RFR: 8291966: SwitchBootstrap.typeSwitch could be faster [v3]

[Claes Redestad]

On Wed, 3 Apr 2024 16:17:57 GMT, ExE Boss <duke at openjdk.org> wrote:

>> Jan Lahoda has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:
>> 
>>  - Reflecting review feedback.
>>  - Merge branch 'master' into JDK-8291966
>>  - Adding comments
>>  - Improving performance
>>  - Merge branch 'master' into JDK-8291966
>>  - 8291966: SwitchBootstrap.typeSwitch could be faster
>
> src/java.base/share/classes/java/lang/runtime/SwitchBootstraps.java line 389:
> 
>> 387:             }
>> 388:         }
>> 389:         return enumMap.map[value.ordinal()];
> 
> `enumMap.map` never gets set before this line.

There's a bug filed for this already: https://bugs.openjdk.org/browse/JDK-8332522 

@lahodaj explained that this broken code is part of an optimization which is never attempted (IIRC due to the bug you noted on line 327). JDK-833522 seem like a good place to continue this conversation..?

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PR Review Comment: https://git.openjdk.org/jdk/pull/9779#discussion_r1649761928