/// <summary>
/// Lift a C# comparison.
///
/// The output instructions should evaluate to <c>false</c> when any of the <c>nullableVars</c> is <c>null</c>.
/// Otherwise, the output instruction should evaluate to the same value as the input instruction.
/// The output instruction should have the same side-effects (incl. exceptions being thrown) as the input instruction.
/// This means unlike LiftNormal(), we cannot rely on the input instruction not being evaluated if
/// a variable is <c>null</c>.
/// </summary>
Comp LiftCSharpComparison(Comp comp, ComparisonKind newComparisonKind)
{
var(left, leftBits) = DoLift(comp.Left);
var(right, rightBits) = DoLift(comp.Right);
if (left != null && right == null && SemanticHelper.IsPure(comp.Right.Flags))
{
// Embed non-nullable pure expression in lifted expression.
right = comp.Right.Clone();
}
if (left == null && right != null && SemanticHelper.IsPure(comp.Left.Flags))
{
// Embed non-nullable pure expression in lifted expression.
left = comp.Left.Clone();
}
// due to the restrictions on side effects, we only allow instructions that are pure after lifting.
// (we can't check this before lifting due to the calls to GetValueOrDefault())
if (left != null && right != null && SemanticHelper.IsPure(left.Flags) && SemanticHelper.IsPure(right.Flags))
{
var bits = leftBits ?? rightBits;
if (rightBits != null)
{
bits.UnionWith(rightBits);
}
if (!bits.All(0, nullableVars.Count))
{
// don't lift if a nullableVar doesn't contribute to the result
return(null);
}
context.Step("NullableLiftingTransform: C# comparison", comp);
return(new Comp(newComparisonKind, ComparisonLiftingKind.CSharp, comp.InputType, comp.Sign, left, right));
}
return(null);
}
public void Run(ILFunction function, ILTransformContext context)
{
try {
if (this.context != null || this.currentFunction != null)
{
throw new InvalidOperationException("Reentrancy in " + nameof(TransformDisplayClassUsage));
}
this.context = context;
var decompilationContext = new SimpleTypeResolveContext(context.Function.Method);
// Traverse nested functions in post-order:
// Inner functions are transformed before outer functions
foreach (var f in function.Descendants.OfType <ILFunction>())
{
foreach (var v in f.Variables.ToArray())
{
if (HandleMonoStateMachine(function, v, decompilationContext, f))
{
continue;
}
if (!(v.IsSingleDefinition && v.StoreInstructions.SingleOrDefault() is StLoc inst))
{
continue;
}
if (IsClosureInit(inst, out ITypeDefinition closureType))
{
// TODO : figure out whether it is a mono compiled closure, without relying on the type name
bool isMono = f.StateMachineCompiledWithMono || closureType.Name.Contains("AnonStorey");
displayClasses.Add(inst.Variable, new DisplayClass {
IsMono = isMono,
Initializer = inst,
Variable = v,
Definition = closureType,
Variables = new Dictionary <IField, DisplayClassVariable>(),
CaptureScope = isMono && IsMonoNestedCaptureScope(closureType) ? null : inst.Variable.CaptureScope
});
instructionsToRemove.Add(inst);
}
}
foreach (var displayClass in displayClasses.Values.OrderByDescending(d => d.Initializer.StartILOffset).ToArray())
{
context.Step($"Transform references to " + displayClass.Variable, displayClass.Initializer);
this.currentFunction = f;
VisitILFunction(f);
}
}
context.Step($"Remove instructions", function);
foreach (var store in instructionsToRemove)
{
if (store.Parent is Block containingBlock)
{
containingBlock.Instructions.Remove(store);
}
}
} finally {
instructionsToRemove.Clear();
displayClasses.Clear();
this.context = null;
this.currentFunction = null;
}
}
private void ReplaceReferencesToDisplayClassThis(Dictionary <MethodDefinitionHandle, LocalFunctionInfo> .ValueCollection localFunctions)
{
foreach (var info in localFunctions)
{
var localFunction = info.Definition;
if (localFunction.Method.IsStatic)
{
continue;
}
var thisVar = localFunction.Variables.SingleOrDefault(VariableKindExtensions.IsThis);
if (thisVar == null)
{
continue;
}
var compatibleArgument = FindCompatibleArgument(
info,
info.UseSites.OfType <CallInstruction>().Select(u => u.Arguments[0]).ToArray(),
ignoreStructure: true
);
if (compatibleArgument == null)
{
continue;
}
context.Step($"Replace 'this' with {compatibleArgument}", localFunction);
localFunction.AcceptVisitor(new DelegateConstruction.ReplaceDelegateTargetVisitor(compatibleArgument, thisVar));
DetermineCaptureAndDeclarationScope(info, -1, compatibleArgument);
}
}
