RFR: 8349638: Build libjdwp with SIZE optimization

[Chris Plummer]

On Wed, 16 Jul 2025 14:30:22 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> So should we give SIZE opt a try now with JDK26 (for libjdwp) ?
> Unfortunately we do not have benchmarks for libjdwp (or are there any?) .
> But this has not stopped us from updating compiler versions etc. ....

I'm still not sure whether or not this is a good idea. For benchmarking, you can try running large test suites like nsk/jdi, but I think you'll find the times vary quite a bit. I'd pay more attention to cpu time than wall clock time.

When debugging libjdwp, I often find that it does quite a bit of inlining of non-trivial functions, even with fastdebug builds. I think for the most part this is done when there is only one call site. Some of this will probably go away with -Os, although I won't miss it since I frequently needs to do builds where I make functions extern instead of static so they are not inlined and stack traces are more accurate.

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PR Comment: https://git.openjdk.org/jdk/pull/23563#issuecomment-3085338361