Cannot debug graph visualisation

[kant2002]

I attempt to make a stab at the marshalling null values for COM, but stuck with producing correct IL. I decide that I'm smart guy and can enable debugging of the DependencyGraph. I'm not sure if this was correct decision, but that's not root cause of the issue which I encounter.

So I start follow Documentation\how-to-debug-compiler-dependency-analysis.md

1. I setup csproj and include <IlcGenerateDgmlFile>true</IlcGenerateDgmlFile>
2. I configure to use locally built version of CoreRT.
3. Launch VS as admin and open ILCompiler-DependencyGraph-Viewer.sln
4. Launch dotnet publish as admin
5. Launch ILCompiler-DependencyGraph-Viewer inside VS

events was not there.
Under debugger, line below return false into restarted variable.

corert/src/ILCompiler.DependencyAnalysisFramework/ILCompiler-DependencyGraph-Viewer/Program.cs

Line 258 in 7f4555b

var restarted = session.EnableProvider("Microsoft-ILCompiler-DependencyGraph");

I suspect that this is related to enabling ETW somehow, or maybe I miss some other step?

[MichalStrehovsky]

Can you try leaving out this: <IlcGenerateDgmlFile>true</IlcGenerateDgmlFile>? I don't think the dependency graph support multiple simultaneous logging facilities.

[MichalStrehovsky]

I don't think the dependency graph will help you though. Try adding --ildump path\to\some\file.il to the ILCompiler command line. This will generate a file with all the generated IL that you can set breakpoints on/step in the debugger.

If you're not even getting that far (e.g. RyuJIT is crashing while compiling the method), your only option is to look at the generated IL in the debugger. We have a debugger visualizer for the MethodIL class so that the VS debugger can show you the IL in a nice format. Set up a breakpoint and inspect the generated MethodIL somewhere around PInvokeILEmitter.EmitIL

[kant2002]

Removing <IlcGenerateDgmlFile>true</IlcGenerateDgmlFile> indeed help. I was confused by this line:
6d088c2#diff-b6a2437f0be65e16801de473eb0316cdR10
I now realize that this is out of context. But maybe I can add word that dependency graph do not support multiple simultaneous logging facilities, so make sure that you do not set IlcGenerateDgmlFile or invoke ILCompiler ith DGML generation on.

I will try --ildump, thanks. that seems to be what I need. Do you know how to fast sketch IL? or you just know it by heart 😄

[MichalStrehovsky]

Yup, that line would be useful to add.

I used to write a piece of equivalent C#, compile with optimizations on, and disassemble that. But yes, at this point I know most of the important patterns by heart.

[kant2002]

Sign. I hope that you know some C# godbolt which can allow me write snippet and see the view of IL. Upon search I found https://sharplab.io/ Is it helpful to use? Because IL optimization likely can be trivial. Or I am miss something important? I'm more or less know IL. Have rusty knowledge and lack of practice.

Also for Windows Forms DGML output and DependencyGraphViewer almost impractical to use 200Mb for trivial app.

[MichalStrehovsky]

Yeah, sharplab.io should work. I use csc.exe/ildasm.exe but that's just because I grew up without internet.

Yeah, the DGML is proportional to the size of the app. Windows.Forms drags in a lot of stuff.