RFR: 8341141: Optimize DirectCodeBuilder [v4]

[Claes Redestad]

On Sun, 29 Sep 2024 13:35:14 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Some DirectCodeBuilder related optimizations to improve startup and running performance:
>> 1. Merge calls, merge writeU1 and writeU2 into writeU3
>> 2. Merge calls, merge writeU1 and writeIndex operations
>> 3. Directly use writeU1 instead of writeBytecode
>> 4. Rewrite the implementation of load and store
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   use array instead of ArrayList

src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java line 115:

> 113: 
> 114:     @ForceInline
> 115:     public void writeU2(int x1, int x2) {

Perhaps a more descriptive name would be `writeU1U1` here, then `writeU1U2`, `writeU1U1U1` and `writeU2U2` for the next methods, respectively? Either way these methods will be a bit of an eye-sore, but let's at least iron out any ambiguities.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21243#discussion_r1780105574