Add dynamic compound assignment transforms

ICSharpCode.Decompiler/CSharp/Syntax/Expressions/AssignmentExpression.cs

@@ -202,6 +202,37 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 					throw new NotSupportedException("Invalid value for AssignmentOperatorType");
 			}
 		}
+
+		public static AssignmentOperatorType GetAssignmentOperatorTypeFromExpressionType(ExpressionType expressionType)
+		{
+			switch (expressionType) {
+				case ExpressionType.AddAssign:
+				case ExpressionType.AddAssignChecked:
+					return AssignmentOperatorType.Add;
+				case ExpressionType.AndAssign:
+					return AssignmentOperatorType.BitwiseAnd;
+				case ExpressionType.DivideAssign:
+					return AssignmentOperatorType.Divide;
+				case ExpressionType.ExclusiveOrAssign:
+					return AssignmentOperatorType.ExclusiveOr;
+				case ExpressionType.LeftShiftAssign:
+					return AssignmentOperatorType.ShiftLeft;
+				case ExpressionType.ModuloAssign:
+					return AssignmentOperatorType.Modulus;
+				case ExpressionType.MultiplyAssign:
+				case ExpressionType.MultiplyAssignChecked:
+					return AssignmentOperatorType.Multiply;
+				case ExpressionType.OrAssign:
+					return AssignmentOperatorType.BitwiseOr;
+				case ExpressionType.RightShiftAssign:
+					return AssignmentOperatorType.ShiftRight;
+				case ExpressionType.SubtractAssign:
+				case ExpressionType.SubtractAssignChecked:
+					return AssignmentOperatorType.Subtract;
+				default:
+					throw new NotSupportedException($"ExpressionType.{expressionType} not supported!");
+			}
+		}
 	}
 	
 	public enum AssignmentOperatorType

ICSharpCode.Decompiler/IL/Transforms/ExpressionTransforms.cs

@@ -336,53 +336,83 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 		}
 
 		/// <summary>
-		/// if (logic.not(dynamic.isevent (ldloc a))) Block IL_0045 {
+		/// op is either add or remove/subtract:
-		///     dynamic.setmember.compound Setter2(ldloc a, dynamic.binary.operator AddAssign(dynamic.getmember Setter2(ldloc a), ldc.i4 5))
+		/// if (dynamic.isevent (target)) {
-		/// } else Block IL_0144 {
+		///     dynamic.invokemember.invokespecial.discard op_Name(target, value)
-		///     dynamic.invokemember.invokespecial.discard add_Setter2(ldloc a, ldc.i4 5)
+		/// } else {
+		///     dynamic.compound.op (dynamic.getmember Name(target), value)
 		/// }
 		/// =>
-		/// dynamic.setmember.compound Setter2(ldloc a, dynamic.binary.operator AddAssign(dynamic.getmember Setter2(ldloc a), ldc.i4 5))
+		/// dynamic.compound.op (dynamic.getmember Name(target), value)
 		/// </summary>
 		bool TransformDynamicAddAssignOrRemoveAssign(IfInstruction inst)
 		{
-			if (!inst.Condition.MatchLogicNot(out var possibleIsEvent))
+			if (!inst.MatchIfInstructionPositiveCondition(out var condition, out var trueInst, out var falseInst))
 				return false;
-			if (!(possibleIsEvent is DynamicIsEventInstruction isEvent))
+			if (!(condition is DynamicIsEventInstruction isEvent))
 				return false;
-			var trueInst = Block.Unwrap(inst.TrueInst);
+			trueInst = Block.Unwrap(trueInst);
-			var falseInst = Block.Unwrap(inst.FalseInst);
+			falseInst = Block.Unwrap(falseInst);
-			if (!(trueInst is DynamicSetMemberInstruction dynamicSetMember
+			if (!(falseInst is DynamicCompoundAssign dynamicCompoundAssign))
-				&& dynamicSetMember.BinderFlags.HasFlag(CSharpBinderFlags.ValueFromCompoundAssignment)
-				&& isEvent.Argument.Match(dynamicSetMember.Target).Success
-				&& dynamicSetMember.Value is DynamicBinaryOperatorInstruction binaryOp
-				&& binaryOp.Left is DynamicGetMemberInstruction dynamicGetMember
-				&& dynamicGetMember.Target.Match(dynamicSetMember.Target).Success
-				&& dynamicSetMember.Name == dynamicGetMember.Name
-				&& falseInst is DynamicInvokeMemberInstruction invokeMember
-				&& invokeMember.BinderFlags.HasFlag(CSharpBinderFlags.InvokeSpecialName)
-				&& invokeMember.Arguments.Count == 2 && invokeMember.Arguments[0].Match(dynamicGetMember.Target).Success)
-			) {
 				return false;
-			}
+			if (!(dynamicCompoundAssign.Target is DynamicGetMemberInstruction getMember))
-			switch (binaryOp.Operation) {
+				return false;
+			if (!isEvent.Argument.Match(getMember.Target).Success)
+				return false;
+			if (!(trueInst is DynamicInvokeMemberInstruction invokeMember))
+				return false;
+			if (!(invokeMember.BinderFlags.HasFlag(CSharpBinderFlags.InvokeSpecialName) && invokeMember.BinderFlags.HasFlag(CSharpBinderFlags.ResultDiscarded)))
+				return false;
+			switch (dynamicCompoundAssign.Operation) {
 				case ExpressionType.AddAssign:
-					if (invokeMember.Name != "add_" + dynamicGetMember.Name)
+					if (invokeMember.Name != "add_" + getMember.Name)
 						return false;
 					break;
 				case ExpressionType.SubtractAssign:
-					if (invokeMember.Name != "remove_" + dynamicGetMember.Name)
+					if (invokeMember.Name != "remove_" + getMember.Name)
 						return false;
 					break;
 				default:
 					return false;
 			}
-			if (!binaryOp.Right.Match(invokeMember.Arguments[1]).Success)
+			if (!dynamicCompoundAssign.Value.Match(invokeMember.Arguments[1]).Success)
 				return false;
-			inst.ReplaceWith(trueInst);
+			if (!invokeMember.Arguments[0].Match(getMember.Target).Success)
+				return false;
+			inst.ReplaceWith(dynamicCompoundAssign);
 			return true;
 		}
 
