<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hi,<div><br></div><div>Yes. Remember that after a lot of deliberation we agreed on a compromise to allow _very_ limited amounts of C++. This ended up being pushed to accept a lot more C++ (including Boost, exceptions, etc.). The decision we made about only allowing single templates also appear to have been broken rapidly...</div><div><br></div><div>Remember that most developers are not professional C++ programmers, and I’m a bit worried that large parts of the code are turning into pretty heavy C++. That might be a necessary evil (I _do_ realize it gives us lots of other features), but before moving this any further it is time to show that all the other C++ code we have is stable on all architectures, that it does not cause portability issues (for instance, that all the C++ compilers support SIMD instruction sets well enough), that it does not hurt performance, and that it works for the vast majority of developers. Remember that we still haven’t released any C++ version of Gromacs yet - 5.0 will be the big test there.</div><div><br></div><div>The question is not whether performance is fine for a vanilla compiler on Intel, but whether it is guaranteed not to suffer over 20 different architectures with lots of different compilers!</div><div><br></div><div>Cheers,</div><div><br></div><div>Erik</div><div><br></div><div><div><div>On 10 Jan 2014, at 22:21, Roland Schulz <<a href="mailto:roland@utk.edu">roland@utk.edu</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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<div dir="ltr">Hi,
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<div>is there any reason to limit C++ in performance critical code as long as it doesn't impact performance? So far it seems that C++ hasn't been used in any compute intensive functions so I wanted to check. Specially we would like to change the variable says
arrays in e.g nbnxn_pairlist_t (those with _nalloc) to stl::vector. This would simplify the code and would it make it easier to copy the data for MIC offload. </div>
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<div>Roland<br clear="all">
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ORNL/UT Center for Molecular Biophysics <a href="http://cmb.ornl.gov/">cmb.ornl.gov</a><br>
865-241-1537, ORNL PO BOX 2008 MS6309 </div>
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