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

Jakub Jelinek <> wrote:
>On Thu, Oct 31, 2013 at 07:02:28PM +0400, Yuri Rumyantsev wrote:
>> Here is a simple fix which allows to vectorize loop marked with
>> 'pragma omp simd' even if cost model tells us that vectorization is
>> not profitable.
>> I checked that on simple test-case is works as expected.
>> Is it Ok for trunk?
>> ChangeLog:
>> 2013-10-31  Yuri Rumyantsev  <>
>> * tree-vect-loop.c (vect_estimate_min_profitable_iters): Override
>> cost estimation for loops marked as vectorizable.
>That looks too simplistics, IMHO it is undesirable to disregard the
>profitability checks together.  For #pragma omp simd or #pragma simd
>loops, I can understand that we should admit our cost model is not very
>quality and so in border cases consider vectorizing rather than not
>vectorizing, say for force_vect by increasing the scalar cost by some
>factor or decreasing vector cost by some factor, but disregarding it
>altogether doesn't look wise.  The question is what factor should we
>150% of scalar cost, something else?

Please improve the cost-model instead.


>	Jakub

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