[cctbxbb] Boost broken on mac?

Luc Bourhis luc_j_bourhis at mac.com
Thu Apr 7 11:30:47 PDT 2016

Hi Marcin,

> On 7 Apr 2016, at 20:13, Marcin Wojdyr <wojdyr at gmail.com> wrote:
> the original problem that Richard located at:
>      if (f_sq > 0) f = std::sqrt(f_sq);
>      else f = 0;
> is interesting. It seems that sqrt is hoisted in some situations which
> causes problems with -ffast-math.
> I wouldn't think that compiler may speculatively run sqrt, but it
> can[1], it must be sometimes faster.
> [1] http://reviews.llvm.org/D2428 <http://reviews.llvm.org/D2428>

I managed to fix the problem by copying f_sq into a volatile temporary f_sq_ of which I then take the square root. So I tend to agree with your guess.

> PS. this is rather heavy-handed:
> r24214 | rjgildea | 2016-04-07 16:42:49 +0100 (czw, 07 kwi 2016) | 1 line
> A couple of dials tests crash after XCode 7.3 update with -O2 or -O3
> flags set: setting -O1 optimization appears 

We discussed with Richard whether to lower optimisation only for the file failing to correctly compile or to do it globally. I concluded that the former is too much work considering the next update of Xcode could solve those and/or introduce new issues elsewhere! 

Is there a release of Phenix or CCP4 looming on the horizon? That would be a good reason to go the extra mile and only disable optimisation where necessary.

Best wishes,


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