[release/8.0-staging] JIT: Fixed incorrect reversed condition for GT #100372
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dotnet-issue-labeler
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
This was referenced Mar 28, 2024
kunalspathak
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AndyAyersMS
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Mar 28, 2024
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@kunalspathak I would have classified this as low risk, we have had the fix in 9.0 for a while and it has not led to further issues. |
jeffschwMSFT
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Mar 28, 2024
rbhanda
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@jeffschwMSFT @AndyAyersMS @TIHan - please assess failures and merge today. |
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Build/test logs are gone, so will need to rerun. |
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going to bounce this as all the assets are gone too. |
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Looking good, @AndyAyersMS |
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Yep. |
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Backport of #92316 to release/8.0-staging
/cc @kunalspathak @TIHan
Customer Impact
This was reported by a customer in #99954, where they were having a wrong functional behavior from a simple condition evaluation
a <= bshould have been evaluated totruebut was evaluating tofalse, leading to having their code take different code path. In the example that customer provided, they were seeing an exception was thrown because of the issue and the correct behavior was that no exception should have been thrown. The circumstances for it to occur is rare though and would trigger under very specific conditions. Thefalseblock (the code follows theelseshould have been optimized in prior phases and should be empty when we were trying to optimize the code in question) and there are some other requirements like what type of blocks they jump to in order the problematic code path to get triggered.Regression
The code has been there since
dotnet/coreclrdays and was introduced back in dotnet/coreclr#17733, but we recently saw it getting exposed.Testing
The fix was verified on the customer provided example in #99954. The code has been there for a while and was not discovered until September 2023 when we found out and fixed it in .NET 9. However, we didn't back-ported to .NET 8 back then. The backport also adds a test case for this scenario.
Risk
Low: This is a rare scenario and we had it .NET 9 for a while without causing any problem.