[RyuJIT/ARM32] Can't run corefx tests with COMPlus_AltJit

[hqueue]

When running corefx tests with COMPlus_AltJit to test ryujit/arm32, test can't start as follows on Rpi3.

hqueue@rpi3:/corefx_tests/AnyOS.AnyCPU.Release/System.Buffers.Tests/netstandard$ COMPlus_AltJit=* /coreoverlay/corerun xunit.console.netcore.exe System.Buffers.Tests.dll  -xml testResults.xml -notrait category=nonnetcoreapptests -notrait category=nonlinuxtests  -notrait category=failing
xUnit.net console test runner (32-bit .NET Core)
Copyright (C) 2014 Outercurve Foundation.

Discovering: System.Buffers.Tests
System.NullReferenceException: Object reference not set to an instance of an object.

Without COMPlus_AltJit, it works well.

hqueue@rpi3:/corefx_tests/AnyOS.AnyCPU.Release/System.Buffers.Tests/netstandard$ /coreoverlay/corerun xunit.console.netcore.exe System.Buffers.Tests.dll  -xml testResults.xml -notrait category=nonnetcoreapptests -notrait category=nonlinuxtests  -notrait category=failing
xUnit.net console test runner (32-bit .NET Core)
Copyright (C) 2014 Outercurve Foundation.

Discovering: System.Buffers.Tests
Discovered:  System.Buffers.Tests
Starting:    System.Buffers.Tests
Finished:    System.Buffers.Tests

=== TEST EXECUTION SUMMARY ===
   System.Buffers.Tests  Total: 77, Errors: 0, Failed: 0, Skipped: 0, Time: 18.411s

Does any body know how to run corefx tests with COMPlus_AltJit option ?
Note: I've used corerun instead of dotnet which is supposed to be used for corefx tests as default.

[hqueue]

/cc: @BruceForstall Please take a look. Is it possible to run corefx tests with AltJit ?

/cc: @dotnet/arm32-contrib

[BruceForstall]

I haven't ever tried running corefx tests with altjit. Have you tried debugging to see where the failure is? I presume protojit.dll (or libprotojit.so?) exists in the same location as the regular clrjit?

A somewhat unsatisfying option is to (temporarily) change clrjit to be RyuJIT, by changing that build to not define LEGACY_BACKEND. You wouldn't get any NYI fallback if you do that.

[hqueue]

Have you tried debugging to see where the failure is?

I tried to debug it with gdb but got no meaningful clue untiil now.

I presume protojit.dll (or libprotojit.so?) exists in the same location as the regular clrjit?

Yes. There is libprotojit.so and I have ran coreclr tests with same coreoverlay using altjit option

A somewhat unsatisfying option is to (temporarily) change clrjit to be RyuJIT, by changing that build to not define LEGACY_BACKEND. You wouldn't get any NYI fallback if you do that.

I also think about this option but as the last choice.

[hqueue]

@BruceForstall Found a reason. It seems that recent regression in ryujit/arm32 caused the failure.

I'm going to close this after the regression is fixed.

[hqueue]

Fixed by dotnet/coreclr#13364