Re: [Boost-bugs] [Boost C++ Libraries] #9231: Suboptimal assignment

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9231: Suboptimal assignment
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-10-12 10:02:41

#9231: Suboptimal assignment
-------------------------------+----------------------------
  Reporter:  psiha             |      Owner:  johnmaddock
      Type:  Bugs              |     Status:  closed
 Milestone:  To Be Determined  |  Component:  multiprecision
   Version:  Boost 1.54.0      |   Severity:  Optimization
Resolution:  fixed             |   Keywords:
-------------------------------+----------------------------

Comment (by johnmaddock):

 >Thanks... ps. did you check why this->resize(other.size(), other.size());
 does not evaluate to a nop (I forgot to add that this happens in powm when
 it copy-constructs the double_type)_?

 Sigh.... this is harder to optimize away - it goes via a general N bit to
 M bit conversion routine (which is already split many different ways, I
 really don't want to split it up any more or it becomes unmaintainable) so
 there is a check that the new size requested doesn't exceed the space
 available.  This situation can also happen in calls to resize() from
 addition/subtraction/multiplication/shift routines, as it has to handle
 overflow in these cases.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9231#comment:5>
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