RFR: 8371626: [linux] use icf=all for linking libraries [v3]

[Matthias Baesken]

On Wed, 12 Nov 2025 15:46:09 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> Identical code folding can reduce the size of some libs, especially libjvm. However not all linkers support the flag/feature so we have to limit it to some environments.
>> See for example this manpage :
>> https://manpages.debian.org/testing/lld-7/ld.lld-7.1
>> 
>> 
>> sizes of libjvm.so with / without -icf=all
>> linux aarch64 : 25888 / 27112 K
>> linux x86_64 : 27952 / 29072 K
>> 
>> 
>> (for most other native libs the identical code folding has no effect, because there is nothing to fold)
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Limit icf to release builds

Hi Lutz , thanks for the review !

Questions to all - should I add a configure flag for this to enable/disable it?  Should I limit it to libjvm like it was done with the  opt:icf,8  setting on Windows (background is that for most other libs there is not much to 'fold' so there the saving are very small or zero.

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PR Comment: https://git.openjdk.org/jdk/pull/28236#issuecomment-3526299914