static void RunOnBlock(Block block, ILTransformContext context, HashSet <ILVariable> splitVariables = null)
{
for (int i = 0; i < block.Instructions.Count; i++)
{
if (block.Instructions[i].MatchStLoc(out ILVariable v, out ILInstruction copiedExpr))
{
if (v.IsSingleDefinition && v.LoadCount == 0 && v.Kind == VariableKind.StackSlot)
{
// dead store to stack
if (SemanticHelper.IsPure(copiedExpr.Flags))
{
// no-op -> delete
context.Step("remove dead store to stack: no-op -> delete", block.Instructions[i]);
block.Instructions.RemoveAt(i);
// This can open up new inlining opportunities:
int c = ILInlining.InlineInto(block, i, InliningOptions.None, context: context);
i -= c + 1;
}
else
{
// evaluate the value for its side-effects
context.Step("remove dead store to stack: evaluate the value for its side-effects", block.Instructions[i]);
copiedExpr.AddILRange(block.Instructions[i]);
block.Instructions[i] = copiedExpr;
}
}
else if (v.IsSingleDefinition && CanPerformCopyPropagation(v, copiedExpr, splitVariables))
{
DoPropagate(v, copiedExpr, block, ref i, context);
}
}
}
}
void IILTransform.Run(ILFunction function, ILTransformContext context)
{
if (!context.Settings.AnonymousMethods)
{
return;
}
this.context = context;
this.decompilationContext = new SimpleTypeResolveContext(function.Method);
var orphanedVariableInits = new List <ILInstruction>();
var targetsToReplace = new List <IInstructionWithVariableOperand>();
var translatedDisplayClasses = new HashSet <ITypeDefinition>();
var cancellationToken = context.CancellationToken;
foreach (var inst in function.Descendants)
{
cancellationToken.ThrowIfCancellationRequested();
if (inst is NewObj call)
{
context.StepStartGroup($"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 VisitStLoc(StLoc inst)
{
base.VisitStLoc(inst);
if (inst.Variable.Kind == VariableKind.Local && inst.Variable.IsSingleDefinition && inst.Variable.LoadCount == 0 && inst.Value is StLoc)
{
context.Step($"Remove unused variable assignment {inst.Variable.Name}", inst);
inst.ReplaceWith(inst.Value);
}
}
public void Run(ILFunction function, ILTransformContext context)
{
try {
if (this.context != null || this.currentFunction != null)
{
throw new InvalidOperationException("Reentrancy in " + nameof(TransformDisplayClassUsage));
}
this.context = context;
var decompilationContext = new SimpleTypeResolveContext(context.Function.Method);
// Traverse nested functions in post-order:
// Inner functions are transformed before outer functions
foreach (var f in function.Descendants.OfType <ILFunction>())
{
foreach (var v in f.Variables.ToArray())
{
if (HandleMonoStateMachine(function, v, decompilationContext, f))
{
continue;
}
if (IsClosure(v, out ITypeDefinition closureType, out var inst))
{
AddOrUpdateDisplayClass(f, v, closureType, inst, localFunctionClosureParameter: false);
}
if (context.Settings.LocalFunctions && f.Kind == ILFunctionKind.LocalFunction && v.Kind == VariableKind.Parameter && v.Index > -1 && f.Method.Parameters[v.Index.Value] is IParameter p && LocalFunctionDecompiler.IsClosureParameter(p, decompilationContext))
{
AddOrUpdateDisplayClass(f, v, ((ByReferenceType)p.Type).ElementType.GetDefinition(), f.Body, localFunctionClosureParameter: true);
}
}
foreach (var displayClass in displayClasses.Values.OrderByDescending(d => d.Initializer.StartILOffset).ToArray())
{
context.Step($"Transform references to " + displayClass.Variable, displayClass.Initializer);
this.currentFunction = f;
VisitILFunction(f);
}
}
if (instructionsToRemove.Count > 0)
{
context.Step($"Remove instructions", function);
foreach (var store in instructionsToRemove)
{
if (store.Parent is Block containingBlock)
{
containingBlock.Instructions.Remove(store);
}
}
}
RemoveDeadVariableInit.ResetHasInitialValueFlag(function, context);
} finally {
instructionsToRemove.Clear();
displayClasses.Clear();
this.context = null;
this.currentFunction = null;
}
}
ILInstruction Lift(IfInstruction ifInst, ILInstruction trueInst, ILInstruction falseInst)
{
if (!MatchNullableCtor(trueInst, out var utype, out var exprToLift))
{
return(null);
}
if (!MatchNull(falseInst, utype))
{
return(null);
}
ILInstruction lifted;
if (nullableVars.Count == 1 && MatchGetValueOrDefault(exprToLift, nullableVars[0]))
{
// v != null ? call GetValueOrDefault(ldloca v) : null
// => conv.nop.lifted(ldloc v)
// This case is handled separately from DoLift() because
// that doesn't introduce nop-conversions.
