private void EmitBinaryExpression(Expression expr, CompilationFlags flags)
{
BinaryExpression b = (BinaryExpression)expr;
Debug.Assert(b.NodeType != ExpressionType.AndAlso && b.NodeType != ExpressionType.OrElse && b.NodeType != ExpressionType.Coalesce);
if (b.Method != null)
{
EmitBinaryMethod(b, flags);
return;
}
// For EQ and NE, if there is a user-specified method, use it.
// Otherwise implement the C# semantics that allow equality
// comparisons on non-primitive nullable structs that don't
// overload "=="
if ((b.NodeType == ExpressionType.Equal || b.NodeType == ExpressionType.NotEqual) &&
(b.Type == typeof(bool) || b.Type == typeof(bool?)))
{
// If we have x==null, x!=null, null==x or null!=x where x is
// nullable but not null, then generate a call to x.HasValue.
Debug.Assert(!b.IsLiftedToNull || b.Type == typeof(bool?));
if (ConstantCheck.IsNull(b.Left) && !ConstantCheck.IsNull(b.Right) && TypeUtils.IsNullableType(b.Right.Type))
{
EmitNullEquality(b.NodeType, b.Right, b.IsLiftedToNull);
return;
}
if (ConstantCheck.IsNull(b.Right) && !ConstantCheck.IsNull(b.Left) && TypeUtils.IsNullableType(b.Left.Type))
{
EmitNullEquality(b.NodeType, b.Left, b.IsLiftedToNull);
return;
}
// For EQ and NE, we can avoid some conversions if we're
// ultimately just comparing two managed pointers.
EmitExpression(GetEqualityOperand(b.Left));
EmitExpression(GetEqualityOperand(b.Right));
}
else
{
// Otherwise generate it normally
EmitExpression(b.Left);
EmitExpression(b.Right);
}
EmitBinaryOperator(b.NodeType, b.Left.Type, b.Right.Type, b.Type, b.IsLiftedToNull);
}
private void EmitBranchComparison(bool branch, BinaryExpression node, Label label)
{
Debug.Assert(node.NodeType == ExpressionType.Equal || node.NodeType == ExpressionType.NotEqual);
Debug.Assert(!node.IsLiftedToNull);
// To share code paths, we want to treat NotEqual as an inverted Equal
bool branchWhenEqual = branch == (node.NodeType == ExpressionType.Equal);
if (node.Method != null)
{
EmitBinaryMethod(node, CompilationFlags.EmitAsNoTail);
// EmitBinaryMethod takes into account the Equal/NotEqual
// node kind, so use the original branch value
EmitBranchOp(branch, label);
}
else if (ConstantCheck.IsNull(node.Left))
{
if (TypeUtils.IsNullableType(node.Right.Type))
{
EmitAddress(node.Right, node.Right.Type);
_ilg.EmitHasValue(node.Right.Type);
}
else
{
Debug.Assert(!node.Right.Type.IsValueType);
EmitExpression(GetEqualityOperand(node.Right));
}
EmitBranchOp(!branchWhenEqual, label);
}
else if (ConstantCheck.IsNull(node.Right))
{
if (TypeUtils.IsNullableType(node.Left.Type))
{
EmitAddress(node.Left, node.Left.Type);
_ilg.EmitHasValue(node.Left.Type);
}
else
{
Debug.Assert(!node.Left.Type.IsValueType);
EmitExpression(GetEqualityOperand(node.Left));
}
EmitBranchOp(!branchWhenEqual, label);
}
else if (TypeUtils.IsNullableType(node.Left.Type) || TypeUtils.IsNullableType(node.Right.Type))
{
EmitBinaryExpression(node);
// EmitBinaryExpression takes into account the Equal/NotEqual
// node kind, so use the original branch value
EmitBranchOp(branch, label);
}
else
{
EmitExpression(GetEqualityOperand(node.Left));
EmitExpression(GetEqualityOperand(node.Right));
if (branchWhenEqual)
{
_ilg.Emit(OpCodes.Beq, label);
}
else
{
_ilg.Emit(OpCodes.Ceq);
_ilg.Emit(OpCodes.Brfalse, label);
}
}
}