Do not modify r18_tls when restoring registers on Windows AArch64 #44
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karianna
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Dec 12, 2025
| /* | ||
| Do not modify r18_tls when restoring registers on Windows as it is used to | ||
| store the pointer to the current thread's TEB (where TLS variables are stored). | ||
| See r18_tls comment in register_aarch64.hpp. |
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Future proofing, will that comment be there permanently? Might be worth inlining the minimum details here.
karianna
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Dec 13, 2025
brianjstafford
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Dec 16, 2025
swesonga
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On Windows, r18_tls is used store the pointer to the current thread's TEB. Therefore, this register should never be modified (see details in register_aarch64.hpp). This issue was identified when investigating hangs and crashes in the virtual threads on the Windows AArch64 jdk25u build. See microsoft/openjdk-jdk25u#19 for details.