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Subject: Re: [boost] Interest in a GPU computing library
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2012-09-18 13:45:12

On Tuesday 18 September 2012 13:58:24 Felipe Magno de Almeida wrote:
> On Tue, Sep 18, 2012 at 1:28 PM, Kyle Lutz <kyle.r.lutz_at_[hidden]> wrote:
> > Thanks for all the comments and feedback so far! I’ve written up
> > answers to your questions below (which should serve as a good start
> > for a FAQ for the library). Please let me know if anything is not
> > clear or if I forgot to answer your question.
> [snip]
> > *** Is it possible to use ordinary C++ functions/functors or C++11
> > lambdas with Boost.Compute? ***
> >
> > Unfortunately no. OpenCL relies on having C99 source code available at
> > run-time in order to execute code on the GPU. Thus compiled C++
> > functions or C++11 lambdas cannot simply be passed to the OpenCL
> > environment to be executed on the GPU.
> >
> > This is the reason why I wrote the Boost.Compute lambda library.
> > Basically it takes C++ lambda expressions (e.g. _1 * sqrt(_1) + 4) and
> > transforms them into C99 source code fragments (e.g. “input[i] *
> > sqrt(input[i]) + 4)”) which are then passed to the Boost.Compute
> > STL-style algorithms for execution. While not perfect, it allows the
> > user to write code closer to C++ that still can be executed through
> > OpenCL.
> Could it use boost.phoenix v3? IUC, Phoenix v3 creates a boost.proto
> expression. The library could make transformations to these
> expressions.

Phoenix actors do contain Proto expressions. But as I understand, actors and
the additional components Phoenix implements to evaluate expressions in a
functional manner are useless in context of Boost.Compute. IIUC, the
constructed expressions are not invoked but translated into strings (the C99
source code). Using Proto directly seems more appropriate.

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