Using descriptor than internal name hashes for CP ClassEntry

[Brian Goetz]

The approach seems promising.

Note that the EntryMap type is fussy about hash values -- you can't pass 
zero as a hash value.  The `hashString(String)` method ensured that the 
hash value was never zero.

On 12/24/2023 11:11 AM, - wrote:
> Hi,
> Since we are using ClassDesc quite often to represent Class constants 
> in Class-File API, yet it's costly to hash them (as they are 
> internal names in CP but descriptors in ClassDesc), that Adam has 
> created shortcuts to speed up fetching of Object CE from CD_Object, I 
> have thought of a new tactic to hash ClassEntry by full descriptor 
> than by internal name alone.
>
> I have made a prototype at 
> https://github.com/liachmodded/jdk/commit/2932a560b0029352f1309883b3c5eecfb3d2c771
>
> The idea is that hashing CE as descriptors is easier than creating 
> substrings for hashing; substring hashing is hard to compute, but 
> appending and prepending and hash is much easier.
>
> Does this look like a good idea? I only included a test to confirm its 
> correctness, but haven't got time to bench it against, say, the port 
> of java.lang,invoke or ProxyGenerator.
>
> Chen
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