+		/// <summary>
+		/// dynamic.setmember.compound Name(target, dynamic.binary.operator AddAssign(dynamic.getmember Name(target), value))
+		/// =>
+		/// dynamic.compound.op (dynamic.getmember Name(target), value)
+		/// </summary>
+		protected internal override void VisitDynamicSetMemberInstruction(DynamicSetMemberInstruction inst)
+		{
+			if (!inst.BinderFlags.HasFlag(CSharpBinderFlags.ValueFromCompoundAssignment)) {
+				base.VisitDynamicSetMemberInstruction(inst);
+				return;
+			}
+			if (!(inst.Value is DynamicBinaryOperatorInstruction binaryOp)) {
+				base.VisitDynamicSetMemberInstruction(inst);
+				return;
+			}
+			if (!(binaryOp.Left is DynamicGetMemberInstruction dynamicGetMember)) {
+				base.VisitDynamicSetMemberInstruction(inst);
+				return;
+			}
+			if (!dynamicGetMember.Target.Match(inst.Target).Success) {
+				base.VisitDynamicSetMemberInstruction(inst);
+				return;
+			}
+			if (inst.Name != dynamicGetMember.Name || !DynamicCompoundAssign.IsExpressionTypeSupported(binaryOp.Operation)) {
+				base.VisitDynamicSetMemberInstruction(inst);
+				return;
+			}
+			inst.ReplaceWith(new DynamicCompoundAssign(binaryOp.Operation, binaryOp.Left, binaryOp.LeftArgumentInfo, binaryOp.Right, binaryOp.RightArgumentInfo));
+		}
+
 		IfInstruction HandleConditionalOperator(IfInstruction inst)
 		{
 			// if (cond) stloc (A, V1) else stloc (A, V2) --> stloc (A, if (cond) V1 else V2)

ICSharpCode.Decompiler/IL/Transforms/TransformAssignment.cs

@@ -293,6 +293,11 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				context.Step($"Compound assignment (user-defined binary)", compoundStore);
 				newInst = new UserDefinedCompoundAssign(operatorCall.Method, CompoundAssignmentType.EvaluatesToNewValue,
 					operatorCall.Arguments[0], rhs);
+			} else if (setterValue is DynamicBinaryOperatorInstruction dynamicBinaryOp) {
+				if (!IsMatchingCompoundLoad(dynamicBinaryOp.Left, compoundStore, forbiddenVariable: storeInSetter?.Variable))
+					return false;
+				context.Step($"Compound assignment (dynamic binary)", compoundStore);
+				newInst = new DynamicCompoundAssign(dynamicBinaryOp.Operation, dynamicBinaryOp.Left, dynamicBinaryOp.LeftArgumentInfo, dynamicBinaryOp.Right, dynamicBinaryOp.RightArgumentInfo);
 			} else {
 				return false;
 			}