On Fri, 14 Nov 2025 11:25:05 GMT, Matthias Baesken <[email protected]> wrote:
> The dead_strip linker option on macOS removes functions and data that are
> unreachable by the entry point or exported symbols.
> Setting it can reduce the size of some binaries we generate quite a lot, for
> example (product build, Xcode 15 is used) :
> (before -> after setting the option)
>
> 1.4M -> 1.1M images/jdk/lib/libfontmanager.dylib
> 264K -> 248K images/jdk/lib/libjavajpeg.dylib
> 152K -> 132K images/jdk/lib/libjli.dylib
> 388K -> 296K images/jdk/lib/liblcms.dylib
> 164K -> 128K images/jdk/lib/libzip.dylib
>
>
> and libjvm :
>
> 20M -> 18M images/jdk/lib/server/libjvm.dylib
> 146M -> 137M images/jdk/lib/server/libjvm.dylib.dSYM
This seems to work:
extern void* _ZTV8Metadata[];
__attribute__((used))
void* foo() {
return _ZTV8Metadata[0];
}
You can put this anywhere since it does not reference any hotspot types. It
just needs to be linked in with libjvm. Note I tried putting the "used"
attribute on _ZTV8Metadata and getting rid of the foo() part, but I got the
following warning and the vtable was dead stripped:
`warning: 'used' attribute ignored on a non-definition declaration
[-Wignored-attributes]`
-------------
PR Comment: https://git.openjdk.org/jdk/pull/28319#issuecomment-3554180419
