[Arm64] jitStressRegs=3 failures

[CarolEidt]

The following tests fail with jitStressRegs=3 when run on x64/windows, using the arm64 altjit:

CoreMangLib\cti\system\mathf\MathFSign\MathFSign.cmd
JIT\Generics\Locals\static_assignment_class01\static_assignment_class01.cmd
JIT\Generics\Constraints\convert_static01\convert_static01.cmd
JIT\IL_Conformance\Old\Conformance_Base\add_ovf_u2\add_ovf_u2.cmd
JIT\jit64\opt\regress\vswhidbey\481244\foo_opt\foo_opt.cmd

Note that this test leg was last run in the CI system on 16 Feb.

[sdmaclea]

Looks like the failures are issues while running the code. So these are not arm64 issues, but rather x64 issues while running x64_altjit. Perhaps related to the config options in test/x64_arm64_altjit.cmd ?

@BruceForstall

[CarolEidt]

I have just realized that I failed to run these with COMPlus_SIMD16ByteOnly. Now none of them are failing either in master or in my branch. Let me rebase and see if I can reproduce the failures that are showing up in PR dotnet/coreclr#16517

[sdmaclea]

@CarolEidt COMPlus_SIMD16ByteOnly should be on by default in altjit arm64 jobs

[CarolEidt]

COMPlus_SIMD16ByteOnly should be on by default in altjit arm64 jobs

Right, but when I ran the tests in my local copy of my branch and master, I forgot - and naturally the jobs failed in both.

[CarolEidt]

They were apparently spurious failures. Closing this.