Test failure: Microsoft.CSharp.RuntimeBinder.Tests.IntegerBinaryOperationTests.ConstantExpressions(x: 0, y: 4294967295, type: LessThanOrEqual, result: True, shouldSucceedChecked: True)

[v-haren]

failed in job:runtime-coreclr libraries-jitstress 20200924.1

net5.0-Linux-Release-x64-CoreCLR_checked-jitminopts-Ubuntu.1804.Amd64.Open

Error message

Assert.Equal() Failure
Expected: True
Actual:   False


Stack trace
   at Microsoft.CSharp.RuntimeBinder.Tests.IntegerBinaryOperationTests.ConstantExpressions(Object x, Object y, ExpressionType type, Object result, Boolean shouldSucceedChecked) in /_/src/libraries/Microsoft.CSharp/tests/IntegerBinaryOperationTests.cs:line 504

Tagging subscribers to this area: @cston
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[v-haren]

failed again in job: runtime-coreclr libraries-jitstress 20201011.1

failed test: Microsoft.CSharp.RuntimeBinder.Tests.IntegerBinaryOperationTests.ConstantExpressions(x: 0, y: 4294967295, type: LessThanOrEqual, result: True, shouldSucceedChecked: True)

net6.0-Windows_NT-Release-x64-CoreCLR_checked-jitminopts-Windows.10.Amd64.Open
net6.0-Windows_NT-Release-x86-CoreCLR_checked-jitminopts-Windows.10.Amd64.Open
net6.0-Linux-Release-x64-CoreCLR_checked-jitminopts-Ubuntu.1804.Amd64.Open

Error message

Assert.Equal() Failure
Expected: True
Actual:   False

Stack trace
   at Microsoft.CSharp.RuntimeBinder.Tests.IntegerBinaryOperationTests.ConstantExpressions(Object x, Object y, ExpressionType type, Object result, Boolean shouldSucceedChecked) in /_/src/libraries/Microsoft.CSharp/tests/IntegerBinaryOperationTests.cs:line 504

[wfurt]

I see ~ 100 failures of the test in last 30 days. I think we should disable it unless we can fix it quickly.

[cston]

To repro locally (thanks @sandreenko for the environment variables):

set COMPlus_JITMinOpts=1
set complus_TieredCompilation=0
dotnet build /t:Test
    /p:XunitMethodName=Microsoft.CSharp.RuntimeBinder.Tests.IntegerBinaryOperationTests.ConstantExpressions

When compiling (0u <= 4294967295u), LambdaCompiler.EmitBinaryExpression() generates the following IL:

ldc.i4.0
ldc.i4.m1
cgt.un
ldc.i4.0
ceq

It appears the result of executing that IL is false rather than true with the environment variables set.

[sandreenko]

Thanks @cston for the investigation, with his repro I can confirm that it is a codegen issue.