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Re: Massive performance regression from switching to gcc 4.5
> Hi,
>
> On Fri, 25 Jun 2010, Jan Hubicka wrote:
>
> > I would be also very interested to know how profile feedback works in this case
> > (and why it does not work in previous releases).
>
> Profiling multi-threading programs needs -fprofile-correction that appeared
> only in 4.4 (but I have no idea whether 4.4 works for Mozilla or not -- the
> initial message only speaks about 4.3 and 4.5). Mozilla code also triggered a
> bug in libgcov ( http://gcc.gnu.org/PR43825 ), and they have probably modified
> their code to never leave non-default alignment at the end of the TU (I have
> posted a patch for the libgcov bug [1], but it was not reviewed and does not
> apply anymore due to build_constructor changes).
>
> [1] http://gcc.gnu.org/ml/gcc-patches/2010-05/msg00292.html
Ah, sorry. I tought the consensus was to disable effect of pragma pack at the end
of parsing to avoid libgcov incompatibility?
Honza