RFR: 8349638: Build libjdwp with SIZE optimization

[Matthias Baesken]

On Tue, 11 Feb 2025 15:56:39 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> The libjdwp is currently built with LOW optimization level, it could be built with SIZE optimization to lower the lib size by ~ 10 % on UNIX.
> On Windows LOW and SIZE currently translate to the same O1 optimization flag so no difference there.
> 
> On Linux x86_64 for example the lib shrinks from
> 300K to 268K and the debuginfo file shrinks from 1.9M to 1.7M .
> 
> On Linux ppc64le for example the lib shrinks from
> 428K to 368K and the debuginfo file shrinks from 2.0M to 1.7M .

To be sure, I did a minimal build on Linux x86_64.  I set `--with-jvm-features=minimal --with-jvm-variants=minimal`  for this.
This leads to 
`JVM_FEATURES_minimal='compiler1 minimal opt-size serialgc'`
So no jvmti, to GCs except serialgc . Just C1, no C2.  The 'opt-size' flag is set so the libjvm is compiled with size optimization (on Linux -Os).  The other native libs (JDK native libs) still use the opt-flags they always use, as I thought.

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PR Comment: https://git.openjdk.org/jdk/pull/23563#issuecomment-2678301414