Re: [boost] Re: BOOST_HAS_NRVO

From: David Abrahams (dave_at_[hidden])
Date: 2002-11-09 21:00:00

"Terje Slettebø" <tslettebo_at_[hidden]> writes:

>>From: "Gennaro Prota" <gennaro_prota_at_[hidden]>
>
>>On Sat, 9 Nov 2002 17:14:49 +0100, "Terje Slettebø"
>><tslettebo_at_[hidden]> wrote:
>
>>> In any case, the
>>>program below detects presence of NRVO, by returning zero, or greater than
>>>zero if NRVO is not present.
>
>>Actually it shows whether that optimization is applied in a specific
>>example.
>
> True. But it's better than nothing. :) Intel C++ applied the NRVO, even with
> all optimisations turned off. In the same way, MSVC 6 did not, regardless of
> settings. 

I suspect that you'll find this to be the case on most compilers. The
RVO doesn't fall into the category of back-end or
intermediate-language optimizations that compilers usually let you
turn on and off. It has to happen in the front-end, since it often
implies observable differences in the code's behavior.

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com

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