/// <summary>
/// Return the boolean expression to be evaluated for the given test. Returns `null` if the test is trivially true.
/// </summary>
protected BoundExpression LowerTest(BoundDagTest test)
{
_factory.Syntax = test.Syntax;
BoundExpression input = _tempAllocator.GetTemp(test.Input);
switch (test)
{
case BoundDagNonNullTest d:
return(_localRewriter.MakeNullCheck(d.Syntax, input, input.Type.IsNullableType() ? BinaryOperatorKind.NullableNullNotEqual : BinaryOperatorKind.NotEqual));
case BoundDagTypeTest d:
// Note that this tests for non-null as a side-effect. We depend on that to sometimes avoid the null check.
return(_factory.Is(input, d.Type));
case BoundDagNullTest d:
return(_localRewriter.MakeNullCheck(d.Syntax, input, input.Type.IsNullableType() ? BinaryOperatorKind.NullableNullEqual : BinaryOperatorKind.Equal));
case BoundDagValueTest d:
Debug.Assert(!input.Type.IsNullableType());
return(MakeEqual(_localRewriter.MakeLiteral(d.Syntax, d.Value, input.Type), input));
default:
throw ExceptionUtilities.UnexpectedValue(test);
}
}
