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Re: [gomp4 simd, RFC] Simple fix to override vectorization cost estimation.


On Tue, Nov 19, 2013 at 03:07:52PM +0100, Richard Biener wrote:
> On Tue, 19 Nov 2013, Sergey Ostanevich wrote:
> 
> > :) agree to you, but as soon as you're a user who tries to introduce
> > vector code and face a bug in cost model you'd like to have a
> > workaround until the bug will be fixed and compiler will come to you
> > with new OS distribution, don't you?
> > 
> > I propose the following, yet SLP have to use a NULL as a loop info
> > which looks somewhat hacky.
> 
> I think this is overengineering.  -fvect-cost-model will do as
> workaround.  And -fsimd-vect-cost-model has what I consider
> duplicate - "simd" and "vect".

I think it is a good idea, though I agree about s/simd-vect/simd/ and
I'd use VECT_COST_MODEL_DEFAULT as the default, which would mean
just use -fvect-cost-model.

> > @@ -2929,6 +2929,11 @@ vect_estimate_min_profitable_iters
> > (loop_vec_info loop_vinfo,
> >    /* vector version will never be profitable.  */
> >    else
> >      {
> > +      if (LOOP_VINFO_LOOP (loop_vinfo)->force_vect)
> > +        {
> > +          pedwarn (vect_location, 0, "Vectorization did not happen
> > for the loop");
> > +        }

pedwarn isn't really desirable for this, you want just warning,
but some warning you can actually also turn off.
-Wopenmp-simd (and we'd use it also when we ignore #pragma omp declare simd
because it wasn't useful/desirable).

	Jakub


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