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Re: Loop fusion.

On Sun, Apr 22, 2018 at 3:27 PM, Toon Moene <> wrote:
> A few days ago there was a rant on the Fortran Standardization Committee's
> e-mail list about Fortran's "whole array arithmetic" being unoptimizable.
> An example picked at random from our weather forecasting code:
> The reaction from one of the members of the committee (about "their"
> compiler):
> 'And multiple consecutive array statements with the same shape are “fused”
> exactly so that the compiler can generate good cache use. This sort of
> optimization is pretty low hanging fruit.'
> As far as I can see loop fusion as a stand-alone optimization is not
> supported as yet, although some mention is made in the context of graphite.
> Is this something that should be pursued ?
I don't know the current status of fusion in graphite.  As for
traditional fusion transformation, I think it's not very difficult to
be implemented along with existing distribution, actually, quite lot
of code should be shared.  What we do need are something like: more
motivation cases, good/conservative cost model.

> Kind regards,
> --
> Toon Moene - e-mail: - phone: +31 346 214290
> Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
> At home:; weather:
> Progress of GNU Fortran:

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