RFR: 8348862: runtime/ErrorHandling/CreateCoredumpOnCrash fails on Windows aarch64

[David Holmes]

On Wed, 3 Sep 2025 14:45:27 GMT, Saint Wesonga <duke at openjdk.org> wrote:

> The Windows AArch64 OpenJDK build uses vectored exception handling. The implementation registers a custom vectored exception handler, which calls the exception filter function that is shared with the x64 platform. However, this call only happens when using -xcomp. This has the side effect of not running the JVM error handling code that would create a core dump if only the interpreter is used. This change fixes this issue by unconditionally using the same exception handler as Windows x64. The CreateCoredumpOnCrash test now passes with this change.
> 
> Although vectored exception handling is used on Windows AArch64, the implementation currently uses the same safefetch implementation as x64, which relies on structured exception handling. This change fixes safefetch on Windows AArch64 to not use the SEH implemenation (in safefetch_windows.hpp). This change defines the static assembly language for the fetching code like the other aarch64 platforms have done and updates the exception handler to recognize exceptions from the safe fetch assembly instructions. This came up because the NMT gtests started failing after the change to the exception handler.
> 
> Exceptions with the DBG_PRINTEXCEPTION_C  exception code are also encountered in routine execution on Windows AArch64 so I excluded them from causing error reporting, similar to how EXCEPTION_BREAKPOINT is handled. I'm not sure if this handling needs to also be extended to exception codes with success codes in https://learn.microsoft.com/en-us/windows/win32/learnwin32/error-codes-in-com (based on the most significant bit of the 32-bit code)

Just a couple of comments on the shared Windows code - I can't review the actual changes here.

Thanks

src/hotspot/os/windows/os_windows.cpp line 2670:

> 2668:   if (handle_safefetch(exception_code, pc, (void*)exceptionInfo->ContextRecord)) {
> 2669:     return EXCEPTION_CONTINUE_EXECUTION;
> 2670:   }

Could you merge with the existing ARM64 section so we only have two distinct code chunks: one for X64 and one for aarch64. Thanks

src/hotspot/share/runtime/safefetch.hpp line 35:

> 33: 
> 34: #if defined(_WIN32) && !defined(_M_ARM64)
> 35:   // Windows uses Structured Exception Handling

Suggestion:

#if defined(_WIN32) && !defined(_M_ARM64)
  // Windows x86_64 uses Structured Exception Handling

And update the main comment in safefetch_windows.hpp to say the same.

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PR Review: https://git.openjdk.org/jdk/pull/27074#pullrequestreview-3183597041
PR Review Comment: https://git.openjdk.org/jdk/pull/27074#discussion_r2320946522
PR Review Comment: https://git.openjdk.org/jdk/pull/27074#discussion_r2320969695