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Subject: Re: [boost] [boostcon12]Trouble with tuples very compiler dependent
From: Larry Evans (cppljevans_at_[hidden])
Date: 2012-11-19 11:38:10

On 11/19/12 10:19, Larry Evans wrote:
> In contrast to the gcc4_8 compiler, with the clangxx compiler, the
> relative qualitative performance, is just the opposite. IOW, the
> bcon12_horizontal implementation is faster than the bcon12_vertical
> implementation. In fact, the rate of change of the performance
> difference accelerates as tree depth goes from 2 to 4. The rate of
> change is so stark that it suggests, at least to me, there may be some
> bug in clang. Of course that conclusion is based on almost no
> knowledge, on my part, of the clang implementation.
> The can be modified to filter out other parts
> of the benchmark run output, which is here:
For example, when the filter criteria restricts
TUPLE_UNROLL_MAX to 10 (the same as TUPLE_SIZE),
then, with compiler=clangxx, bcon12_vertical
performs relatively better than bcon12_horizontal
as TREE_DEPTH increases, as shown in the attached.


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