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Re: [autovect] Why all these redundant computations?
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: Dorit Naishlos <DORIT at il dot ibm dot com>
- Cc: Sebastian Pop <sebastian dot pop at cri dot ensmp dot fr>, gcc at gcc dot gnu dot org, Ira Rosen <IRAR at il dot ibm dot com>
- Date: Mon, 01 Aug 2005 10:43:10 -0400
- Subject: Re: [autovect] Why all these redundant computations?
- References: <OF5E73C6F8.674D4592-ONC2257050.004E1219-C2257050.004F7436@il.ibm.com>
On Mon, 2005-08-01 at 17:27 +0300, Dorit Naishlos wrote:
>
>
>
> > ...
> >
> > The problem seems to be that analyze_offset_expr calls the scev
> > analyzer explicitely asking for recomputation (third parameter is
> > true):
> >
> > ...
> >
> > Why should we start the analysis from scratch in this case? The same
> > question could be asked for all the uses of analyze_scalar_evolution
> > in the vectorizer... Grepping for analyze_scalar_evolution, you get
> > the following places (in autovect branch) that explicitely ask for
> > scev recomputation:
> >
>
> I don't think there was an intention to force recomputation - probably just
> overlooked what the third argument actually stands for. These occurrences
> could probably be changed to false.
>
Yeah, i agree with dorit.
The only other possible reason i can think of is that it fixed a bug
somewhere due to not properly invalidating the cache, and that fix was
just copied around.
> dorit
>