RFR: 8339576: Speed up raw bytecode processing in ClassFile API

[Chen Liang]

On Thu, 5 Sep 2024 14:04:19 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Yes, things like storing `endBci()` to a local variable can be great if it both reduces code size and improves interpreter/C1 speed - but don't over-do it as it's likely never-ending work for a kind of optimizations leyden might make pointless.
>
> It is not necessary to use RawBytecodeHelper in the StackMapGenerator#detectFrameOffsets method. It may be better to operate directly on the `byte[] bytecode`.

We could have just tracked the offsets when labels from DirectCodeBuilder are bound; we can explore such a fix in another patch.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20863#discussion_r1745759169