Re: [PATCH, take 2] Build java as two separate DLLs on windows.

[Dave Korn <dave dot korn dot cygwin at googlemail dot com>]

Andrew Haley wrote:
> Dave Korn wrote:
>> Andrew Haley wrote:
>>
>>> I had a look, and while it looks OK it seems to be written only for
>>> Windows. That's a shame.  Will it work on GNU/Linux?  Can it be made to?
>>> That would help to keep the facility from bitrotting.
>>   It doesn't quite work on linux.  Builds both the libraries, but then there's
>> some kind of problem caused by the use of ELF visibility when it starts trying
>> to link the tools against them:
> 
>>   I would guess that when the functions were all in one library together they
>> could see each other even if not externally visible, and now they're in
>> separate libraries they can't.  PE targets don't support visibility so it
>> doesn't prevent the functions being imported by libgcj-noncore from libgcj.
>>
>>   Not being a major ELF-head, I don't know what would be the right thing to do
>> about this.  Make them visible?  Is there any way of declaring a "friend library"?
> 
> Maybe just disable the linker script when split into two libraries?  It'd still
> work.

  You mean the version script?  Nope, didn't help any.  The symbols are
already marked hidden in the objects before they get linked anyway, by
hardcoded statements like "DECL_VISIBILITY (decl) = VISIBILITY_HIDDEN;" in
places like build_java_method_aliases(), java_mark_cni_decl_local() and
java_hide_decl().

  What did work, which I tried as an experiment, was commenting out the
definition of HAVE_GAS_HIDDEN in $objdir/gcc/config.h, rebuilding in
$objdir/gcc to rebuild the compiler with no ability to use hidden symbols at
all, then cleaning and remaking in $objdir/$target/libjava.  That got me two
fully-working split .so libraries, and the testsuite ran all the way through
without any failures.

  That's obviously just a crude proof-of-concept.  Would we need to do
something like add a switch to the java compiler to tell it not to use hidden
aliases and use that in the libtool compile flags when building libjava?

    cheers,
      DaveK