Re: Proposed C++ optimization with big speed gains with big objects

[Mike Dupont <jamesmikedupont at googlemail dot com>]

Hi,
I think what you want is a  custom allocator :
http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt04ch11.html
http://www.boost.org/doc/libs/1_45_0/doc/html/interprocess/allocators_containers.html
http://stackoverflow.com/questions/2439536/strategy-to-allocate-free-lots-of-small-objects
hope that helps,
mike


On Mon, Sep 24, 2012 at 1:02 PM, _ <neuralll@gmail.com> wrote:
> Hi guys
>
> I wana discuss proposed optimization step(optional switch?) to c++
> compiller that would make old and new code in some cases order of
> magnitude faster by just pure recompilation.
>
> ...After all those attempts to store anything via = without waste I
> think that compiller should do "placement new" transparently for us
> whenever he encounters = on movable object.  Instead of forcing us to
> implement zillion && operators that solve only heap side of problem.
> Deciding what kind of "this" object should use is easy since static
> analysis deciding what object is movable is already part of new
> compiller support for &&.
>
> Skyscrapper city[1000];                         // instead of temp
> city[1] = Skyscrapper("Empire State Building"); // compiller should
> use &city[1] as this pointer
>
> This would fix heap and static(which && can't) waste = zero alloc/copy.
> Why is static mem waste equally if not more important? Majority of
> objects are small thus majority of their memory is static.
>
> Benchmark results in article www codeproject
> com/Articles/453022/The-new-Cplusplus-11-rvalue-reference-and-why-you
>
> I am actively attemting to test this change in gcc
> But I am kinda lost in gcc code. maybe somebody from you guys can
> trow togethed this auto placement new instead of temp a lot faster
> since you know your
> code.
> I just can't wait to see the numbers of speed gained from untouched c++ code.
> Like running benchmark code from my article but with such compiller
> changes.
>
> I  love what you guys do. Keep up the great opensource work.
>
> Best Regards Ladislav [Unemployed]
> neuralll[@]gmail[.]com



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