context.Step("if => conv.nop.lifted", ifInst);
var inputUType = NullableType.GetUnderlyingType(nullableVars[0].Type);
lifted = new Conv(
new LdLoc(nullableVars[0]),
inputUType.GetStackType(), inputUType.GetSign(), utype.ToPrimitiveType(),
checkForOverflow: false,
isLifted: true
)
{
ILRange = ifInst.ILRange
};
}
else
{
context.Step("NullableLiftingTransform.DoLift", ifInst);
BitSet bits;
(lifted, bits) = DoLift(exprToLift);
if (lifted != null && !bits.All(0, nullableVars.Count))
{
// don't lift if a nullableVar doesn't contribute to the result
lifted = null;
}
}
if (lifted != null)
{
Debug.Assert(lifted is ILiftableInstruction liftable && liftable.IsLifted &&
liftable.UnderlyingResultType == exprToLift.ResultType);
}
return(lifted);
}
internal static bool DoInline(ILVariable v, StLoc originalStore, LdLoc loadInst, InliningOptions options, ILTransformContext context)
{
if ((options & InliningOptions.Aggressive) == 0 && originalStore.ILStackWasEmpty)
{
return(false);
}
context.Step($"Introduce named argument '{v.Name}'", originalStore);
var call = (CallInstruction)loadInst.Parent;
if (!(call.Parent is Block namedArgBlock) || namedArgBlock.Kind != BlockKind.CallWithNamedArgs)
{
// create namedArgBlock:
namedArgBlock = new Block(BlockKind.CallWithNamedArgs);
call.ReplaceWith(namedArgBlock);
namedArgBlock.FinalInstruction = call;
if (call.IsInstanceCall)
{
IType thisVarType = call.Method.DeclaringType;
if (CallInstruction.ExpectedTypeForThisPointer(thisVarType) == StackType.Ref)
{
thisVarType = new ByReferenceType(thisVarType);
}
var function = call.Ancestors.OfType <ILFunction>().First();
var thisArgVar = function.RegisterVariable(VariableKind.NamedArgument, thisVarType, "this_arg");
namedArgBlock.Instructions.Add(new StLoc(thisArgVar, call.Arguments[0]));
call.Arguments[0] = new LdLoc(thisArgVar);
}
}
v.Kind = VariableKind.NamedArgument;
namedArgBlock.Instructions.Insert(call.IsInstanceCall ? 1 : 0, originalStore);
return(true);
}
public void Run(ILFunction function, ILTransformContext context)
{
try {
if (this.context != null)
{
throw new InvalidOperationException("Reentrancy in " + nameof(TransformDisplayClassUsage));
}
this.context = context;
var decompilationContext = new SimpleTypeResolveContext(context.Function.Method);
// Traverse nested functions in post-order:
// Inner functions are transformed before outer functions
foreach (var f in function.Descendants.OfType <ILFunction>())
{
foreach (var v in f.Variables.ToArray())
{
if (context.Settings.YieldReturn && HandleMonoStateMachine(function, v, decompilationContext, f))
{
continue;
}
if ((context.Settings.AnonymousMethods || context.Settings.ExpressionTrees) && IsClosure(context, v, out ITypeDefinition closureType, out var inst))
{
if (!CanRemoveAllReferencesTo(context, v))
{
continue;
}
if (inst is StObj || inst is StLoc)
{
instructionsToRemove.Add(inst);
}
AddOrUpdateDisplayClass(f, v, closureType, inst, localFunctionClosureParameter: false);
continue;
}
if (context.Settings.LocalFunctions && f.Kind == ILFunctionKind.LocalFunction && v.Kind == VariableKind.Parameter && v.Index > -1 && f.Method.Parameters[v.Index.Value] is IParameter p && LocalFunctionDecompiler.IsClosureParameter(p, decompilationContext))
{
AddOrUpdateDisplayClass(f, v, ((ByReferenceType)p.Type).ElementType.GetDefinition(), f.Body, localFunctionClosureParameter: true);
continue;
}
AnalyzeUseSites(v);
}
}
VisitILFunction(function);
if (instructionsToRemove.Count > 0)
{
context.Step($"Remove instructions", function);
foreach (var store in instructionsToRemove)
{
if (store.Parent is Block containingBlock)
{
containingBlock.Instructions.Remove(store);
}
}
}
RemoveDeadVariableInit.ResetHasInitialValueFlag(function, context);
} finally {
