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Re: [patch] for PR 18316 (updated)

Zdenek Dvorak wrote:

I am quite sure now that the regression would show there also.  What
happens is that we strength reduce and create a new iv for every single
memory reference in one of the loops (ending up with some 40 induction
variables).  It seems hard to do anything sane with ivs in the loops
that occur in mgrid; I am now trying to persuade the patch to just do nothing on
this type of weird testcases, which seems to be the best choice to me.

Note that the mgrid *program* might be weird as a program, spending 65 % of its time in a single loop.

The loop itself, however, is perfectly run-of-the-mill Fortran 77. If we can't handle the induction variable elimination here, we could just as well not handle it at all.

--
Toon Moene - e-mail: toon@moene.indiv.nluug.nl - phone: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
A maintainer of GNU Fortran 95: http://gcc.gnu.org/fortran/
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