64bit: C++ templates

Corinna Vinschen corinna-cygwin@cygwin.com
Tue Jun 4 13:51:00 GMT 2013


On May 16 10:25, Corinna Vinschen wrote:
> Hi Yaakov,
> 
> On May 15 11:32, Kai Tietz wrote:
> > Hi,
> > 
> > the issue is a more general on and related to harfbuzz' use of
> > -fvisibility-inlines-hidden for mingw-targets, but not for cygwin
> > targets.  Btw the issue should be latent present for 32-bit too.
> > Well, nevertheless my test have shown that this option indeed fixes
> > that described issue.
> 
> Yesterday it turned out that the visibility stuff is not the real
> problem.  Mingw gcc 4.8 also produces the same set of symbols, but it
> doesn't fail when linking.
> 
> Some more testing now showed clearly that this problem is related to the
> high address used as base addresses in the Cygwin toolchain.  If you
> build the harfbuzz DLL not with
> 
>   -Wl,--enable-auto-image-base
> 
> but instead with a fixed address in the lower 31 bit address area,
> for instance
> 
>   -Wl,--image-base -Wl,0x7ff00000
> 
> the problem disappears and you can successfully build the DLL.
> Alternatively, you can also workaround this issue by building harfbuzz
> with the -mcmodel=large option, which doesn't suffer this problem due to
> the way symbols are only indirectly addressed.
> 
> Right now it seems this is a bfd bug in the relocation code.  The code
> tests these 32 bit pc-relative offsets by checking if the result still
> fits into 31 bit, without taking the high image base into account.
> Also, for some reason this doesn't occur with all symbols, but only with
> a very specific set of symbols (weak and a special kind of section
> symbols).
> 
> That's it for now.  We're still looking into providing a solution.

This is it, probably:

http://cygwin.com/ml/cygwin-apps/2013-06/msg00057.html


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat



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