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Subject: Re: [boost] performance of a linear algebra/matrix library
From: joel falcou (joel.falcou_at_[hidden])
Date: 2010-05-11 12:20:31

DE wrote:
> here a question arises:
> since a compiler is able to generate very fast code involving simd
> instructions is one supposed to provide simd-enabled implementation of
> a generic library? personally i think now that it is worthless
Yeah sure, let's look how icc is able to vectorize arbitrary large
arithmetic function
(like cos, sqrt etc that don't have a 1-1 SIMD intrinsic mapping). Other
think. If you
work on dynamic memory, the compiler won't be doing any vectorization as
the memory
may not be aligned properly.

Add to that loop with dependencies that human know how to rewirte (but
not compiler),
arbitrary function support, SoA support for thing like complex or other
ADS ...

Oh and, if your code as right, then both would have been inlined. That's
what happen in our library
(which lead us to rmeove the unroll settings)

Joel Falcou - Assistant Professor
PARALL Team - LRI - Universite Paris Sud XI
Tel : (+33)1 69 15 66 35

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