instructionsToRemove.Clear();
displayClasses.Clear();
fieldAssignmentsWithVariableValue.Clear();
this.context = null;
}
}
static void DoPropagate(ILVariable v, ILInstruction copiedExpr, Block block, ref int i, ILTransformContext context)
{
context.Step($"Copy propagate {v.Name}", copiedExpr);
// un-inline the arguments of the ldArg instruction
ILVariable[] uninlinedArgs = new ILVariable[copiedExpr.Children.Count];
for (int j = 0; j < uninlinedArgs.Length; j++)
{
var arg = copiedExpr.Children[j];
var type = context.TypeSystem.Compilation.FindType(arg.ResultType.ToKnownTypeCode());
uninlinedArgs[j] = new ILVariable(VariableKind.StackSlot, type, arg.ResultType, arg.ILRange.Start)
{
Name = "C_" + arg.ILRange.Start
};
block.Instructions.Insert(i++, new StLoc(uninlinedArgs[j], arg));
}
CollectionExtensions.AddRange(v.Function.Variables, uninlinedArgs);
// perform copy propagation:
foreach (var expr in v.LoadInstructions.ToArray())
{
var clone = copiedExpr.Clone();
for (int j = 0; j < uninlinedArgs.Length; j++)
{
clone.Children[j].ReplaceWith(new LdLoc(uninlinedArgs[j]));
}
expr.ReplaceWith(clone);
}
block.Instructions.RemoveAt(i);
int c = ILInlining.InlineInto(block, i, aggressive: false, context: context);
i -= c + 1;
}
/// <summary>
/// Introduce a named argument for 'arg' and evaluate it before the other arguments
/// (except for the "this" pointer)
/// </summary>
internal static void IntroduceNamedArgument(ILInstruction arg, ILTransformContext context)
{
var call = (CallInstruction)arg.Parent;
Debug.Assert(context.Function == call.Ancestors.OfType <ILFunction>().First());
var v = context.Function.RegisterVariable(VariableKind.NamedArgument, arg.ResultType);
context.Step($"Introduce named argument '{v.Name}'", arg);
if (!(call.Parent is Block namedArgBlock) || namedArgBlock.Kind != BlockKind.CallWithNamedArgs)
{
// create namedArgBlock:
namedArgBlock = new Block(BlockKind.CallWithNamedArgs);
call.ReplaceWith(namedArgBlock);
namedArgBlock.FinalInstruction = call;
if (call.IsInstanceCall)
{
IType thisVarType = call.Method.DeclaringType;
if (CallInstruction.ExpectedTypeForThisPointer(thisVarType) == StackType.Ref)
{
thisVarType = new ByReferenceType(thisVarType);
}
var thisArgVar = context.Function.RegisterVariable(VariableKind.NamedArgument, thisVarType, "this_arg");
namedArgBlock.Instructions.Add(new StLoc(thisArgVar, call.Arguments[0]));
call.Arguments[0] = new LdLoc(thisArgVar);
}
}
int argIndex = arg.ChildIndex;
Debug.Assert(call.Arguments[argIndex] == arg);
namedArgBlock.Instructions.Insert(call.IsInstanceCall ? 1 : 0, new StLoc(v, arg));
call.Arguments[argIndex] = new LdLoc(v);
}
private bool TryTransform(Block block, int i, ILTransformContext context)
{
if (block.Instructions[i] is not StLoc {
Variable : var s, Value : LdLoca {
Variable : var v
}
} inst1)
{
return(false);
}
if (block.Instructions.ElementAtOrDefault(i + 1) is not StObj inst2)
{
return(false);
}
if (!(inst2.Target.MatchLdLoc(s) &&
TypeUtils.IsCompatibleTypeForMemoryAccess(v.Type, inst2.Type) &&
inst2.UnalignedPrefix == 0 &&
!inst2.IsVolatile &&
inst2.Value is DefaultValue))
{
return(false);
}
context.Step("LdLocaDupInitObjTransform", inst1);
block.Instructions[i] = new StLoc(v, inst2.Value).WithILRange(inst2);
block.Instructions[i + 1] = inst1;
return(true);
}
public void Run(ILFunction function, ILTransformContext context)
{
foreach (var catchBlock in function.Descendants.OfType <TryCatchHandler>())
{
if (catchBlock.Filter is BlockContainer container &&
MatchCatchWhenEntryPoint(catchBlock.Variable, container, container.EntryPoint,
out var exceptionType, out var exceptionSlot, out var whenConditionBlock) &&
exceptionType.GetStackType() == catchBlock.Variable.StackType)
{
