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 .

The results for LOW/SIZE/HIGHEST  for LIBJDWP  are here  (at least for our build envs at SAP) 
https://wiki.openjdk.org/display/Build/Native+library+optimization+level+research

>From what I see,  if we really care about speed in this lib we could also use HIGHEST optimization;  there is not much code bloat with this.
If we care about size of the lib/image size, SIZE brings us some improvements especially on Linux.
I can also try HIGHEST + lto (this might bring us speed + smaller lib size at least with gcc).

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PR Comment: https://git.openjdk.org/jdk/pull/23563#issuecomment-2761344464