Test failure: JIT/Methodical/NaN/intrinsic_cs_ro/intrinsic_cs_ro.dll

[BruceForstall]

runtime-coreclr jitstress-random

win-arm64:

set DOTNET_TieredCompilation=0
set DOTNET_JitStress=312

linux-x64:

export DOTNET_TieredCompilation=0
export DOTNET_JitStress=ab

https://dev.azure.com/dnceng-public/public/_build/results?buildId=329904&view=ms.vss-test-web.build-test-results-tab

20:59:12.414 Running test: JIT/Methodical/NaN/intrinsic_cs_ro/intrinsic_cs_ro.dll
...
Tanh(NaN) == NaN  OK
System.Exception: Tanh(NaN) failed: expected -∞, got -1
   at Test_intrinsic.JitTest.Test.Fail(String func, Double arg, Double exp, Double res)
   at Test_intrinsic.JitTest.Test.TestEntryPoint()
=== FAILED ===
20:59:12.938 Failed test: JIT/Methodical/NaN/intrinsic_cs_ro/intrinsic_cs_ro.dll

@dotnet/jit-contrib

[ghost]

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
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Issue Details

---

runtime-coreclr jitstress-random

win-arm64:

set DOTNET_TieredCompilation=0
set DOTNET_JitStress=312

linux-x64:

export DOTNET_TieredCompilation=0
export DOTNET_JitStress=ab

https://dev.azure.com/dnceng-public/public/_build/results?buildId=329904&view=ms.vss-test-web.build-test-results-tab

20:59:12.414 Running test: JIT/Methodical/NaN/intrinsic_cs_ro/intrinsic_cs_ro.dll
...
Tanh(NaN) == NaN  OK
System.Exception: Tanh(NaN) failed: expected -∞, got -1
   at Test_intrinsic.JitTest.Test.Fail(String func, Double arg, Double exp, Double res)
   at Test_intrinsic.JitTest.Test.TestEntryPoint()
=== FAILED ===
20:59:12.938 Failed test: JIT/Methodical/NaN/intrinsic_cs_ro/intrinsic_cs_ro.dll

@dotnet/jit-contrib

Author:	BruceForstall
Assignees:	-
Labels:	JitStress, area-CodeGen-coreclr
Milestone:	8.0.0

[v-wenyuxu]

Failed again in: runtime-coreclr jitstress-random 20230723.1

Failed tests:

coreclr osx x64 Checked jitstress_random_2 @ OSX.1200.Amd64.Open
    - JIT/Methodical/NaN/intrinsic_cs_ro/intrinsic_cs_ro.dll
coreclr windows arm64 Checked jitstress_random_2 @ Windows.11.Arm64.Open
    - JIT/Methodical/NaN/intrinsic_cs_do/intrinsic_cs_do.dll

Error message:

Assert.Equal() Failure
Expected: 100
Actual:   101

Stack trace:

   at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/xunit.assert/Asserts/EqualityAsserts.cs:line 96
   at Program.<<Main>$>g__TestExecutor85|0_86(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)

[v-wenyuxu]

Failed again in: runtime-coreclr jitstress-random 20230806.1

Failed tests:

coreclr osx arm64 Checked jitstress_random_2 @ OSX.1200.ARM64.Open
    - JIT/Methodical/NaN/intrinsic_cs_do/intrinsic_cs_do.dll

Error message:

Assert.Equal() Failure
Expected: 100
Actual:   101

Stack trace:

   at Xunit.Assert.Equal[T](T expected, T actual, IEqualityComparer`1 comparer) in /_/src/xunit.assert/Asserts/EqualityAsserts.cs:line 96
   at Program.<<Main>$>g__TestExecutor84|0_85(StreamWriter tempLogSw, StreamWriter statsCsvSw, <>c__DisplayClass0_0&)

[jakobbotsch]

This looks like a bug in constant folding:

public static void Main()
{
    Console.WriteLine(Math.Tanh(double.NegativeInfinity));
    Console.WriteLine(Math.Tanh(NegativeInfinity()));
}

[MethodImpl(MethodImplOptions.NoInlining)]
private static double NegativeInfinity() => double.NegativeInfinity;

Result:

NaN
-1

JitStress causes us to inline the second TestTanh call which exposes the issue. Also, many of the Fail calls in this file are passing the wrong arguments to the wrong parameters, which gives very confusing output.