[boost] Re: Re: RE: Math Constants Formal Review - recap & summary

From: Ed Brey (brey_at_[hidden])
Date: 2003-06-10 08:29:49

Paul A. Bristow wrote:
>> 
>> For example, VC 7.1 discards d1 if it is not referenced, so there is
>> no issue with paying for what you don't use when using that method on
>> that compiler.
> 
> This is good news. What optimisation did you chose?

/O2

>>  It would be useful to know what compilers do retain
>> unused constants.
> 
> But is tiresome to find out, and will keep changing.  (and if the
> scheme becomes widely used, compiler writers will have a strong
> incentive to make sure it is optimized away.

Agreed, an active search would be a lot of effort.  I passive approach may be practical however.  My thinking is to start from a position that all compilers optimize well.  Then when someone says, "Sorry, that interface triggers this pessimization on compiler x," just make a note of x and its limitation.  This way to don't need to look for compiler limitations; news of such will come to you.

There probably aren't a ton of limitations; so the list may well be short, and it can be a big timer saver to know exactly which compilers to care about when they get reved, especially if a removal of a key limitation eliminates the need for a complex workaround.