illinkanalyzer [options] <linker-dependency-file.xml.gz>
Linker analyzer is a command line tool to analyze dependencies, which were recorded during linker processing, and led linker to mark an item to keep it in the resulting linked assembly.
It works on an oriented graph of dependencies, which are collected and dumped during the linker run. The vertices of this graph are the items of interest like assemblies, types, methods, fields, linker steps, etc. The edges represent the dependencies.
How to Dump Dependencies
The linker analyzer needs a linker dependencies file as an input. It can be retrieved by enabling dependencies dumping during linking of a Xamarin.Android or a Xamarin.iOS project.
That can be done on the command line by setting LinkerDumpDependencies property to true and building the project. (make sure the LinkAssemblies task is called, it might require cleaning the project sometimes) Usually it is enough to build the project like this:
rm -f obj/Release/link.flag msbuild /p:LinkerDumpDependencies=true /p:Configuration=Release YourAppProject.csproj
After a successful build, there will be a linker-dependencies.xml.gz file created, containing the information for the analyzer.
-a, --alldeps show all dependencies --csvoutput=VALUE outputs types and optionally size analysis to CSV file -h, --help show this message and exit. -l, --linkedpath=VALUE sets the linked assemblies directory path. Enables displaying size estimates. -r, --rawdeps=VALUE show raw vertex dependencies. Raw vertex VALUE is in the raw format written by linker to the dependency XML file. VALUE can be regular expression --roots show root dependencies. --stat show statistic of loaded dependencies. --tree reduce the dependency graph to the tree. --types show all types dependencies. -t, --typedeps=VALUE show type dependencies. The VALUE can be regular expression -f, --flat show all dependencies per vertex and their distance -v, --verbose be more verbose. Enables stat and roots options.
Let say you would like to know, why a type, Android.App.Activity for example, was marked by the linker. So run the analyzer like this:
illinkanalyzer -t Android.App.Activity linker-dependencies.xml.gz
Loading dependency tree from: linker-dependencies.xml.gz --- Type dependencies: 'Android.App.Activity' ----------------------- --- TypeDef:Android.App.Activity dependencies ----------------------- Dependency #1 TypeDef:Android.App.Activity | TypeDef:XA.App.MainActivity [2 deps] | Assembly:XA.App, Version=220.127.116.11, Culture=neutral, PublicKeyToken=null [3 deps] | Other:Mono.Linker.Steps.ResolveFromAssemblyStep
The output contains dependencies string(s), starting with the type and continuing with the item of interest, which depends on the type. The dependency could be result of multiple reasons. For example the type was referenced from a method, or the type was listed in the linker xml file to be protected.
In our example there is only one dependency string called Dependency #1. It shows us that the type Android.App.Activity was marked during processing of type XA.App.MainActivity by the linker. In this case because the MainActivity type is based on the Activity type and thus the linker marked it and kept it in the linked assembly. We can also see that there are 2 dependencies for the MainActivity class. Note that in the string (above) we see only 1st dependency of the 2, the dependency on the assembly XA.App. And finally the assembly vertex depends on the ResolveFromAssemblyStep vertex. So we see that the assembly was processed in the ResolveFromAssembly linker step.
Now we might want to see the MainActivity dependencies. That could be done by the following analyzer run:
illinkanalyzer -r TypeDef:XA.App.MainActivity linker-dependencies.xml.gz
Loading dependency tree from: linker-dependencies.xml.gz --- Raw dependencies: 'TypeDef:XA.App.MainActivity' ----------------- --- TypeDef:XA.App.MainActivity dependencies ------------------------ Dependency #1 TypeDef:XA.App.MainActivity | Assembly:XA.App, Version=18.104.22.168, Culture=neutral, PublicKeyToken=null [3 deps] | Other:Mono.Linker.Steps.ResolveFromAssemblyStep Dependency #2 TypeDef:XA.App.MainActivity | TypeDef:XA.App.MainActivity/<>c__DisplayClass1_0 [2 deps] | TypeDef:XA.App.MainActivity [2 deps] | Assembly:XA.App, Version=22.214.171.124, Culture=neutral, PublicKeyToken=null [3 deps] | Other:Mono.Linker.Steps.ResolveFromAssemblyStep