// set exceptionType
catchBlock.Variable.Type = exceptionType;
// Block entryPoint (incoming: 1) {
// stloc temp(isinst exceptionType(ldloc exceptionVar))
// if (comp(ldloc temp != ldnull)) br whenConditionBlock
// br falseBlock
// }
// =>
// Block entryPoint (incoming: 1) {
// stloc temp(ldloc exceptionSlot)
// br whenConditionBlock
// }
var instructions = container.EntryPoint.Instructions;
if (instructions.Count == 3)
{
// stloc temp(isinst exceptionType(ldloc exceptionVar))
// if (comp(ldloc temp != ldnull)) br whenConditionBlock
// br falseBlock
context.Step($"Detected catch-when for {catchBlock.Variable.Name} (extra store)", instructions[0]);
((StLoc)instructions[0]).Value = exceptionSlot;
instructions[1].ReplaceWith(new Branch(whenConditionBlock));
instructions.RemoveAt(2);
container.SortBlocks(deleteUnreachableBlocks: true);
}
else if (instructions.Count == 2)
{
// if (comp(isinst exceptionType(ldloc exceptionVar) != ldnull)) br whenConditionBlock
// br falseBlock
context.Step($"Detected catch-when for {catchBlock.Variable.Name}", instructions[0]);
instructions[0].ReplaceWith(new Branch(whenConditionBlock));
instructions.RemoveAt(1);
container.SortBlocks(deleteUnreachableBlocks: true);
}
PropagateExceptionVariable(context, catchBlock);
}
}
}
internal static bool StObjToStLoc(StObj inst, ILTransformContext context)
{
if (inst.Target.MatchLdLoca(out ILVariable v) &&
TypeUtils.IsCompatibleTypeForMemoryAccess(new ByReferenceType(v.Type), inst.Type) &&
inst.UnalignedPrefix == 0 &&
!inst.IsVolatile)
{
context.Step($"stobj(ldloca {v.Name}, ...) => stloc {v.Name}(...)", inst);
inst.ReplaceWith(new StLoc(v, inst.Value));
return(true);
}
return(false);
}
internal static bool LdObjToLdLoc(LdObj inst, ILTransformContext context)
{
if (inst.Target.MatchLdLoca(out ILVariable v) &&
TypeUtils.IsCompatibleTypeForMemoryAccess(v.Type, inst.Type) &&
inst.UnalignedPrefix == 0 &&
!inst.IsVolatile)
{
context.Step($"ldobj(ldloca {v.Name}) => ldloc {v.Name}", inst);
inst.ReplaceWith(new LdLoc(v).WithILRange(inst));
return(true);
}
return(false);
}
/// <summary>
/// Inlines the stloc instruction at block.Instructions[pos] into the next instruction.
///
/// Note that this method does not check whether 'v' has only one use;
/// the caller is expected to validate whether inlining 'v' has any effects on other uses of 'v'.
/// </summary>
public static bool InlineOne(StLoc stloc, InliningOptions options, ILTransformContext context)
{
ILVariable v = stloc.Variable;
Block block = (Block)stloc.Parent;
int pos = stloc.ChildIndex;
if (DoInline(v, stloc.Value, block.Instructions.ElementAtOrDefault(pos + 1), options, context))
{
// Assign the ranges of the stloc instruction:
stloc.Value.AddILRange(stloc);
// Remove the stloc instruction:
Debug.Assert(block.Instructions[pos] == stloc);
block.Instructions.RemoveAt(pos);
return(true);
}
else if (v.LoadCount == 0 && v.AddressCount == 0)
{
// The variable is never loaded
if (SemanticHelper.IsPure(stloc.Value.Flags))
{
// Remove completely if the instruction has no effects
// (except for reading locals)
context.Step("Remove dead store without side effects", stloc);
block.Instructions.RemoveAt(pos);
return(true);
}
else if (v.Kind == VariableKind.StackSlot)
{
context.Step("Remove dead store, but keep expression", stloc);
// Assign the ranges of the stloc instruction:
stloc.Value.AddILRange(stloc);
// Remove the stloc, but keep the inner expression
stloc.ReplaceWith(stloc.Value);
return(true);
}
}
return(false);
}
/// <summary>
/// Inlines 'expr' into 'next', if possible.
///
/// Note that this method does not check whether 'v' has only one use;
/// the caller is expected to validate whether inlining 'v' has any effects on other uses of 'v'.
