RFR: 8354996: Reduce dynamic code generation for a single downcall [v2]

[Chen Liang]

On Mon, 28 Apr 2025 13:50:17 GMT, Chen Liang <liach at openjdk.org> wrote:

>> make/jdk/src/classes/build/tools/classlist/HelloClasslist.java line 184:
>> 
>>> 182:                 ADDRESS, ADDRESS, ADDRESS,
>>> 183:                 JAVA_BOOLEAN, ADDRESS, ADDRESS);
>>> 184:         Linker.nativeLinker().downcallHandle(signature);
>> 
>> Why do we care specifically about this shape, but not about others?
>
> That was from the past attempt of linking Class forName0. Tge exact shape doesn't really matter here as we are mainly saving on DMH.

Can I just change this signature to `FunctionDescriptor.ofVoid()`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24742#discussion_r2063776900