[jdk25u] RFR: 8357289: Break down the String constructor into smaller methods [v2]

[Chen Liang]

On Fri, 31 Oct 2025 08:46:44 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Through JVM Option +PrintInlining, we found that String has a constructor codeSize of 852, which is too large. This caused failed to inline.
>> 
>> The following is the output information of PrintInlining:
>> 
>>                 @ 9   java.lang.String::<init> (12 bytes)   inline (hot)
>> !m                 @ 1   java.nio.charset.Charset::defaultCharset (52 bytes)   inline (hot)
>> !                  @ 8   java.lang.String::<init> (852 bytes)   failed to inline: hot method too big
>> 
>> 
>> In Java code, the big method that cannot be inlined is the following constructor
>> 
>> 
>> String(Charset charset, byte[] bytes, int offset, int length) {}
>> 
>> The above String constructor is too large; break it down into smaller methods with a codeSize under 325 to allow them to be inlined by the C2.
>
> Shaojin Wen has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
> 
>   8357289: Break down the String constructor into smaller methods
>   
>   Reviewed-by: liach, rriggs

Now that Oracle stops maintaining 25u, I believe you should open backport PRs should be in https://github.com/openjdk/jdk25u-dev repository instead.

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PR Comment: https://git.openjdk.org/jdk25u/pull/351#issuecomment-3582430824