> But I am still missing something, why is the performance so different?
> Code layout putting the constructors' body in the reverse order they
> are called?
Yes, as I understand it. Cache and TLB prefetching works better when
code executes from lower to higher addresses than when executing from
h
> This has a long and complicated history. I tried to explain some of that here:
>
> http://gcc.gnu.org/ml/gcc-bugs/2010-12/msg01493.html
>
> I wasn't part of the GCC community at the time, but I think that
> .ctors was originally used instead of .init or .init_array precisely
> because the order
>> Furthermore, if you're working in chromium, you should be aware that
>> the new behavior is exactly what the Chrome developers are arguing
>> for, as it makes the startup faster. It sounds to me like you're
>> working at cross purposes with the other developers on that project.
>
> Ah, perhaps t
On Mon, Jun 18, 2012 at 11:08 AM, Cary Coutant wrote:
>> So this is not as bad as I was expecting (old programs still work),
>> but it is still a somewhat annoying ABI change to handle. I think we
>> can add support for this in clang in 3 ways:
>>
>> 1) Require new linkers when using gcc 4.7 libra
[Re-sending this to try to got through to the GCC mailing list...
Sorry for the duplication to others... My reply is at the bottom]
On Mon, Jun 18, 2012 at 11:08 AM, Chandler Carruth wrote:
> On Mon, Jun 18, 2012 at 10:49 AM, Rafael Espíndola
> wrote:
>>
>> > The GNU linker has support to merge
> So this is not as bad as I was expecting (old programs still work),
> but it is still a somewhat annoying ABI change to handle. I think we
> can add support for this in clang in 3 ways:
>
> 1) Require new linkers when using gcc 4.7 libraries.
> 2) Ship our own versions of crtbeginS.o (and similar
> The GNU linker has support to merge .ctor's into init_array. Does the
> gold linker have the same feature? This seems more like the real fix
> rather than just hacking around the issue.
Recent version have it. I found the bug when using gold 2.21 which
doesn't. What seems to happen is:
* In a
On Mon, Jun 18, 2012 at 7:20 AM, Rafael Espíndola
wrote:
> ccing the gcc list and Cary Coutant.
>
> The issue comes from gcc pr46770. Cary, have you tried implementing
> the --reverse-init-array option? Does it solve the problems you were
> seeing?
>
> Can libstdc++ be fixed to work with the iostr
ccing the gcc list and Cary Coutant.
The issue comes from gcc pr46770. Cary, have you tried implementing
the --reverse-init-array option? Does it solve the problems you were
seeing?
Can libstdc++ be fixed to work with the iostream static constructors
being in .ctor or .init_array? Would you be in
