RFR: 8339317: Optimize ClassFile writeBuffer [v2]

[Claes Redestad]

On Tue, 3 Sep 2024 12:17:45 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> A small optimization, optimize the BufferWriter implementation and use of ClassFile, provide faster patchInt and skip
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update src/java.base/share/classes/jdk/internal/classfile/impl/Util.java
>   
>   Co-authored-by: Claes Redestad <claes.redestad at oracle.com>

Looks ok, a couple of nits.

src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java line 197:

> 195:             grow(nextOffset);
> 196:         }
> 197:         this.offset = nextOffset;

Let's not duplicate code to get rid of a simple addition
Suggestion:

        reserveSpace(skipSize);
        this.offset += skipSize;

src/java.base/share/classes/jdk/internal/classfile/impl/Util.java line 285:

> 283:                                     b.writeBytes(bytecode.array(), 0, bytecode.limit());
> 284:                                     b.skip(2);//exception handlers
> 285:                                     b.skip(2);//attributes

Suggestion:

                                    b.skip(4); //exception handlers (2) + attributes (2)

-------------

PR Review: https://git.openjdk.org/jdk/pull/20780#pullrequestreview-2277250897
PR Review Comment: https://git.openjdk.org/jdk/pull/20780#discussion_r1741955557
PR Review Comment: https://git.openjdk.org/jdk/pull/20780#discussion_r1741948921