[Bug tree-optimization/39201] [meta-bug] ivopts metabug

[bonzini at gnu dot org]

------- Comment #3 from bonzini at gnu dot org  2009-02-16 09:56 -------
Subject: Re:  [meta-bug] ivopts metabug

> I'm adding PR 34163 in the hope that ivopts pass will someday know how to
> handle x[n] = f (x[n-1]) from "... very tight loops that calculate x[n] from
> the value x[n-1], where x[n-1] is the result of a previous step."
>
> This is especially important for unrolled loops, see PR 34163, comment #8

Isn't what you want simply load PRE?  That looks like a pass ordering
problem...


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39201