Bug 39201 - [meta-bug] ivopts metabug
Summary: [meta-bug] ivopts metabug
Status: RESOLVED FIXED
Alias: None
Product: gcc
Classification: Unclassified
Component: tree-optimization (show other bugs)
Version: 4.4.0
: P3 normal
Target Milestone: ---
Assignee: Not yet assigned to anyone
URL:
Keywords: meta-bug, missed-optimization
Depends on: 18219 21676 27440 31849 32283 34163 36905 39200
Blocks:
  Show dependency tree / graph
 
Reported: 2009-02-16 09:06 UTC by Paolo Bonzini
Modified: 2019-03-05 16:33 UTC (History)
2 users (show)

See Also:
Host:
Target:
Build:
Known to work:
Known to fail:
Last reconfirmed: 2009-02-16 09:11:03

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Description Paolo Bonzini 2009-02-16 09:06:46 UTC 
Metabug for ivopts issues
Comment 1 Paolo Bonzini 2009-02-16 09:11:03 UTC 
I'm adding the regressions for now.  Anyone can feel free to add more. :-)
Comment 2 Uroš Bizjak 2009-02-16 09:44:37 UTC 
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.
Comment 3 Paolo Bonzini 2009-02-16 09:56:19 UTC 
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...
Comment 4 Eric Gallager 2019-03-05 16:33:59 UTC 
All the bugs that this one depends upon have been closed so I'm closing this one as well; feel free to reopen if there are new bugs for this one to depend upon.