RFR: 8331187: Optimize MethodTypeDesc and ClassDesc.ofDescriptor for primitive types [v3]

[Claes Redestad]

On Fri, 26 Apr 2024 20:35:44 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>> While I agree it may seem non-sensical to define `CD_Object` for `Object`, there's precedent in that `Wrapper.primitiveType` is `Object.class` - so for consistency I wired it up the same way. For the usage patterns introduced with this patch we'll never call `primitiveClassDescriptor()` on `Wrapper.OBJECT`, though - and `Wrapper.forPrimitiveType` will throw an `IAE` if you try - so we can always revisit this. 
>>  
>> `void.class` is the primitive type for `Void.class`, allowed as a return type and recognized by `Wrapper.forPrimitiveType`. There are checks in for example `ConstantUtils.parseMethodDescriptor` which disallows `void.class` anywhere but as a return type.
>
> I know it'll never call `primitiveClassDescriptor()` besides primitive types.   While `void.class.isPrimitive()` returns true, `void` is not a primitive type and called out explicitly in the spec.
> 
> My point is about the behavior does not match the method name.  It may be better to rename it to `classDescriptor` instead.  It's okay to clean up in your other performance fix (perhaps #18945).

Updated #18945, will try ignoring the pre-existing `Wrapper.primitiveType` inconsistencies.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18971#discussion_r1581580674