[nullables] Add lifting for operator~.

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -345,33 +345,30 @@ namespace ICSharpCode.Decompiler.CSharp
 		protected internal override TranslatedExpression VisitBitNot(BitNot inst, TranslationContext context)
 		{
 			var argument = Translate(inst.Argument);
+			var argUType = NullableType.GetUnderlyingType(argument.Type);
 
-			if (argument.Type.GetStackType().GetSize() < inst.ResultType.GetSize()
-			    || argument.Type.Kind == TypeKind.Enum && argument.Type.IsSmallIntegerType())
+			if (argUType.GetStackType().GetSize() < inst.UnderlyingResultType.GetSize()
+			    || argUType.Kind == TypeKind.Enum && argUType.IsSmallIntegerType()
+				|| argUType.GetStackType() == StackType.I
+				|| argUType.IsKnownType(KnownTypeCode.Boolean)
+				|| argUType.IsKnownType(KnownTypeCode.Char))
 			{
 				// Argument is undersized (even after implicit integral promotion to I4)
 				// -> we need to perform sign/zero-extension before the BitNot.
 				// Same if the argument is an enum based on a small integer type
 				// (those don't undergo numeric promotion in C# the way non-enum small integer types do).
-				argument = argument.ConvertTo(compilation.FindType(inst.ResultType.ToKnownTypeCode(argument.Type.GetSign())), this);
-			}
-			
-			var type = argument.Type.GetDefinition();
-			if (type != null) {
-				// Handle those types that don't support operator ~
+				// Same if the type is one that does not support ~ (IntPtr, bool and char).
+				StackType targetStackType = inst.UnderlyingResultType;
+				if (targetStackType == StackType.I) {
+					// IntPtr doesn't support operator ~.
 					// Note that it's OK to use a type that's larger than necessary.
-				switch (type.KnownTypeCode) {
-					case KnownTypeCode.Boolean:
-					case KnownTypeCode.Char:
-						argument = argument.ConvertTo(compilation.FindType(KnownTypeCode.UInt32), this);
-						break;
-					case KnownTypeCode.IntPtr:
-						argument = argument.ConvertTo(compilation.FindType(KnownTypeCode.Int64), this);
-						break;
-					case KnownTypeCode.UIntPtr:
-						argument = argument.ConvertTo(compilation.FindType(KnownTypeCode.UInt64), this);
-						break;
+					targetStackType = StackType.I8;
+				}
+				IType targetType = compilation.FindType(targetStackType.ToKnownTypeCode(argUType.GetSign()));
+				if (inst.IsLifted) {
+					targetType = NullableType.Create(compilation, targetType);
 				}
+				argument = argument.ConvertTo(targetType, this);
 			}
 			
 			return new UnaryOperatorExpression(UnaryOperatorType.BitNot, argument)

ICSharpCode.Decompiler/IL/Instructions.cs

@@ -952,9 +952,6 @@ namespace ICSharpCode.Decompiler.IL
 	/// <summary>Bitwise NOT</summary>
 	public sealed partial class BitNot : UnaryInstruction
 	{
-		public BitNot(ILInstruction argument) : base(OpCode.BitNot, argument)
-		{
-		}
 
 		public override void AcceptVisitor(ILVisitor visitor)
 		{
@@ -971,7 +968,7 @@ namespace ICSharpCode.Decompiler.IL
 		protected internal override bool PerformMatch(ILInstruction other, ref Patterns.Match match)
 		{
 			var o = other as BitNot;
-			return o != null && this.Argument.PerformMatch(o.Argument, ref match);
+			return o != null && this.Argument.PerformMatch(o.Argument, ref match) && IsLifted == o.IsLifted && UnderlyingResultType == o.UnderlyingResultType;
 		}
 	}
 }
@@ -5092,16 +5089,6 @@ namespace ICSharpCode.Decompiler.IL
 			body = default(ILInstruction);
 			return false;
 		}
-		public bool MatchBitNot(out ILInstruction argument)
-		{
-			var inst = this as BitNot;
-			if (inst != null) {
-				argument = inst.Argument;
-				return true;
-			}
-			argument = default(ILInstruction);
-			return false;
-		}
 		public bool MatchArglist()
 		{
 			var inst = this as Arglist;

ICSharpCode.Decompiler/IL/Instructions.tt

@@ -70,7 +70,7 @@
 			CustomClassName("CompoundAssignmentInstruction"), CustomConstructor, CustomComputeFlags,
 			MayThrow, CustomArguments("target", "value"), HasTypeOperand, ResultType("type.GetStackType()"), CustomWriteTo,
 			MatchCondition("CheckForOverflow == o.CheckForOverflow && Sign == o.Sign && Operator == o.Operator")),
-		new OpCode("bit.not", "Bitwise NOT", Unary),
+		new OpCode("bit.not", "Bitwise NOT", Unary, CustomConstructor, MatchCondition("IsLifted == o.IsLifted && UnderlyingResultType == o.UnderlyingResultType")),
 		new OpCode("arglist", "Retrieves the RuntimeArgumentHandle.", NoArguments, ResultType("O")),
 		new OpCode("br", "Unconditional branch. <c>goto target;</c>",
 			CustomClassName("Branch"), NoArguments, CustomConstructor, UnconditionalBranch, MayBranch, CustomComputeFlags,

ICSharpCode.Decompiler/IL/Instructions/UnaryInstruction.cs

@@ -16,15 +16,37 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System.Diagnostics;
 
 namespace ICSharpCode.Decompiler.IL
 {
-	partial class BitNot
+	partial class BitNot : ILiftableInstruction
 	{
+		public BitNot(ILInstruction arg) : base(OpCode.BitNot, arg)
+		{
+			this.UnderlyingResultType = arg.ResultType;
+		}
+
+		public BitNot(ILInstruction arg, bool isLifted, StackType stackType) : base(OpCode.BitNot, arg)
+		{
+			this.IsLifted = isLifted;
+			this.UnderlyingResultType = stackType;
+		}
+
+		public bool IsLifted { get; }
+		public StackType UnderlyingResultType { get; }
+
 		public override StackType ResultType {
 			get {
 				return Argument.ResultType;
 			}
 		}
+
+		internal override void CheckInvariant(ILPhase phase)
+		{
+			base.CheckInvariant(phase);
+			Debug.Assert(IsLifted == (ResultType == StackType.O));
+			Debug.Assert(IsLifted || ResultType == UnderlyingResultType);
+		}
 	}
 }

ICSharpCode.Decompiler/IL/Transforms/NullableLiftingTransform.cs

@@ -370,6 +370,14 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					};
 					return (newInst, bits);
 				}
+			} else if (inst is BitNot bitnot) {
+				var (arg, bits) = DoLift(bitnot.Argument);
+				if (arg != null) {
+					var newInst = new BitNot(arg, isLifted: true, stackType: bitnot.ResultType) {
+						ILRange = bitnot.ILRange
+					};
+					return (newInst, bits);
+				}
 			} else if (inst is BinaryNumericInstruction binary) {
 				var (left, leftBits) = DoLift(binary.Left);
 				var (right, rightBits) = DoLift(binary.Right);