Add a test for determinism

[MichalStrehovsky]

Resolves #73931. This checks that the result of parallel build is the same as the result of single-threaded build.

I'd like to add some more code to this so that there's more junk to compile but don't have a good idea of what to add. XmlSerializer? Suggestions welcome.

Cc @dotnet/ilc-contrib

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Issue Details

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Resolves #73931. This checks that the result of parallel build is the same as the result of single-threaded build.

I'd like to add some more code to this so that there's more junk to compile but don't have a good idea of what to add. XmlSerializer? Suggestions welcome.

Cc @dotnet/ilc-contrib

Author:	MichalStrehovsky
Assignees:	MichalStrehovsky
Labels:	area-NativeAOT-coreclr
Milestone:	-

[SingleAccretion]

Invoke these via reflection? Downstream, I have seen determinism issues (RyuJit-induced, since then fixed) pop up in reflection internals.

[jkotas]

Suggested change

	for (int i = 0; i < baseline.Length; i++)
	long length = baseline.Length;
	for (int i = 0; i < length; i++)

[jkotas]

more junk to compile

Roslyn?

[MichalStrehovsky]

more junk to compile

Roslyn?

The unfortunate part about doing that would be that we then compile Roslyn single-threaded. We want more stuff, but not too much stuff.

[MichalStrehovsky]

I made this call into the other test that does a bunch of random things and exercises things like static virtuals, generic virtual methods, etc.

[jkotas]

Looks like it found a bug:

   nativeaot\SmokeTests\Determinism\Determinism\Determinism.cmd [FAIL]
      Unhandled exception. System.Exception: Different sizes
         at Program.<Main>$(String[] args) + 0x32e

[MichalStrehovsky]

Looks like it found a bug:

   nativeaot\SmokeTests\Determinism\Determinism\Determinism.cmd [FAIL]
      Unhandled exception. System.Exception: Different sizes
         at Program.<Main>$(String[] args) + 0x32e

And of course the diff is in the .debug$S section because any other section would be too easy to root cause 😭

[MichalStrehovsky]

Looks like it found a bug:

   nativeaot\SmokeTests\Determinism\Determinism\Determinism.cmd [FAIL]
      Unhandled exception. System.Exception: Different sizes
         at Program.<Main>$(String[] args) + 0x32e

And of course the diff is in the .debug$S section because any other section would be too easy to root cause 😭

I was wrong. The debug info part is just a symptom of the problem.

The problem is that codegen wasn't deterministic. Filed #93843. @SingleAccretion was right that the reflection stack is problematic.

[jkotas]

LGTM. Thanks!