/// </summary>
static bool DoInline(ILVariable v, ILInstruction inlinedExpression, ILInstruction next, InliningOptions options, ILTransformContext context)
{
var r = FindLoadInNext(next, v, inlinedExpression, options);
if (r.Type == FindResultType.Found || r.Type == FindResultType.NamedArgument)
{
var loadInst = r.LoadInst;
if (loadInst.OpCode == OpCode.LdLoca)
{
if (!IsGeneratedValueTypeTemporary((LdLoca)loadInst, v, inlinedExpression))
{
return(false);
}
}
else
{
Debug.Assert(loadInst.OpCode == OpCode.LdLoc);
bool aggressive = (options & InliningOptions.Aggressive) != 0;
if (!aggressive && v.Kind != VariableKind.StackSlot &&
!NonAggressiveInlineInto(next, r, inlinedExpression, v))
{
return(false);
}
}
if (r.Type == FindResultType.NamedArgument)
{
NamedArgumentTransform.IntroduceNamedArgument(r.CallArgument, context);
// Now that the argument is evaluated early, we can inline as usual
}
context.Step($"Inline variable '{v.Name}'", inlinedExpression);
// Assign the ranges of the ldloc instruction:
inlinedExpression.AddILRange(loadInst);
if (loadInst.OpCode == OpCode.LdLoca)
{
// it was an ldloca instruction, so we need to use the pseudo-opcode 'addressof'
// to preserve the semantics of the compiler-generated temporary
Debug.Assert(((LdLoca)loadInst).Variable == v);
loadInst.ReplaceWith(new AddressOf(inlinedExpression, v.Type));
}
else
{
loadInst.ReplaceWith(inlinedExpression);
}
return(true);
}
return(false);
}
private bool DoTransform(Block block, ILTransformContext context)
{
if (!MatchBlock1(block, out var s, out int value, out var br))
{
return(false);
}
if (!MatchBlock2(br.TargetBlock, s, value, out var exitInst))
{
return(false);
}
context.Step("RemoveInfeasiblePath", br);
br.ReplaceWith(exitInst.Clone());
s.RemoveIfRedundant = true;
return(true);
}
/// <summary>
/// Inlines 'expr' into 'next', if possible.
///
/// Note that this method does not check whether 'v' has only one use;
/// the caller is expected to validate whether inlining 'v' has any effects on other uses of 'v'.
/// </summary>
static bool DoInline(ILVariable v, ILInstruction inlinedExpression, ILInstruction next, InliningOptions options, ILTransformContext context)
{
var r = FindLoadInNext(next, v, inlinedExpression, out var loadInst);
if (r == FindResult.Found)
{
if (loadInst.OpCode == OpCode.LdLoca)
{
if (!IsGeneratedValueTypeTemporary(next, (LdLoca)loadInst, v, inlinedExpression))
{
return(false);
}
}
else
{
Debug.Assert(loadInst.OpCode == OpCode.LdLoc);
bool aggressive = (options & InliningOptions.Aggressive) != 0;
if (!aggressive && v.Kind != VariableKind.StackSlot &&
!NonAggressiveInlineInto(next, loadInst, inlinedExpression, v))
{
return(false);
}
}
context.Step($"Inline variable '{v.Name}'", inlinedExpression);
// Assign the ranges of the ldloc instruction:
inlinedExpression.AddILRange(loadInst.ILRange);
if (loadInst.OpCode == OpCode.LdLoca)
{
// it was an ldloca instruction, so we need to use the pseudo-opcode 'addressof'
// to preserve the semantics of the compiler-generated temporary
loadInst.ReplaceWith(new AddressOf(inlinedExpression));
}
else
{
loadInst.ReplaceWith(inlinedExpression);
}
return(true);
}
else if (r == FindResult.NamedArgument && (options & InliningOptions.IntroduceNamedArguments) != 0)
{
return(NamedArgumentTransform.DoInline(v, (StLoc)inlinedExpression.Parent, (LdLoc)loadInst,
options, context));
}
return(false);
}
internal static ILInstruction HandleCall(Call inst, ILTransformContext context)
{
if (inst.Method.IsConstructor && !inst.Method.IsStatic && inst.Method.DeclaringType.Kind == TypeKind.Struct)
{
Debug.Assert(inst.Arguments.Count == inst.Method.Parameters.Count + 1);
context.Step("Transform call to struct constructor", inst);
// call(ref, ...)
// => stobj(ref, newobj(...))
var newObj = new NewObj(inst.Method);
newObj.ILRange = inst.ILRange;
newObj.Arguments.AddRange(inst.Arguments.Skip(1));
var expr = new StObj(inst.Arguments[0], newObj, inst.Method.DeclaringType);
inst.ReplaceWith(expr);
return(expr);
}
return(null);
}
/// <summary>
/// stobj(target, binary.op(ldobj(target), ...))
/// where target is pure
/// => compound.op(target, ...)
/// </summary>
/// <remarks>
/// Called by ExpressionTransforms.
