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Re: Avoid privatization of TLS variables
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Ian Lance Taylor <iant at google dot com>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, Jan Hubicka <hubicka at ucw dot cz>, Markus Trippelsdorf <markus at trippelsdorf dot de>, Ian Lance Taylor <ian at airs dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 25 Sep 2014 18:29:57 +0200
- Subject: Re: Avoid privatization of TLS variables
- Authentication-results: sourceware.org; auth=none
- References: <20140920031617 dot GB2325 at kam dot mff dot cuni dot cz> <20140924175326 dot GE29454 at x4> <20140924181836 dot GE6871 at kam dot mff dot cuni dot cz> <CAKOQZ8xMx8bpXGTXN8pd2RC2T9i31brdQTH13ZWiYdooTVq_aw at mail dot gmail dot com> <20140925015835 dot GC26922 at atrey dot karlin dot mff dot cuni dot cz> <CAKOQZ8zwpGfLE02C55iLnDX6rNYAH89nkGFXay2zSTmPidef4w at mail dot gmail dot com> <CAMe9rOqez8GmTu0ZGfyfORJq=fGY8j9J79Ar=LEied=34cgqxw at mail dot gmail dot com> <CAKOQZ8yMkZeaRnmH4Y+coGOFUeK0p5cSuQvsCPDCTn+DHeqw+w at mail dot gmail dot com>
> On Thu, Sep 25, 2014 at 8:37 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> > On Thu, Sep 25, 2014 at 8:24 AM, Ian Lance Taylor <iant@google.com> wrote:
> >> On Wed, Sep 24, 2014 at 6:58 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> >>>
> >>> b: 00 00
> >>> 9: R_X86_64_TPOFF32 __gcov_indirect_call_counters_ltopriv
> >>
> >> Look at the .o file where __gcov_indirect_call_counters_ltopriv is
> >> defined. That .o file must have the symbol marked as STT_TLS and it
> >> must be defined in a section with the SHF_TLS flag. If that is not
> >> true, then that is your problem.
> >
> > SHF_TLS isn't required.
> >
> > 16: 0000000000000008 8 TLS GLOBAL HIDDEN COM
> > __gcov_indirect_call_counters_ltopriv
> > 17: 0000000000000008 8 TLS GLOBAL HIDDEN COM
> > __gcov_indirect_call_callee_ltopriv
> >
> > are also sufficient.
>
> I can create a .o file with a hidden common symbol, but I can't
> recreate the problem. When I try, gold creates a TLS section and TLS
> segment itself.
>
> How exactly is gold being invoked?
It seems to happen with LTO compilation only, just build mainline tree
and try the original testcase.
Honza
>
> Ian