RFR: 8349638: Build libjdwp with SIZE optimization

[Matthias Baesken]

On Wed, 9 Apr 2025 12:33:26 GMT, Magnus Ihse Bursie <ihse 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 .
>
> I'd like to move to a world where we basically have just two optimization levels, "size" and "speed", and libraries do not in general have the level specified, so it falls back on a default, which could then be set by configure. For individual libraries we might need to override the default value, if we know that certain compilers make a mess of certain optimization levels, or if some libraries are especially performance sensitive. (Making hotspot `-Os` would certainly never make any sense, for example.)

@magicus should we close this one and follow up with another JBS issue, making opt-size the default for JDK libs ? I think you proposed something like this ?

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PR Comment: https://git.openjdk.org/jdk/pull/23563#issuecomment-2863156276