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Re: [PATCH] Fix PR40062, exponential behavior in SCEV


On Fri, May 8, 2009 at 05:09, Richard Guenther <rguenther@suse.de> wrote:
>
> This fixes PR40062, a case where SCEV at -O3 uses up all memory
> in my machine (no idea what it would take if it would finish).
> The issue is that while we limit recursion depth in walking
> PHI nodes somewhat we do not effectively limit breath of the search
> for a path through the loop. ÂThis effectively makes the
> complexity exponential if you have, like in the testcase, several
> non-loop PHI nodes with a large number of arguments.
>
> The fix is to take this into account like for example with the following.
>
> Bootstrap / regtest in progress. ÂSebastian - are you ok with that?

Yes, thank you for fixing this.

Sebastian Pop
--
AMD - GNU Tools


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