public override void Emit(EmitContext ec)
{
Label end_label = ec.DefineLabel();
if (unwrap != null)
{
Label is_null_label = ec.DefineLabel();
unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brfalse, is_null_label);
//
// When both expressions are nullable the unwrap
// is needed only for null check not for value uwrap
//
if (type.IsNullableType && TypeSpecComparer.IsEqual(NullableInfo.GetUnderlyingType(type), unwrap.Type))
{
unwrap.Load(ec);
}
else
{
left.Emit(ec);
}
ec.Emit(OpCodes.Br, end_label);
ec.MarkLabel(is_null_label);
right.Emit(ec);
ec.MarkLabel(end_label);
return;
}
left.Emit(ec);
ec.Emit(OpCodes.Dup);
// Only to make verifier happy
if (left.Type.IsGenericParameter)
{
ec.Emit(OpCodes.Box, left.Type);
}
ec.Emit(OpCodes.Brtrue, end_label);
ec.Emit(OpCodes.Pop);
right.Emit(ec);
ec.MarkLabel(end_label);
}
void EmitBitwiseBoolean(EmitContext ec)
{
ILGenerator ig = ec.ig;
Label load_left = ig.DefineLabel();
Label load_right = ig.DefineLabel();
Label end_label = ig.DefineLabel();
left_unwrap.Emit(ec);
ig.Emit(OpCodes.Brtrue_S, load_right);
right_unwrap.Emit(ec);
ig.Emit(OpCodes.Brtrue_S, load_left);
left_unwrap.EmitCheck(ec);
ig.Emit(OpCodes.Brfalse_S, load_right);
// load left
ig.MarkLabel(load_left);
if (Oper == Operator.BitwiseAnd)
{
left_unwrap.Load(ec);
}
else
{
right_unwrap.Load(ec);
right_unwrap = left_unwrap;
}
ig.Emit(OpCodes.Br_S, end_label);
// load right
ig.MarkLabel(load_right);
right_unwrap.Load(ec);
ig.MarkLabel(end_label);
}
public override void Emit(EmitContext ec)
{
Label end_label = ec.DefineLabel();
if (unwrap != null)
{
Label is_null_label = ec.DefineLabel();
unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brfalse, is_null_label);
//
// When both expressions are nullable the unwrap
// is needed only for null check not for value uwrap
//
if (type.IsNullableType && TypeSpecComparer.IsEqual(NullableInfo.GetUnderlyingType(type), unwrap.Type))
{
unwrap.Load(ec);
}
else
{
left.Emit(ec);
}
ec.Emit(OpCodes.Br, end_label);
ec.MarkLabel(is_null_label);
right.Emit(ec);
ec.MarkLabel(end_label);
return;
}
//
// Null check is done on original expression not after expression is converted to
// result type. This is in most cases same but when user conversion is involved
// we can end up in situation when user operator does the null handling which is
// not what the operator is supposed to do.
// There is tricky case where cast of left expression is meant to be cast of
// whole source expression (null check is done on it) and cast from right-to-left
// conversion needs to do null check on unconverted source expression.
//
if (user_conversion_left)
{
var op_expr = (UserCast)left;
op_expr.Source.Emit(ec);
LocalTemporary temp;
// TODO: More load kinds can be special cased
if (!(op_expr.Source is VariableReference))
{
temp = new LocalTemporary(op_expr.Source.Type);
temp.Store(ec);
temp.Emit(ec);
op_expr.Source = temp;
}
else
{
temp = null;
}
var right_label = ec.DefineLabel();
ec.Emit(OpCodes.Brfalse_S, right_label);
left.Emit(ec);
ec.Emit(OpCodes.Br, end_label);
ec.MarkLabel(right_label);
if (temp != null)
{
temp.Release(ec);
}
}
else
{
//
// Common case where expression is not modified before null check and
// we generate better/smaller code
//
left.Emit(ec);
ec.Emit(OpCodes.Dup);
// Only to make verifier happy
if (left.Type.IsGenericParameter)
{
ec.Emit(OpCodes.Box, left.Type);
}
ec.Emit(OpCodes.Brtrue, end_label);
ec.Emit(OpCodes.Pop);
}
right.Emit(ec);
ec.MarkLabel(end_label);
}
void EmitBitwiseBoolean(EmitContext ec)
{
Label load_left = ec.DefineLabel();
Label load_right = ec.DefineLabel();
Label end_label = ec.DefineLabel();
// null & value, null | value
if (left_unwrap == null)
{
left_unwrap = right_unwrap;
right_unwrap = null;
right = left;
}
left_unwrap.Emit(ec);
ec.Emit(OpCodes.Brtrue_S, load_right);
// value & null, value | null
if (right_unwrap != null)
{
right_unwrap.Emit(ec);
ec.Emit(OpCodes.Brtrue_S, load_left);
}
left_unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brfalse_S, load_right);
// load left
ec.MarkLabel(load_left);
if (Oper == Operator.BitwiseAnd)
{
left_unwrap.Load(ec);
}
else
{
if (right_unwrap == null)
{
right.Emit(ec);
if (right is EmptyConstantCast || right is EmptyCast)
{
ec.Emit(OpCodes.Newobj, NullableInfo.GetConstructor(type));
}
}
else
{
right_unwrap.Load(ec);
right_unwrap = left_unwrap;
}
}
ec.Emit(OpCodes.Br_S, end_label);
// load right
ec.MarkLabel(load_right);
if (right_unwrap == null)
{
if (Oper == Operator.BitwiseAnd)
{
right.Emit(ec);
if (right is EmptyConstantCast || right is EmptyCast)
{
ec.Emit(OpCodes.Newobj, NullableInfo.GetConstructor(type));
}
}
else
{
left_unwrap.Load(ec);
}
}
else
{
right_unwrap.Load(ec);
}
ec.MarkLabel(end_label);
}