How to See What C# Turns Into
I’ve been writing a lot recently about the C++ and assembly that C# code turns into when it’s run through IL2CPP and a C++ compiler. Today’s article shows you the steps so that you can see what your own game’s C# code turns into.
iOS Build on macOS
Open the Unity editor and go to File > Build Settings. Under Platform, choose iOS then click Switch Platform.
Click Build, enter a folder name (e.g. iOS), then click Save.
When the build is complete, double-click Unity-iPhone.xcodeproj to open Xcode.
Click the magnifying glass in the top-left corner of the Xcode window and type in MyType::MyMethod to search for a method in your game. Press return and click each of the results until you find the corresponding C++ code.
Select the method’s C++ name (e.g. TestScript_Start_m1023860210) and copy it to the clipboard. Click the “four squares” icon in the top-left of the text editor area and click Assembly.
Press Command + F and paste in the method’s C++ name into the text field.
Android Build on macOS
Open the Unity editor and go to File > Build Settings. Under Platform, choose Android then click Switch Platform.
Click Build, enter an APK name (e.g. UnityPlayground.apk), then click Save.
When the build is complete, use Finder to open the Temp/il2CppOutput/il2CppOutput directory. Click in the Search field in the top-right corner of the Finder window and type MyType::MyMethod to search for a method in your game. Double-click on the files that were found to open them in Xcode.
Press Command + F and enter MyType::MyMethod into the text field. Select the method’s C++ name (e.g. TestScript_Start_m1023860210) and copy it to the clipboard.
Open the Terminal application and enter objdump --disassemble /path/to/project/Temp/StagingArea/libs/armeabi-v7a/libil2cpp.so > /path/to/output.s. Replace /path/to/project with the path to your Unity project and /path/to/output.s with the path to a file to put the assembly code in.
Open the assembly code file (e.g. output.s) in a text editor. Xcode may take a long time to open such a large file. Press Command + F and paste in the method’s C++ name into the text field.
iOS Build on Windows
Make an iOS build per the macOS instructions and then inspect the C++ source code in the Classes/Native directory. Xcode is not available to generate iOS assembly code on Windows.
Android Build on Windows
Make an Android build and inspect the C++ source per the macOS instructions. Use \path\to\android-ndk\toolchains\arm-linux-androideabi-4.9\prebuilt\windows-x86_64\bin\arm-linux-androideabi-objdump.exe instead of just objdump to generate the assembly code from a Command Prompt.