Re: Re: ROOT 5.22 with gcc 4.4 (.1)

From: Fons Rademakers <Fons.Rademakers_at_cern.ch>
Date: Mon, 17 Aug 2009 18:58:01 +0200

Btw, 4.4.x with -O2 is the ONLY compiler that shows this issue. Other compilers Sun Studio CC, Intel icc, gcc -O, beg to differ. So I keep calling this a regression. ;-)

Cheers, Fons.

Fons Rademakers wrote:

> My gripe is that the behavior of the compiler should not change between 
> -O and -O2. With -O they obviously can generate these inline 
> instantiations, but at -O2 not anymore. Not good.
> 
> -- Fons
> 
> 
> Christophe Saout wrote:

>> Hi,
>>
>>> this R__EXPLICIT_FUNCTION_INSTANTIATION is needed to work around a
>>> bug in the -O2 mode of gcc 4.4.0. The bug was reported to the
>>> developers, but obviously not yet fixed in the 4.4.1 release. I'll
>>> update to Module.mk to also include the 4.4.1 release. Not that e.g.
>>> with -O there is no problem.
>>
>> I believe this is not a bug, but valid behaviour.
>>
>> Andrew Pinski seems to think so as well.
>>
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40056
>>
>> I would not call this a regression. New gcc optimisations just lead gcc
>> to another decision in that particular case, I am sure that you could
>> also trick gcc to perform a similar decision in older versions.
>>
>> Christophe
>>
>>

>

-- 
Org:    CERN, European Laboratory for Particle Physics.
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E-Mail: Fons.Rademakers_at_cern.ch              Phone: +41 22 7679248
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Received on Mon Aug 17 2009 - 18:58:05 CEST