static bool ValidateCompoundAssign(BinaryNumericInstruction binary, Conv conv, IType targetType)
{
if (!NumericCompoundAssign.IsBinaryCompatibleWithType(binary, targetType))
{
return(false);
}
if (conv != null && !(conv.TargetType == targetType.ToPrimitiveType() && conv.CheckForOverflow == binary.CheckForOverflow))
{
return(false); // conv does not match binary operation
}
return(true);
}
/// <summary>
/// Transform compound assignments where the return value is not being used,
/// or where there's an inlined assignment within the setter call.
///
/// Patterns handled:
/// 1.
/// callvirt set_Property(ldloc S_1, binary.op(callvirt get_Property(ldloc S_1), value))
/// ==> compound.op.new(callvirt get_Property(ldloc S_1), value)
/// 2.
/// callvirt set_Property(ldloc S_1, stloc v(binary.op(callvirt get_Property(ldloc S_1), value)))
/// ==> stloc v(compound.op.new(callvirt get_Property(ldloc S_1), value))
/// 3.
/// stobj(target, binary.op(ldobj(target), ...))
/// where target is pure
/// => compound.op(target, ...)
/// </summary>
/// <remarks>
/// Called by ExpressionTransforms, or after the inline-assignment transform for setters.
/// </remarks>
internal static bool HandleCompoundAssign(ILInstruction compoundStore, StatementTransformContext context)
{
if (!context.Settings.MakeAssignmentExpressions || !context.Settings.IntroduceIncrementAndDecrement)
{
return(false);
}
if (compoundStore is CallInstruction && compoundStore.SlotInfo != Block.InstructionSlot)
{
// replacing 'call set_Property' with a compound assignment instruction
// changes the return value of the expression, so this is only valid on block-level.
return(false);
}
if (!IsCompoundStore(compoundStore, out var targetType, out var setterValue, context.TypeSystem))
{
return(false);
}
// targetType = The type of the property/field/etc. being stored to.
// setterValue = The value being stored.
var storeInSetter = setterValue as StLoc;
if (storeInSetter != null)
{
// We'll move the stloc to top-level:
// callvirt set_Property(ldloc S_1, stloc v(binary.op(callvirt get_Property(ldloc S_1), value)))
// ==> stloc v(compound.op.new(callvirt get_Property(ldloc S_1), value))
setterValue = storeInSetter.Value;
if (storeInSetter.Variable.Type.IsSmallIntegerType())
{
// 'stloc v' implicitly truncates the value.
// Ensure that type of 'v' matches the type of the property:
if (storeInSetter.Variable.Type.GetSize() != targetType.GetSize())
{
return(false);
}
if (storeInSetter.Variable.Type.GetSign() != targetType.GetSign())
{
return(false);
}
}
}
ILInstruction newInst;
if (UnwrapSmallIntegerConv(setterValue, out var smallIntConv) is BinaryNumericInstruction binary)
{
if (compoundStore is StLoc)
{
// transform local variables only for user-defined operators
return(false);
}
if (!IsMatchingCompoundLoad(binary.Left, compoundStore, out var target, out var targetKind, out var finalizeMatch, forbiddenVariable: storeInSetter?.Variable))
{
return(false);
}
if (!ValidateCompoundAssign(binary, smallIntConv, targetType))
{
return(false);
}
context.Step($"Compound assignment (binary.numeric)", compoundStore);
finalizeMatch?.Invoke(context);
newInst = new NumericCompoundAssign(
binary, target, targetKind, binary.Right,
targetType, CompoundEvalMode.EvaluatesToNewValue);
}
else if (setterValue is Call operatorCall && operatorCall.Method.IsOperator)
{
if (operatorCall.Arguments.Count == 0)
{
return(false);
}
if (!IsMatchingCompoundLoad(operatorCall.Arguments[0], compoundStore, out var target, out var targetKind, out var finalizeMatch, forbiddenVariable: storeInSetter?.Variable))
{
return(false);
}
ILInstruction rhs;
if (operatorCall.Arguments.Count == 2)
{
if (CSharp.ExpressionBuilder.GetAssignmentOperatorTypeFromMetadataName(operatorCall.Method.Name) == null)
{
return(false);
}
rhs = operatorCall.Arguments[1];
}
else if (operatorCall.Arguments.Count == 1)
{
if (!(operatorCall.Method.Name == "op_Increment" || operatorCall.Method.Name == "op_Decrement"))
{
return(false);
}
// use a dummy node so that we don't need a dedicated instruction for user-defined unary operator calls
rhs = new LdcI4(1);
}
else
{
return(false);
}
if (operatorCall.IsLifted)
{
return(false); // TODO: add tests and think about whether nullables need special considerations
}
context.Step($"Compound assignment (user-defined binary)", compoundStore);
finalizeMatch?.Invoke(context);
newInst = new UserDefinedCompoundAssign(operatorCall.Method, CompoundEvalMode.EvaluatesToNewValue,
target, targetKind, rhs);
}
