On Tue, 22 Apr 2025 17:20:15 GMT, Chen Liang <li...@openjdk.org> wrote:

>> The downcallHandle method in Linker has a complex implementation, and type 
>> switches is triggered in multiple places in that handle.
>> 
>> After bytestacks analysis of a simple program that links the native 
>> implementation of Class::forName0, it turns out that:
>> 1. there are a few missed usages of type switch in ClassFile API
>> 2. type switch can speed up generation by using explicit stack maps, as 
>> stack map gen is over 50% of the generation instructions because the switch 
>> is branch-heavy, but the frames are actually simple.
>> 
>> These two combined are not that significant in the overall overhead of 
>> downcallHandle, but would be helpful for other workloads.
>
> Chen Liang has updated the pull request with a new target base due to a merge 
> or a rebase. The incremental webrev excludes the unrelated changes brought in 
> by the merge/rebase. The pull request contains four additional commits since 
> the last revision:
> 
>  - Rollback classfile boot speed changes
>  - Merge branch 'master' of https://github.com/openjdk/jdk into 
> fix/switch-gen-speed
>  - Fix adding potentially unbound labels
>  - 8354899: Reduce overhead associated with type switches

Thanks for the reviews!

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PR Comment: https://git.openjdk.org/jdk/pull/24705#issuecomment-2825558849

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