/// </remarks>
internal static bool HandleStObjCompoundAssign(StObj inst, ILTransformContext context)
{
if (!(UnwrapSmallIntegerConv(inst.Value, out var conv) is BinaryNumericInstruction binary))
{
return(false);
}
if (!(binary.Left is LdObj ldobj))
{
return(false);
}
if (!inst.Target.Match(ldobj.Target).Success)
{
return(false);
}
if (!SemanticHelper.IsPure(ldobj.Target.Flags))
{
return(false);
}
// ldobj.Type may just be 'int' (due to ldind.i4) when we're actually operating on a 'ref MyEnum'.
// Try to determine the real type of the object we're modifying:
IType targetType = ldobj.Target.InferType();
if (targetType.Kind == TypeKind.Pointer || targetType.Kind == TypeKind.ByReference)
{
targetType = ((TypeWithElementType)targetType).ElementType;
if (targetType.Kind == TypeKind.Unknown || targetType.GetSize() != ldobj.Type.GetSize())
{
targetType = ldobj.Type;
}
}
else
{
targetType = ldobj.Type;
}
if (!ValidateCompoundAssign(binary, conv, targetType))
{
return(false);
}
context.Step("compound assignment", inst);
inst.ReplaceWith(new CompoundAssignmentInstruction(
binary, binary.Left, binary.Right,
targetType, CompoundAssignmentType.EvaluatesToNewValue));
return(true);
}
internal static bool LdObjToLdLoc(LdObj inst, ILTransformContext context)
{
if (inst.Target.MatchLdLoca(out ILVariable v) &&
TypeUtils.IsCompatibleTypeForMemoryAccess(v.Type, inst.Type) &&
inst.UnalignedPrefix == 0 &&
!inst.IsVolatile)
{
context.Step($"ldobj(ldloca {v.Name}) => ldloc {v.Name}", inst);
ILInstruction replacement = new LdLoc(v).WithILRange(inst);
if (v.StackType == StackType.Unknown && inst.Type.Kind != TypeKind.Unknown)
{
replacement = new Conv(replacement, inst.Type.ToPrimitiveType(),
checkForOverflow: false, Sign.None);
}
inst.ReplaceWith(replacement);
return(true);
}
return(false);
}
protected internal override void VisitLdFlda(LdFlda inst)
{
base.VisitLdFlda(inst);
// Get display class info
if (!IsDisplayClassFieldAccess(inst, out _, out DisplayClass displayClass, out IField field))
return;
var keyField = (IField)field.MemberDefinition;
var v = displayClass.VariablesToDeclare[keyField];
context.Step($"Replace {field.Name} with captured variable {v.Name}", inst);
ILVariable variable = v.GetOrDeclare();
inst.ReplaceWith(new LdLoca(variable).WithILRange(inst));
// add captured variable to all descendant functions from the declaring function to this use-site function
foreach (var f in currentFunctions) {
if (f == variable.Function)
break;
f.CapturedVariables.Add(variable);
}
}
/// <summary>
/// Inlines 'expr' into 'next', if possible.
///
/// Note that this method does not check whether 'v' has only one use;
/// the caller is expected to validate whether inlining 'v' has any effects on other uses of 'v'.
/// </summary>
static bool DoInline(ILVariable v, ILInstruction inlinedExpression, ILInstruction next, bool aggressive, ILTransformContext context)
{
ILInstruction loadInst;
if (FindLoadInNext(next, v, inlinedExpression, out loadInst) == true)
{
if (loadInst.OpCode == OpCode.LdLoca)
{
if (!IsGeneratedValueTypeTemporary(next, loadInst.Parent, loadInst.ChildIndex, v, inlinedExpression))
{
return(false);
}
}
else
{
Debug.Assert(loadInst.OpCode == OpCode.LdLoc);
if (!aggressive && v.Kind != VariableKind.StackSlot && !NonAggressiveInlineInto(next, loadInst, inlinedExpression, v))
{
return(false);
}
}
context.Step($"Inline variable '{v.Name}'", inlinedExpression);
// Assign the ranges of the ldloc instruction:
inlinedExpression.AddILRange(loadInst.ILRange);
if (loadInst.OpCode == OpCode.LdLoca)
{
// it was an ldloca instruction, so we need to use the pseudo-opcode 'addressof'
// to preserve the semantics of the compiler-generated temporary
loadInst.ReplaceWith(new AddressOf(inlinedExpression));
}
else
{
loadInst.ReplaceWith(inlinedExpression);
}
return(true);
}
return(false);
}
internal static void FixComparisonKindLdNull(Comp inst, ILTransformContext context)
