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Re: (a+b)+c should be replaced by a+(b+c)

From: Robert Dewar <dewar at gnat dot com>
To: Joost VandeVondele <jv244 at hermes dot cam dot ac dot uk>
Cc: gcc at gcc dot gnu dot org
Date: Thu, 25 Mar 2004 08:45:43 -0500
Subject: Re: (a+b)+c should be replaced by a+(b+c)
References: <Pine.SOL.4.58.0403250711490.18567@yellow.csi.cam.ac.uk> <4062D287.7050100@gnat.com> <Pine.SOL.4.58.0403251240250.18567@yellow.csi.cam.ac.uk>

Joost VandeVondele wrote:

No, I'm only happy there are compilers that make my code 100 times faster
without doing a lot of work myself, keeping my code easy to maintain and
read.


Well it is fine to have this kind of transformation available as an
option, though in general it is better to rely on BLAS written by
competent numerical programmers, than on transformations of unknown
impact.

Another example that relies on this kind of optimization that comes to my
mind is OMP/MPI code. There is just a large class of problems for which
this optimization is just what is needed.

Please do not call this an optimization, call it a transformation

Follow-Ups:
- Re: (a+b)+c should be replaced by a+(b+c)
  - From: Joost VandeVondele

References:
- (a+b)+c should be replaced by a+(b+c)
  - From: Joost VandeVondele
- Re: (a+b)+c should be replaced by a+(b+c)
  - From: Robert Dewar
- Re: (a+b)+c should be replaced by a+(b+c)
  - From: Joost VandeVondele

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