RFR: 8354996: Reduce dynamic code generation for a single downcall [v3]

[Chen Liang]

On Sun, 4 May 2025 20:25:02 GMT, Chen Liang <liach at openjdk.org> wrote:

>> src/java.base/share/classes/java/lang/foreign/Linker.java line 866:
>> 
>>> 864:                     .map(CapturableState::forName)
>>> 865:                     .mapToInt(state -> 1 << state.ordinal())
>>> 866:                     .sum();
>> 
>> Using `sum` means the result will be incorrect if `capturedState` contains a valid name multiple times:
>> 
>> var option = (LinkerOptions.CaptureCallState)Linker.Option.captureCallState("WSAGetLastError", "WSAGetLastError");
>> 
>> // will print [ERRNO] on Windows
>> System.out.println(option.saved());
>> 
>> 
>> option = (LinkerOptions.CaptureCallState)Linker.Option.captureCallState("errno", "errno");
>> 
>> // will throw IndexOutOfBoundsException on all platforms
>> option.saved();
>
> Hmm, I intentionally checked `toSet` does not reject duplicates but forgot about this part. Anyways this stream code is problematic; will fix this in a patch that removes this stream code wholesale.

I created an issue to revisit CapturableState https://bugs.openjdk.org/browse/JDK-8356126 and will fix these problem with new unit test ensuring the toString message and nonexistent/duplicate behaviors, also removing redundant stream usage.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/24742#discussion_r2072721337