{
if (inst.IsLifted)
{
return;
}
if (inst.Right.MatchLdNull())
{
if (inst.Kind == ComparisonKind.GreaterThan)
{
context.Step("comp(left > ldnull) => comp(left != ldnull)", inst);
inst.Kind = ComparisonKind.Inequality;
}
else if (inst.Kind == ComparisonKind.LessThanOrEqual)
{
context.Step("comp(left <= ldnull) => comp(left == ldnull)", inst);
inst.Kind = ComparisonKind.Equality;
}
}
else if (inst.Left.MatchLdNull())
{
if (inst.Kind == ComparisonKind.LessThan)
{
context.Step("comp(ldnull < right) => comp(ldnull != right)", inst);
inst.Kind = ComparisonKind.Inequality;
}
else if (inst.Kind == ComparisonKind.GreaterThanOrEqual)
{
context.Step("comp(ldnull >= right) => comp(ldnull == right)", inst);
inst.Kind = ComparisonKind.Equality;
}
}
if (inst.Right.MatchLdNull() && inst.Left.MatchBox(out var arg, out var type) && type.Kind == TypeKind.TypeParameter)
{
if (inst.Kind == ComparisonKind.Equality)
{
context.Step("comp(box T(..) == ldnull) -> comp(.. == ldnull)", inst);
inst.Left = arg;
}
if (inst.Kind == ComparisonKind.Inequality)
{
context.Step("comp(box T(..) != ldnull) -> comp(.. != ldnull)", inst);
inst.Left = arg;
}
}
}
/// <summary>
/// Called by expression transforms.
/// Handles the `array[System.Index]` cases.
/// </summary>
public static bool HandleLdElema(LdElema ldelema, ILTransformContext context)
{
if (!context.Settings.Ranges)
{
return(false);
}
if (!ldelema.Array.MatchLdLoc(out ILVariable array))
{
return(false);
}
if (ldelema.Indices.Count != 1)
{
return(false); // the index/range feature doesn't support multi-dimensional arrays
}
var index = ldelema.Indices[0];
if (index is CallInstruction call && call.Method.Name == "GetOffset" && call.Method.DeclaringType.IsKnownType(KnownTypeCode.Index))
{
// ldelema T(ldloc array, call GetOffset(..., ldlen.i4(ldloc array)))
// -> withsystemindex.ldelema T(ldloc array, ...)
if (call.Arguments.Count != 2)
{
return(false);
}
if (!(call.Arguments[1].MatchLdLen(StackType.I4, out var arrayLoad) && arrayLoad.MatchLdLoc(array)))
{
return(false);
}
context.Step("ldelema with System.Index", ldelema);
foreach (var node in call.Arguments[1].Descendants)
{
ldelema.AddILRange(node);
}
ldelema.AddILRange(call);
ldelema.WithSystemIndex = true;
// The method call had a `ref System.Index` argument for the this pointer, but we want a `System.Index` by-value.
ldelema.Indices[0] = new LdObj(call.Arguments[0], call.Method.DeclaringType);
return(true);
}
internal static void AddressOfLdLocToLdLoca(LdObj inst, ILTransformContext context)
{
// ldobj(...(addressof(ldloc V))) where ... can be zero or more ldflda instructions
// =>
// ldobj(...(ldloca V))
var temp = inst.Target;
var range = temp.ILRanges;
while (temp.MatchLdFlda(out var ldfldaTarget, out _))
{
temp = ldfldaTarget;
range = range.Concat(temp.ILRanges);
}
if (temp.MatchAddressOf(out var addressOfTarget, out _) && addressOfTarget.MatchLdLoc(out var v))
{
context.Step($"ldobj(...(addressof(ldloca {v.Name}))) => ldobj(...(ldloca {v.Name}))", inst);
var replacement = new LdLoca(v).WithILRange(addressOfTarget);
foreach (var r in range)
{
replacement = replacement.WithILRange(r);
}
temp.ReplaceWith(replacement);
}
}
protected internal override void VisitStLoc(StLoc inst)
{
base.VisitStLoc(inst);
if (inst.Parent is Block && inst.Variable.IsSingleDefinition)
{
if (inst.Variable.Kind == VariableKind.Local && inst.Variable.LoadCount == 0 && inst.Value is StLoc)
{
context.Step($"Remove unused variable assignment {inst.Variable.Name}", inst);
inst.ReplaceWith(inst.Value);
return;
}
if (inst.Value.MatchLdLoc(out var displayClassVariable) && displayClasses.TryGetValue(displayClassVariable, out var displayClass))
{
context.Step($"Found copy-assignment of display-class variable {displayClassVariable.Name}", inst);
displayClasses.Add(inst.Variable, displayClass);
instructionsToRemove.Add(inst);
return;
}
}
}
