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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Generic;
using System.Diagnostics;
using Mono.Cecil;
namespace Mono.Linker.Steps
{
public class DiscoverOperatorsHandler : IMarkHandler
{
LinkContext? _context;
LinkContext Context {
get {
Debug.Assert (_context != null);
return _context;
}
}
bool _seenLinqExpressions;
readonly HashSet<TypeDefinition> _trackedTypesWithOperators;
Dictionary<TypeDefinition, List<MethodDefinition>>? _pendingOperatorsForType;
Dictionary<TypeDefinition, List<MethodDefinition>> PendingOperatorsForType {
get {
if (_pendingOperatorsForType == null)
_pendingOperatorsForType = new Dictionary<TypeDefinition, List<MethodDefinition>> ();
return _pendingOperatorsForType;
}
}
public DiscoverOperatorsHandler ()
{
_trackedTypesWithOperators = new HashSet<TypeDefinition> ();
}
public void Initialize (LinkContext context, MarkContext markContext)
{
_context = context;
markContext.RegisterMarkTypeAction (ProcessType);
}
void ProcessType (TypeDefinition type)
{
CheckForLinqExpressions (type);
// Check for custom operators and either:
// - mark them, if Linq.Expressions was already marked, or
// - track them to be marked in case Linq.Expressions is marked later
var hasOperators = ProcessCustomOperators (type, mark: _seenLinqExpressions);
if (!_seenLinqExpressions) {
if (hasOperators)
_trackedTypesWithOperators.Add (type);
return;
}
// Mark pending operators defined on other types that reference this type
// (these are only tracked if we have already seen Linq.Expressions)
if (PendingOperatorsForType.TryGetValue (type, out var pendingOperators)) {
foreach (var customOperator in pendingOperators)
MarkOperator (customOperator);
PendingOperatorsForType.Remove (type);
}
}
void CheckForLinqExpressions (TypeDefinition type)
{
if (_seenLinqExpressions)
return;
if (type.Namespace != "System.Linq.Expressions" || type.Name != "Expression")
return;
_seenLinqExpressions = true;
foreach (var markedType in _trackedTypesWithOperators)
ProcessCustomOperators (markedType, mark: true);
_trackedTypesWithOperators.Clear ();
}
void MarkOperator (MethodDefinition method)
{
Context.Annotations.Mark (method, new DependencyInfo (DependencyKind.PreservedOperator, method.DeclaringType));
}
bool ProcessCustomOperators (TypeDefinition type, bool mark)
{
if (!type.HasMethods)
return false;
bool hasCustomOperators = false;
foreach (var method in type.Methods) {
if (!IsOperator (method, out var otherType))
continue;
if (!mark)
return true;
Debug.Assert (_seenLinqExpressions);
hasCustomOperators = true;
if (otherType == null || Context.Annotations.IsMarked (otherType)) {
MarkOperator (method);
continue;
}
// Wait until otherType gets marked to mark the operator.
if (!PendingOperatorsForType.TryGetValue (otherType, out var pendingOperators)) {
pendingOperators = new List<MethodDefinition> ();
PendingOperatorsForType.Add (otherType, pendingOperators);
}
pendingOperators.Add (method);
}
return hasCustomOperators;
}
TypeDefinition? _nullableOfT;
TypeDefinition? NullableOfT {
get {
if (_nullableOfT == null)
_nullableOfT = BCL.FindPredefinedType ("System", "Nullable`1", Context);
return _nullableOfT;
}
}
TypeDefinition? NonNullableType (TypeReference type)
{
var typeDef = Context.TryResolve (type);
if (typeDef == null)
return null;
if (!typeDef.IsValueType || typeDef != NullableOfT)
return typeDef;
// Unwrap Nullable<T>
Debug.Assert (typeDef.HasGenericParameters);
// The original type reference might be a TypeSpecification like array of Nullable<T>
// that we need to unwrap until we get to the Nullable<T>
while (!type.IsGenericInstance)
type = ((TypeSpecification) type).ElementType;
var nullableType = type as GenericInstanceType;
Debug.Assert (nullableType != null && nullableType.HasGenericArguments && nullableType.GenericArguments.Count == 1);
return Context.TryResolve (nullableType.GenericArguments[0]);
}
bool IsOperator (MethodDefinition method, out TypeDefinition? otherType)
{
otherType = null;
if (!method.IsStatic || !method.IsPublic || !method.IsSpecialName || !method.Name.StartsWith ("op_"))
return false;
var operatorName = method.Name.Substring (3);
var self = method.DeclaringType;
switch (operatorName) {
// Unary operators
case "UnaryPlus":
case "UnaryNegation":
case "LogicalNot":
case "OnesComplement":
case "Increment":
case "Decrement":
case "True":
case "False":
// Parameter type of a unary operator must be the declaring type
if (method.Parameters.Count != 1 || NonNullableType (method.Parameters[0].ParameterType) != self)
return false;
// ++ and -- must return the declaring type
if (operatorName is "Increment" or "Decrement" && NonNullableType (method.ReturnType) != self)
return false;
return true;
// Binary operators
case "Addition":
case "Subtraction":
case "Multiply":
case "Division":
case "Modulus":
case "BitwiseAnd":
case "BitwiseOr":
case "ExclusiveOr":
case "LeftShift":
case "RightShift":
case "Equality":
case "Inequality":
case "LessThan":
case "GreaterThan":
case "LessThanOrEqual":
case "GreaterThanOrEqual":
if (method.Parameters.Count != 2)
return false;
var nnLeft = NonNullableType (method.Parameters[0].ParameterType);
var nnRight = NonNullableType (method.Parameters[1].ParameterType);
if (nnLeft == null || nnRight == null)
return false;
// << and >> must take the declaring type and int
if (operatorName is "LeftShift" or "RightShift" && (nnLeft != self || nnRight.MetadataType != MetadataType.Int32))
return false;
// At least one argument must be the declaring type
if (nnLeft != self && nnRight != self)
return false;
if (nnLeft != self)
otherType = nnLeft;
if (nnRight != self)
otherType = nnRight;
return true;
// Conversion operators
case "Implicit":
case "Explicit":
if (method.Parameters.Count != 1)
return false;
var nnSource = NonNullableType (method.Parameters[0].ParameterType);
var nnTarget = NonNullableType (method.ReturnType);
// Exactly one of source/target must be the declaring type
if (nnSource == self == (nnTarget == self))
return false;
otherType = nnSource == self ? nnTarget : nnSource;
return true;
default:
return false;
}
}
}
}
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