/// <summary>
/// 当指定的本地变量值为该类型的默认值时跳到指定块。
/// </summary>
/// <param name="ilGen">ilGen</param>
/// <param name="local">本地变量</param>
/// <param name="label">代码块</param>
public static void BranchDefaultValue(this ILGenerator ilGen, LocalBuilder local, Label label)
{
var type = local.LocalType;
if (type.IsClass ||
type.IsInterface ||
type.IsPointer ||
type.IsByRef ||
type == typeof(IntPtr) ||
type == typeof(UIntPtr))
{
ilGen.LoadLocal(local);
ilGen.BranchFalse(label);
return;
}
switch (Type.GetTypeCode(type))
{
case TypeCode.Boolean:
case TypeCode.Char:
case TypeCode.SByte:
case TypeCode.Byte:
case TypeCode.Int16:
case TypeCode.UInt16:
case TypeCode.Int32:
case TypeCode.UInt32:
case TypeCode.Single:
case TypeCode.Int64:
case TypeCode.UInt64:
case TypeCode.Double:
ilGen.LoadLocal(local);
ilGen.BranchFalse(label);
return;
}
var size = TypeHelper.SizeOf(type);
var labNotEmpty = ilGen.DefineLabel();
while (size >= 4)
{
size -= 4;
ilGen.LoadLocalAddress(local);
if (size != 0)
{
ilGen.LoadConstant(size);
ilGen.Emit(OpCodes.Add);
}
ilGen.Emit(OpCodes.Ldind_I4);
ilGen.BranchTrue(labNotEmpty);
}
if (size >= 2)
{
size -= 2;
ilGen.LoadLocalAddress(local);
if (size != 0)
{
ilGen.LoadConstant(size);
ilGen.Emit(OpCodes.Add);
}
ilGen.Emit(OpCodes.Ldind_I2);
ilGen.BranchTrue(labNotEmpty);
}
if (size >= 1)
{
ilGen.LoadLocalAddress(local);
ilGen.Emit(OpCodes.Ldind_I1);
ilGen.BranchTrue(labNotEmpty);
}
ilGen.Branch(label);
ilGen.MarkLabel(labNotEmpty);
}
