[Bug tree-optimization/18595] [4.0 Regression] IV-OPTS is O(N^3)

[dberlin at dberlin dot org]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-01-24 23:12 -------
Subject: Re:  [4.0 Regression] IV-OPTS is O(N^3)



On Mon, 24 Jan 2005, rakdver at atrey dot karlin dot mff dot cuni dot cz wrote:

>
> ------- Additional Comments From rakdver at atrey dot karlin dot mff dot cuni dot cz  2005-01-24 23:09 -------
> Subject: Re:  [4.0 Regression] IV-OPTS is O(N^3)
>
>>> Other part is that scev tries to be too clever.  Without need to
>>> represent nonaffine induction variables (that we do not use anywhere)
>>> we could use more memory efficient representation of ivs.
>>> Without need to handle symbolic references (that we also do not use
>>> anywhere, we could store evolutions in a fully instantiated form, and
>>> we would not need instantiate_parameters/resolve_mixers functions atall.
>>
>> Uh, symbolic references are or will be used to do data dependence when
>> MEM_REF and ARRAY_REF couldn't be generated from the pointers.
>
> How?  If the reference is left in symbolic form, it means that you know
> nothing about its value,

Wrong.

We could know things about it's value, such as ranges. We just don't know 
an exact number.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18595