerItemsCount = index.Value - pos - 1;
}
// The initializer would be empty, there's nothing to do here.
if (initializerItemsCount <= 0)
{
return(false);
}
context.Step("CollectionOrObjectInitializer", inst);
// Create a new block and final slot (initializer target variable)
var initializerBlock = new Block(blockKind);
ILVariable finalSlot = context.Function.RegisterVariable(VariableKind.InitializerTarget, v.Type);
initializerBlock.FinalInstruction = new LdLoc(finalSlot);
initializerBlock.Instructions.Add(new StLoc(finalSlot, initInst.Clone()));
// Move all instructions to the initializer block.
for (int i = 1; i <= initializerItemsCount; i++)
{
switch (body.Instructions[i + pos])
{
case CallInstruction call:
if (!(call is CallVirt || call is Call))
{
continue;
}
var newCall = call;
var newTarget = newCall.Arguments[0];
foreach (var load in newTarget.Descendants.OfType <IInstructionWithVariableOperand>())
{
if ((load is LdLoc || load is LdLoca) && load.Variable == v)
{
load.Variable = finalSlot;
}
}
initializerBlock.Instructions.Add(newCall);
break;
case StObj stObj:
var newStObj = stObj;
foreach (var load in newStObj.Target.Descendants.OfType <IInstructionWithVariableOperand>())
{
if ((load is LdLoc || load is LdLoca) && load.Variable == v)
{
load.Variable = finalSlot;
}
}
initializerBlock.Instructions.Add(newStObj);
break;
case StLoc stLoc:
var newStLoc = stLoc;
initializerBlock.Instructions.Add(newStLoc);
break;
}
}
initInst.ReplaceWith(initializerBlock);
body.Instructions.RemoveRange(pos + 1, initializerItemsCount);
ILInlining.InlineIfPossible(body, pos, context);
}
return(true);
}
/// <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();
}
}
}
