On this page of ReSharper options, you can specify files and code regions containing automatically generated code. For these items, ReSharper runs only those code inspections that check code for compiler errors and warnings. Some file masks and regions, which are used by Visual Studio for generated code, e.g. *.designer.cs are included in this list by default, but you can change the default settings if necessary.
The list of items containing generated code can also be used for disabling code style and cleanup for generated code.