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Getting different results on different machines and wonder if this is expected behaviour or a potential error in implementation of '>>>' operation for certain CPUs?
Linux qemux86-64 4.18.41-yocto-standard #1 SMP PREEMPT Tue Oct 8 20:33:31 UTC 2019 x86_64 GNU/Linux
root@qemux86-64:~# node --v8-options|head -n 1
SSE3=1 SSSE3=1 SSE4_1=0 SAHF=1 AVX=0 FMA3=0 BMI1=0 BMI2=0 LZCNT=0 POPCNT=0 ATOM=0
root@qemux86-64:~# node -v
v8.12.0
root@qemux86-64:~# node -e 'console.log(undefined >>> 0)'
4294967295
(undefined >>> 0) evaluates to 0 on other machines I tested. But, then with CPU features enabled: AVX FMA3 BMI1 BMI2 LZCNT POPCNT
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You check the console and see TypeError: Cannot read properties of undefined (reading '0'). What’s going on here? Chances are you are either using an array, a string, or an object literal in your code that you’ve attempted to index using [0].
An error occurred while fetching the assigned iteration of the selected issue. Sometimes a build job fails randomly with the exit code 4294967295. It does not happen always, but frequently (maybe 1 out of 3 builds) It always happens at a different time during the build, which is why I provided two different build logs as an example
It happened with different windows docker images (python, mcr.microsoft.com/dotnet/framework/sdk:3.5) The windows event log shows that there is a problem with the username/password used in the container The job fails with the exit code 4294967295. The build should succeed. The GitLab runner is running on a Windows VM with Docker-Desktop installed.
According to draft N1256 (C99) §6.3.1.4, you are invoking undefined behavior: When a finite value of real floating type is converted to an integer type other than _Bool, the fractional part is discarded (i.e., the value is truncated toward zero). If the value of the integral part cannot be represented by the integer type, the behavior is undefined.
V8 developer here. That's clearly a bug (undefined >>> 0 is always supposed to return 0), but it's unclear where that bug might be: could be in V8, could be in the C++ compiler that was used, could be in kernel or system libraries, could even be in the hardware (or emulator? The host name "qemux86-64" sounds like it might be a virtual machine); could also be less of a bug per se and more of an unexpected interaction between any of these components. FWIW, I can't repro.
Node 8 is also fairly old, so the first thing to try would be a newer Node/V8. Maybe whatever it was has been fixed already.
If you can still reproduce with a recent version (say, Node 12 / V8 7.7 or newer), then please file a bug at crbug.com/v8/new and include instructions on how to reproduce. Feel free to leave the bug number in a comment here.
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