RFR: 8349638: Build libjdwp with SIZE optimization

[Matthias Baesken]

On Wed, 9 Apr 2025 20:34:42 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

> > Wait, `LOW` is `-O2`? 👀 I thought it was like no optimization at all. I'm sooo confused with these levels. So maybe going from `LOW` to `SIZE` will actually lose more optimization than I thought. _sigh_
> 
> -Os is the same as -O2 minus some optimizations that increase footprint.
> 
> https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
> 
> -O3 mostly adds more serious footprint increasing optimizations like loop unrolling. I've seen a number of warnings that suggest in some cases the larger code can reduce performance, so you may be best off with -O2 or -Os for best performance.


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.   ....

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PR Comment: https://git.openjdk.org/jdk/pull/23563#issuecomment-3078868634