Re: [boost] Boost.Convert. Take 2.

Subject: Re: [boost] Boost.Convert. Take 2.
From: Rob Stewart (robertstewart_at_[hidden])
Date: 2014-02-21 05:31:51

On February 21, 2014 3:12:08 AM EST, Vladimir Batov <vb.mail.247_at_[hidden]> wrote:
>Rob Stewart <robertstewart <at> comcast.net> writes:
>> On February 20, 2014 6:27:42 PM EST, Vladimir Batov <Vladimir.Batov
><at>
>constrainttec.com> wrote:
>> 
>> >I am especially surprised by the fact that its performance seems 
>> > quite adequate (without any optimization):
>> [snip]
>> >tests. On the other hand the test could not be any more
>> >straightforward:

[snip]

>> I assume you're timing an optimized build,  on which case you are
>being
>misled by the optimizer because
>> you're not using the results of the conversions. 
>
>Rob,
>
>Nice hearing from you. I had that suspicion also and I do not think
>optimization was at play. The reason is that I timed twice with "-g"
>and
>without and definitely did not have optimization flags (never use
>them). And
>it's hard not to notice when the code is optimized -- stepping through
>is,
>well, difficult. :-)

Using -g simply includes symbols. It has nothing to do with optimizations. Not testing with optimizations is not worthwhile. sprintf() is highly tuned and C++ code relies on inlining,  copy elision, etc. Users of your library will certainly use it with optimizations. 

> Secondly, my actual code is different (for the
>post I
>cut it to bare minimum). All loops are actually like
>
>for (int k = 0; k < local::num_cycles; ++k)
>{
>    int k = boost::convert<int>::from("12345", ccnv).value();
>    BOOST_ASSERT(k == 12345);
>}
>
>Do you think there still might be something I missed?

The assertion won't help in an optimized build, of course. Save the values and print them at the end,  after you've captured the elapsed times. 

___
Rob

(Sent from my portable computation engine)