RFR: 8344802: Crash in StubRoutines::verify_mxcsr with -XX:+EnableX86ECoreOpts and -Xcheck:jni [v3]

[Volodymyr Paprotski]

On Thu, 23 Jan 2025 18:23:01 GMT, Volodymyr Paprotski <vpaprotski at openjdk.org> wrote:

>> (Also see `8319429: Resetting MXCSR flags degrades ecore`) 
>> 
>> For performance, signaling flags (bottom 6 bits) are set by default in MXCSR. This PR fixes the Xcheck:jni comparison that is producing these copious warnings:
>> 
>> OpenJDK 64-Bit Server VM warning: MXCSR changed by native JNI code, use -XX:+RestoreMXCSROnJNICall
>> 
>> 
>> **This in fact happens on both Windows _AND_ Linux.** However, _only_ on Windows there is a crash. This PR fixes the crash but I have not been able to track down the source of the crash (i.e. crash in the warn handler).
>
> Volodymyr Paprotski has updated the pull request incrementally with one additional commit since the last revision:
> 
>   whitespace

src/hotspot/os_cpu/windows_x86/os_windows_x86.cpp line 185:

> 183:       // On ECore, restore with signaling flags enabled
> 184:       MxCsr |= 0x3F;
> 185:     }

@JornVernee I came across your comment https://github.com/openjdk/jdk/pull/14523/files#r1236920072

I believe I am following the 'spirit' of that comment here, but would appreciate you having a look.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22673#discussion_r1927463691